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  • 301. Encinas, S.
    et al.
    Climent, M. J.
    Gil, S.
    Abrahamsson, U. O.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Physical Chemistry. Department of Physical and Analytical Chemistry, Physical Chemistry I.
    Davidsson, J.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Physical Chemistry. Department of Physical and Analytical Chemistry, Physical Chemistry I.
    Miranda, M.A.
    Singlet excited-state interactions in naphthalene-thymine dyads2004In: Chemphyschem, Vol. 5, no 11, p. 1704-Article in journal (Refereed)
  • 302.
    Englund, S
    et al.
    Uppsala University, Centre for Surface Biotechnology.
    Bolske, G
    Ballagi-Pordany, A
    Johansson, KE
    Detection of Mycobacterium avium subsp paratuberculosis in tissue samples by single, fluorescent and nested PCR based on the IS900 gene2001In: VETERINARY MICROBIOLOGY, ISSN 0378-1135, Vol. 81, no 3, p. 257-271Article in journal (Refereed)
    Abstract [en]

    The aim of this study was to determine if fluorescent PCR could be used instead of nested PCR, for the detection of Mycobacterium avium subsp. paratuberculosis (M. paratuberculosis) in clinical specimens, to improve the sensitivity without increasing the

  • 303.
    Engman, Mattias
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Biochemistry and Organic Chemistry.
    Cheruku, Pradeep
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Biochemistry and Organic Chemistry.
    Tolstoy, Päivi
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Biochemistry and Organic Chemistry.
    Bergquist, Jonas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry.
    Völker, Sebastian F
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Biochemistry and Organic Chemistry.
    Andersson, Pher G
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Biochemistry and Organic Chemistry.
    Highly Selective Iridium-Catalyzed Asymmetric Hydrogenation of Trifluoromethyl Olefins: A New Route to Trifluoromethyl-Bearing Stereocenters2009In: Advanced Synthesis and Catalysis, ISSN 1615-4150, E-ISSN 1615-4169, Vol. 351, no 3, p. 375-378Article in journal (Refereed)
    Abstract [en]

    Fluorine-containing compounds are useful in many applications ranging from pharmaceuticals to ferroelectric crystals. We have developed a new, highly enantioselective synthetic route to trifluoromethyl-bearing stereocenters in up to 96% ee via asymmetric hydrogenation using N,P-ligated iridium catalysts. We also hydrogenated an isomeric mixture of olefins; this reaction gave the hydrogenation product highly enantioselectively (87% ee), and only the E isomer was present after the reaction had reached 56% conversion.

  • 304.
    Enmark, Martin
    et al.
    Department of Chemistry and Biomedical Sciences, Karlstad University, Sweden.
    Samuelsson, Jörgen
    Department of Chemistry and Biomedical Sciences, Karlstad University, Sweden.
    Undin, Torgny
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Analytical Chemistry.
    Fornstedt, Torgny
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Analytical Chemistry.
    Characterization of an unusual adsorption behavior of racemic methyl-mandelate on a tris-(3,5-dimethylphenyl) carbamoyl cellulose chiral stationary phase2011In: Journal of Chromatography A, ISSN 0021-9673, E-ISSN 1873-3778, Vol. 1218, no 38, p. 6688-6696Article in journal (Refereed)
    Abstract [en]

    An interesting adsorption behavior of racemic methyl mandelate on a tris-(3,5-dimethylphenyl)carbamoyl cellulose chiral stationary phase was theoretically and experimentally investigated. The overloaded band of the more retained enantiomer had a peculiar shape indicating a type V adsorption isotherm whereas the overloaded band of the less retained enantiomer had a normal shape indicating a type I adsorption behavior. For a closer characterization of this separation, adsorption isotherms were determined and analyzed using an approach were Scatchard plots and adsorption energy distribution (AED) calculations are combined for a deeper analysis. It was found that the less retained enantiomer was best described by a Tóth adsorption isotherm while the second one was best described with a bi-Moreau adsorption isotherm. The latter model comprises non-ideal adsorbate–adsorbate interactions, providing an explanation to the non-ideal adsorption of the more retained enantiomer. Furthermore, the possibility of using the Moreau model as a local model for adsorption in AED calculations was evaluated using synthetically generated raw adsorption slope data. It was found that the AED accurately could predict the number of adsorption sites for the generated data. The adsorption behavior of both enantiomers was also studied at several different temperatures and found to be exothermic; i.e. the adsorbate–adsorbate interaction strength decreases with increasing temperature. Stochastic analysis of the adsorption process revealed that the average amount of adsorption/desorption events increases and the sojourn time decreases with increasing temperature.

  • 305.
    Enquist, Per-Anders
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Organic Pharmaceutical Chemistry.
    Nilsson, Peter
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry.
    Sjöberg, Per
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry.
    Larhed, Mats
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry.
    ESI-MS Detection of Proposed Reaction Intermediates in the Air-Promoted and Ligand-Modulated Oxidative Heck Reaction2006In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 71, no 23, p. 8779-8786Article in journal (Refereed)
    Abstract [en]

    Electrospray ionization mass spectrometry (ESI-MS) and subsequent MS/MS analyses were used to directly detect palladium-containing cationic reaction intermediates in a ligand controlled palladium(II)-catalyzed oxidative Heck arylation. All potential intermediates were observed as dmphen-ligated palladium(II) species, suggesting that the dmphen bidentate ligand is attached to the metal center during the entire catalytic cycle. The study supports previous mechanistic propositions and provides new information regarding the composition of aryl-containing Pd(II) complexes in an ongoing oxidative Heck reaction. In addition, sodium acetate was found to be a useful base alternative to previously used tertiary amines.

  • 306.
    Erdélyi, Máté
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry. Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Biochemistry and Organic Chemistry.
    Varedian, Miranda
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Biochemistry and Organic Chemistry.
    Sköld, Christian
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry.
    Niklasson, Ida B.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry.
    Nurbo, Johanna
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry.
    Persson, Åsa
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry.
    Bergquist, Jonas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry.
    Gogoll, Adolf
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Biochemistry and Organic Chemistry.
    Chemistry and folding of photomodulable peptides: stilbene and thioaurone-type candidates for conformational switches2008In: Organic and biomolecular chemistry, ISSN 1477-0520, E-ISSN 1477-0539, Vol. 6, no 23, p. 4356-4373Article in journal (Refereed)
    Abstract [en]

    Optimized synthetic strategies for the preparation of photoswitchable molecular scaffolds based on stilbene or on thioaurone chromophores and their conformationally directing properties, as studied by computations and by NMR spectroscopy, are addressed. For the stilbene peptidomimetics 1, 2 and 3, the length of connecting linkers between the chromophore and the peptide strands was varied, resulting in photochromic dipeptidomimetics with various flexibility. Building blocks of higher rigidity, based on para-substituted thioaurone ( 4 and 6) and meta-substituted thioaurone chromophores ( 5 and 7) are shown to have a stronger conformationally directing effect. Design, synthesis, theoretical and experimental conformational analyses are presented.

