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  • 1.
    Ajalloueian, Fatemeh
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Polymer Chemistry.
    Zeiai, S.
    Fossum, M.
    Hilborn, Jöns
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Polymer Chemistry.
    A bedside collagen-PLGA nanofibrous construct for autologous transplantation of minced bladder mucosal2012In: Journal of Tissue Engineering and Regenerative Medicine, ISSN 1932-6254, Vol. 6, no suppl 1, p. 128-128Article in journal (Other academic)
    Abstract [en]

    Introduction: Bladder regeneration using minced bladder mucosa is an alternative to costly and time-consuming conventional in vitro culturing of urothelial cells. In this method, the uroepithelium expands in vivo and the patient body appears as an incubator. With our preliminary successes, designing an appropriate scaffold that supports in vivo cell expansion and surgical handling in a clinical setting was our aim. This study, investigates cell expansion in a hybrid construct of collagen/poly (lactic-co-glycolide)(PLGA).

    Materials and methods: An electrospun PLGA mat was placed on a semi-gel collagen inside a mold and covered with a second collagen layer. After gel formation, minced particles of pig bladder mucosa were seeded on the hybrid construct and then processed by plastic compression (PC). The scaffolds were incubated for 2, 4 and 6 weeks in vitro for further studies.

    Results: Tensile tests show an increase in tensile strength of 0.6 ± 0.1 MPa in PC collagen to 3.6 ± 1.1 MPa in hybrid construct. Morphological studies, histological staining and SEM show that the construct has kept its integrity during the time and proliferated urothelial cells have reached confluence after 4 weeks and a multi-layered urothelium after 6 weeks.

    Conclusion: We have designed a mechanically robust scaffold that permits surgical handling and tissue expansion in vivo. The construct is easy-to-use for clinical application in an ordinary surgical operating theater for bladder regeneration.

  • 2.
    Asfaw, Habtom Desta
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Multifunctional Carbon Foams by Emulsion Templating: Synthesis, Microstructure, and 3D Li-ion Microbatteries2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Carbon foams are among the existing electrode designs proposed for use in 3D Li-ion microbatteries. For such electrodes to find applications in practical microbatteries, however, their void sizes, specific surface areas and pore volumes need be optimized. This thesis concerns the synthesis of highly porous carbon foams and their multifunctional applications in 3D microbatteries. The carbon foams are derived from polymers that are obtained by polymerizing high internal phase water-in-oil emulsions (HIPEs).

    In general, the carbonization of the sulfonated polymers yielded hierarchically porous structures with void sizes ranging from 2 to 35 µm and a BET specific surface area as high as 630 m2 g-1. Thermogravimetric and spectroscopic evidence indicated that the sulfonic acid groups, introduced during sulfonation, transformed above 250 oC to thioether (-C-S-) crosslinks which were responsible for the thermal stability and charring tendency of the polymer precursors. Depending on the preparation of the HIPEs, the specific surface areas and void-size distributions were observed to vary considerably. In addition, the pyrolysis temperature could also affect the microstructures, the degree of graphitization, and the surface chemistry of the carbon foams.

    Various potential applications were explored for the bespoke carbon foams. First, their use as freestanding active materials in 3D microbatteries was studied. The carbon foams obtained at 700 to 1500 oC suffered from significant irreversible capacity loss during the initial discharge. In an effort to alleviate this drawback, the pyrolysis temperature was raised to 2200 oC. The resulting carbon foams were observed to deliver high, stable areal capacities over several cycles. Secondly, the possibility of using these structures as 3D current collectors for various active materials was investigated in-depth. As a proof-of-concept demonstration, positive active materials like polyaniline and LiFePO4 were deposited on the 3D architectures by means of electrodeposition and sol-gel approach, respectively. In both cases, the composite electrodes exhibited reasonably high cyclability and rate performance at different current densities. The syntheses of niobium and molybdenum oxides and their potential application as electrodes in microbatteries were also studied. In such applications, the carbon foams served dual purposes as 3D scaffolds and as reducing reactants in the carbothermal reduction process. Finally, a facile method of coating carbon substrates with oxide nanosheets was developed. The approach involved the exfoliation of crystalline VO2 to prepare dispersions of hydrated V2O5, which were subsequently cast onto CNT paper to form oxide films of different thicknesses.

    List of papers
    1. Boosting the thermal stability of emulsion–templated polymers via sulfonation: an efficient synthetic route to hierarchically porous carbon foams
    Open this publication in new window or tab >>Boosting the thermal stability of emulsion–templated polymers via sulfonation: an efficient synthetic route to hierarchically porous carbon foams
    Show others...
    2016 (English)In: ChemistrySelect, ISSN 2365-6549, Vol. 1, no 4, p. 784-792Article in journal (Refereed) Published
    Abstract [en]

    Hierarchically porous carbon foams with specific surface areas exceeding 600 m2 g−1 can be derived from polystyrene foams that are synthesized via water-in-oil emulsion templating. However, most styrene-based polymers lack strong crosslinks and are degraded to volatile products when heated above 400 oC. A common strategy employed to avert depolymerization is to introduce potential crosslinking sites such as sulfonic acids by sulfonating the polymers. This article unravels the thermal and chemical processes leading up to the conversion of sulfonated high internal phase emulsion polystyrenes (polyHIPEs) to sulfur containing carbon foams. During pyrolysis, the sulfonic acid groups (-SO3H) are transformed to sulfone (-C-SO2-C-) and then to thioether (-C−S-C-) crosslinks. These chemical transformations have been monitored using spectroscopic techniques: in situ IR, Raman, X-ray photoelectron and X-ray absorption near edge structure spectroscopy. Based on thermal analyses, the formation of thioether links is associated with increased thermal stability and thus a substantial decrease in volatilization of the polymers.

    Keywords
    Emulsion-templated polymer, sulfonation, pyrolysis, spectroscopy, carbon foam
    National Category
    Materials Chemistry
    Research subject
    Chemistry with specialization in Materials Chemistry
    Identifiers
    urn:nbn:se:uu:diva-283174 (URN)10.1002/slct.201600139 (DOI)000395395900026 ()
    Projects
    3D microbatteries
    Available from: 2016-04-11 Created: 2016-04-11 Last updated: 2017-10-30Bibliographically approved
    2. Emulsion-templated bicontinuous carbon network electrodes for use in 3D microstructured batteries
    Open this publication in new window or tab >>Emulsion-templated bicontinuous carbon network electrodes for use in 3D microstructured batteries
    2013 (English)In: Journal of Materials Chemistry, ISSN 0959-9428, E-ISSN 1364-5501, Vol. 1, no 44, p. 13750-13758Article in journal (Refereed) Published
    Abstract [en]

    High surface area carbon foams were prepared and characterized for use in 3D structured batteries. Twopotential applications exist for these foams: firstly as an anode and secondly as a current collector supportfor electrode materials. The preparation of the carbon foams by pyrolysis of a high internal phase emulsionpolymer (polyHIPE) resulted in structures with cage sizes of 25 mm and a surface area enhancement pergeometric area of approximately 90 times, close to the optimal configuration for a 3D microstructuredbattery support. The structure was probed using XPS, SEM, BET, XRD and Raman techniques; revealingthat the foams were composed of a disordered carbon with a pore size in the <100 nm range resultingin a BET measured surface area of 433 m2 g-1. A reversible capacity exceeding 3.5 mA h cm2 at acurrent density of 0.37 mA cm-2 was achieved. SEM images of the foams after 50 cycles showed thatthe structure suffered no degradation. Furthermore, the foams were tested as a current collector bydepositing a layer of polyaniline cathode over their surface. High footprint area capacities of500 mA h cm-2 were seen in the voltage range 3.8 to 2.5 V vs. Li and a reasonable rate performancewas observed.

    Place, publisher, year, edition, pages
    United Kingdom: , 2013
    Keywords
    Carbon foam, High internal phase emulsion polymer, microbattery, 3D microbattery, Lithium ion
    National Category
    Chemical Sciences Materials Chemistry
    Research subject
    Materials Science; Chemistry; Materials Science; Physical Chemistry
    Identifiers
    urn:nbn:se:uu:diva-210659 (URN)10.1039/C3TA12680C (DOI)000326463400009 ()
    Projects
    STEM-VR-Microbattery
    Funder
    Swedish Energy AgencySwedish Research Council
    Available from: 2013-11-12 Created: 2013-11-12 Last updated: 2017-12-06Bibliographically approved
    3. Emulsion-templated graphitic carbon foams with optimum porosity for 3D Li-ion microbatteries
    Open this publication in new window or tab >>Emulsion-templated graphitic carbon foams with optimum porosity for 3D Li-ion microbatteries
    (English)Manuscript (preprint) (Other academic)
    Keywords
    carbon, foam, graphitic, anode, three-dimensional, microbattery, lithium
    National Category
    Polymer Technologies Chemical Process Engineering Materials Chemistry Polymer Chemistry Inorganic Chemistry Physical Chemistry
    Identifiers
    urn:nbn:se:uu:diva-312893 (URN)
    Funder
    Swedish Research Council, 2012–4681StandUp
    Available from: 2017-01-14 Created: 2017-01-14 Last updated: 2017-12-30
    4. Nanosized LiFePO4-decorated emulsion-templated carbon foam for 3D micro batteries: a study of structure and electrochemical performance
    Open this publication in new window or tab >>Nanosized LiFePO4-decorated emulsion-templated carbon foam for 3D micro batteries: a study of structure and electrochemical performance
    Show others...
    2014 (English)In: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 6, no 15, p. 8804-8813Article in journal (Refereed) Published
    Abstract [en]

    In this article, we report a novel 3D composite cathode fabricated from LiFePO4 nanoparticles deposited conformally on emulsion-templated carbon foam by a sol–gel method. The carbon foam is synthesized via a facile and scalable method which involves the carbonization of a high internal phase emulsion (polyHIPE) polymer template. Various techniques (XRD, SEM, TEM and electrochemical methods) are used to fully characterize the porous electrode and confirm the distribution and morphology of the cathode active material. The major benefits of the carbon foam used in our work are closely connected with its high surface area and the plenty of space suitable for sequential coating with battery components. After coating with a cathode material (LiFePO4nanoparticles), the 3D electrode presents a hierarchically structured electrode in which a porous layer of the cathode material is deposited on the rigid and bicontinuous carbon foam. The composite electrodes exhibit impressive cyclability and rate performance at different current densities affirming their importance as viable power sources in miniature devices. Footprint area capacities of 1.72 mA h cm−2 at 0.1 mA cm−2 (lowest rate) and 1.1 mA h cm−2 at 6 mA cm−2(highest rate) are obtained when the cells are cycled in the range 2.8 to 4.0 V vs. lithium.

    Place, publisher, year, edition, pages
    Royal Society of Chemistry: , 2014
    National Category
    Physical Chemistry Polymer Chemistry Materials Chemistry Inorganic Chemistry
    Identifiers
    urn:nbn:se:uu:diva-228630 (URN)10.1039/C4NR01682C (DOI)000339861500051 ()
    Projects
    STEM-VR-Microbattery
    Available from: 2014-07-18 Created: 2014-07-18 Last updated: 2017-12-05Bibliographically approved
    5. Surface-oxidized NbO2 nanoparticles for high performance lithium microbatteries
    Open this publication in new window or tab >>Surface-oxidized NbO2 nanoparticles for high performance lithium microbatteries
    (English)Manuscript (preprint) (Other academic)
    Keywords
    niobium, oxide, nanoparticle, power, energy, carbon, foam, lithium, microbattery
    National Category
    Natural Sciences Inorganic Chemistry Materials Chemistry Physical Chemistry Condensed Matter Physics Materials Engineering Chemical Engineering
    Research subject
    Chemistry with specialization in Materials Chemistry
    Identifiers
    urn:nbn:se:uu:diva-312894 (URN)
    Projects
    3D Lithium-ion microbattery
    Funder
    Swedish Research Council, 2012–4681StandUp
    Available from: 2017-01-14 Created: 2017-01-14 Last updated: 2017-12-30
    6. A one-step water based strategy for synthesizing hydrated vanadium pentoxide nanosheets from VO2(B) as free-standing electrodes for lithium battery applications
    Open this publication in new window or tab >>A one-step water based strategy for synthesizing hydrated vanadium pentoxide nanosheets from VO2(B) as free-standing electrodes for lithium battery applications
    Show others...
    2016 (English)In: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 4, no 46, p. 17988-18001Article in journal (Refereed) Published
    Abstract [en]

    The synthesis of two dimensional (2D) materials from transition metal oxides, chalcogenides, and carbides mostly involve multiple exfoliation steps in which hazardous solvents and reagents are used. In this study, hydrated vanadium pentoxide (V2O5[middle dot]nH2O) nanosheets with a thickness of a few nanometers were prepared via a facile environmentally friendly water based exfoliation technique. The exfoliation process involved refluxing the precursor, vanadium dioxide (VO2(B)), in water for a few days at 60 [degree]C. The proposed exfoliation mechanism is based on the intercalation/insertion of water molecules into the VO2(B) crystals and the subsequent cleavage of the covalent bonds holding the layers of VO2(B) together. The thermal and chemical analyses showed that the approximate chemical composition of the nanosheets is H0.4V2O5[middle dot]0.55H2O, and the percentage of VV content to that of VIV in the nanosheets is about 80(3)% to 20(3)%. The exfoliated aqueous suspension of the V2O5[middle dot]0.55H2O nanosheets was successfully deposited onto multi-walled carbon nanotube (MW-CNT) paper to form free-standing electrodes with a thickness of the V2O5[middle dot]0.55H2O layer ranging between 45 and 4 [small mu ]m. A series of electrochemical tests were conducted on the electrodes to determine the cyclability and rate capability of lithium insertion into V2O5[middle dot]0.55H2O nanosheets. The electrodes with the thinnest active material coating ([similar]4 [small mu ]m) delivered gravimetric capacities of up to 480 and 280 mA h g-1 when cycled at current densities of 10 and 200 mA g-1, respectively.

    Keywords
    2D materials, vanadium oxides, free-standing, battery, lithium
    National Category
    Materials Chemistry
    Identifiers
    urn:nbn:se:uu:diva-311357 (URN)10.1039/C6TA06571F (DOI)000388505400010 ()
    Funder
    Swedish Research Council, 2012-4681Swedish Energy AgencyBerzelii Centre EXSELENTStandUp
    Available from: 2016-12-24 Created: 2016-12-24 Last updated: 2017-12-30
  • 3.
    Asfaw, Habtom Desta
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Roberts, Matthew R.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström.
    Tai, Cheuk-Wai
    Stockholm University.
    Younesi, Reza
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry. DTU.
    Valvo, Mario
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Nyholm, Leif
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Edström, Kristina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Nanosized LiFePO4-decorated emulsion-templated carbon foam for 3D micro batteries: a study of structure and electrochemical performance2014In: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 6, no 15, p. 8804-8813Article in journal (Refereed)
    Abstract [en]

    In this article, we report a novel 3D composite cathode fabricated from LiFePO4 nanoparticles deposited conformally on emulsion-templated carbon foam by a sol–gel method. The carbon foam is synthesized via a facile and scalable method which involves the carbonization of a high internal phase emulsion (polyHIPE) polymer template. Various techniques (XRD, SEM, TEM and electrochemical methods) are used to fully characterize the porous electrode and confirm the distribution and morphology of the cathode active material. The major benefits of the carbon foam used in our work are closely connected with its high surface area and the plenty of space suitable for sequential coating with battery components. After coating with a cathode material (LiFePO4nanoparticles), the 3D electrode presents a hierarchically structured electrode in which a porous layer of the cathode material is deposited on the rigid and bicontinuous carbon foam. The composite electrodes exhibit impressive cyclability and rate performance at different current densities affirming their importance as viable power sources in miniature devices. Footprint area capacities of 1.72 mA h cm−2 at 0.1 mA cm−2 (lowest rate) and 1.1 mA h cm−2 at 6 mA cm−2(highest rate) are obtained when the cells are cycled in the range 2.8 to 4.0 V vs. lithium.