  • 307.
    Erenpreisa, Je
    et al.
    Uppsala University, Centre for Surface Biotechnology.
    Ivanov, A
    Dekena, G
    Vitina, A
    Krampe, R
    Uppsala University, Centre for Surface Biotechnology.
    Freivalds, T
    Selivanova, G
    Roach, H.I
    Arrest in Metaphase and Anatomy of Mitotic Catastrophe: Mild Heat Shock in Two Human Osteosarcoma Cell Lines2000In: Cell Biology International, Vol. 24, no 2, p. 61-70Article in journal (Refereed)
  • 308.
    Erenpreisa, Je., Krampe, R., Dekena, G., Vitina A., Freivalds, T., Fringes, B.
    Uppsala University, Centre for Surface Biotechnology.
    Interphase and Mitotic (delayed) Cell Death in Heat Shock Treated Osteosarcoma Cell Line (Hos Te85)1998In: Deutsche Gesellschaft für Pathologic. Kassel Abstr., Vol. 59, p. 002-006Article in journal (Refereed)
  • 309.
    Ericsson, Marie
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Quantum Chemistry.
    Holonomic quantum logic gates2002In: Quantum Theory: Reconsideration of Foundations / [ed] A. Khrennikov, 2002, p. 75-81Conference paper (Other academic)
    Abstract [en]

    This is a brief overview of quantum holonomies in the context of quantum computation. We choose an adequate set of quantum logic gates, namely, a phase gate, the Hadamard gate, and a conditional-phase gate and show how they can be implemented by purely geometric means. Such gates may be more resilient to certain types of errors.

  • 310.
    Ericsson, Marie
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Quantum Chemistry.
    Montangero, Simone
    Quantum Information and Many Body Quantum Systems2008Conference proceedings (editor) (Other academic)
  • 311.
    Ericzon, Christina
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Analytical Chemistry.
    Pettersson, Jean
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Analytical Chemistry.
    Andersson, Marit
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Analytical Chemistry.
    Olin, Åke
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Analytical Chemistry.
    Determination and speciation of selenium in end products from a garbage incinerator1989In: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Environmental Science & Technology, Vol. 23, no 12, p. 1524-1528Article in journal (Refereed)
  • 312.
    Eriksson, Anna
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Physical Chemistry.
    Bergquist, Jonas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Analytical Chemistry.
    Edwards, Katarina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Physical Chemistry.
    Hagfeldt, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Physical Chemistry.
    Malmström, David
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Analytical Chemistry.
    Agmo Hernández, Víctor
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Physical Chemistry.
    Optimized Protocol for On-Target Phosphopeptide Enrichment Prior to Matrix-Assisted Laser Desorption-Ionization Mass Spectrometry Using Mesoporous Titanium Dioxide2010In: Analytical Chemistry, ISSN 0003-2700, E-ISSN 1520-6882, Vol. 82, no 11, p. 4577-4583Article in journal (Refereed)
    Abstract [en]

    A novel on-target phosphopeptide enrichment method is presented that allows specific enrichment and direct analysis by matrix assisted laser desorption-ionization mass spectrometry (MALDI-MS) of phosphorylated peptides. Spots consisting of a thin film of anatase titanium dioxide are sintered onto a conductive glass surface. Enrichment and analysis can be performed on the modified target with minimal sample handling. The protocol leads to an enrichment efficiency that is superior to what has been reported before for similar methods. The method was tested using beta-casein as a model phosphorylated protein as well as with a custom peptide mixed with its phosphorylated form. A very low detection limit, a significantly improved phosphoprofiling capability, and a simple experimental approach provide a powerful tool for the enrichment, detection, and analysis of phosphopeptides.

  • 313.
    Eriksson, Anna
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Physical Chemistry.
    Bergquist, Jonas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Analytical Chemistry.
    Edwards, Katarina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Physical Chemistry.
    Hagfeldt, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Physical Chemistry.
    Malmström, David
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Analytical Chemistry.
    Hernandez, Victor Agmo
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Physical Chemistry.
    Mesoporous TiO2-Based Experimental Layout for On-Target Enrichment and Separation of Multi- and Monophosphorylated Peptides Prior to Analysis with Matrix-Assisted Laser Desorption-Ionization Mass Spectrometry2011In: Analytical Chemistry, ISSN 0003-2700, E-ISSN 1520-6882, Vol. 83, no 3, p. 761-766Article in journal (Refereed)
    Abstract [en]

    A simple method for on-target enrichment and subsequent separation and analysis of phosphorylated peptides is presented. The tryptic digest of a phosphorylated protein, in this case beta-casein, is loaded onto a spot on a thin stripe made of mesoporous TiO2 sintered onto a conductive glass surface. After washing with a salicylic buffer in order to remove the nonphosphorylated peptides, the stripe is placed in an elution chamber containing a phosphate solution. In a way analogous to thin layer chromatography (TLC), the phosphate solution acts as an eluent, clearly separating multi- and monophosphorylated peptides. By performing matrix-assisted laser desorption-ionization mass spectrometry (MALDI-MS) along the stripe, the detection of all phosphorylated peptides present in the digest is facilitated, as they are isolated from each other. The method was also tested on commercial drinking milk, achieving successful separation between multi- and monophosphorylated peptides, as well as a detection limit in the femtomole range. As the enrichment, separation, and analysis take place in the same substrate, sample handling and risk of contamination and sample loss is minimized. The results obtained suggest that the method, once optimized, may successfully provide a complete phosphoproteome.

  • 314. Eriksson, Hanna M.
    et al.
    Wessman, Per
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry.
    Ge, Changrong
    Edwards, Katarina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Physical Chemistry.
    Wieslander, Åke
    Massive Formation of Intracellular Membrane Vesicles in Escherichia coli by a Monotopic Membrane-bound Lipid Glycosyltransferase2009In: Journal of Biological Chemistry, ISSN 0021-9258, E-ISSN 1083-351X, Vol. 284, no 49, p. 33904-33914Article in journal (Refereed)
    Abstract [en]

    The morphology and curvature of biological bilayers are determined by the packing shapes and interactions of their participant molecules. Bacteria, except photosynthetic groups, usually lack intracellular membrane organelles. Strong overexpression in Escherichia coli of a foreign monotopic glycosyltransferase (named monoglycosyldiacylglycerol synthase), synthesizing a nonbilayer-prone glucolipid, induced massive formation of membrane vesicles in the cytoplasm. Vesicle assemblies were visualized in cytoplasmic zones by fluorescence microscopy. These have a very low buoyant density, substantially different from inner membranes, with a lipid content of ≥60% (w/w). Cryo-transmission electron microscopy revealed cells to be filled with membrane vesicles of various sizes and shapes, which when released were mostly spherical (diameter ≈100 nm). The protein repertoire was similar in vesicle and inner membranes and dominated by the glycosyltransferase. Membrane polar lipid composition was similar too, including the foreign glucolipid. A related glycosyltransferase and an inactive monoglycosyldiacylglycerol synthase mutant also yielded membrane vesicles, but without glucolipid synthesis, strongly indicating that vesiculation is induced by the protein itself. The high capacity for membrane vesicle formation seems inherent in the glycosyltransferase structure, and it depends on the following: (i) lateral expansion of the inner monolayer by interface binding of many molecules; (ii) membrane expansion through stimulation of phospholipid synthesis, by electrostatic binding and sequestration of anionic lipids; (iii) bilayer bending by the packing shape of excess nonbilayer-prone phospholipid or glucolipid; and (iv) potentially also the shape or penetration profile of the glycosyltransferase binding surface. These features seem to apply to several other proteins able to achieve an analogous membrane expansion.

  • 315. Eriksson, Sven B.
    et al.
    Ågren, Per Olof
    Henriksson, Ann-Sofie
    Uppsala University, University Administration.
    Elmgren, Maja
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Physical Chemistry. Uppsala University, University Administration.
    Supporting Pedagogical Leaders2010Conference paper (Refereed)
  • 316. Ersson, B
    et al.
    Rydén, L
    Uppsala University, Disciplinary Domain of Science and Technology, För teknisk-naturvetenskapliga fakulteten gemensamma enheter, Uppsala Centre for Sustainable Development.
    Janson, Jan-Christer
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Surface Biotechnology.
    Introduction to protein purification2011In: Protein Purification, Principles, High Resolution Methods and Applications / [ed] J-C Janson, John Wiley & Sons Inc. , 2011, 3, p. 3-22Chapter in book (Other academic)
  • 317. Essén, Sofia A.
    et al.
    Bylund, Dan
    Holmström, Sara J.M.
    Moberg, My
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Physical and Analytical Chemistry, Analytical Chemistry. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Physical and Analytical Chemistry. Analytisk kemi.
    Lundström, Ulla S.
    Quantification of hydroxamate siderophores in soil solutions of podzolic soil profiles in Sweden2006In: BioMetals, no 19, p. 269-282Article in journal (Refereed)
  • 318. Essén, Sofia
    et al.
    Bylund, Dan
    Holmström, Sara J. M.
    Moberg, My
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Physical and Analytical Chemistry, Analytical Chemistry.
    Lundström, Ulla S.
    Quantification of hydroxamate siderophores in soil solutions of podzolic soil profiles in Sweden2006In: BioMetals, ISSN 0966-0844, Vol. 19, no 3, p. 269-282Article in journal (Refereed)
  • 319. Fabregat-Santiago, Francisco
    et al.
    Bisquert, Juan
    Garcia-Belmonte, Germa
    Boschloo, Gerrit
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Physical Chemistry I.
    Hagfeldt, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Physical Chemistry I.
    Influence of electrolyte in transport and recombination in dye-sensitized solar cells studied by impedance spectroscopy2005In: Solar Energy Materials and Solar Cells, ISSN 0927-0248, E-ISSN 1879-3398, Vol. 87, no 1-4, p. 117-131Article in journal (Refereed)
    Abstract [en]

    The main features of the characteristic impedance spectra of dye-sensitized solar cells are described in a wide range of potential conditions: from open to short circuit. An equivalent circuit model has been proposed to describe the parameters of electron transport, recombination, accumulation and other interfacial effects separately. These parameters were determined in the presence of three different electrolytes, both in the dark and under illumination. Shift in the conduction band edge due to the electrolyte composition was monitored in terms of the changes in transport resistance and charge accumulation in TiO2. The interpretation of the current-potential curve characteristics, fill factor, open-circuit photopotential and efficiency in the different conditions, was correlated with this shift and the features of the recombination resistance.

  • 320.
    Fedulova, Natalia
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Biochemistry and Organic Chemistry.
    Hanrieder, Jörg
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Analytical Chemistry.
    Bergquist, Jonas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Analytical Chemistry.
    Emrén, Lars O.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Biochemistry and Organic Chemistry.
    Expression and purification of catalytically active human PHD3 in Escherichia coli2007In: Protein Expression and Purification, ISSN 1046-5928, E-ISSN 1096-0279, Vol. 54, no 1, p. 1-10Article in journal (Refereed)
    Abstract [en]

    Transcription factor HIF-1 is a key regulator in cellular adaptation to hypoxia. HIF prolyl hydroxylases (PHDs) control HIF-1 accumulation by hydroxylation dependent on molecular oxygen. Due to this regulation, PHDs have been pointed out as potential drug targets. We have purified catalytically active human PHD3 after heterologous expression in Escherichia coli. Histidine-tagged enzyme was isolated as monomer by immobilized Ni-affinity chromatography followed by gel filtration. Overexpression of bacterial chaperonins GroEL/ES at 30 °C substantially increased the yield of soluble PHD3. High concentrations of salt and reducing agent during purification prevented protein aggregation. The enzyme activity with peptide derived from HIF-1α was inhibited by Zn2+, desferrioxamine and imidazole. The hydroxylation activity was verified by mass spectrometry, and Pro567 in HIF-1α was discovered as a new site of hydroxylation.

  • 321.
    Feiler, Adam A.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry.
    Davies, Paul T.
    Vincent, Brian
    Adsorption of anionic gold nanoparticles by a layer of cationic microgel particles deposited on a gold-coated, quartz surface: studied by quartz crystal microbalance and atomic force microscopy2011In: Soft Matter, ISSN 1744-683X, E-ISSN 1744-6848, Vol. 7, no 14, p. 6660-6670Article in journal (Refereed)
    Abstract [en]

    The uptake of gold [Au-MES] nanoparticles by pH-responsive poly(2-vinylpyridine) [P2VP] microgel particles, deposited on a surface, has been studied using a quartz crystal microbalance with dissipation monitoring [QCM-D]. QCM-D, which has not previously been applied to such systems, has been shown to be a promising technique for their analysis, especially when combined with a complementary technique such as atomic force microscopy [AFM]. The QCM-D technique, which provides information on mass and viscosity changes of material adsorbed to a surface, has been used to follow the adsorption of microgel particles to a surface, their subsequent swelling and collapse due to changing the system pH, and the uptake of Au-MES nanoparticles by the P2VP particles. Microgel particles with differing cross-linker content have been compared, following uptake by microgel particles in both their collapsed and swollen states. Qualitative differences in the QCM-D response were observed between microgels with differing cross-linker content (and hence different swelling properties). It was shown that uptake of Au-MES nanoparticles acted to fully and irreversibly collapse the swollen P2VP microgels, inhibiting their pH response. The Sauerbrey relationship was used to equate frequency changes measured by QCM-D to mass allowing sorption amounts for the uptake of Au-MES nanoparticles by P2VP particles to be obtained for these surface-constrained systems.

  • 322.
    Feiler, Adam A.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Surface Biotechnology.
    Sahlholm, Anna
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Surface Biotechnology.
    Sandberg, Tomas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Surface Biotechnology.
    Caldwell, Karin D.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Surface Biotechnology.
    Adsorption and viscoelastic properties of fractionated mucin (BSM) and bovine serum albumin (BSA) studied with quartz crystal microbalance (QCM-D)2007In: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 315, no 2, p. 475-481Article in journal (Refereed)
    Abstract [en]

    The adsorption profile and viscoelastic properties of bovine submaxillary gland mucin (BSM) and bovine serum albumin (BSA), extracted from a commercial mucin preparation, adsorbing to polystyrene surfaces has been studied using quartz crystal microbalance with dissipation monitoring (QCM-D). A significant difference in the adsorption properties of the different proteins was detected; with the BSA adsorbing in a flat rigid layer whilst the mucin adsorbed in a diffuse, highly viscoelastic layer. Subsequent addition of BSA to the preadsorbed mucin layer resulted in stiffening of the protein layer which was attributed to complexation of the mucin by BSA. In contrast, a preadsorbed layer of BSA prevented mucin adsorption altogether. Combined mixtures of mucin and BSA in well defined ratios revealed intermediate properties between the two separate protein species which varied systematically with the protein ratios. The results shed light on the synergistic effects of complexation of lower molecular weight biomolecular species with mucin. The possibility to selectively control protein uptake and tailor the physical properties of the adsorbed layer makes mucin an attractive option for application in biomaterial coatings.