  • 4.
    Asfaw, Habtom Desta
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Tai, Cheuk-Wai
    Stockholm University.
    Nyholm, Leif
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Edström, Kristina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Emulsion-templated graphitic carbon foams with optimum porosity for 3D Li-ion microbatteriesManuscript (preprint) (Other academic)
  • 5.
    Asplund, Basse
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry, Polymer Chemistry.
    Sperens, Jenny
    Mathisen, Torbjorn
    Hilborn, Jons
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry, Polymer Chemistry.
    Effects of hydrolysis on a new biodegradable co-polymer2006In: Journal of Biomaterials Science. Polymer Edition, ISSN 0920-5063, E-ISSN 1568-5624, Vol. 17, no 6, p. 615-630Article in journal (Refereed)
    Abstract [en]

    The aim of this study was to examine the feasibility of using a new low-modulus biodegradable thermoplastic elastomer for in vivo application as a stent cover. The new polymer, a thermoplastic elastomer, consists of a three-armed co-polymer of poly(lactide)acid (PLLA), poly(trimethylene carbonate) (PTMC) and poly(caprolactone) (PCL). A degradation study was performed in a buffer solution at 37 degrees C for 4 and 6 weeks. The effect of degradation on mechanical properties was studied by stress-strain measurements and explained by using modulated DSC, GPC and mass measurements. A tapered block of PLLA and trimethylene carbonate connecting the crystalline outer part and the inner elastic part was highly susceptible to hydrolysis and caused rapid degradation and subsequent loss of mechanical properties. Random chain scission and homogenous hydrolysis resulted in a loss in mass and molecular weight. After 6 weeks of in vitro hydrolysis the molecular weight had decreased 54% and the elongation-at-break dropped from more than 300% to 90%. A medium free cell seeding study showed that endothelial cells adhered well to the polymeric material. An indicative animal study with the polymer acting as a stent cover showed very low levels of inflammation however, pronounced neointima thickening was observed which was probably due to the premature failure of the material.

  • 6.
    Aulin, Cecilia
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry.
    Extracellular Matrix Based Materials for Tissue Engineering2010Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The extracellular matrix is (ECM) is a network of large, structural proteins and polysaccharides, important for cellular behavior, tissue development and maintenance. Present thesis describes work exploring ECM as scaffolds for tissue engineering by manipulating cells cultured in vitro or by influencing ECM expression in vivo. By culturing cells on polymer meshes under dynamic culture conditions, deposition of a complex ECM could be achieved, but with low yields. Since the major part of synthesized ECM diffused into the medium the rate limiting step of deposition was investigated. This quantitative analysis showed that the real rate limiting factor is the low proportion of new proteins which are deposited as functional ECM. It is suggested that cells are pre-embedded in for example collagen gels to increase the steric retention and hence functional deposition.

    The possibility to induce endogenous ECM formation and tissue regeneration by implantation of growth factors in a carrier material was investigated. Bone morphogenetic protein-2 (BMP-2) is a growth factor known to be involved in growth and differentiation of bone and cartilage tissue. The BMP-2 processing and secretion was examined in two cell systems representing endochondral (chondrocytes) and intramembranous (mesenchymal stem cells) bone formation. It was discovered that chondrocytes are more efficient in producing BMP-2 compared to MSC. The role of the antagonist noggin was also investigated and was found to affect the stability of BMP-2 and modulate its effect. Finally, an injectable gel of the ECM component hyaluronan has been evaluated as delivery vehicle in cartilage regeneration. The hyaluronan hydrogel system showed promising results as a versatile biomaterial for cartilage regeneration, could easily be placed intraarticulary and can be used for both cell based and cell free therapies.

    List of papers
    1. Extracellular matrix-polymer hybrid materials produced in a pulsed-flow bioreactor system
    Open this publication in new window or tab >>Extracellular matrix-polymer hybrid materials produced in a pulsed-flow bioreactor system
    2009 (English)In: Journal of Tissue Engineering and Regenerative Medicine, ISSN 1932-6254, Vol. 3, no 3, p. 188-195Article in journal (Refereed) Published
    Abstract [en]

    Cell adhesion, interaction with material, cell proliferation and the production of an extracellular matrix (ECM) are all important factors determining the successful performance of an engineered scaffold. Scaffold design should aim at creating structures which can guide cells into forming new, functional tissue. In this study, the concept of in situ deposition of ECM by human dermal fibroblasts onto a compliant, knitted poly (ethyleneterephtalate) support is demonstrated, creating in vitro produced ECM polymer hybrid materials for tissue engineering. Comparison of cells cultured under static and dynamic conditions were examined, and the structure and morphology of the materials so formed were evaluated, along with the amount collagen deposited by the seeded cells. In vitro produced ECM polymer hybrid scaffolds could be created in this way, with the dynamic culture conditions increasing ECM deposition. Histological analysis indicated a homogenous distribution of cells in the 1 mm thick scaffold, surrounded by a matrix-like structure. ECM deposition was observed throughout the materials wigh 81.6 µg/cm2 of collagen deposited after 6 weeks. Cell produced bundles of ECM fibres bridged the polymer filaments and anchored cells to the support. These findings open hereto unknown possibilities of producing materials with structure designed by engineering together with biochemical composition given by cells.

    Place, publisher, year, edition, pages
    John Wiley & Sons, Ltd, 2009
    Keywords
    extracellular matrix, scaffold, polymer support, fibroblasts, bioreactor, dynamic culture conditions
    National Category
    Chemical Sciences
    Research subject
    Inorganic Chemistry
    Identifiers
    urn:nbn:se:uu:diva-106096 (URN)10.1002/term.152 (DOI)000265268400003 ()
    Available from: 2009-06-15 Created: 2009-06-15 Last updated: 2010-08-02Bibliographically approved
    2. Bulk collagen incorporation rates into knitted stiff fibre polymer in tissue-engineered scaffolds: the rate-limiting step
    Open this publication in new window or tab >>Bulk collagen incorporation rates into knitted stiff fibre polymer in tissue-engineered scaffolds: the rate-limiting step
    Show others...
    2008 (English)In: Journal of Tissue Engineering and Regenerative Medicine, ISSN 1932-6254, Vol. 2, no 8, p. 507-514Article in journal (Refereed) Published
    Abstract [en]

    Fabrication of tissue-engineered constructs in vitro relies on sufficient synthesis of extracellular matrix (ECM) by cells to form a material suitable for normal function in vivo. Collagen synthesis by human dermal fibroblasts grown in vitro on two polymers, polyethylene terephthalate (PET) and polyglycolic acid (PGA), was measured by high-performance liquid chromatography (HPLC). Cells were either cultured in a dynamic environment, where meshes were loaded onto a pulsing tube in a bioreactor, or in a static environment without pulsing. Collagen synthesis by cells cultured on a static mesh increased by six-fold compared to monolayer culture, and increased by up to a further 5.4-fold in a pulsed bioreactor. However, little of the collagen synthesized was deposited onto the meshes, almost all being lost to the medium. The amount of collagen deposited onto meshes was highest when cells were cultured dynamically on PET meshes (17.6 µg), but deposition still represented only 1.4% of the total synthesized. Although total collagen synthesis was increased by the use of 3D culture and the introduction of pulsing, the results suggest that the limiting factor for fabrication of a tissue-engineered construct within practical timescales is not the amount of collagen synthesized but the quantity retained (i.e. deposited) within the construct during culture. This may be enhanced by systems which promote or assemble true 3D multi-layers of cells.

    Place, publisher, year, edition, pages
    John Wiley & Sons, Ltd., 2008
    Keywords
    collagen synthesis, collagen deposition, tissue engineering, polyethylene terephthalate, 3D culture, bioreactors
    National Category
    Chemical Sciences
    Research subject
    Inorganic Chemistry
    Identifiers
    urn:nbn:se:uu:diva-99347 (URN)10.1002/term.126 (DOI)000262272900007 ()
    Available from: 2009-03-12 Created: 2009-03-12 Last updated: 2010-08-04Bibliographically approved
    3. Comparative studies on BMP-2 processing and secretion in chondrocytes and mesenchymal cells and the effect of noggin
    Open this publication in new window or tab >>Comparative studies on BMP-2 processing and secretion in chondrocytes and mesenchymal cells and the effect of noggin
    (English)Manuscript (preprint) (Other academic)
    Keywords
    bone formation, BMP-2, noggin, chondrocytes, mesenchymal stem cells
    Identifiers
    urn:nbn:se:uu:diva-110746 (URN)
    Available from: 2009-11-24 Created: 2009-11-24
    4. Evaluation of an injectable hyaluronan hydrogel for cartilage regeneration
    Open this publication in new window or tab >>Evaluation of an injectable hyaluronan hydrogel for cartilage regeneration
    Show others...
    (English)Manuscript (preprint) (Other academic)
    Keywords
    hyaluronan, chondrocytes, mesenchymal stem cells, cartilage, injectable, bone morphogenetic protein-2, rabbit model
    Identifiers
    urn:nbn:se:uu:diva-110750 (URN)
    Available from: 2009-11-24 Created: 2009-11-24
  • 7.
    Aulin, Cecilia
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry, Polymer Chemistry.
    Bergman, Kristoffer
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry, Polymer Chemistry.
    Jensen-Waern, Marianne
    Hedenqvist, Patricia
    Hilborn, Jöns
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry, Polymer Chemistry.
    Engstrand, Thomas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry, Polymer Chemistry.
    In situ cross-linkable hyaluronan hydrogel enhances chondrogenesis2011In: Journal of tissue engineering and regenerative medicine, ISSN 1932-6254, Vol. 5, no 8, p. E188-E196Article in journal (Refereed)
    Abstract [en]

    The present work describes the feasibility of a cross-linkable injectable hyaluronan hydrogel for cartilage repair. The hydrogel used is a two-component system based on aldehyde-modified hyaluronan and hydrazide-modified polyvinyl alcohol, which are rapidly cross-linked in situ upon mixing. The in vitro study showed that chondrocytes and mesenchymal cells cultured in the gel form cartilage-like tissue, rich in glycosaminoglycans, collagen type II and aggrecan. In a rabbit animal model the injection of the hydrogel improved the healing of a full-thickness cartilage defect created in the knee as compared to non-treated controls. This rabbit study showed that the regenerated cartilage defects stained more intensely for type II collagen upon treatment with the hydrogel. The hyaluronan-based hydrogel may be used as a delivery vehicle for both growth factors and/or cells for cartilage repair. The in vivo study also indicated that the hydrogel alone has a beneficial effect on cartilage regeneration.

  • 8.
    Azuma, Tomoyuki
    et al.
    Univ Tokyo, Dept Bioengn, Bunkyo Ku, 7-3-1 Hongo, Tokyo 1138656, Japan..
    Ohmori, Ryuichi
    Shibaura Inst Technol, Dept Mat Sci & Engn, Coll Engn, Koto Ku, 3-7-5 Toyosu, Tokyo 1358548, Japan..
    Teramura, Yuji
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Immunology, Genetics and Pathology. Univ Tokyo, Dept Bioengn, Bunkyo Ku, 7-3-1 Hongo, Tokyo 1138656, Japan..
    Ishizaki, Takahiro
    Shibaura Inst Technol, Dept Mat Sci & Engn, Coll Engn, Koto Ku, 3-7-5 Toyosu, Tokyo 1358548, Japan..
    Takai, Madoka
    Univ Tokyo, Dept Bioengn, Bunkyo Ku, 7-3-1 Hongo, Tokyo 1138656, Japan..
    Nano-structural comparison of 2-methacryloyloxyethyl phosphorylcholine- and ethylene glycol-based surface modification for preventing protein and cell adhesion2017In: Colloids and Surfaces B: Biointerfaces, ISSN 0927-7765, E-ISSN 1873-4367, Vol. 159, p. 655-661Article in journal (Refereed)
    Abstract [en]

    Polymer brush, owing to its precisely controllable nanostructure, has great potential for surface modification in the biomedical field. In this study, we evaluated the bio-inertness of polymer brush, monomer monolayers, and polymer-coated surfaces based on their structures, to identify the most effective bio-inert modification. We focused on two well-known bio-inert materials, 2-methacryloyloxyethyl phosphorylcholine (MPC) and ethylene glycol (EG). The amount of adsorbed proteins on the surface was found to be dependent on the monomer unit density in the case of MPC, whereas this correlation was not observed in the case of EG. Cell adhesion was suppressed on the brush structure of both MPC and EG units, regardless of their density. The brush structure of MPC and EG units showed better anti-protein and anti-cell-adhesion than monolayers and polymer-coated surfaces. Thus, the steric repulsion was not only important in EG units-based surface, but also in MPC-based surface. In addition, multiple polymer layers formed by MPC-based polymer coating also displayed similar properties. (C) 2017 Elsevier B.V. All rights reserved.

  • 9.
    Bergfelt, Andreas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Polymer Chemistry.
    Block Copolymer Electrolytes: Polymers for Solid-State Lithium Batteries2018Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The use of solid polymer electrolytes (SPEs) for lithium battery devices is a rapidly growing research area. The liquid electrolytes that are used today are inflammable and harmful towards the battery components. The adoption of SPEs could drastically improve this situation, but they still suffer from a too low performance at ambient temperatures for most practical applications. However, by increasing the operating temperature to between 60 °C and 90 °C, the electrolyte performance can be drastically increased. The drawback of this approach, partly, is that parasitic side reactions become noticeable at these elevated temperatures, thus affecting battery lifetime and performance. Furthermore, the ionically conductive polymer loses its mechanical integrity, thus triggering a need for an external separator in the battery device.

    One way of combining both mechanical properties and electrochemical performance is to design block copolymer (BCP) electrolytes, that is, polymers that are tailored to combine one ionic conductive block with a mechanical block, into one polymer. The hypothesis is that the BCP electrolytes should self-assemble into well-defined microphase separated regions in order to maximize the block properties. By varying monomer composition and structure of the BCP, it is possible to design electrolytes with different battery device performance. In Paper I and Paper II two types of methacrylate-based triblock copolymers with different mechanical blocks were synthesized, in order to evaluate morphology, electrochemical performance, and battery performance. In Paper III and Paper IV a different strategy was adopted, with a focus on diblock copolymers. In this strategy, the ethylene oxide was replaced by poly(e-caprolactone) and poly(trimethylene carbonate) as the lithium-ion dissolving group. The investigated mechanical blocks in these studies were poly(benzyl methacrylate) and polystyrene. The battery performance for these electrolytes was superior to the methacrylate-based battery devices, thus resulting in stable battery cycling at 40 °C and 30 °C.

    List of papers
    1. d8-poly(methyl methacrylate)-poly[(oligo ethylene glycol) methyl ether methacrylate] tri-block-copolymer electrolytes: Morphology, conductivity and battery performance
    Open this publication in new window or tab >>d8-poly(methyl methacrylate)-poly[(oligo ethylene glycol) methyl ether methacrylate] tri-block-copolymer electrolytes: Morphology, conductivity and battery performance
    Show others...
    2017 (English)In: Polymer, ISSN 0032-3861, E-ISSN 1873-2291, Vol. 131, p. 234-242Article in journal (Refereed) Published
    Abstract [en]

    A series of deuterated tri-block copolymers with the general structure d(8)-PMMA-POEGMA-d(8)-PMMA, with variation in d(8)-PMMA chain length, were synthesized using sequential controlled radical polymerization (ATRP). Solid polymer electrolytes (SPEs) were produced by blending tri-block copolymers and lithium bis(trifluoro methylsulfonate) (LiTFSI). Small-angle neutron scattering (SANS) was used to study the bulk morphology of the deuterated tri-block copolymer electrolyte series at 25 degrees C, 60 degrees C and 95 degrees C. The lack of a second T-g in DSC analysis together with modelling with the random phase approximation model (RPA) confirmed that the electrolytes are in the mixed state, with negative Flory-Huggins interaction parameters. AC impedance spectroscopy was used to study the ionic conductivity of the SPE series in the temperature interval 30 degrees C-90 degrees C, and a battery device was constructed to evaluate a 25 wt% d(8)-PMMA electrolyte. The Li | SPE | LiFePO4 cell cycled at 60 degrees C, giving a discharge capacity of 120 mAh g(-1), while cyclic voltammetry showed that the SPE was stable at 60 degrees C.

    National Category
    Polymer Chemistry
    Identifiers
    urn:nbn:se:uu:diva-337667 (URN)10.1016/j.polymer.2017.10.044 (DOI)000415014300026 ()
    Funder
    Swedish Research Council
    Available from: 2018-01-03 Created: 2018-01-03 Last updated: 2018-02-22Bibliographically approved
    2. Poly(benzyl methacrylate)-Poly[(oligo ethylene glycol) methyl ether methacrylate] Triblock-Copolymers as Solid Electrolyte for Lithium Batteries
    Open this publication in new window or tab >>Poly(benzyl methacrylate)-Poly[(oligo ethylene glycol) methyl ether methacrylate] Triblock-Copolymers as Solid Electrolyte for Lithium Batteries
    2018 (English)In: Solid State Ionics, ISSN 0167-2738, E-ISSN 1872-7689, Vol. 321, p. 55-61Article in journal (Refereed) Published
    Abstract [en]

    A triblock copolymer of benzyl methacrylate and oligo(ethylene glycol) methyl ether methacrylate was polymerized to form the general structure PBnMA-POEGMA-PBnMA, using atom transfer radical polymerization (ATRP). The block copolymer (BCP) was blended with lithium bis(trifluoro methylsulfonate) (LiTFSI) to form solid polymer electrolytes (SPEs). AC impedance spectroscopy was used to study the ionic conductivity of the SPE series in the temperature interval 30 °C to 90 °C. Small-angle X-ray scattering (SAXS) was used to study the morphology of the electrolytes in the temperature interval 30 °C to 150 °C. By using benzyl methacrylate as a mechanical block it was possible to tune the microphase separation by the addition of LiTFSI, as proven by SAXS. By doing so the ionic conductivity increased to values higher than ones measured on a methyl methacrylate triblock copolymer-based electrolyte in the mixed state, which was investigated in an earlier paper by our group. A Li|SPE|LiFePO4 half-cell was constructed and cycled at 60 °C. The cell produced a discharge capacity of about 100 mAh g−1 of LiFePO4 at C/10, and the half-cell cycled for more than 140 cycles.

    National Category
    Polymer Chemistry
    Research subject
    Chemistry with specialization in Polymer Chemistry
    Identifiers
    urn:nbn:se:uu:diva-340851 (URN)10.1016/j.ssi.2018.04.006 (DOI)000437372200009 ()
    Funder
    Swedish Energy AgencyStandUp
    Available from: 2018-02-04 Created: 2018-02-04 Last updated: 2018-10-11Bibliographically approved
    3. ε-Caprolactone-based solid polymer electrolytes for lithium-ion batteries: synthesis, electrochemical characterization and mechanical stabilization by block copolymerization
    Open this publication in new window or tab >>ε-Caprolactone-based solid polymer electrolytes for lithium-ion batteries: synthesis, electrochemical characterization and mechanical stabilization by block copolymerization
    Show others...
    2018 (English)In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 8, no 30, p. 16716-16725Article in journal (Refereed) Published
    Abstract [en]

    In this work, three types of polymers based on epsilon-caprolactone have been synthesized: poly(epsilon-caprolactone), polystyrene-poly(epsilon-caprolactone), and polystyrene-poly(epsilon-caprolactone-r-trimethylene carbonate) (SCT), where the polystyrene block was introduced to improve the electrochemical and mechanical performance of the material. Solid polymer electrolytes (SPEs) were produced by blending the polymers with 10-40 wt% lithium bis(trifluoromethane) sulfonimide (LiTFSI). Battery devices were thereafter constructed to evaluate the cycling performance. The best performing battery half-cell utilized an SPE consisting of SCT and 17 wt% LiTFSI as both binder and electrolyte; a Li vertical bar SPE vertical bar LiFePO4 cell that cycled at 40 degrees C gave a discharge capacity of about 140 mA h g(-1) at C/5 for 100 cycles, which was superior to the other investigated electrolytes. Dynamic mechanical analysis (DMA) showed that the storage modulus E' was about 5 MPa for this electrolyte.

    National Category
    Polymer Chemistry
    Identifiers
    urn:nbn:se:uu:diva-340854 (URN)10.1039/c8ra00377g (DOI)000431814500034 ()
    Funder
    Swedish Energy Agency, 42031-1EU, Horizon 2020, 685716
    Available from: 2018-02-04 Created: 2018-02-04 Last updated: 2018-08-27Bibliographically approved
    4. A Mechanical Robust yet highly Conductive Diblock Copolymer-based Solid Polymer Electrolyte for Room Temperature Structural Battery Applications
    Open this publication in new window or tab >>A Mechanical Robust yet highly Conductive Diblock Copolymer-based Solid Polymer Electrolyte for Room Temperature Structural Battery Applications
    Show others...
    (English)Manuscript (preprint) (Other academic)
    National Category
    Polymer Chemistry
    Identifiers
    urn:nbn:se:uu:diva-340855 (URN)
    Available from: 2018-02-04 Created: 2018-02-04 Last updated: 2018-02-04
  • 10.
    Bergfelt, Andreas
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Polymer Chemistry.
    Lacey, Matthew J.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Hedman, Jonas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Sångeland, Christofer
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Brandell, Daniel
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Bowden, Tim
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Polymer Chemistry.
    ε-Caprolactone-based solid polymer electrolytes for lithium-ion batteries: synthesis, electrochemical characterization and mechanical stabilization by block copolymerization2018In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 8, no 30, p. 16716-16725Article in journal (Refereed)
    Abstract [en]

    In this work, three types of polymers based on epsilon-caprolactone have been synthesized: poly(epsilon-caprolactone), polystyrene-poly(epsilon-caprolactone), and polystyrene-poly(epsilon-caprolactone-r-trimethylene carbonate) (SCT), where the polystyrene block was introduced to improve the electrochemical and mechanical performance of the material. Solid polymer electrolytes (SPEs) were produced by blending the polymers with 10-40 wt% lithium bis(trifluoromethane) sulfonimide (LiTFSI). Battery devices were thereafter constructed to evaluate the cycling performance. The best performing battery half-cell utilized an SPE consisting of SCT and 17 wt% LiTFSI as both binder and electrolyte; a Li vertical bar SPE vertical bar LiFePO4 cell that cycled at 40 degrees C gave a discharge capacity of about 140 mA h g(-1) at C/5 for 100 cycles, which was superior to the other investigated electrolytes. Dynamic mechanical analysis (DMA) showed that the storage modulus E' was about 5 MPa for this electrolyte.

  • 11.
    Bergfelt, Andreas
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Polymer Chemistry.
    Mogensen, Ronnie
    Lacey, Matthew
    Hernández, Guiomar
    Brandell, Daniel
    Bowden, Tim
    A Mechanical Robust yet highly Conductive Diblock Copolymer-based Solid Polymer Electrolyte for Room Temperature Structural Battery ApplicationsManuscript (preprint) (Other academic)
  • 12.
    Bergfelt, Andreas
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Polymer Chemistry.
    Rubatat, Laurent
    CNRS/UNIV Pau & Pays Adour, Institut des Sciences Analytiques et de Physico-Chimie pour l´ Environnement et les Materiaux, Pau, France.
    Brandell, Daniel
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Bowden, Tim
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Polymer Chemistry.
    Poly(benzyl methacrylate)-Poly[(oligo ethylene glycol) methyl ether methacrylate] Triblock-Copolymers as Solid Electrolyte for Lithium Batteries2018In: Solid State Ionics, ISSN 0167-2738, E-ISSN 1872-7689, Vol. 321, p. 55-61Article in journal (Refereed)
    Abstract [en]

    A triblock copolymer of benzyl methacrylate and oligo(ethylene glycol) methyl ether methacrylate was polymerized to form the general structure PBnMA-POEGMA-PBnMA, using atom transfer radical polymerization (ATRP). The block copolymer (BCP) was blended with lithium bis(trifluoro methylsulfonate) (LiTFSI) to form solid polymer electrolytes (SPEs). AC impedance spectroscopy was used to study the ionic conductivity of the SPE series in the temperature interval 30 °C to 90 °C. Small-angle X-ray scattering (SAXS) was used to study the morphology of the electrolytes in the temperature interval 30 °C to 150 °C. By using benzyl methacrylate as a mechanical block it was possible to tune the microphase separation by the addition of LiTFSI, as proven by SAXS. By doing so the ionic conductivity increased to values higher than ones measured on a methyl methacrylate triblock copolymer-based electrolyte in the mixed state, which was investigated in an earlier paper by our group. A Li|SPE|LiFePO4 half-cell was constructed and cycled at 60 °C. The cell produced a discharge capacity of about 100 mAh g−1 of LiFePO4 at C/10, and the half-cell cycled for more than 140 cycles.

  • 13.
    Bergfelt, Andreas
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Polymer Chemistry.
    Rubatat, Laurent
    Univ Pau & Pays Adour, CNRS, Inst Sci Analyt & Physicochim Environm & Mat, UMR5254, F-64000 Pau, France.
    Mogensen, Ronnie
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Brandell, Daniel
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Bowden, Tim
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Polymer Chemistry.
    d8-poly(methyl methacrylate)-poly[(oligo ethylene glycol) methyl ether methacrylate] tri-block-copolymer electrolytes: Morphology, conductivity and battery performance2017In: Polymer, ISSN 0032-3861, E-ISSN 1873-2291, Vol. 131, p. 234-242Article in journal (Refereed)
    Abstract [en]

    A series of deuterated tri-block copolymers with the general structure d(8)-PMMA-POEGMA-d(8)-PMMA, with variation in d(8)-PMMA chain length, were synthesized using sequential controlled radical polymerization (ATRP). Solid polymer electrolytes (SPEs) were produced by blending tri-block copolymers and lithium bis(trifluoro methylsulfonate) (LiTFSI). Small-angle neutron scattering (SANS) was used to study the bulk morphology of the deuterated tri-block copolymer electrolyte series at 25 degrees C, 60 degrees C and 95 degrees C. The lack of a second T-g in DSC analysis together with modelling with the random phase approximation model (RPA) confirmed that the electrolytes are in the mixed state, with negative Flory-Huggins interaction parameters. AC impedance spectroscopy was used to study the ionic conductivity of the SPE series in the temperature interval 30 degrees C-90 degrees C, and a battery device was constructed to evaluate a 25 wt% d(8)-PMMA electrolyte. The Li | SPE | LiFePO4 cell cycled at 60 degrees C, giving a discharge capacity of 120 mAh g(-1), while cyclic voltammetry showed that the SPE was stable at 60 degrees C.

  • 14.
    Bergman, Kristoffer
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry.
    Hyaluronan Derivatives and Injectable Gels for Tissue Engineering2008Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The present work describes the preparation of hyaluronan derivatives and hydrogels with potential use in tissue engineering applications. A potentially injectable hydrogel consisting of hyaluronan and collagen was successfully used to grow neurons in vitro by encapsulation of neural stem and progenitor cells. Attempts were further made to establish a suitable modification strategy which could be used for the preparation of in vivo cross-linkable hyaluronan derivatives. The synthesis of a model substance consisting of a D-glucuronate derivative which could simplify the development of such a modification technique is described, although a new method to prepare hyaluronan derivatives was found without its use. The modification strategy involves the use of a triazine-reagent which enables the covalent attachment of hydrophilic and hydrophobic amines to hyaluronan carboxyl groups in a controlled fashion under mild conditions. Using triazine-activated amidation we synthesized an aldehyde-derivative of hyaluronan which was used to prepare gels by cross-linking with hydrazide-modified polyvinyl-alcohol. Gels were formed in less than 1 minute by mixing equal volumes of the polymer derivatives and they were subsequently used as a carrier for bone morphogenetic protein-2. An in vitro release study showed that approximately 88% of the growth factor is retained in the gel over a 4 week period. The ability to form new bone in vivo was further evaluated in an ectopic rat model by the injection of gels containing 30 µg BMP-2. Radiographic and histological examination 4 and 10 weeks after injection showed the formation of new bone without any signs of inflammation or foreign body response. Hydroxyapatite particles were further added to improve the mechanical properties of the gel, and a comparative study was conducted. This time the induced tissue consisted not only of bone, but also of interconnected cartilage and tendon, as confirmed by histology and immunohistochemistry.

    List of papers
    1. Enhanced neuronal differentiation in a three-dimensional collagen-hyaluronan matrix
    Open this publication in new window or tab >>Enhanced neuronal differentiation in a three-dimensional collagen-hyaluronan matrix
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    2007 (English)In: Journal of Neuroscience Research, ISSN 0360-4012, E-ISSN 1097-4547, Vol. 85, no 10, p. 2138-2146Article in journal (Refereed) Published
    Abstract [en]

    Efficient 3D cell systems for neuronal induction are needed for future use in tissue regeneration. In this study, we have characterized the ability of neural stem/progenitor cells (NS/PC) to survive, proliferate, and differentiate in a collagen type I-hyaluronan scaffold. Embryonic, postnatal, and adult NS/PC were seeded in the present 3D scaffold and cultured in medium containing epidermal growth factor and fibroblast growth factor-2, a condition that stimulates NS/PC proliferation. Progenitor cells from the embryonic brain had the highest proliferation rate, and adult cells the lowest, indicating a difference in mitogenic responsiveness. NS/PC from postnatal stages down-regulated nestin expression more rapidly than both embryonic and adult NS/PC, indicating a faster differentiation process. After 6 days of differentiation in the 3D scaffold, NS/PC from the postnatal brain had generated up to 70% neurons, compared with 14% in 2D. NS/PC from other ages gave rise to approximately the same proportion of neurons in 3D as in 2D (9-26% depending on the source for NS/PC). In the postnatal NS/PC cultures, the majority of III-tubulin-positive cells expressed glutamate, -aminobutyric acid, and synapsin I after 11 days of differentiation, indicating differentiation to mature neurons. Here we report that postnatal NS/PC survive, proliferate, and efficiently form synapsin I-positive neurons in a biocompatible hydrogel.

    Keywords
    3D cultures, neural stem/progenitor cells, hydrogel, scaffold, neurogenesis
    National Category
    Medical and Health Sciences
    Identifiers
    urn:nbn:se:uu:diva-11683 (URN)10.1002/jnr.21358 (DOI)000248516700008 ()17520747 (PubMedID)
    Available from: 2007-10-17 Created: 2007-10-17 Last updated: 2017-12-11Bibliographically approved
    2. Selective Michael-type addition of a D-glucuronic acid derivative in the synthesis of model substances for uronic acid containing polysaccharides
    Open this publication in new window or tab >>Selective Michael-type addition of a D-glucuronic acid derivative in the synthesis of model substances for uronic acid containing polysaccharides
    2008 (English)In: Express Polymer Letters, ISSN 1788-618X, Vol. 2, no 8, p. 553-559Article in journal (Refereed) Published
    Abstract [en]

    A flexible protocol for the preparation of model substances for uronic acid containing polysaccharides is presented.We have synthesized a D-glucuronic acid derivative which is designed so that it easily can be conjugated with differentstructures and architectures by selective Michael-type addition. By successful coupling of the glucuronic acidderivative to polyethylene glycol with high degree of conversion, products were obtained that were easily characterized andwhich resembled polysaccharides in terms of solubility and purification methods that could be employed. The model substancecan potentially be used to facilitate optimization of low-degree modification reactions of high molecular weightD-glucuronic acid containing polysaccharides.