  • 323.
    Feiler, Adam A.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Surface Biotechnology, Centre for Surface Biotechnology.
    Stiernstedt, Johanna
    Theander, Katarina
    Jenkins, Paul
    Rutland, Mark W.
    Effect of Capillary Condensation on Friction Force and Adhesion2007In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 23, no 2, p. 517-522Article in journal (Refereed)
    Abstract [en]

    Friction force measurements have been conducted with a colloid probe on mica and silica (both hydrophilic and

    hydrophobized) after long (24 h) exposure to high-humidity air. Adhesion and friction measurements have also been

    performed on cellulose substrates. The long exposure to high humidity led to a large hysteresis between loading and

    unloading in the friction measurements with separation occurring at large negative applied loads. The large hysteresis

    in the friction-load relationship is attributed to a contact area hysteresis of the capillary condensate which built up

    during loading and did not evaporate during the unloading regime. The magnitude of the friction force varied dramatically

    between substrates and was lowest on the mica substrate and highest on the hydrophilic silica substrate, with the

    hydrophobized silica and cellulose being intermediate. The adhesion due to capillary forces on cellulose was small

    compared to that on the other substrates, due to the greater roughness of these surfaces.

  • 324.
    Feiler, Adam
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Surface Biotechnology. Department of Physical and Analytical Chemistry, Surface Biotechnology.
    Jenkins, Paul
    Rutland, Mark W
    Effect of relative humidity on adhesion and frictional properties of micro- and nano-scopic contacts2005In: Journal of Adhesion Science and Technology, ISSN 0169-4243 (Paper) 1568-5616 (Online), Vol. 19, no 3-5, p. 165-179Article in journal (Refereed)
    Abstract [en]

    The effect of relative humidity (RH) on the interactions of AFM tips and colloidal probes with hydrophilic silica substrates is investigated. Both friction and adhesion are studied. For the case of a colloidal probe the interaction is characteristic of a multiasperity contact, the adhesion increased with increasing RH and above a certain threshold relative humidity a large increase in adhesion was measured. This behaviour is explained in terms of a recent model where the Kelvin radius of the condensate becomes larger than some characteristic roughness on the surface. The interaction between the tip and the substrate also exhibited an increase in adhesion above a threshold RH although the increase was much less marked than with the colloid probe. The friction decreased with increasing humidity for both tip and colloid probe although the friction force was much less sensitive than adhesion to changes in RH. Stick-slip behaviour was observed between tip and substrate for all humidities at high loads, but only at the lowest RH (about 5%) it was observed at all loads. At higher humidity the behaviour became increasingly continuum on the experimental timescale, presumably due to viscous contributions from the water. Stick-slip was not observed for the colloidal probe friction measurements.

  • 325. Feitosa, Eloi
    et al.
    Karlsson, Göran
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Physical and Analytical Chemistry, Physical Chemistry. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Physical and Analytical Chemistry. Avdelningen för fysikalisk kemi.
    Dioctadecyldimethylammonium bromide vesicles prepared by the surfactant removal method.2006In: J Colloid Interface Sci, ISSN 0021-9797, Vol. 298, no 2, p. 1000-1Article in journal (Refereed)
  • 326. Feitosa, Eloi
    et al.
    Karlsson, Göran
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Physical and Analytical Chemistry, Physical Chemistry. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Physical and Analytical Chemistry. Avdelningen för fysikalisk kemi.
    Edwards, Katarina
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Physical and Analytical Chemistry, Physical Chemistry. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Physical and Analytical Chemistry. Avdelningen för fysikalisk kemi.
    Unilamellar vesicles obtained by simply mixing dioctadecyldimethylammonium chloride and bromide with water.2006In: Chem Phys Lipids, ISSN 0009-3084, Vol. 140, no 1-2, p. 66-74Article in journal (Refereed)
  • 327.
    Feldt, Sandra M.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Physical Chemistry.
    Cappel, Ute B.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Physical Chemistry.
    Johansson, Erik M. J.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Physical Chemistry.
    Boschloo, Gerrit
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Physical Chemistry.
    Hagfeldt, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Physical Chemistry.
    Characterization of surface passivation by poly(methylsiloxane) for dye-sensitized solar cells employing the ferrocene redox couple.2010In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 114, no 23, p. 10551-10558Article in journal (Refereed)
    Abstract [en]

    One-electron outer-sphere redox couples, such as ferrocene/ferrocenium, are an interesting alternative to the iodide/triiodide redox couple that is normally employed in dye-sensitized solar cells (DSCs) because they should reduce the driving force needed to regenerate the dye. Unfortunately, one-electron redox couples also show enhanced recombination with photoinjected electrons, and methods to inhibit this recombination are needed for functioning DSCs. In this study, dye-sensitized titanium dioxide surfaces were passivated by a trichloromethylsilane reaction in order to decrease the fast recombination rates when using the ferrocene redox couple. The formation and binding of poly(methylsiloxane) on the dye-sensitized TiO2 surface was verified with infrared spectroscopy and photoelectron spectroscopy. Photoelectrochemical characterization of the silanization method showed that the treatment decreased the recombination rate of photoinjected electrons with ferrocenium and thereby improved the efficiency of the DSC. Transient absorption spectroscopy revealed, however, that the poly(methylsiloxane) coatings slowed down the regeneration of the oxidized dye by the ferrocene and prevented the regeneration of some of the dye molecules.

  • 328.
    Feldt, Sandra M.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Physical Chemistry.
    Gibson, Elizabeth A.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Physical Chemistry.
    Gabrielsson, Erik
    KTH, Organisk kemi.
    Sun, Licheng
    KTH, Organisk kemi.
    Boschloo, Gerrit
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Physical Chemistry.
    Hagfeldt, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Physical Chemistry.
    Design of organic dyes and cobalt polypyridine redox mediators for high-efficiency dye-sensitized solar cells2010In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 132, no 46, p. 16714-16724Article in journal (Refereed)
    Abstract [en]

    Dye-sensitized solar cells (DSCs) with cobalt-based mediators with efficiencies surpassing the record for DSCs with iodide-free electrolytes were developed by selecting a suitable combination of a cobalt polypyridine complex and an organic sensitizer. The effect of the steric properties of two triphenylamine-based organic sensitizers and a series of cobalt polypyridine redox mediators on the overall device performance in DSCs as well as on transport and recombination processes in these devices was compared. The recombination and mass-transport limitations that, previously, have been found to limit the performance of these mediators were avoided by matching the properties of the dye and the cobalt redox mediator. Organic dyes with higher extinction coefficients than the standard ruthenium sensitizers were employed in DSCs in combination with outer-sphere redox mediators, enabling thinner TiO2 films to be used. Recombination was reduced further by introducing insulating butoxyl chains on the dye rather than on the cobalt redox mediator, enabling redox couples with higher diffusion coefficients and more suitable redox potential to be used, simultaneously improving the photocurrent and photovoltage of the device. Optimization of DSCs sensitized with a triphenylamine-based organic dye in combination with tris(2,2'-bipyridyl)cobalt(II/III) yielded solar cells with overall conversion efficiencies of 6.7% and open-circuit potentials of more than 0.9 V under 1000 W m(-2) AM1.5 G illumination. Excellent performance was also found under low light intensity indoor conditions.

  • 329.
    Feldt, Sandra M.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Physical Chemistry.
    Wang, Gang
    Boschloo, Gerrit
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Physical Chemistry.
    Hagfeldt, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Physical Chemistry.
    Effects of Driving Forces for Recombination and Regeneration on the Photovoltaic Performance of Dye-Sensitized Solar Cells using Cobalt Polypyridine Redox Couples2011In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 115, no 43, p. 21500-21507Article in journal (Refereed)
    Abstract [en]

    Dye-sensitized solar cells (DSCs) with open-circuit potentials above 1 V were obtained by employing the triphenylamine based organic dye D35 in combination with cobalt phenanthroline redox couples. A series of cobalt bipyridine and cobalt phenanthroline complexes with different redox potentials were investigated to examine the dependence of the driving force for recombination and dye regeneration on the photovoltaic performance. The photovoltage of the devices was found to increase and the photocurrent to decrease with increasing redox potential of the complexes. The halftime for regeneration of the oxidized dye by cobalt trisbipyrine was about 20 mu s, similar to that found for the iodide/triiodide redox couple, whereas regeneration kinetics became slower for cobalt complexes with less driving force for regeneration. A driving force for dye regeneration of 390 mV for cobalt(II/III) tris(5-chloro-1,10-phenanthroline) was found sufficient to regenerate more than 80% of the D35 dye molecules, resulting in a conversion of incident photons to electric current of above 80%. The photocurrent of the D35 sensitized DSCs using cobalt phenanthroline complexes decreased, however, with increasing Nernst potential of the redox couples, due to the increased recombination and the decreased regeneration rate constants.

  • 330.
    Ferraz, Natalia
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry. Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Surface Biotechnology.
    Effect of Surface Nanotopography on Blood-Biomaterial Interactions2010Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Biologically inspired materials are being developed with the aim of improving the integration of medical implants and minimizing non-desirable host reactions. A promising strategy is the design of topographically patterned surfaces that resemble those found in the extracellular environment.

    Nanoporous alumina has been recognized as a potential biomaterial and as an important template for the fabrication of nanostructures.

    In this thesis in vitro studies were done to elucidate the role of alumina nanoporosity on the inflammatory response. Specifically, by comparing alumina membranes with two pore sizes (20 and 200 nm in diameter). Complement and platelet activation were evaluated as well as monocyte/macrophage behaviour.

    Whole blood was incubated with the alumina membranes and thereafter the biomaterial surfaces were evaluated in terms of protein and platelet adhesion as well as procoagulant properties. The fluid phase was analyzed for complement activation products and platelet activation markers. Besides, human mononuclear cells were cultured on the alumina membranes and cell adhesion, viability, morphology and release of pro-inflammatory cytokines were evaluated.

    The results indicated that nanoporous alumina with 200 nm pores promotes higher complement activation than alumina with 20 nm pores.

    In addition, platelet response to nanoporous alumina was found to be highly dependent on the material porosity, as reflected by differences in adhesion, PMP generation and procoagulant characteristics.

    A clear difference in monocyte/macrophage adhesion and activation was found between the two pore size alumina membranes. Few but highly activated cells adhered to the 200 nm membrane in contrast to many but less activated monocytes/macrophages on the 20 nm surface.

    The outcome of this work emphasizes that nanotopography plays an important role in the host response to biomaterials.

    Better understanding of molecular interactions on nano-level will undoubtedly play a significant role in biomaterial implant development and will contribute to design strategies for controlling specific biological events.

    List of papers
    1. Nanoporesize affects complement activation
    Open this publication in new window or tab >>Nanoporesize affects complement activation
    2008 (English)In: Journal of biomedical materials research. Part A, ISSN 1552-4965, Vol. 87, no 3, p. 575-81Article in journal (Refereed) Published
    Abstract [en]

    In the present study, we have shown the vast importance of biomaterial nanotexture when evaluating inflammatory response. For the first time in an in vitro whole blood system, we have proven that a small increase in nanoporesize, specifically 180 nm (from 20 to 200 nm), has a huge effect on the complement system. The study was done using nanoporous aluminiumoxide, a material that previously has been evaluated for potential implant use, showing good biocompatibility. This material can easily be manufactured with different pore sizes making it an excellent candidate to govern specific protein and cellular events at the tissue-material interface. We performed whole blood studies, looking at complement activation after blood contact with two pore size alumina membranes (pore diameters, 20 and 200 nm). The fluid phase was analyzed for complement soluble components, C3a and sC5b-9. In addition, surface adsorbed proteins were eluted and dot blots were performed to detect IgG, IgM, C1q, and C3. All results point to the fact that 200 nm pore size membranes are more complement activating. Significantly, higher values of complement soluble components were found after whole blood contact with 200 nm alumina and all studied proteins adsorbed more readily to this membrane than to the 20 nm pore size membrane. We hypothesize that the difference in complement activation between our two test materials is caused by the type and the amount of adsorbed proteins, as well as their conformation and orientation. The different protein patterns created on the two alumina membranes are most likely a consequence of the material topography.

    Keywords
    nanotopography, nanoporous alumina, complement, whole blood, protein adsorption
    National Category
    Chemical Sciences
    Identifiers
    urn:nbn:se:uu:diva-88357 (URN)10.1002/jbm.a.31818 (DOI)000260984800002 ()18186072 (PubMedID)
    Available from: 2009-01-30 Created: 2009-01-29 Last updated: 2009-07-13Bibliographically approved
    2. Influence of nanoporesize on platelet adhesion and activation
    Open this publication in new window or tab >>Influence of nanoporesize on platelet adhesion and activation
    2008 (English)In: Journal of materials science. Materials in medicine, ISSN 0957-4530, E-ISSN 1573-4838, Vol. 19, no 9, p. 3115-21Article in journal (Refereed) Published
    Abstract [en]

    In this study we have evaluated the influence of biomaterial nano-topography on platelet adhesion and activation. Nano-porous alumina membranes with pore diameters of 20 and 200 nm were incubated with whole blood and platelet rich plasma. Platelet number, adhesion and activation were determined by using a coulter hematology analyzer, scanning electron microscopy, immunocytochemical staining in combination with light microscopy and by enzyme immunoassay. Special attention was paid to cell morphology, microparticle generation, P-selectin expression and beta-TG production. Very few platelets were found on the 200 nm alumina as compared to the 20 nm membrane. The platelets found on the 20 nm membrane showed signs of activation such as spread morphology and protruding filipodia as well as P-selectin expression. However no microparticles were detected on this surface. Despite the fact that very few platelets were found on the 200 nm alumina in contrast to the 20 nm membrane many microparticles were detected on this surface. Interestingly, all microparticles were found inside circular shaped areas of approximately 3 mum in diameter. Since this is the approximate size of a platelet we speculate that this is evidence of transient, non-adherent platelet contact with the surface, which has triggered platelet microparticle generation. To the authors knowledge, this is the first study that demonstrates how nanotexture can influence platelet microparticle generation. The study highlights the importance of understanding molecular and cellular events on nano-level when designing new biomaterials.