    Keywords
    polymer gels, polysaccharides, Michael-type addition, model substance, NMR
    National Category
    Polymer Chemistry
    Identifiers
    urn:nbn:se:uu:diva-97728 (URN)10.3144/expresspolymlett.2008.67 (DOI)000263687000004 ()
    Available from: 2008-11-14 Created: 2008-11-14 Last updated: 2010-08-25Bibliographically approved
    3. Hyaluronic acid derivatives prepared in aqueous media by triazine-activated amidation
    Open this publication in new window or tab >>Hyaluronic acid derivatives prepared in aqueous media by triazine-activated amidation
    Show others...
    2007 (English)In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 8, no 7, p. 2190-2195Article in journal (Refereed) Published
    Abstract [en]

    A method is presented for the preparation of hyaluronic acid derivatives obtained through triazine-activated amidation. A number of amines were successfully reacted with hyaluronic acid carboxyl groups using 2-chloro-4,6-dimethoxy-1,3,5-triazine as an activating species in a mixture of water and acetonitrile under neutral conditions. By varying the amount of triazine reagent, it was possible to control the degree of modification. Depending on the amine chosen, degrees of modification ranging from 3 to 20% were obtained when using 0.5 equiv of the triazine to hyaluronic acid carboxyl groups. The possibility to perform the reaction in a mixture of water and acetonitrile facilitates the introduction of a wide range of both hydrophilic and hydrophobic amines. Triazine-activated amidation appears to be a highly versatile, controllable, and relatively mild technique for modification of hyaluronic acid, and we predict that it will be useful in the design of novel hyaluronic acid based biomaterials.

    Keywords
    Oside polymer, Experimental study, Mild operating conditions, Aqueous medium, Triazine derivatives, Activation, Primary amine, Amidation, Chemical modification, Preparation, Modified material, Hyaluronic acid
    National Category
    Chemical Sciences
    Identifiers
    urn:nbn:se:uu:diva-97729 (URN)10.1021/bm0701604 (DOI)000247820000022 ()17579475 (PubMedID)
    Available from: 2008-11-14 Created: 2008-11-14 Last updated: 2017-12-14Bibliographically approved
    4. Injectable cell-free template for bone-tissue formation
    Open this publication in new window or tab >>Injectable cell-free template for bone-tissue formation
    Show others...
    2009 (English)In: Journal of Biomedical Materials Research-Part A, ISSN 1549-3296, Vol. 91A, no 4, p. 1111-1118Article in journal (Refereed) Published
    Abstract [en]

    Here we present a novel injectable hydrogel which forms a template for de novo formation of bone tissue. Hydrogel formation takes place in situ in less than 1 min by the cross-linking of multifunctional hyaluronic acid and polyvinyl alcohol derivatives. Endogenous cells are recruited in vivo by incorporating bone morphogenetic protein-2 (BMP-2), a powerful promoter for osteogenic differentiation. The hydrogel was evaluated in vitro by performing a cell viability test and a release study and in vivo by a rat ectopic model. Examination by X-ray, microcomputed tomography, and histology revealed a significant bone formation at the target site for gels containing BMP-2, and a complete degradation was observed for gels without BMP-2 four weeks after injection. There were no signs of inflammation or foreign body response in either group and we believe that this system has the potential as an off-the-shelf injectable to be used where bone tissue is needed.

    Place, publisher, year, edition, pages
    Wiley Periodicals, Inc, 2009
    Keywords
    hydrogel, hyaluronan, injectable, bone tissue engineering, bone morphogenetic protein, polyvinyl alcohol
    National Category
    Chemical Sciences
    Research subject
    Inorganic Chemistry
    Identifiers
    urn:nbn:se:uu:diva-97730 (URN)10.1002/jbm.a.32289 (DOI)000272196900017 ()
    Available from: 2008-11-14 Created: 2008-11-14 Last updated: 2010-06-23Bibliographically approved
    5. Ectopic induction of the tendon-bone interface
    Open this publication in new window or tab >>Ectopic induction of the tendon-bone interface
    Show others...
    Article in journal (Refereed) Submitted
    Identifiers
    urn:nbn:se:uu:diva-97731 (URN)
    Available from: 2008-11-14 Created: 2008-11-14Bibliographically approved
  • 15.
    Bergman, Kristoffer
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry, Polymer Chemistry.
    Hilborn, Jöns
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry, Polymer Chemistry.
    Bowden, Tim
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry, Polymer Chemistry.
    Selective Michael-type addition of a D-glucuronic acid derivative in the synthesis of model substances for uronic acid containing polysaccharides2008In: Express Polymer Letters, ISSN 1788-618X, Vol. 2, no 8, p. 553-559Article in journal (Refereed)
    Abstract [en]

    A flexible protocol for the preparation of model substances for uronic acid containing polysaccharides is presented.We have synthesized a D-glucuronic acid derivative which is designed so that it easily can be conjugated with differentstructures and architectures by selective Michael-type addition. By successful coupling of the glucuronic acidderivative to polyethylene glycol with high degree of conversion, products were obtained that were easily characterized andwhich resembled polysaccharides in terms of solubility and purification methods that could be employed. The model substancecan potentially be used to facilitate optimization of low-degree modification reactions of high molecular weightD-glucuronic acid containing polysaccharides.

  • 16.
    Bermejo-Velasco, Daniel
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Polymer Chemistry.
    Insights into Covalent Chemistry for the Developmen­t of Biomaterials2019Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Covalent cross-linking chemistry is currently exploited in the preparation of biomaterial for biomedical applications. Choice of these chemistries for the preparation of biomaterials and bioconjugates strongly influences the biological output of these materials. Therefore, this thesis aims to develop novel bioconjugation strategies understanding their advantages and drawbacks. Our results provide new insight to adapt these chemical transformations for a specific application.

    The first part of this thesis points out the relevance of tuning different properties of biomaterials with specific emphasis on the development of hyaluronic acid (HA) hydrogels. The second part of the thesis describes how different chemical transformations including hydrazone formation (Paper I), thiazolidine formation (Paper II), cross-aldol addition reaction (Paper III) and disulfide formation (Paper IV) dictate material properties.

    This thesis explores both basic organic reaction mechanism and application of these reactions to influence material characteristics. The detailed study of the reaction conditions, kinetics, and stability of the products will help to understand the mechanical properties, hydrolytic stability, and degradability of the materials described here.

    Additionally, we performed degradation studies of gadolinium labeled HA hydrogels using magnetic resonance imaging. Furthermore, we also explored post-synthetic modification of hydrogels to link model fluorescent moieties as well as explored the tissue adhesive properties using Schiff-base formation.

    In summary, this thesis presents a selection of different covalent chemistries for the design of advanced biomaterials. The advantages and disadvantages of these chemistries are rigorously investigated. We believe, such an investigation provides a better understanding of the bioconjugation strategies for the preparation of biomaterials with potential clinical translation.

    List of papers
    1. Injectable hyaluronic acid hydrogels with the capacity for magnetic resonance imaging
    Open this publication in new window or tab >>Injectable hyaluronic acid hydrogels with the capacity for magnetic resonance imaging
    Show others...
    2018 (English)In: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 197, p. 641-648Article in journal (Refereed) Published
    Abstract [en]

    Monitoring hydrogel degradation in real time using noninvasive imaging techniques is of great interest for designing a scaffold in tissue engineering. We report the preparation of gadolinium (Gd)-labeled and injectable hyaluronic acid (HA) hydrogels that can be visualized using T-1- and T-2-weighted magnetic resonance imaging (MRI). An HA derivative functionalized with thiol and hydrazide was labeled using a diethylenetriaminepentaacetate complex modified with "clickable" dithiopyridyl functionalities (degree of modification was 3.77% with respect to HA repeat units). The HA derivative modified with cross-linkable groups and Gd complex exhibited relaxivities r(1) = 3.78 mM(-1)s(-1) and r(2) = 56.3 mM(-1)s(-1). A hydrazone hydrogel network was obtained by mixing Gd-labeled HA-hydrazide and HA-aldehyde derivatives. Enzymatic hydrogel degradation could be followed using MRI because the MR images showed great correlation with the hydrogel mass loss. Ex vivo MRI of injected Gd-labeled hydrogels demonstrated that they show a significant contrast difference (SNRcoronal = 456; SNRaxial = 459) from the surrounding tissues. These results indicate that our Gd-labeled HA hydrogel has great potential as an injectable biocompatible hydrogel that can be used for longitudinal tracking in vivo using MRI.

    Place, publisher, year, edition, pages
    ELSEVIER SCI LTD, 2018
    Keywords
    Gadolinium complex, Hyaluronic acid, Injectable hydrogels, Magnetic resonance imaging, Biodegradation
    National Category
    Polymer Chemistry
    Identifiers
    urn:nbn:se:uu:diva-361020 (URN)10.1016/j.carbpol.2018.06.028 (DOI)000438466500070 ()30007657 (PubMedID)
    Available from: 2018-09-20 Created: 2018-09-20 Last updated: 2019-01-24
    2. Thiazolidine chemistry revisited: a fast, efficient and stable click-type reaction at physiological pH
    Open this publication in new window or tab >>Thiazolidine chemistry revisited: a fast, efficient and stable click-type reaction at physiological pH
    Show others...
    2018 (English)In: Chemical Communications, ISSN 1359-7345, E-ISSN 1364-548X, Vol. 54, no 88, p. 12507-12510Article in journal (Refereed) Published
    Abstract [en]

    We describe the fast reaction kinetics between 1,2-aminothiols and aldehydes. Under physiological conditions such a click-type reaction afforded a thiazolidine product that remains stable and did not require any catalyst. This type of bioorthogonal reaction offers enormous potential for the coupling of biomolecules in an efficient and biocompatible manner.

    National Category
    Polymer Chemistry
    Identifiers
    urn:nbn:se:uu:diva-364896 (URN)10.1039/c8cc05405c (DOI)000448947000019 ()30345438 (PubMedID)
    Available from: 2018-11-06 Created: 2018-11-06 Last updated: 2019-06-26Bibliographically approved
    3. First Aldol-Crosslinked Hyaluronic Acid Hydrogel: Fast and Hydrolytically Stable Gel with Tissue Adhesive Properties
    Open this publication in new window or tab >>First Aldol-Crosslinked Hyaluronic Acid Hydrogel: Fast and Hydrolytically Stable Gel with Tissue Adhesive Properties
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    (English)In: Chemical Sciences Journal, ISSN 2150-3494Article in journal (Refereed) Submitted
    Abstract [en]

    Currently, there are limited approaches to tailor 3D scaffolds crosslinked with a stable covalent C-C bond that does not require any catalysts or initiators. We present here the first hydrogels employing aldol condensation chemistry that exhibit exceptional physicochemical properties. We investigated the aldol-crosslinking chemistry using two types of aldehyde-modified hyaluronic acid (HA) derivatives, namely; an enolizable HA-aldehyde (HA-Eal) and a non-enolizable HA-aldehyde (HA-Nal). Hydrogels formed using HA-Eal demonstrate inferior crosslinking efficiency (due to intramolecular loop formation), when compared with hydrogels formed by mixing HA-Eal and HA-NaI leading to a cross-aldol product. The change in mechanical properties as a result of crosslinking at different pH is determined using rheological measurements and is interpreted in terms of molecular weight between cross-links (Mc). The novel HA cross-aldol hydrogels demonstrate excellent hydrolytic stability and favorable mechanical properties but allow hyaluronidase mediated enzymatic degradation. Interestingly, residual aldehyde functionality within the aldol product leads to adhesion to tissue as demonstrated by bonding two bone tissues. The aldehyde functionality also permits facile post-synthetic modifications with nucleophilic reagents such as Alexa FluorTM 488. Finally, we demonstrate that the novel hydrogel is biocompatible with encapsulated stem cells that show a linear rate of expansion in our 3–6 days of study.

    Keywords
    hyaluronic acid, aldol chemisty, stable hydrogels, tissue adhesive
    National Category
    Materials Chemistry
    Research subject
    Chemistry with specialization in Materials Chemistry
    Identifiers
    urn:nbn:se:uu:diva-374999 (URN)
    Available from: 2019-01-24 Created: 2019-01-24 Last updated: 2019-01-24
    4. Modulating thiol pKa promotes disulfide formation at physiological pH: An elegant strategy to design disulfide cross-linked hyaluronic acid hydrogels
    Open this publication in new window or tab >>Modulating thiol pKa promotes disulfide formation at physiological pH: An elegant strategy to design disulfide cross-linked hyaluronic acid hydrogels
    Show others...
    2019 (English)In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 20, no 3, p. 1412-1420Article in journal (Refereed) Published
    Abstract [en]

    The disulfide bond plays a crucial role in protein biology and has been exploited by scientists to develop antibody-drug conjugates, sensors and for the immobilization other biomolecules to materials surfaces. In spite of its versatile use, the disulfide chemistry suffers from some inevitable limitations such as the need for basic conditions (pH > 8.5), strong oxidants and long reaction times. We demonstrate here that thiol-substrates containing electron-withdrawing groups at the β-position influence the deprotonation of the thiol group, which is the key reaction intermediate in the formation of disulfide bonds. Evaluation of reaction kinetics using small molecule substrate such as L-cysteine indicated disulfide formation at a 2.8-fold higher (k1 = 5.04 x 10-4 min-1) reaction rate as compared to the conventional thiol substrate, namely 3-mercaptopropionic acid (k1 = 1.80 x 10-4 min-1) at physiological pH (pH 7.4). Interestingly, the same effect could not be observed when N-acetyl-L-cysteine substrate (k1 = 0.51 x 10-4 min-1) was used. We further grafted such thiol-containing molecules (cysteine, N-acetyl-cysteine, and 3-mercaptopropionic acid) to a biopolymer namely hyaluronic acid (HA) and determined the pKa value of different thiol groups by spectrophotometric analysis. The electron-withdrawing group at the β-position reduced the pKa of the thiol group to 7.0 for HA-cysteine (HA-Cys); 7.4 for N-acetyl cysteine (HA-ActCys) and 8.1 for HA-thiol (HA-SH) derivatives respectively. These experiments further confirmed that the concentration of thiolate (R-S-) ions could be increased with the presence of electron-withdrawing groups, which could facilitate disulfide cross-linked hydrogel formation at physiological pH. Indeed, HA grafted with cysteine or N-acetyl groups formed hydrogels within 3.5 minutes or 10 hours, respectively at pH 7.4. After completion of crosslinking reaction both gels demonstrated a storage modulus G’ ≈3300–3500 Pa, indicating comparable levels of crosslinking. The HA-SH gel, on the other hand, did not form any gel at pH 7.4 even after 24 h. Finally, we demonstrated that the newly prepared hydrogels exhibited excellent hydrolytic stability but can be degraded by cell-directed processes (enzymatic and reductive degradation). We believe our study provides a valuable insight on the factors governing the disulfide formation and our results are useful to develop strategies that would facilitate generation of stable thiol functionalized biomolecules or promote fast thiol oxidation according to the biomedical needs.