    National Category
    Medical and Health Sciences
    Identifiers
    urn:nbn:se:uu:diva-88354 (URN)10.1007/s10856-008-3449-7 (DOI)000256964300016 ()18414999 (PubMedID)
    Available from: 2009-01-30 Created: 2009-01-29 Last updated: 2017-12-14Bibliographically approved
    3. Procoagulant behavior and platelet microparticle generation on nanoporous alumina
    Open this publication in new window or tab >>Procoagulant behavior and platelet microparticle generation on nanoporous alumina
    2010 (English)In: Journal of biomaterials applications, ISSN 0885-3282, E-ISSN 1530-8022, Vol. 24, no 8, p. 675-692Article in journal (Refereed) Published
    Abstract [en]

    In the present work, we have investigated platelet microparticle(PMP) generation in whole blood after contact with nanoporous alumina.Alumina membranes with pore sizes of 20 and 200nm in diameter were incubated with whole blood and the number of PMP in the fluid phase was determined by flow cytometry. The role of the complement system in PMP generation was investigated using an analog of the potent complement inhibitor compstatin. Moreover, the procoagulant activity of the two pore size membranes were compared by measuring thrombin formation. Results indicated that PMP were not present in the fluid phase after whole blood contact with either of the alumina membranes. However, scanning electron microscope micrographs clearly showed the presence of PMP clusters on the 200nm pore size alumina, while PMP were practically absent on the 20nm membrane. We probed no influence of complement activation in PMP generation and adhesion and we hypothesize that other specific material-related protein–platelet interactions are taking place. A clear difference in procoagulant activity between the membranes could also be seen, 20nm alumina showed 100% higher procoagulant activity than 200nm membrane. By combining surface evaluation and flow cytometry analyses of the fluid phase, we are able to conclude that 200nm pore size alumina promotes PMP generation and adhesion while the 20nm membrane does not appreciably cause any release or adhesion of PMP, thus indicating a direct connection between PMP generation and nanoporosity.

    Place, publisher, year, edition, pages
    SAGE, 2010
    Keywords
    nanoporous alumina, nanotopography, platelets, platelet microparticles, procoagulant activity, compstatin
    National Category
    Chemical Sciences
    Research subject
    Immunology; Materials Science
    Identifiers
    urn:nbn:se:uu:diva-130496 (URN)10.1177/0885328209338639 (DOI)000277806100001 ()19581322 (PubMedID)
    Available from: 2010-09-08 Created: 2010-09-08 Last updated: 2017-12-12Bibliographically approved
    4. Time sequence of blood activation by nanoporous alumina: Studies on platelets and complement system
    Open this publication in new window or tab >>Time sequence of blood activation by nanoporous alumina: Studies on platelets and complement system
    2010 (English)In: Microscopy research and technique (Print), ISSN 1059-910X, E-ISSN 1097-0029, Vol. 73, no 12, p. 1101-1109Article in journal (Refereed) Published
    Abstract [en]

    In the present work the time sequence of blood activation by alumina membranes with different porosities (20 and 200 nm in diameter) was studied. The membranes were incubated with whole blood from 2 min to 4 h. Platelet adhesion and activation in addition to complement activation were monitored at different time points. Evaluation of platelet adhesion and activation was done by determining the change in platelet number and the levels of thrombospondin-1 in the fluid phase. Scanning electron microscopy studies were done to further evaluate platelet adhesion and morphology. Immunocytochemical staining was used to evaluate the presence of CD41 and CD62P antigens on the material surface. Complement activation was monitored by measuring C3a and sC5b-9 in plasma samples by means of enzyme immunoassays. Both alumina membranes displayed similar complement activation time profiles, with levels of C3a and sC5b-9 increasing with incubation time. A statistically significant difference between the membranes was found after 60 min of incubation. Platelet activation characteristics and time profile were different between the two membranes. Platelet adhesion increased over time for the 20 nm surface, while the clusters of microparticles on the 200 nm surface did not appreciably change during the course of the experiment. The release of thrombospondin-1 increased with time for both membranes, however much later for the 200 nm alumina (240 min) as compared to the 20 nm membrane (60 min). The surface topography of the alumina most probably influence protein transition rate, which in turn affects material-platelet activation kinetics.

    Place, publisher, year, edition, pages
    Wiley-Liss Inc., 2010
    Keywords
    nanotopography, biomaterial, whole blood, thrombospondin-1, platelet microparticles
    National Category
    Other Basic Medicine
    Research subject
    Immunology; Materials Science
    Identifiers
    urn:nbn:se:uu:diva-110620 (URN)10.1002/jemt.20854 (DOI)000284063800005 ()
    Available from: 2009-11-18 Created: 2009-11-18 Last updated: 2018-01-12Bibliographically approved
    5. Nanoporosity of alumina surfaces induces different patterns of activation in adhering monocytes/macrophages
    Open this publication in new window or tab >>Nanoporosity of alumina surfaces induces different patterns of activation in adhering monocytes/macrophages
    2010 (English)In: International Journal of Biomaterials, ISSN 1687-8787, E-ISSN 1687-8795, Vol. 2010, p. 402715-Article in journal (Refereed) Published
    Abstract [en]

    The present study shows that alumina nanotopography affects monocyte/macrophage behaviour. Human mononuclear cells cultured on alumina membranes with pore diameters of 20 and 200 nm were evaluated in terms of cell adhesion, viability, morphology and release of pro-inflammatory cytokines. After 24 hours, cell adhesion was assessed by means of light microscopy and cell viability by measuring LDH release. The inflammatory response was evaluated by quantifying interleukin-1ß and tumour necrosis factor-α. Finally, scanning electron microscopy was used to study cell morphology. Results showed pronounced differences in cell number, morphology and cytokine release depending on the nanoporosity. Few but highly activated cells were found on the 200 nm porous alumina, while relatively larger number of cells was found on the 20 nm porous surface. However, despite their larger number, the cells adhering on the 20 nm surface exhibited reduced pro-inflammatory activity. It can be speculated that the difference in surface topography may lead to distinct protein adsorption patterns and therefore to different degree of cell activation. The data of this paper emphasize the role played by the material nanotexture in dictating cell responses and implies that nanotopography could be exploited for controlling the inflammatory response to implants.

    Keywords
    macrophages, nanoporous alumina, biomaterials, nanotopography, inflammatory response
    National Category
    Other Basic Medicine
    Research subject
    Immunology
    Identifiers
    urn:nbn:se:uu:diva-110623 (URN)10.1155/2010/402715 (DOI)21234322 (PubMedID)
    Available from: 2009-11-18 Created: 2009-11-18 Last updated: 2018-01-12Bibliographically approved
  • 331.
    Ferraz, Natalia
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Physical and Analytical Chemistry. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Physical and Analytical Chemistry, Surface Biotechnology. Ytbioteknik.
    Pro-inflammatory characteristics af nano-porous alumina: Effect o9f surface topography2007Licentiate thesis, monograph (Other scientific)
  • 332.
    Ferraz, Natalia
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry.
    Carlsson, Jan
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry.
    Hong, Jaan
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Oncology, Radiology and Clinical Immunology.
    Ott, Marjam Karlsson
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry.
    Influence of nanoporesize on platelet adhesion and activation2008In: Journal of materials science. Materials in medicine, ISSN 0957-4530, E-ISSN 1573-4838, Vol. 19, no 9, p. 3115-21Article in journal (Refereed)
    Abstract [en]

    In this study we have evaluated the influence of biomaterial nano-topography on platelet adhesion and activation. Nano-porous alumina membranes with pore diameters of 20 and 200 nm were incubated with whole blood and platelet rich plasma. Platelet number, adhesion and activation were determined by using a coulter hematology analyzer, scanning electron microscopy, immunocytochemical staining in combination with light microscopy and by enzyme immunoassay. Special attention was paid to cell morphology, microparticle generation, P-selectin expression and beta-TG production. Very few platelets were found on the 200 nm alumina as compared to the 20 nm membrane. The platelets found on the 20 nm membrane showed signs of activation such as spread morphology and protruding filipodia as well as P-selectin expression. However no microparticles were detected on this surface. Despite the fact that very few platelets were found on the 200 nm alumina in contrast to the 20 nm membrane many microparticles were detected on this surface. Interestingly, all microparticles were found inside circular shaped areas of approximately 3 mum in diameter. Since this is the approximate size of a platelet we speculate that this is evidence of transient, non-adherent platelet contact with the surface, which has triggered platelet microparticle generation. To the authors knowledge, this is the first study that demonstrates how nanotexture can influence platelet microparticle generation. The study highlights the importance of understanding molecular and cellular events on nano-level when designing new biomaterials.