    National Category
    Materials Chemistry
    Research subject
    Chemistry with specialization in Materials Chemistry
    Identifiers
    urn:nbn:se:uu:diva-375001 (URN)10.1021/acs.biomac.8b01830 (DOI)000461270500028 ()30726668 (PubMedID)
    Funder
    Swedish Foundation for Strategic Research , 139400127EU, FP7, Seventh Framework Programme, 607868Swedish Foundation for Strategic Research , 139400126
    Available from: 2019-01-24 Created: 2019-01-24 Last updated: 2019-04-11Bibliographically approved
  • 17.
    Bermejo-Velasco, Daniel
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Polymer Chemistry.
    Dou, Weiqiang
    Radboud Univ Nijmegen, Med Ctr, Dept Radiol & Nucl Med, Nijmegen, Netherlands.
    Heerschap, Arend
    Radboud Univ Nijmegen, Med Ctr, Dept Radiol & Nucl Med, Nijmegen, Netherlands.
    Ossipov, Dmitri A.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Polymer Chemistry.
    Hilborn, Jöns
    Uppsala Univ, Dept Chem, Angstrom Lab, Div Polymer Chem, Uppsala, Sweden.
    Injectable hyaluronic acid hydrogels with the capacity for magnetic resonance imaging2018In: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 197, p. 641-648Article in journal (Refereed)
    Abstract [en]

    Monitoring hydrogel degradation in real time using noninvasive imaging techniques is of great interest for designing a scaffold in tissue engineering. We report the preparation of gadolinium (Gd)-labeled and injectable hyaluronic acid (HA) hydrogels that can be visualized using T-1- and T-2-weighted magnetic resonance imaging (MRI). An HA derivative functionalized with thiol and hydrazide was labeled using a diethylenetriaminepentaacetate complex modified with "clickable" dithiopyridyl functionalities (degree of modification was 3.77% with respect to HA repeat units). The HA derivative modified with cross-linkable groups and Gd complex exhibited relaxivities r(1) = 3.78 mM(-1)s(-1) and r(2) = 56.3 mM(-1)s(-1). A hydrazone hydrogel network was obtained by mixing Gd-labeled HA-hydrazide and HA-aldehyde derivatives. Enzymatic hydrogel degradation could be followed using MRI because the MR images showed great correlation with the hydrogel mass loss. Ex vivo MRI of injected Gd-labeled hydrogels demonstrated that they show a significant contrast difference (SNRcoronal = 456; SNRaxial = 459) from the surrounding tissues. These results indicate that our Gd-labeled HA hydrogel has great potential as an injectable biocompatible hydrogel that can be used for longitudinal tracking in vivo using MRI.

  • 18.
    Bermejo-Velasco, Daniel
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Polymer Chemistry.
    Nawale, Ganesh N.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Polymer Chemistry.
    Oommen, Oommen P.
    Bioengineering and Nanomedicine Lab, Faculty of Biomedical Sciences and Engineering, Tampere University of Technology, and BioMediTech Institute, 33720, Tampere, Finland.
    Hilborn, Jöns
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Polymer Chemistry.
    Varghese, Oommen P.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Polymer Chemistry.
    Thiazolidine chemistry revisited: a fast, efficient and stable click-type reaction at physiological pH2018In: Chemical Communications, ISSN 1359-7345, E-ISSN 1364-548X, Vol. 54, no 88, p. 12507-12510Article in journal (Refereed)
    Abstract [en]

    We describe the fast reaction kinetics between 1,2-aminothiols and aldehydes. Under physiological conditions such a click-type reaction afforded a thiazolidine product that remains stable and did not require any catalyst. This type of bioorthogonal reaction offers enormous potential for the coupling of biomolecules in an efficient and biocompatible manner.

  • 19.
    Berts, Ida
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström.
    Relating the Bulk and Interface Structure of Hyaluronan to Physical Properties of Future Biomaterials2013Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This dissertation describes a structural investigation of hyaluronan (HA) with neutron scattering techniques. HA is a natural biopolymer and one of the major components of the extracellular matrix, synovial fluid, and vitreous humor.  It is used in several biomedical applications like tissue engineering, drug delivery, and treatment of osteoarthritis. Although HA is extensively studied, very little is known about its three-dimensional conformation and how it interacts with ions and other molecules. The study aims to understand the bulk structure of a cross-linked HA hydrogel, as well as the conformational arrangement of HA at solid-liquid interfaces. In addition, the structural changes of HA are investigated by simulation of physiological environments, such as changes in ions, interactions with nanoparticles, and proteins etc. Small-angle neutron scattering and neutron reflectivity are the two main techniques applied to investigate the nanostructure of hyaluronan in its original, hydrated state.

    The present study on hydrogels shows that they possess inhomogeneous structures best described with two correlation lengths, one of the order of a few nanometers and the other in the order of few hundred nanometers. These gels are made up of dense polymer-rich clusters linked to each other. The polymer concentration and mixing governs the connectivity between these clusters, which in turn determines the viscoelastic properties of the gels. Surface-tethered HA at a solid-liquid interface is best described with a smooth varying density profile. The shape of this profile depends on the immobilization chemistry, the deposition protocol, and the ionic interactions. HA could be suitably modified to enhance adherence to metal surfaces, as well as incorporation of proteins like growth factors with tunable release properties. This could be exploited for surface coating of implants with bioactive molecules. The knowledge gained from this work would significantly help to develop future biomaterials and surface coatings of implants and biomedical devices.

    List of papers
    1. Structure of polymer and particle aggregates in hydrogel composites
    Open this publication in new window or tab >>Structure of polymer and particle aggregates in hydrogel composites
    2013 (English)In: Journal of Polymer Science Part B: Polymer Physics, ISSN 0887-6266, E-ISSN 1099-0488, Vol. 51, no 6, p. 421-429Article in journal (Refereed) Published
    Abstract [en]

    Knowledge of the structure of a biomaterial is usually vital to control its function. This article provides a structural characterization of a hyaluronan scaffold that has demonstrated good biocompatibility and is used to induce bone regeneration. Hyaluronan hydrogels are appealing materials that can function as a matrix to incorporate both organic and inorganic substances to enhance tissue growth. Because of the intrinsic properties of this swollen matrix, one needs a very sensitive technique that can be applied in situ to determine the organization of the polymers in a gel. Small-angle neutron scattering is used to determine the characteristics of the inhomogeneous structure of the hydrogel both with and without added particles. The results are interpreted using models of structure with two length scales that are beyond the traditional picture of homogeneous gels. The observed structure and the dimensions can explain the previously reported rheological properties of gels containing different amount of polymers. Hydroxyapatite nanoparticles added to the gel are frozen in the gel matrix. We are able to determine the distribution and shape of these particles as they aggregate around the polymer chains. We have also concluded, in this case, that the particle structure is concentration independent. Information about the nanostructure for an applicable biomaterial guides the formulation, preparation, and use that should lead to further understanding of its exploitation.

    Keywords
    biopolymers, correlation length, hyaluronan, hydrogels, nanocomposites, neutron scattering
    National Category
    Natural Sciences
    Identifiers
    urn:nbn:se:uu:diva-197038 (URN)10.1002/polb.23230 (DOI)000315050800005 ()
    Available from: 2013-03-19 Created: 2013-03-18 Last updated: 2017-12-06Bibliographically approved
    2. Tuning the density profile of surface-grafted hyaluronan and the effect of counter-ions
    Open this publication in new window or tab >>Tuning the density profile of surface-grafted hyaluronan and the effect of counter-ions
    2013 (English)In: European Physical Journal E, ISSN 1292-8941, Vol. 36, no 7, p. 70-Article in journal (Refereed) Published
    Abstract [en]

    The present paper investigates the structure and composition of grafted sodium hyaluronanat a solid-liquid interface using neutron reflection. The solvated polymer at the surface could be described with a density profile that decays exponentially towards the bulk solution. The density profileof the polymer varied depending on the deposition protocol. A single-stage deposition resulted in denser polymer layers, while layers created with a two-stage deposition process were more diffuse and had an overall lower density. Despite the diffuse density profile, two-stage deposition leads to a highersurface excess. Addition of calcium ions causes a strong collapse of the sodium hyaluronan chains, increasing the polymer density near the surface. This effect is more pronounced on the sample prepared by two-stage deposition due to the initial less dense profile. This study provides an understanding at a molecular level of how surface functionalization alters the structure and howsurface layers respond to changes in calcium ions in the solvent.

    National Category
    Polymer Technologies Polymer Chemistry
    Identifiers
    urn:nbn:se:uu:diva-197814 (URN)10.1140/epje/i2013-13070-7 (DOI)000322872700002 ()
    Available from: 2013-04-04 Created: 2013-04-04 Last updated: 2014-02-17Bibliographically approved
    3. Adsorption and co-adsorption of human serum albumin and myoglobin with hyaluronan on different substrates
    Open this publication in new window or tab >>Adsorption and co-adsorption of human serum albumin and myoglobin with hyaluronan on different substrates
    Show others...
    (English)Manuscript (preprint) (Other academic)
    National Category
    Polymer Chemistry Materials Chemistry
    Identifiers
    urn:nbn:se:uu:diva-197815 (URN)
    Available from: 2013-04-12 Created: 2013-04-04 Last updated: 2013-05-06
    4. Polymeric Smart Coating Strategy for Titanium Implants
    Open this publication in new window or tab >>Polymeric Smart Coating Strategy for Titanium Implants
    Show others...
    2014 (English)In: Advanced Engineering Materials, ISSN 1438-1656, E-ISSN 1527-2648, Vol. 16, no 11, p. 1340-1350Article in journal (Refereed) Published
    Abstract [en]

    Hyaluronan based hydrogel coatings can mimic extracellular matrix components and incorporate growth factors that can be released during a progressive degradation while new tissue regenerates. This paper describes a structural characterization of a hydrogel coating made of modified hyaluronan polymers and how these coatings interact with bone morphogenetic protein-2 (BMP-2). Quartz crystal microbalance and neutron reflectivity measurements were used for in-situ, real-time measurements of the adsorption properties of polymers and proteins on smooth titanium oxide surfaces that mimic implant products in orthopedics. The adsorption of BMP-2 on a bare titanium oxide surface is compared to that on titanium oxide coated with different chemically modified hyaluronan, the most important being hyaluronan with bisphosphonate groups (HA-BP). The subsequent release of the BMP-2 from these hydrogel coatings could be triggered by calcium ions. The amount of adsorbed protein on the surfaces as well as the amount of released protein both depend on the type of hyaluronan coating. We conclude that HA-BP coated titanium oxide surfaces provide an excellent material for growth factor delivery in-vivo.

    National Category
    Biomaterials Science Polymer Chemistry Polymer Technologies Materials Chemistry
    Identifiers
    urn:nbn:se:uu:diva-197816 (URN)10.1002/adem.201400009 (DOI)000344790000004 ()
    Available from: 2013-04-16 Created: 2013-04-04 Last updated: 2017-12-06Bibliographically approved
  • 20.
    Berts, Ida
    et al.
    Uppsala University, Science for Life Laboratory, SciLifeLab. Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Polymer Chemistry.
    Fragneto, Giovanna
    Institut Laue-Langevin.
    Hilborn, Jöns
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Polymer Chemistry. Uppsala University, Science for Life Laboratory, SciLifeLab.
    Rennie, Adrian R.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Physics.
    Tuning the density profile of surface-grafted hyaluronan and the effect of counter-ions2013In: European Physical Journal E, ISSN 1292-8941, Vol. 36, no 7, p. 70-Article in journal (Refereed)
    Abstract [en]

    The present paper investigates the structure and composition of grafted sodium hyaluronanat a solid-liquid interface using neutron reflection. The solvated polymer at the surface could be described with a density profile that decays exponentially towards the bulk solution. The density profileof the polymer varied depending on the deposition protocol. A single-stage deposition resulted in denser polymer layers, while layers created with a two-stage deposition process were more diffuse and had an overall lower density. Despite the diffuse density profile, two-stage deposition leads to a highersurface excess. Addition of calcium ions causes a strong collapse of the sodium hyaluronan chains, increasing the polymer density near the surface. This effect is more pronounced on the sample prepared by two-stage deposition due to the initial less dense profile. This study provides an understanding at a molecular level of how surface functionalization alters the structure and howsurface layers respond to changes in calcium ions in the solvent.

  • 21.
    Berts, Ida
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström.
    Fragneto, Giovanna
    Institut Laue-Langevin.
    Porcar, Lionel
    Institut Laue-Langevin.
    Hellsing, Maja S.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Rennie, Adrian. R
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Adsorption and co-adsorption of human serum albumin and myoglobin with hyaluronan on different substratesManuscript (preprint) (Other academic)
  • 22.
    Berts, Ida
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström. Uppsala University, Science for Life Laboratory, SciLifeLab.
    Ossipov, Dmitri
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström. Uppsala University, Science for Life Laboratory, SciLifeLab.
    Fragneto, Giovanna
    Institut Laue-Langevin.
    Frisk, Andreas
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Physics.
    Rennie, Adrian. R
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Physics.
    Polymeric Smart Coating Strategy for Titanium Implants2014In: Advanced Engineering Materials, ISSN 1438-1656, E-ISSN 1527-2648, Vol. 16, no 11, p. 1340-1350Article in journal (Refereed)
    Abstract [en]

    Hyaluronan based hydrogel coatings can mimic extracellular matrix components and incorporate growth factors that can be released during a progressive degradation while new tissue regenerates. This paper describes a structural characterization of a hydrogel coating made of modified hyaluronan polymers and how these coatings interact with bone morphogenetic protein-2 (BMP-2). Quartz crystal microbalance and neutron reflectivity measurements were used for in-situ, real-time measurements of the adsorption properties of polymers and proteins on smooth titanium oxide surfaces that mimic implant products in orthopedics. The adsorption of BMP-2 on a bare titanium oxide surface is compared to that on titanium oxide coated with different chemically modified hyaluronan, the most important being hyaluronan with bisphosphonate groups (HA-BP). The subsequent release of the BMP-2 from these hydrogel coatings could be triggered by calcium ions. The amount of adsorbed protein on the surfaces as well as the amount of released protein both depend on the type of hyaluronan coating. We conclude that HA-BP coated titanium oxide surfaces provide an excellent material for growth factor delivery in-vivo.

  • 23.
    Billström, Gry Hulsart
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Orthopaedics.
    Piskounova, Sonya
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Polymer Chemistry.
    Gedda, Lars
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Radiology, Oncology and Radiation Science, Biomedical Radiation Sciences.
    Hilborn, Jöns
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Polymer Chemistry.
    Bowden, Tim
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Polymer Chemistry.
    Larsson, Sune
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Orthopaedics.
    Improved bone formation by altering surface area of hyaluronan-based hydrogel carrier for bone morphogenetic protein-22012In: Bone, ISSN 8756-3282, E-ISSN 1873-2763, Vol. 50, p. S114-S114Article in journal (Other academic)
  • 24.
    Burghelea, Teodor
    et al.
    Univ Nantes, Nantes Atlant Univ, CNRS, Lab Thermocinet Nantes,UMR 6607, Rue Christian Pauc,BP 50609, F-44306 Nantes 3, France..
    Moyers-Gonzalez, Miguel
    Univ Canterbury, Sch Math & Stat, Private Bag 4800, Christchurch 8041, New Zealand..
    Sainudiin, Raazesh
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Mathematics.
    A nonlinear dynamical system approach for the yielding behaviour of a viscoplastic material2017In: Soft Matter, ISSN 1744-683X, E-ISSN 1744-6848, Vol. 13, no 10, p. 2024-2039Article in journal (Refereed)
    Abstract [en]

    A nonlinear dynamical system model that approximates a microscopic Gibbs field model for the yielding of a viscoplastic material subjected to varying external stresses recently reported in R. Sainudiin, M. Moyers-Gonzalez and T. Burghelea, Soft Matter, 2015, 11(27), 5531-5545 is presented. The predictions of the model are in fair agreement with microscopic simulations and are in very good agreement with the micro-structural semi-empirical model reported in A. M. V. Putz and T. I. Burghelea, Rheol. Acta, 2009, 48, 673-689. With only two internal parameters, the nonlinear dynamical system model captures several key features of the solid-fluid transition observed in experiments: the effect of the interactions between microscopic constituents on the yield point, the abruptness of solid-fluid transition and the emergence of a hysteresis of the micro-structural states upon increasing/decreasing external forces. The scaling behaviour of the magnitude of the hysteresis with the degree of the steadiness of the flow is consistent with previous experimental observations. Finally, the practical usefulness of the approach is demonstrated by fitting a rheological data set measured with an elasto-viscoplastic material.

  • 25.
    Carlsson, Daniel O
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Hua, Kai
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Forsgren, Johan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Mihranyan, Albert
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Aspirin stability in anionically charged crystalline nanocellulose2013Conference paper (Refereed)
  • 26.
    Carlsson, Daniel O
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Lindh, Jonas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Nyholm, Leif
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Strømme, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Mihranyan, Albert
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Cooxidant-free TEMPO-mediated oxidation of highly crystalline Cladophora nanocellulose2015Conference paper (Refereed)
  • 27.
    Carlsson, Daniel O
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Lindh, Jonas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Strømme, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Mihranyan, Albert
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Susceptibility of Iα- and Iβ-Dominated Cellulose to TEMPO-Mediated Oxidation2015In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 16, no 5, p. 1643-1649Article in journal (Refereed)
  • 28.
    Dahlstrand, Christian
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Physical Organic Chemistry.
    Jahn, Burkhard
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC.
    Grigoriev, Anton
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Villaume, Sebastien
    Ahuja, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Ottosson, Henrik
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Physical Organic Chemistry.
    Tuning the Band Gap of Polyfulvenes by Use of “Handles”: On the Effects of Exocyclic Substitution, Benzannulation, and Ring Methylation.Manuscript (preprint) (Other academic)
  • 29. Detta, Nicola
    et al.
    Brown, Toby D.
    Edin, Fredrik K.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Biology Education Centre.
    Albrecht, Krystyna
    Chiellini, Federica
    Chiellini, Emo
    Dalton, Paul D.
    Hutmacher, Dietmar W.
    Melt electrospinning of polycaprolactone and its blends with poly(ethylene glycol)2010In: Polymer international, ISSN 0959-8103, E-ISSN 1097-0126, Vol. 59, no 11, p. 1558-1562Article in journal (Refereed)
    Abstract [en]

    Melt electrospinning is one aspect of electrospinning with relatively little published literature, although the technique avoids solvent accumulation and/or toxicity which is favoured in certain applications In the study reported, we melt-electrospun blends of poly(epsilon-caprolactone) (PCL) and an amphiphilic diblock copolymer consisting of poly(ethylene glycol) and PCL segments (PEG-block PCL) A custom-made electrospinning apparatus was built and various combinations of instrument parameters such as voltage and polymer feeding rate were investigated Pure PEG-block-PCL copolymer melt electrospinning did not result in consistent and uniform fibres due to the low molecular weight, while blends of PCL and PEG-block-PCL, for some parameter combinations and certain weight ratios of the two components, were able to produce continuous fibres significantly thinner (average diameter of ca 2 mu m) compared to pure PCL The PCL fibres obtained had average diameters ranging from 6 to 33 mu m and meshes were uniform for the lowest voltage employed while mesh uniformity decreased when the voltage was increased This approach shows that PCL and blends of PEG block-PCL and PCL can be readily processed by melt electrospinning to obtain fibrous meshes with varied average diameters and morphologies that are of interest for tissue engineering purposes.

  • 30.
    Diba, Mani
    et al.
    Radboud Univ Nijmegen Med Ctr, Dept Biomat, NL-6525 EX Nijmegen, Netherlands..
    An, Jie
    Radboud Univ Nijmegen Med Ctr, Dept Biomat, NL-6525 EX Nijmegen, Netherlands..
    Schmidt, Stephan
    Heinrich Heine Univ Dusseldorf, Inst Organ & Macromol Chem, D-40225 Dusseldorf, Germany..
    Hembury, Mathew
    Univ Utrecht, Fac Sci, UIPS, Dept Pharmaceut, NL-3508 TB Utrecht, Netherlands..
    Ossipov, Dmitri
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Polymer Chemistry.
    Boccaccini, Aldo R.
    Univ Erlangen Nurnberg, Dept Mat Sci & Engn, Inst Biomat, D-91058 Erlangen, Germany..
    Leeuwenburgh, Sander C. G.
    Radboud Univ Nijmegen Med Ctr, Dept Biomat, NL-6525 EX Nijmegen, Netherlands..
    Exploiting Bisphosphonate-Bioactive-Glass Interactions for the Development of Self-Healing and Bioactive Composite Hydrogels2016In: Macromolecular rapid communications, ISSN 1022-1336, E-ISSN 1521-3927, Vol. 37, no 23, p. 1952-1959Article in journal (Refereed)
    Abstract [en]

    Hydrogels are widely recognized as promising candidates for various biomedical applications, such as tissue engineering. Recently, extensive research efforts have been devoted to the improvement of the biological and mechanical performance of hydrogel systems by incorporation of functional groups and/or inorganic particles in their composition. Bisphosphonates are a class of drugs, commonly used for treatment of osteoporosis, which exhibit a strong binding affinity for hydroxyapatite. In this study, the binding affinity of a bisphosphonate-functionalized polymer, hyaluronan, toward a bioactive glass (i.e., 45S5 Bioglass) is evaluated using force-distance measurements with atomic force microscopy. The strong interaction between bisphosphonate and bioactive glass is then exploited to develop organic-inorganic composite hydrogels and the viscoelastic and self-healing ability of these materials are investigated. Finally, the stability and mineralization behavior of these hydrogels are evaluated in simulated body fluid. Following this approach, injectable, bioactive and self-healing organic-inorganic composite hydrogels are produced, which mineralize abundantly and rapidly in simulated body fluid. These properties render these composite gels suitable for applications in bone-tissue engineering.

  • 31.
    Dunér, Gunnar
    et al.
    Department of Chemistry, KTH.
    Anderson, Henrik
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Myrskog, Annica
    IFM, Linköping University.
    Hedlund, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science.
    Aastrup, Teodor
    Attana AB.
    Ramström, Olof
    Department of Chemistry, KTH.
    Surface-Confined Photopolymerization of pH-Responsive Acrylamide/Acrylate Brushes on Polymer Thin Films2008In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 24, no 14, p. 7559-7564Article in journal (Refereed)
    Abstract [en]

    Dynamic acrylamide/acrylate polymeric brushes were synthesized at gold-plated quartz crystal surfaces. The crystals were initially coated with polystyrene-type thin films, derivatized with photolabile iniferter groups, and subsequently subjected to photoinitiated polymerization in acrylamide/acrylate monomer feeds. This surface-confined polymerizationmethod enabled direct photocontrol over the polymerization, as followed by increased frequency responses of the crystal oscillations in a quartz crystal microbalance (QCM). The produced polymer layers were also found to be highlysensitive to external acid/base stimuli. Large oscillation frequency shifts were detected when the brushes were exposedto buffer solutions of different pH. The dynamic behavior of the resulting polymeric brushes was evaluated, and theextent of expansion and contraction of the films was monitored by the QCM setup in situ in real time. The resultingresponses were rapid, and the effects were fully reversible. Low pH resulted in full contractions of the films, whereashigher pH yielded maximal expansion in order to minimize repulsion around the charged acrylate centers. The surfacesalso proved to be very robust because the responsiveness was reproducible over many cycles of repeated expansionand contraction. Using ellipsometry, copolymer layers were estimated to be ∼220 nm in a collapsed state and ∼340nm in the expanded state, effectively increasing the thickness of the film by 55%.

  • 32.
    Dunér, Gunnar
    et al.
    Department of Chemistry, KTH.
    Anderson, Henrik
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics. Attana AB.
    Pei, Zhichao
    Attana AB.
    Ingemarsson, Björn
    Attana AB.
    Aastrup, Teodor
    Attana AB.
    Ramström, Olof
    Department of Chemistry, KTH.
    Signal Enhancement in Ligand-Receptor Interactions using Dynamic Polymers at Quartz Crystal Microbalance Surfaces2016In: The Analyst, ISSN 0003-2654, E-ISSN 1364-5528, Vol. 141, no 13, p. 3993-3996Article in journal (Refereed)
    Abstract [en]

    The potential for signal amplification on QCM sensors by use of in situ polymerized poly(acrylic acid) brushes has been studied. A biotin derivative was immobilized on these surfaces and the interaction with anti-biotin Fabs was evaluated. Interaction data was found to be specific for the studied binding events, and the level of non-specific binding was shown to be low. The surface was proven to be suitable for regeneration, of importance for biomolecular interaction analysis and repetitive immunoassays.

    For comparison, the same interaction system was tested using commercial sensor surfaces with carboxylated self-assembled monolayers. The poly(acrylic acid) surface showed a dramatic increase in signal response with more than ten times the signal of the carboxylated self-assembled monolayer surface. Thus, the present study shows that polymers can be successfully applied to amplify responses on QCM sensors, valuable for studies of interactions between receptors and low molecular weight compounds.

  • 33.
    Edin, Elle
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Polymer Chemistry.
    Composite Regenerative Scaffolds2018Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Regenerative medicine and tissue engineering solutions of heavily innervated tissues are at this point lacklustre. This thesis expands our knowledge of appropriate acellular scaffolds for tissue repair in general and nerve regeneration in particular. The optimal surgical procedure for the implantation of artificial extracellular matrix (ECM) was evaluated for recombinant human collagen (RHCIII) implants. Suturing techniques, as well as the usage of human amniotic membrane “bandages” were evaluated. While complete regeneration of corneal tissues occurred, only slight differences in effects of surgical technique could be found.

    The safety and efficacy of clinical trials using mesenchymal stromal cells (MSCs) was evaluated by conducting a systematic review and meta-analysis. MSC therapy was shown to be safe, with no increases mortality, rehospitalization or adverse events. There was also an indication of efficacy, as the overall mortality in the studies included was significantly smaller in the MSC treated group.

    Multicomponent hydrogel capsules encapsulating single cells were developed. Capsules manufactured from gelatin, agarose and fibrinogen were compared to pure gelatin capsules. The composite capsules successfully delayed cell release and prolonged cell survival.

    Surface patterning of collagen based biomimetic corneas was performed by microcontact printing. The ability of different sizes of fibronectin stripes to stimulate cell adhesion and proliferation was compared. The patterned surfaces improved cell adhesion, as well as proliferation markers.

    Conductive polymer composites were manufactured for use as nerve guides. The guides were created from electrospun polycaprolactone fibers coated with a series of different poly(3,4-ethylenedioxythiophene) films. A comparison of nerve progenitor growth and differentiation on the composite fibers was performed. Both the effects of fiber composition and MSC co-culture was investigated, with or without electrostimulation. MSC treatments and polymer coating was both important for nerve cell differentiation and growth.

    List of papers
    1. Effect of Surgical Technique on Corneal Implant Performance.
    Open this publication in new window or tab >>Effect of Surgical Technique on Corneal Implant Performance.
    Show others...
    2014 (English)In: Translational vision science & technology, ISSN 2164-2591, Vol. 3, no 2, article id 6Article in journal (Refereed) Published
    Abstract [en]

    PURPOSE: Our aim was to determine the effect of a surgical technique on biomaterial implant performance, specifically graft retention.

    METHODS: Twelve mini pigs were implanted with cell-free, 1-ethyl-3-(3-dimethyl aminopropyl) carbodiimide (EDC)/N-hydroxysuccinimide (NHS) cross-linked recombinant human collagen type III (RHCIII) hydrogels as substitutes for donor corneal allografts using overlying sutures with or without human amniotic membrane (HAM) versus interrupted sutures with HAM. The effects of the retention method were compared as well as the effects of collagen concentration (13.7% to 15% RHCIII).

    RESULTS: All implanted corneas showed initial haze that cleared with time, resulting in corneas with optical clarity matching those of untreated controls. Biochemical analysis showed that by 12 months post operation, the initial RHCIII implants had been completely remodeled, as type I collagen, was the major collagenous protein detected, whereas no RHCIII could be detected. Histological analysis showed all implanted corneas exhibited regeneration of epithelial and stromal layers as well as nerves, along with touch sensitivity and tear production. Most neovascularization was seen in corneas stabilized by interrupted sutures.

    CONCLUSIONS: This showed that the surgical technique used does have a significant effect on the overall performance of corneal implants, overlying sutures caused less vascularization than interrupted sutures.

    TRANSLATIONAL RELEVANCE: Understanding the significance of the suturing technique can aid the selection of the most appropriate procedure when implanting artificial corneal substitutes. The same degree of regeneration, despite a higher collagen content indicates that future material development can progress toward stronger, more resistant implants.

    Keywords
    biomaterials, biosynthetic cornea, corneal regeneration, corneal transplantation, recombinant human collagen
    National Category
    Surgery
    Identifiers
    urn:nbn:se:uu:diva-364450 (URN)10.1167/tvst.3.2.6 (DOI)24749003 (PubMedID)
    Available from: 2018-10-29 Created: 2018-10-29 Last updated: 2018-10-29
    2. Conductive PEDOT based coatings on microfibrous scaffolds: a nerve guide component
    Open this publication in new window or tab >>Conductive PEDOT based coatings on microfibrous scaffolds: a nerve guide component
    Show others...
    2018 (English)Manuscript (preprint) (Other (popular science, discussion, etc.))
    National Category
    Biomaterials Science
    Identifiers
    urn:nbn:se:uu:diva-364452 (URN)
    Available from: 2018-10-29 Created: 2018-10-29 Last updated: 2018-10-29
    3. Mesenchymal Stromal Cells for the Treatment of Ischemic Injury and Vascular Trauma: A Systematic Review and Meta-Analysis
    Open this publication in new window or tab >>Mesenchymal Stromal Cells for the Treatment of Ischemic Injury and Vascular Trauma: A Systematic Review and Meta-Analysis
    Show others...
    2018 (English)Manuscript (preprint) (Other (popular science, discussion, etc.))
    National Category
    Other Clinical Medicine
    Identifiers
    urn:nbn:se:uu:diva-364451 (URN)
    Available from: 2018-10-29 Created: 2018-10-29 Last updated: 2018-10-29
    4. Functional fabrication of recombinant human collagen-phosphorylcholine hydrogels for regenerative medicine applications.
    Open this publication in new window or tab >>Functional fabrication of recombinant human collagen-phosphorylcholine hydrogels for regenerative medicine applications.
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    2015 (English)In: Acta Biomaterialia, ISSN 1742-7061, E-ISSN 1878-7568, Vol. 12, p. 70-80, article id S1742-7061(14)00486-3Article in journal (Refereed) Published
    Abstract [en]

    The implant-host interface is a critical element in guiding tissue or organ regeneration. We previously developed hydrogels comprising interpenetrating networks of recombinant human collagen type III and 2-methacryloyloxyethyl phosphorylcholine (RHCIII-MPC) as substitutes for the corneal extracellular matrix that promote endogenous regeneration of corneal tissue. To render them functional for clinical application, we have now optimized their composition and thereby enhanced their mechanical properties. We have demonstrated that such optimized RHCIII-MPC hydrogels are suitable for precision femtosecond laser cutting to produce complementing implants and host surgical beds for subsequent tissue welding. This avoids the tissue damage and inflammation associated with manual surgical techniques, thereby leading to more efficient healing. Although we previously demonstrated in clinical testing that RHCIII-based implants stimulated cornea regeneration in patients, the rate of epithelial cell coverage of the implants needs improvement, e.g. modification of the implant surface. We now show that our 500μm thick RHCIII-MPC constructs comprising over 85% water are suitable for microcontact printing with fibronectin. The resulting fibronectin micropatterns promote cell adhesion, unlike the bare RHCIII-MPC hydrogel. Interestingly, a pattern of 30μm wide fibronectin stripes enhanced cell attachment and showed the highest mitotic rates, an effect that potentially can be utilized for faster integration of the implant. We have therefore shown that laboratory-produced mimics of naturally occurring collagen and phospholipids can be fabricated into robust hydrogels that can be laser profiled and patterned to enhance their potential function as artificial substitutes of donor human corneas.