  • 333.
    Ferraz, Natalia
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Surface Biotechnology.
    Hong, Jaan
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Oncology, Radiology and Clinical Immunology, Clinical Immunology.
    Karlsson Ott, Marjam
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Surface Biotechnology.
    Procoagulant behavior and platelet microparticle generation on nanoporous alumina2010In: Journal of biomaterials applications, ISSN 0885-3282, E-ISSN 1530-8022, Vol. 24, no 8, p. 675-692Article in journal (Refereed)
    Abstract [en]

    In the present work, we have investigated platelet microparticle(PMP) generation in whole blood after contact with nanoporous alumina.Alumina membranes with pore sizes of 20 and 200nm in diameter were incubated with whole blood and the number of PMP in the fluid phase was determined by flow cytometry. The role of the complement system in PMP generation was investigated using an analog of the potent complement inhibitor compstatin. Moreover, the procoagulant activity of the two pore size membranes were compared by measuring thrombin formation. Results indicated that PMP were not present in the fluid phase after whole blood contact with either of the alumina membranes. However, scanning electron microscope micrographs clearly showed the presence of PMP clusters on the 200nm pore size alumina, while PMP were practically absent on the 20nm membrane. We probed no influence of complement activation in PMP generation and adhesion and we hypothesize that other specific material-related protein–platelet interactions are taking place. A clear difference in procoagulant activity between the membranes could also be seen, 20nm alumina showed 100% higher procoagulant activity than 200nm membrane. By combining surface evaluation and flow cytometry analyses of the fluid phase, we are able to conclude that 200nm pore size alumina promotes PMP generation and adhesion while the 20nm membrane does not appreciably cause any release or adhesion of PMP, thus indicating a direct connection between PMP generation and nanoporosity.

  • 334.
    Ferraz, Natalia
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Surface Biotechnology.
    Hong, Jaan
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Oncology, Radiology and Clinical Immunology, Clinical Immunology.
    Santin, Matteo
    School of Pharmacy & Biomolecualr Sciences, University of Brighton.
    Karlsson Ott, Marjam
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Surface Biotechnology.
    Nanoporosity of alumina surfaces induces different patterns of activation in adhering monocytes/macrophages2010In: International Journal of Biomaterials, ISSN 1687-8787, E-ISSN 1687-8795, Vol. 2010, p. 402715-Article in journal (Refereed)
    Abstract [en]

    The present study shows that alumina nanotopography affects monocyte/macrophage behaviour. Human mononuclear cells cultured on alumina membranes with pore diameters of 20 and 200 nm were evaluated in terms of cell adhesion, viability, morphology and release of pro-inflammatory cytokines. After 24 hours, cell adhesion was assessed by means of light microscopy and cell viability by measuring LDH release. The inflammatory response was evaluated by quantifying interleukin-1ß and tumour necrosis factor-α. Finally, scanning electron microscopy was used to study cell morphology. Results showed pronounced differences in cell number, morphology and cytokine release depending on the nanoporosity. Few but highly activated cells were found on the 200 nm porous alumina, while relatively larger number of cells was found on the 20 nm porous surface. However, despite their larger number, the cells adhering on the 20 nm surface exhibited reduced pro-inflammatory activity. It can be speculated that the difference in surface topography may lead to distinct protein adsorption patterns and therefore to different degree of cell activation. The data of this paper emphasize the role played by the material nanotexture in dictating cell responses and implies that nanotopography could be exploited for controlling the inflammatory response to implants.

  • 335.
    Ferraz, Natalia
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Surface Biotechnology.
    Karlsson Ott, Marjam
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Surface Biotechnology.
    Hong, Jaan
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Oncology, Radiology and Clinical Immunology, Clinical Immunology.
    Time sequence of blood activation by nanoporous alumina: Studies on platelets and complement system2010In: Microscopy research and technique (Print), ISSN 1059-910X, E-ISSN 1097-0029, Vol. 73, no 12, p. 1101-1109Article in journal (Refereed)
    Abstract [en]

    In the present work the time sequence of blood activation by alumina membranes with different porosities (20 and 200 nm in diameter) was studied. The membranes were incubated with whole blood from 2 min to 4 h. Platelet adhesion and activation in addition to complement activation were monitored at different time points. Evaluation of platelet adhesion and activation was done by determining the change in platelet number and the levels of thrombospondin-1 in the fluid phase. Scanning electron microscopy studies were done to further evaluate platelet adhesion and morphology. Immunocytochemical staining was used to evaluate the presence of CD41 and CD62P antigens on the material surface. Complement activation was monitored by measuring C3a and sC5b-9 in plasma samples by means of enzyme immunoassays. Both alumina membranes displayed similar complement activation time profiles, with levels of C3a and sC5b-9 increasing with incubation time. A statistically significant difference between the membranes was found after 60 min of incubation. Platelet activation characteristics and time profile were different between the two membranes. Platelet adhesion increased over time for the 20 nm surface, while the clusters of microparticles on the 200 nm surface did not appreciably change during the course of the experiment. The release of thrombospondin-1 increased with time for both membranes, however much later for the 200 nm alumina (240 min) as compared to the 20 nm membrane (60 min). The surface topography of the alumina most probably influence protein transition rate, which in turn affects material-platelet activation kinetics.

  • 336.
    Ferraz, Natalia
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Surface Biotechnology.
    Leverrier, Julieta
    Biochemistry Department, University of the Republic, Uruguay.
    Batista-Viera, Francisco
    Biochemistry Department, University of the Republic, Uruguay.
    Manta, Carmen
    Biochemistry Department, University of the Republic, Uruguay.
    Thiopropyl-agarose as a solid phase reducing agent for chemical modification of IgG and F(ab´)22008In: Biotechnology progress (Print), ISSN 8756-7938, E-ISSN 1520-6033, Vol. 24, no 5, p. 1154-1159Article in journal (Refereed)
  • 337.
    Ferraz, Natalia
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Surface Biotechnology.
    Nilsson, Bo
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Oncology, Radiology and Clinical Immunology.
    Hong, Jaan
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Oncology, Radiology and Clinical Immunology.
    Karlsson Ott, Marjam
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Surface Biotechnology.
    Nanoporesize affects complement activation2008In: Journal of biomedical materials research. Part A, ISSN 1552-4965, Vol. 87, no 3, p. 575-81Article in journal (Refereed)
    Abstract [en]

    In the present study, we have shown the vast importance of biomaterial nanotexture when evaluating inflammatory response. For the first time in an in vitro whole blood system, we have proven that a small increase in nanoporesize, specifically 180 nm (from 20 to 200 nm), has a huge effect on the complement system. The study was done using nanoporous aluminiumoxide, a material that previously has been evaluated for potential implant use, showing good biocompatibility. This material can easily be manufactured with different pore sizes making it an excellent candidate to govern specific protein and cellular events at the tissue-material interface. We performed whole blood studies, looking at complement activation after blood contact with two pore size alumina membranes (pore diameters, 20 and 200 nm). The fluid phase was analyzed for complement soluble components, C3a and sC5b-9. In addition, surface adsorbed proteins were eluted and dot blots were performed to detect IgG, IgM, C1q, and C3. All results point to the fact that 200 nm pore size membranes are more complement activating. Significantly, higher values of complement soluble components were found after whole blood contact with 200 nm alumina and all studied proteins adsorbed more readily to this membrane than to the 20 nm pore size membrane. We hypothesize that the difference in complement activation between our two test materials is caused by the type and the amount of adsorbed proteins, as well as their conformation and orientation. The different protein patterns created on the two alumina membranes are most likely a consequence of the material topography.