    Keywords
    Collagen, Cornea, Hydrogel, Laser profiling, Surface modification
    National Category
    Biomaterials Science
    Identifiers
    urn:nbn:se:uu:diva-364449 (URN)10.1016/j.actbio.2014.10.035 (DOI)25448347 (PubMedID)
    Available from: 2018-10-29 Created: 2018-10-29 Last updated: 2018-10-29
    5. Controlled Delivery of Human Cells by Temperature Responsive Microcapsules.
    Open this publication in new window or tab >>Controlled Delivery of Human Cells by Temperature Responsive Microcapsules.
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    2015 (English)In: Journal of Functional Biomaterials, ISSN 2079-4983, E-ISSN 2079-4983, Vol. 6, no 2, p. 439-53Article in journal (Refereed) Published
    Abstract [en]

    Cell therapy is one of the most promising areas within regenerative medicine. However, its full potential is limited by the rapid loss of introduced therapeutic cells before their full effects can be exploited, due in part to anoikis, and in part to the adverse environments often found within the pathologic tissues that the cells have been grafted into. Encapsulation of individual cells has been proposed as a means of increasing cell viability. In this study, we developed a facile, high throughput method for creating temperature responsive microcapsules comprising agarose, gelatin and fibrinogen for delivery and subsequent controlled release of cells. We verified the hypothesis that composite capsules combining agarose and gelatin, which possess different phase transition temperatures from solid to liquid, facilitated the destabilization of the capsules for cell release. Cell encapsulation and controlled release was demonstrated using human fibroblasts as model cells, as well as a therapeutically relevant cell line-human umbilical vein endothelial cells (HUVECs). While such temperature responsive cell microcapsules promise effective, controlled release of potential therapeutic cells at physiological temperatures, further work will be needed to augment the composition of the microcapsules and optimize the numbers of cells per capsule prior to clinical evaluation.

    Keywords
    cell delivery, cell encapsulation, human fibroblast, human umbilical vein endothelial cells, hydrogel, microcapsules, temperature responsive
    National Category
    Biomaterials Science
    Identifiers
    urn:nbn:se:uu:diva-364448 (URN)10.3390/jfb6020439 (DOI)26096147 (PubMedID)
    Available from: 2018-10-29 Created: 2018-10-29 Last updated: 2018-10-29
  • 34. Engelhardt, Eva-Maria
    et al.
    Micol, Lionel A.
    Houis, Stephanie
    Wurm, Florian M.
    Hilborn, Jöns
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry, Polymer Chemistry.
    Hubbell, Jeffrey A.
    Frey, Peter
    A collagen-poly(lactic acid-co-epsilon-caprolactone) hybrid scaffold for bladder tissue regeneration2011In: Biomaterials, ISSN 0142-9612, E-ISSN 1878-5905, Vol. 32, no 16, p. 3969-3976Article in journal (Refereed)
    Abstract [en]

    Scaffold materials should favor cell attachment and proliferation, and provide designable 3D structures with appropriate mechanical strength. Collagen matrices have proven to be beneficial scaffolds for tissue regeneration. However, apart from small intestinal submucosa, they offer a limited mechanical strength even if crosslinking can enhance their mechanical properties. A more cell-friendly way to increase material strength is to combine synthetic polymer meshes with plastic compressed collagen gels. This work describes the potential of plastic compressed collagen poly(lactic acid-co-epsilon-caprolactone) (PLAC) hybrids as scaffolds for bladder tissue regeneration. Human bladder smooth muscle and urothelial cells were cultured on and inside collagen PLAC hybrids in vitro. Scaffolds were analyzed by electron microscopy, histology, immunohistochemistry, and AlamarBlue assay. Both cell types proliferated in and on the hybrid, forming dense cell layers on top after two weeks. Furthermore, hybrids were implanted subcutaneously in the backs of nude mice. Host cell infiltration, scaffold degradation, and the presence of the seeded bladder cells were analyzed. Hybrids showed a lower inflammatory reaction in vivo than PLAC meshes alone, and first signs of polymer degradation were visible at six months. Collagen PLAC hybrids have potential for bladder tissue regeneration, as they show efficient cell seeding, proliferation, and good mechanical properties.

  • 35.
    Engstrand, Johanna
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Hilborn, Jöns
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Polymer Chemistry.
    Engqvist, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Polymers influencing the strength of injectable calcium phosphate bone cements-a preliminary study2012In: 22nd Interdisciplinary Research Conference on Biomaterials May 10th -12th, 2012, Uppsala, Swden.European Cells and Materials Vol 23 Suppl 3 2012 (page 32), 2012, p. 32-Conference paper (Refereed)
  • 36.
    Eriksson, Therese
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Mindemark, Jonas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Yue, Ma
    Northwestern Polytech Univ, Ctr Nano Energy Mat, Sch Mat Sci & Engn, Youyi West Rd 127, Xian, Shaanxi, Peoples R China.
    Brandell, Daniel
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Effects of nanoparticle addition to poly(epsilon-caprolactone) electrolytes: Crystallinity, conductivity and ambient temperature battery cycling2019In: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 300, p. 489-496Article in journal (Refereed)
    Abstract [en]

    It has previously been shown that nanoparticle additives can, in a simple way, significantly improve the ionic conductivity in solid polymer electrolyte systems with the semi-crystalline poly(ethylene oxide) (PEO) as a host material. It has been suggested that the improved ionic conductivity is a result of reduced degree of crystallinity and additional conductivity mechanisms occurring in the material. In this work, this principle is applied to another semi-crystalline polymer host: poly(epsilon-caprolactone) (PCL). This is a polymer with comparable properties (T-g, T-m, etc.) as PEO, and constitute a promising material for use in solid polymer electrolytes for lithium ion batteries. 15 wt% of the respective nanoparticles TiO2, Al2O3 and h-BN have been added to the PCL-LiTFSI solid polymer electrolyte in an attempt to increase the conductivity and achieve stable room temperature cyclability. The crystallinity, ionic conductivity and electrochemical properties were investigated by differential scanning calorimetry, electrochemical impedance spectroscopy and galvanostatic cycling of cells. The results showed that with an addition of 15 wt% Al2O3, the degree of crystallinity is reduced to 6-7% and the ionic conductivity increased to 6-7 x 10(-6) S cm(-1) at room temperature, allowing successful cycling of cells at 30 degrees C, while h-BN did not contribute to similar improvements. The effect of nanoparticles, however, differ significantly from previous observations in PEO systems, which could be explained by different surface-polymer interactions or the degree of ordering in the amorphous phases of the materials.

  • 37. Ferreira, Silvia A
    et al.
    Motwani, Meghna S
    Faull, Peter A
    Seymour, Alexis J
    Yu, Tracy T L
    Enayati, Marjan
    Taheem, Dheraj K
    Salzlechner, Christoph
    Haghighi, Tabasom
    Kania, Ewa M
    Oommen, Oommen P
    Ahmed, Tarek
    Loaiza, Sandra
    Parzych, Katarzyna
    Dazzi, Francesco
    Varghese, Oommen P.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Polymer Chemistry. Uppsala University, Science for Life Laboratory, SciLifeLab.
    Festy, Frederic
    Grigoriadis, Agamemnon E
    Auner, Holger W
    Snijders, Ambrosius P
    Bozec, Laurent
    Gentleman, Eileen
    Bi-directional cell-pericellular matrix interactions direct stem cell fate2018In: Nature Communications, ISSN 2041-1723, E-ISSN 2041-1723, Vol. 9, no 1, article id 4049Article in journal (Refereed)
    Abstract [en]

    Modifiable hydrogels have revealed tremendous insight into how physical characteristics of cells' 3D environment drive stem cell lineage specification. However, in native tissues, cells do not passively receive signals from their niche. Instead they actively probe and modify their pericellular space to suit their needs, yet the dynamics of cells' reciprocal interactions with their pericellular environment when encapsulated within hydrogels remains relatively unexplored. Here, we show that human bone marrow stromal cells (hMSC) encapsulated within hyaluronic acid-based hydrogels modify their surroundings by synthesizing, secreting and arranging proteins pericellularly or by degrading the hydrogel. hMSC's interactions with this local environment have a role in regulating hMSC fate, with a secreted proteinaceous pericellular matrix associated with adipogenesis, and degradation with osteogenesis. Our observations suggest that hMSC participate in a bi-directional interplay between the properties of their 3D milieu and their own secreted pericellular matrix, and that this combination of interactions drives fate.

  • 38.
    Fjällström, Alma
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences.
    Draxler, Emmy
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences.
    Adan, Saida
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences.
    Andersson, Sandra
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences.
    Aidanpää, Louise
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences.
    The discolouration of Hyaluronan in presence of phosphate buffer2018Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Hyaluronan is a polymer that among other things is used in fillers. Products containing Hyaluronan is sometimes discoloured over time and the mechanism behind this discolouration is still unknown. However, it was suspected that discolouration occurs during the degradation due to high pH values or with a phosphate buffer. The discolouration of Hyaluronan that occurs with phosphate buffer was studied in more detail in this project. The samples of Hyaluronan with different concentrations of phosphate buffer were left at 90 °C in an oven to speed up the discolouration. These samples were then analyzed byusing UV/Vis spectrophotometry to measure the absorption and capillary viscometry to measure the molecular weight. The results showed that the discolouration increased with time and that the samples with the higher concentration of buffer got more discoloured faster. The molecular weight showed a decreasing trend with time. It also suggested that the phosphate buffer had an impact on the molecular weight. The samples with the highest concentration of phosphate buffer had a lower molecular weight compared to samples with no phosphate buffer. The main conclusion from this study is that the phosphate buffer had an effect on the discolouration of Hyaluronan.

  • 39.
    Forsgren, Johan
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials. Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Brohede, Ulrika
    Sandvik AB, Stockholm.
    Piskounova, Sonya
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry, Polymer Chemistry.
    Mihranyan, Albert
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Larsson, Sune
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Orthopaedics.
    Maria, Strømme
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Engqvist, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    In Vivo Evaluation of Functionalized Biomimetic Hydroxyapatite for Local Delivery of Active Agents2011In: Journal of Biomaterials and Nanobiotechnology, ISSN 2158-7027, 2158-7043, Vol. 2, no 2, p. 149-154Article in journal (Refereed)
    Abstract [en]

    This study was carried out to investigate the biological response in vivo to biomimetic hydroxyapatite implant coatings functionalized with bisphosphonates and bone morphogenetic proteins. The functionalization was carried out by a simple soaking procedure in the operating room immediately prior to surgery. Cylindrical titanium samples with and without coatings were implanted in the distal femoral epiphysis of sheep and retrieved after 6 weeks. The histological analysis proved that all samples were integrated well in the tissue with no signs of intolerance. Fewer osteoclasts were observed in the vicinity of bisphosphonate-functionalized samples and the bone was denser around these samples compared to the other samples. Samples functionalized with bone morphogenetic protein induced more bone/implant contact but showed a more inconsistent outcome with reduced bone density around the samples. This study demonstrates a simple method to functionalize implant coatings, which provides surgeons with an option of patient-specific functionalization of implants. The observed biological impact due to the delivery of active molecules from the coatings suggests that this strategy may also be employed to deliver antibiotics from similar coatings.

  • 40.
    Fu, Lian-Hua
    et al.
    Beijing Forestry Univ, Coll Mat Sci & Technol, Beijing Key Lab Lignocellulos Chem, Beijing 100083, Peoples R China..
    Liu, Yan-Jun
    Beijing Forestry Univ, Coll Mat Sci & Technol, Beijing Key Lab Lignocellulos Chem, Beijing 100083, Peoples R China..
    Ma, Ming-Guo
    Beijing Forestry Univ, Coll Mat Sci & Technol, Beijing Key Lab Lignocellulos Chem, Beijing 100083, Peoples R China..
    Zhang, Xue-Ming
    Beijing Forestry Univ, Coll Mat Sci & Technol, Beijing Key Lab Lignocellulos Chem, Beijing 100083, Peoples R China..
    Xue, Zhi-Min
    Beijing Forestry Univ, Coll Mat Sci & Technol, Beijing Key Lab Lignocellulos Chem, Beijing 100083, Peoples R China..
    Zhu, Jie-Fang
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Microwave-Assisted Hydrothermal Synthesis of Cellulose/Hydroxyapatite Nanocomposites2016In: Polymers, ISSN 2073-4360, E-ISSN 2073-4360, Vol. 8, no 9, article id 316Article in journal (Refereed)
    Abstract [en]

    In this paper, we report a facile, rapid, and green strategy for the synthesis of cellulose/hydroxyapatite (HA) nanocomposites using an inorganic phosphorus source (sodium dihydrogen phosphate dihydrate (NaH(2)PO(4)2H(2)O)), or organic phosphorus sources (adenosine 5-triphosphate disodium salt (ATP), creatine phosphate disodium salt tetrahydrate (CP), or D-fructose 1,6-bisphosphate trisodium salt octahydrate (FBP)) through the microwave-assisted hydrothermal method. The effects of the phosphorus sources, heating time, and heating temperature on the phase, size, and morphology of the products were systematically investigated. The experimental results revealed that the phosphate sources played a critical role on the phase, size, and morphology of the minerals in the nanocomposites. For example, the pure HA was obtained by using NaH(2)PO(4)2H(2)O as phosphorus source, while all the ATP, CP, and FBP led to the byproduct, calcite. The HA nanostructures with various morphologies (including nanorods, pseudo-cubic, pseudo-spherical, and nano-spherical particles) were obtained by varying the phosphorus sources or adjusting the reaction parameters. In addition, this strategy is surfactant-free, avoiding the post-treatment procedure and cost for the surfactant removal from the product. We believe that this work can be a guidance for the green synthesis of cellulose/HA nanocomposites in the future.

  • 41. Furlani, Maurizio
    et al.
    Stappen, Christopher
    Mellander, Bengt-Erik
    Niklasson, Gunnar A.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Concentration dependence of ionic relaxation in lithium doped polymer electrolytes2010In: Journal of Non-Crystalline Solids, ISSN 0022-3093, E-ISSN 1873-4812, Vol. 356, no 11-17, p. 710-714Article in journal (Refereed)
    Abstract [en]

    A detailed impedance spectroscopy study at ambient temperature was carried out on polymer electrolytes based on low molecular weight poly(ethylene oxide) 400, poly(propylene oxide) 400 and a random copolymer of molecular weight 600, to which were added LiN(CF3SO2)(2) (LiTFSI) salt. The ionic conductivity exhibits a maximum at intermediate salt concentrations and is significantly higher for poly(ethylene oxide) and the copolymer. A dielectric relaxation was found in a frequency region above the one, where the ion conductivity dominates the dielectric response, and below the region of the relaxations of the polymer host. The relaxation strength scales with ion concentration, as appropriate for an ion pair relaxation in systems above the glass transition. The frequency of this relaxation, multiplied by the relaxation strength, has been found to be proportional to the ion conductivity, and the relaxation has therefore been assigned to short-range ionic motion in the polymer. It exhibits characteristics similar to conductivity relaxations in inorganic solid ion conductors, and is considered to be due to the same species that give rise to the ion conductivity.

  • 42.
    Galkin, Maxim
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Synthetical Organic Chemistry.
    Palladium-catalyzed lignin valorization: Towards a lignin-based biorefinery2015Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The work described in this thesis focuses on the cleavage of the β-O-4′ bond, which is the most abundant interunit linkage in the lignin polymer.

    In the first part, three methods based on palladium catalysis have been developed and their applicability has been verified using lignin model compounds. A transfer hydrogenolysis of the β-O-4′ bond using formic acid as a mild hydrogen donor together with a base. An aerobic oxidation of the benzylic alcohol motif in the β-O-4′ linkage to generate a key intermediate in the cleavage reaction was performed. A redox neutral cleavage of the β-O-4′ bond was accomplished in which no stoichiometric reducing or oxidizing agents were added.

    In the second part of the thesis, a mechanistic study is presented. The corresponding ketone from a dehydrogenation reaction of the benzylic alcohol motif was identified to be the key intermediate. This ketone and its enol tautomer was found to be responsible for the β-O-4′ bond cleavage reaction under the employed reaction conditions.

    In the final part of this thesis, the methodologies have been applied to native lignin. The depolymerization reaction was combined with organosolv pulping. This approach was successful, and together with cellulose and hemicellulose, propenyl aryls were generated in excellent yields directly from wood. In this transformation, the lignin derived molecules have been reduced by an endogenous hydrogen donor from the wood.

    List of papers
    1. Mild Heterogeneous Palladium-Catalyzed Cleavage of beta-O-4 '-Ether Linkages of Lignin Model Compounds and Native Lignin in Air
    Open this publication in new window or tab >>Mild Heterogeneous Palladium-Catalyzed Cleavage of beta-O-4 '-Ether Linkages of Lignin Model Compounds and Native Lignin in Air
    Show others...
    2014 (English)In: ChemCatChem, ISSN 1867-3880, E-ISSN 1867-3899, Vol. 6, no 1, p. 179-184Article in journal (Refereed) Published
    Abstract [en]

    A mild and robust heterogeneous palladium-catalyzed CO bond cleavage of 2-aryloxy-1-arylethanols using formic acid as reducing agent in air was developed. The cleaved products were isolated in 92-98% yield; and by slightly varying the reaction conditions, a ketone, an alcohol, or an alkane can be generated in near-quantitative yield. This reaction is applicable to cleaving the -O-4-ether bond found in lignin polymers of different origin. The reaction was performed on a lignin polymer model to generate either the monomeric aryl ketone or alkane in a quantitative yield. Moderate depolymerization was achieved with native lignin at similar reaction conditions. Mechanistic studies under kinetic control indicate that an initial palladium-catalyzed dehydrogenation of the alcohol is followed by insertion of palladium to an enol equivalent. A palladium-formato complex reductively cleaves the palladium-enolate complex to generate the ketone.

    Keywords
    heterogeneous catalysis, cleavage reactions, green chemistry, palladium, polymers, lignin
    National Category
    Natural Sciences
    Identifiers
    urn:nbn:se:uu:diva-220309 (URN)10.1002/cctc.201300540 (DOI)000330636800023 ()
    Note

    De två första författarna delar första författarskapet.

    Available from: 2014-03-17 Created: 2014-03-12 Last updated: 2017-12-05Bibliographically approved
    2. Selective Aerobic Benzylic Alcohol Oxidation of Lignin Model Compounds: Route to Aryl Ketones
    Open this publication in new window or tab >>Selective Aerobic Benzylic Alcohol Oxidation of Lignin Model Compounds: Route to Aryl Ketones
    2015 (English)In: ChemCatChem, ISSN 1867-3880, E-ISSN 1867-3899, Vol. 7, no 3, p. 401-404Article in journal (Refereed) Published
    Abstract [en]

    A mild and chemoselective oxidation of the -alcohol in -O-4-ethanoaryl and -O-4-glycerolaryl ethers has been developed. The benzylic alcohols were selectively dehydrogenated to the corresponding ketones in 60-93% yield. A one-pot selective route to aryl ethyl ketones was performed. The catalytic system comprises recyclable heterogeneous palladium, mild reaction conditions, green solvents, and oxygen in air as oxidant. Catalytic amounts of a coordinating polyol were found pivotal for an efficient aerobic oxidation.

    Keywords
    biomass valorization, heterogeneous catalysis, lignin, oxidation, palladium
    National Category
    Chemical Sciences
    Identifiers
    urn:nbn:se:uu:diva-246820 (URN)10.1002/cctc.201402825 (DOI)000349147100005 ()
    Available from: 2015-03-11 Created: 2015-03-10 Last updated: 2017-12-04Bibliographically approved
    3. Mild and Robust Redox-Neutral Pd/C-Catalyzed Lignol -O-4 Bond Cleavage Through a Low-Energy-Barrier Pathway
    Open this publication in new window or tab >>Mild and Robust Redox-Neutral Pd/C-Catalyzed Lignol -O-4 Bond Cleavage Through a Low-Energy-Barrier Pathway
    2015 (English)In: ChemSusChem, ISSN 1864-5631, E-ISSN 1864-564X, Vol. 8, no 13, p. 2187-2192Article in journal (Refereed) Published
    Abstract [en]

    A Pd/C catalyzed redox neutral CO bond cleavage of 2-aryloxy-1-arylethanols has been developed. The reactions are carried out at 80 degrees C, in air, using a green solvent system to yield the aryl ketones in near quantitative yields. Addition of catalytic amounts of a hydrogen source to the reaction mixture activates the catalyst to proceed through a low energy barrier pathway. Initial studies support a transfer hydrogenolysis reaction mechanism that proceeds through an initial dehydrogenation followed by an enol adsorption to Pd/C and a reductive CO bond cleavage.

    Keywords
    heterogeneous catalysis, lignin, palladium, reaction mechanisms, transfer hydrogenolysis
    National Category
    Chemical Sciences
    Identifiers
    urn:nbn:se:uu:diva-259649 (URN)10.1002/cssc.201500117 (DOI)000357619000004 ()25925736 (PubMedID)
    Funder
    Swedish Energy Agency
    Available from: 2015-08-20 Created: 2015-08-10 Last updated: 2017-12-04Bibliographically approved
    4. Selective Route to 2-Propenyl Aryls Directly from Wood by a Tandem Organosolv and Palladium-Catalysed Transfer Hydrogenolysis
    Open this publication in new window or tab >>Selective Route to 2-Propenyl Aryls Directly from Wood by a Tandem Organosolv and Palladium-Catalysed Transfer Hydrogenolysis
    2014 (English)In: ChemSusChem, ISSN 1864-5631, E-ISSN 1864-564X, Vol. 7, no 8, p. 2154-2158Article in journal (Refereed) Published
    Abstract [en]

    A tandem organosolv pulping and Pd-catalysed transfer hydrogenolysis depolymerisation and deoxygenation has been developed. The tandem process generated 2-methoxy-4-(prop-1-enyl)phenol in 23 % yield (92 % theoretical monomer yield) starting from pine wood and 2,6-dimethoxy-4-(prop-1-enyl)phenol in 49 % yield (92 % theoretical monomer yield) starting from birch wood. Only endogenous hydrogen from wood was consumed, and the reaction was performed using green solvents.

    Keywords
    Biomass, Lignin Green, Chemistry, Palladium, catalysis
    National Category
    Organic Chemistry
    Research subject
    Chemistry with specialization in Organic Chemistry
    Identifiers
    urn:nbn:se:uu:diva-226637 (URN)10.1002/cssc.201402017 (DOI)000340519500016 ()
    Funder
    Swedish Energy Agency
    Available from: 2014-06-18 Created: 2014-06-18 Last updated: 2017-12-05Bibliographically approved
  • 43.
    Gerz, Isabelle
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Kullgren, Jolla
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Mindemark, Jonas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Oligomer electrolytes for light-emitting electrochemical cells: Experimental and computational insights2018Conference paper (Refereed)
  • 44. Golker, Kerstin
    et al.
    Karlsson, Bjorn C. G.
    Wiklander, Jesper G.
    Rosengren, Annika M.
    Nicholls, Ian A.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC.
    Hydrogen bond diversity in the pre-polymerization stage contributes to morphology and MIP-template recognition - MAA versus MMA2015In: European Polymer Journal, ISSN 0014-3057, E-ISSN 1873-1945, Vol. 66, p. 558-568Article in journal (Refereed)
    Abstract [en]

    This report demonstrates that the diversity of hydrogen bond interactions present in molecularly imprinted polymer pre-polymerization mixtures, typically associated with binding-site heterogeneity, can also contribute to morphological characteristics that may influence polymer-template recognition. Comparisons have been made between a series of bupivacaine molecularly imprinted methacrylic acid (MAA)-ethylene glycol dimethacrylate (EGDMA) copolymers and a series of analogous methyl methacrylate (MMA)-EGDMA copolymers using comprehensive molecular dynamics studies of the respective pre-polymerization mixtures, template-polymer binding studies and detailed BET surface area and BJH porosity analyses. The role of the carboxylic acid functionality of MAA, and in particular the acidic proton, in generating morphological features conducive to analyte access (slit-like rather than ink bottle-like structures) and recognition is discussed.

  • 45.
    Golker, Kerstin
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC. Linnaeus Univ, Ctr Biomat Chem, Bioorgan & Biophys Chem Lab, SE-39182 Kalmar, Sweden.
    Nicholls, Ian A.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC. Linnaeus Univ, Ctr Biomat Chem, Bioorgan & Biophys Chem Lab, SE-39182 Kalmar, Sweden.
    The effect of crosslinking density on molecularly imprinted polymer morphology and recognition2016In: European Polymer Journal, ISSN 0014-3057, E-ISSN 1873-1945, Vol. 75, p. 423-430Article in journal (Refereed)
    Abstract [en]

    In this report, the crosslinking density of bupivacaine molecularly imprinted methacrylic acid (MAA)-ethylene glycol dimethacrylate (EGDMA) copolymers was investigated through replacement of EGDMA by methyl methacrylate (MMA). The effects were examined using a series of full-scale MD simulations of pre-polymerization mixtures, equilibrium rebinding studies on the corresponding synthesized polymers and morphology characterization through nitrogen sorption measurements. While the extent of hydrogen bonding between the functional monomer MAA and bupivacaine observed in the MD pre-polymerization mixtures was comparable in each of the systems studied, the decrease in degree of crosslinking impacted directly on polymer morphology as observed in BET and BJH studies of surface area and porosity. Further, decreases in the crosslinking density induced reductions in template rebinding capacity as seen from a series of radio-ligand binding studies, demonstrating the importance of crosslinking on the performance of molecularly imprinted MAA-EGDMA copolymers, the polymer system most commonly used in molecular imprinting science and technology.

  • 46.
    Golker, Kerstin
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC. Linnaeus Univ, Bioorgan & Biophys Chem Lab, Ctr Biomat Chem, Dept Chem & Biomed Sci, SE-39182 Kalmar, Sweden..
    Olsson, Gustaf D.
    Linnaeus Univ, Bioorgan & Biophys Chem Lab, Ctr Biomat Chem, Dept Chem & Biomed Sci, SE-39182 Kalmar, Sweden..
    Nicholls, Ian
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Organic Chemistry. Linnaeus Univ, Bioorgan & Biophys Chem Lab, Ctr Biomat Chem, Dept Chem & Biomed Sci, SE-39182 Kalmar, Sweden..
    The influence of a methyl substituent on molecularly imprinted polymer morphology and recognition - Acrylic acid versus methacrylic acid2017In: European Polymer Journal, ISSN 0014-3057, E-ISSN 1873-1945, Vol. 92, p. 137-149Article in journal (Refereed)
    Abstract [en]

    In this report, we have investigated factors contributing to the morphology and template recognition of bupivacaine-imprinted copolymers of methacrylic acid (MAA) and ethyleneglycol dimethacrylate (EGDMA). To this end, MAA, the most commonly used functional monomer in non-covalent molecular imprinting protocols, was compared and contrasted with the closely related acrylic acid (AA) in terms of polymer morphologies, recognition characteristics, and molecular level events in the corresponding pre-polymerization mixtures. Two series of analogous bupivacaine-imprinted EGDMA-copolymers containing increasing fractions of either AA or MAA were studied through all-component MD simulations in the pre-polymerization phase, equilibrium binding experiments on corresponding synthesized polymers and morphology characterization by N-2-sorption measurements. A higher degree of hydrogen bonding frequency between respective functional monomer and bupivacaine was recorded for the mixtures containing AA compared to those containing MAA. In contrast, results from binding experiments demonstrated higher binding capacities for the polymers prepared with MAA than for those prepared with AA, which is explained by differences in polymer morphology. The surface areas and pore volumes of the AA-polymers were higher than for the MAA-polymers and the overall pore structure in the AA-polymers was ink-bottle shaped while the pores in the MAA-polymers were slit-shaped. We suggest that the methyl substituent of MAA contributes to differences in the reaction kinetics for AA and MAA during polymerization and resulted in different morphologies, in particular pore shape, which affected mass-transfer and consequently the binding qualities of the materials.

  • 47.
    Green, Joshua P.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Synthetic Molecular Chemistry. Imperial Coll London, Dept Chem, London SW7 2AZ, England.
    Cha, Hyojung
    Imperial Coll London, Dept Chem, London SW7 2AZ, England.
    Shahid, Munazza
    Imperial Coll London, Dept Chem, London SW7 2AZ, England.
    Creamer, Adam
    Imperial Coll London, Dept Chem, London SW7 2AZ, England.
    Durrant, James R.
    Imperial Coll London, Dept Chem, London SW7 2AZ, England.
    Heeney, Martin
    Imperial Coll London, Dept Chem, London SW7 2AZ, England.
    Dithieno[3,2-b:2,3-d]arsole-containing conjugated polymers in organic photovoltaic devices2019In: Dalton Transactions, ISSN 1477-9226, E-ISSN 1477-9234, Vol. 48, no 20, p. 6676-6679Article in journal (Refereed)
    Abstract [en]

    Arsole-derived conjugated polymers are a relatively new class of materials in the field of organic electronics. Herein, we report the synthesis of two new donor polymers containing fused dithieno[3,2-b:2,3-d]arsole units and report their application in bulk heterojunction solar cells for the first time. Devices based upon blends with PC71BM display high open circuit voltages around 0.9 V and demonstrate power conversion efficiencies around 4%.

  • 48.
    Gurav, Deepanjali
    et al.
    Savitri Bai Phule Pune Univ, Dept Chem, Pune, Maharashtra, India..
    Varghese, Oommen P.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Polymer Chemistry.
    Hamad, Osama A.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Immunology, Genetics and Pathology.
    Nilsson, Bo
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Immunology, Genetics and Pathology, Clinical Immunology.
    Hilborn, Jöns
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Polymer Chemistry.
    Oommen, Oommen Podiyan
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Polymer Chemistry.
    Chondroitin sulfate coated gold nanoparticles: a new strategy to resolve multidrug resistance and thromboinflammation2016In: Chemical Communications, ISSN 1359-7345, E-ISSN 1364-548X, Vol. 52, no 5, p. 966-969Article in journal (Refereed)
    Abstract [en]

    We have developed the first chondroitin sulfate polymer coated gold nanoparticles that can simultaneously overcome mulidrug resistance in cancer cells and suppress thromboinflammation triggered by the chemotherapeutic drug.

  • 49.
    Hasan, Mohammad Nazmul
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström.
    Developing Glycopeptide based nanocarriers by ring opening polymerization for drug delivery applications2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Synthetic glycopeptides have attracted much interest in the biomedical field due to their structural similarities to the natural glycopeptides or glycoproteins. It is still difficult to synthesize glycopeptides with greater efficiency and ring opening polymerization remains an effective way to do so. Proteoglycans are a special class of glycoproteins with glycosaminoglycan chains. In this study, I tried to do controlled ring opening polymerization of Hyaluronic acid derivatives with smaller to higher molecular weight while avoiding side reactions. It is challenging to work with higher molecular weight molecules and do a click reaction in water effectively. Making nanopolymers with a desired size, studies of the characteristics, and how to build nanocarriers for drug delivery application was the focus of this work. Polymeric characteristics, e.g., modification and polymer formation were studied by nuclear magnetic resonance technique; Particle size was studied by dynamic light scattering and the loading of rhodamine B encapsulated into the polymer was measured by confocal imaging technique.

  • 50.
    Hellsing, Maja S.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Physics.
    Rennie, Adrian R.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Physics.
    Porcar, Lionel
    Englund, Carl-Johan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Scattering from Dilute and Lamellar Phase Solutions of Aerosol-OT Simultaneous Probe of Surface Structures and Bulk2011In: Trends in colloid andinterface science XXIV / [ed] Viktor Starov, Karel Procházka, 2011, Vol. 138, p. 139-142Conference paper (Refereed)
    Abstract [en]

    The benefits of simultaneous studies of adsorbed layers and bulk structures are shown for solutions of the surfactant Aerosol-OT. Above the critical micelle concentration, Aerosol-OT forms an aligned lamellar phase at the sapphire/solution interface which is in equilibrium with a bulk phase that consists of coexisting micellar solution and dispersed lamellar phase. Measurements of the aligned surface layers and the bulk scattering from a 2% wt solution by grazing incidence and small-angle neutron scattering show that the bulk consist of lamellar structures with the same d-spacing as seen at the surface but without the surface induced alignment. The surface lamellar structure corresponds to a 10% volume fraction for a 2% wt bulk which implies that there must be coexistence of regions of different concentration. Scattering patterns measured in grazing incidence geometry clearly show the relative contributions from small-angle scattering and specular reflectivity.

1234 1 - 50 of 166
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