  • 338. Ferreira, Denise Alves
    et al.
    Bentley, Maria Vitoria L B
    Karlsson, Göran
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Physical and Analytical Chemistry, Physical Chemistry. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Physical and Analytical Chemistry. Avdelningen för fysikalisk kemi.
    Edwards, Katarina
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Physical and Analytical Chemistry, Physical Chemistry. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Physical and Analytical Chemistry. Avdelningen för fysikalisk kemi.
    Cryo-TEM investigation of phase behaviour and aggregate structure in dilute2006In: Int J Pharm, ISSN 0378-5173, Vol. 310, no 1-2, p. 203-12Article in journal (Refereed)
  • 339.
    Fidder, H.
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Physical Chemistry. Department of Physical and Analytical Chemistry, Physical Chemistry I.
    Rini, M.
    Nibbering, E. T. J.
    The role of large conformational changes in efficient ultrafast internal conversion: Deviations from the energy gap law2004In: Journal of the American Chemical Society, Vol. 126, no 12, p. 3789-3794Article in journal (Refereed)
  • 340.
    Figgemeier, Egbert
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Physical Chemistry.
    Aranyos, Viviane
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Physical Chemistry.
    Constable, E. C.
    Handel, R. W.
    Housecroft, C. E.
    Risinger, Christian
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Physical Chemistry.
    Hagfeldt, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Physical Chemistry.
    Mukhtar, Emad
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Physical Chemistry.
    Modification of electron transfer properties in photoelectrochemical solar cells by substituting {Ru(terpy)(2)}(2+) dyes with thiophene2004In: Inorganic Chemistry Communications, ISSN 1387-7003, E-ISSN 1879-0259, Vol. 7, no 1, p. 117-121Article in journal (Refereed)
    Abstract [en]

    A comparison of the properties of the 2-thienyl-substituted carboxyphenyl {RuII(terpy)2} dyes with their non-substituted analogues has enabled us to gain insight into the electronic properties that are prerequisite for efficient electron injection into the TiO2 conduction band in photoelectrochemical solar cells. Introducing the thienyl group has a profound effect upon the efficiency of photoinduced electron injection. This effect can be explained by a significant shift in the LUMO position from the terpy ligand anchored on the TiO2 surface towards the 2-thienyl substituted ligand, which is shown by means of electrochemistry and semiempirical calculations.

  • 341.
    Figgemeier, Egbert
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Physical Chemistry. Department of Physical and Analytical Chemistry, Physical Chemistry I.
    Hagfeldt, Anders
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Physical Chemistry. Department of Physical and Analytical Chemistry, Physical Chemistry I.
    Are dye-sensitized nano-structured solar cells stable? An overview of device testing and component analyses2004In: International Journal of Photoenergy, Vol. 6, no 3, p. 127-140Article in journal (Refereed)
  • 342.
    Filippov, Sergey K
    et al.
    Institute of Macromolecular Chemistry, Academy of Sciences of the Czech Republic.
    Lezov, Andrey V.
    Sergeeva, Olga Yu
    Olifirenko, Alexey S
    Lesnichin, Stephan B.
    Domnina, Nina S.
    Komarova, Elena A.
    Almgren, Mats
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Physical Chemistry.
    Karlsson, Göran
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Physical Chemistry.
    Stepanic, Petr
    Aggregation of dextran hydrophobically modified by sterically-hindered phenols in aqueous solutions: Aggregates vs. single molecules2008In: European Polymer Journal, ISSN 0014-3057, E-ISSN 1873-1945, Vol. 44, no 10, p. 3361-3369Article in journal (Refereed)
    Abstract [en]

    The hydrodynamic properties of dextrans hydrophobically modified by sterically-hindered phenols in aq. soln. were characterized by a combination of Cryogenic Transmission Electron Microscopy (Cryo-TEM), fluorescent spectroscopy, and Dynamic Light Scattering (DLS). All solns. investigated contained aggregates the structure, shape, and crit. aggregation concn. of which are influenced by the amt. of the inserted phenol groups in the polymer matrix. We found that increasing of temp. enhances aggregation. It was established that the crit. aggregation concn. could be well approximated by a logarithmic function of the substitution degree of the glycoside units. The results suggest that the proportion of aggregates is nevertheless negligible in comparison with the proportion of single mols.

  • 343.
    Filippov, Sergey K.
    et al.
    Institute of Macromelecular Chemistry, Academy of Sciences of the Czech Republic.
    Starovoytova, Larisa
    Institute of Macromelecular Chemistry, Academy of Sciences of the Czech Republic.
    Konák, Cestmír
    Institute of Macromelecular Chemistry, Academy of Sciences of the Czech Republic.
    Hrubý, Martin
    Institute of Macromelecular Chemistry, Academy of Sciences of the Czech Republic.
    Macková, Hana
    Karlsson, Göran
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Physical Chemistry.
    Stepánek, Petr
    Institute of Macromelecular Chemistry, Academy of Sciences of the Czech Republic.
    pH sensitive polymer nanoparticles: effect of hydrophobicity on self-assembly2010In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 26, no 18, p. 14450-14457Article in journal (Refereed)
    Abstract [en]

    The influence of hydrophobicity on formation, stability, and size of pH-responsive methacryloylated oligopeptide-based polymer nanoparticles has been studied by dynamic light scattering (DLS), transmission electron microscopy (Cryo-TEM), and NMR. Different polyanions/surfactant systems have been studied at constant polymer concentration and within a broad range of surfactant concentrations. The two newly synthesized pH-sensitive hydrophobic polyanions, poly(N(ω)-methacryloyl glycyl-L-leucine) and poly(N(ω)-methacryloyl glycyl-L-phenylalanyl-L-leucinyl-glycine), and three nonionic surfactants (Brij97, Brij98, and Brij700) have been investigated. The surfactants were different in the length of hydrophilic poly(ethylene oxide) (PEO) chain. In surfactant-free solution at basic pH, the polyanions form hydrophobic domains. In the presence of a surfactant, our results prove the complex formation at high pH between the nonionic surfactant and the polyelectrolyte; a pearl-necklace structure is formed. At low pH below critical pH (pH(tr)), reversible nanoscale structures occur in solutions for all systems. The detailed mechanism of the formation of pH-sensitive nanoparticles from polymer-surfactant complex with varying pH is established. Our results suggest that the polymer hydrophobicity is of primary importance in pretransitional behavior of the complex. Once preliminary nanoparticle nuclei are formed, the hydrophobicity of the polymer plays a minor role on further behavior of formed nanostructures. The subsequent transformation of nanoparticles is determined by the surfactant hydrophilicity, the length of hydrophilic tail that prevents further aggregation due to steric repulsions.

  • 344. Flood, Charlie
    et al.
    Dreiss, Cécile A
    Croce, Vania
    Cosgrove, Terence