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Hulsart Billström, G., Stelzl, C., Procter, P., Pujari-Palmer, M., Insley, G., Engqvist, H. & Larsson, S. (2020). In vivo safety assessment of a bio-inspired bone adhesive. Journal of materials science. Materials in medicine, 31(2), Article ID 24.
Open this publication in new window or tab >>In vivo safety assessment of a bio-inspired bone adhesive
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2020 (English)In: Journal of materials science. Materials in medicine, ISSN 0957-4530, E-ISSN 1573-4838, Vol. 31, no 2, article id 24Article in journal (Refereed) Published
Abstract [en]

A new class of materials, bone adhesives, could revolutionise the treatment of highly fragmented fractures. We present the first biological safety investigation of a bio-inspired bone adhesive. The formulation was based upon a modified calcium phosphate cement that included the amino acid phosphoserine. This material has recently been described as substantially stronger than other bioresorbable calcium phosphate cements. Four adhesive groups with the active substance (phosphoserine) and two control groups without phosphoserine were selected for in vitro and in vivo biocompatibility testing. The test groups were subject for cell viability assay and subcutaneous implantation in rats that was followed by gene expression analysis and histology assessment after 6 and 12 weeks. All adhesive groups supported the same rate of cell proliferation compared to the alpha-TCP control and had viability between 45-64% when compared to cell control. There was no evidence of an increased immune response or ectopic bone formation in vivo. To conclude, this bio-inspired bone adhesive has been proven to be safe, in the present study, without any harmful effects on the surrounding soft tissue. 

Place, publisher, year, edition, pages
SPRINGER, 2020
National Category
Medical Materials
Identifiers
urn:nbn:se:uu:diva-407133 (URN)10.1007/s10856-020-6362-3 (DOI)000511787900001 ()32036502 (PubMedID)
Funder
Swedish Research Council, RMA15-390 0110
Note

De två första författarna delar förstaförfattarskapet.

Available from: 2020-03-20 Created: 2020-03-20 Last updated: 2020-03-20Bibliographically approved
Berg, C., Unosson, E., Engqvist, H. & Xia, W. (2019). ACP-Mg particles for treatment of dental hypersensitivity: a mode of action study. In: : . Paper presented at Euromat 2019, 1-5 September 2019, Stockholm, Sweden.
Open this publication in new window or tab >>ACP-Mg particles for treatment of dental hypersensitivity: a mode of action study
2019 (English)Conference paper, Poster (with or without abstract) (Other academic)
Abstract [en]

Introduction/purpose:

Dental hypersensitivity is a common clinical condition usually associated with exposed dentinal tubules. Occlusion of those, hindering fluid movement as a response to external stimuli, is one approach to reduce pain.[1] The occluding agent should induce mineralization and have a good filling effect. In this study, particles (200-400 nm) of Amorphous Calcium Phosphate with Mg (ACP-Mg) were used aiming to evaluate the mode of action with in-vitro studies on dentine as well as degradation properties in buffered systems.

Methods:

Degradation properties and ion-release was monitored by dispersing the particles in Tris-HCl (10 mg/mL) storing the dispersions at 37 °C.  In-vitro testing was performed on 1 mm thick dentine discs cut from extracted human molars. Specimens were etched in 35 % phosphoric acid, rinsed with DI-water followed by treatment by applying a gel formulation containing the particles using a soft bristled toothbrush, brushing 1 min on each side and leaving the specimen to rest for 3 min. Treatment was repeated four times during one day and samples were incubated at 37 °C in artificial saliva.

Results:

In vitro tests and degradation studies showed that ACP-Mg particles induced formation of Hydroxyapatite (HA). ICP-OES, XRD and SEM showed that there was a rapid release of all ions up to 6 hours followed by a re-precipitation of HA at 24 hours with a lower Mg-content. The crystallinity increased with time as the concentration of all ions decreased in the solutions. Morphological evaluation for the in-vitro tests showed that HA-like structures formed already after 24 hours on the dentine surface.  Cross-sections revealed that the particles reached as far as 80 µm from the surface and tubules, fully occluded by HA-like structures, was visible at comparable depths after 7 days.

Conclusions:

ACP-Mg particles can be used to reduce dentine hypersensitivity by effective occlusion of dentine tubules via rapid formation of surface and intra-tubular HA.

References:

1. Splieth CH, Tachou A. 2013. Epidemiology of dentin hypersensitivity. Clin Oral Investig. 17:3–8. 

National Category
Engineering and Technology Medical Engineering
Identifiers
urn:nbn:se:uu:diva-398211 (URN)
Conference
Euromat 2019, 1-5 September 2019, Stockholm, Sweden
Available from: 2019-12-03 Created: 2019-12-03 Last updated: 2019-12-09Bibliographically approved
Liu, X., Pujari-Palmer, M., Wenner, D., Procter, P., Insley, G. & Engqvist, H. (2019). Adhesive Cements That Bond Soft Tissue Ex Vivo. Materials, 12(15), Article ID 2473.
Open this publication in new window or tab >>Adhesive Cements That Bond Soft Tissue Ex Vivo
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2019 (English)In: Materials, ISSN 1996-1944, E-ISSN 1996-1944, Vol. 12, no 15, article id 2473Article in journal (Refereed) Published
Abstract [en]

The aim of the present study was to evaluate the soft tissue bond strength of a newly developed, monomeric, biomimetic, tissue adhesive called phosphoserine modified cement (PMC). Two types of PMCs were evaluated using lap shear strength (LSS) testing, on porcine skin: a calcium metasilicate (CS1), and alpha tricalcium phosphate (alpha TCP) PMC. CS1 PCM bonded strongly to skin, reaching a peak LSS of 84, 132, and 154 KPa after curing for 0.5, 1.5, and 4 h, respectively. Cyanoacrylate and fibrin glues reached an LSS of 207 kPa and 33 kPa, respectively. alpha TCP PMCs reached a final LSS of approximate to 110 kPa. In soft tissues, stronger bond strengths were obtained with alpha TCP PMCs containing large amounts of amino acid (70-90 mol%), in contrast to prior studies in calcified tissues (30-50 mol%). When alpha TCP particle size was reduced by wet milling, and for CS1 PMCs, the strongest bonding was obtained with mole ratios of 30-50% phosphoserine. While PM-CPCs behave like stiff ceramics after setting, they bond to soft tissues, and warrant further investigation as tissue adhesives, particularly at the interface between hard and soft tissues.

Place, publisher, year, edition, pages
MDPI, 2019
Keywords
tissue adhesive, phosphoserine, phosphoserine modified cement, biomaterial, bioceramic, lap shear, bone cement, silicate, calcium phosphate, self-setting
National Category
Medical Materials
Identifiers
urn:nbn:se:uu:diva-393904 (URN)10.3390/ma12152473 (DOI)000482576900134 ()31382566 (PubMedID)
Funder
Swedish Research Council, RMA15-0110
Note

De två första författarna delar förstaförfattarskapet.

Available from: 2019-10-18 Created: 2019-10-18 Last updated: 2019-10-18Bibliographically approved
Yu, Y., Guo, H., Pujari-Palmer, M., Stevensson, B., Grins, J., Engqvist, H. & Eden, M. (2019). Advanced solid-state H-1/P-31 NMR characterization of pyrophosphate-doped calcium phosphate cements for biomedical applications: The structural role of pyrophosphate. Ceramics International, 45(16), 20642-20655
Open this publication in new window or tab >>Advanced solid-state H-1/P-31 NMR characterization of pyrophosphate-doped calcium phosphate cements for biomedical applications: The structural role of pyrophosphate
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2019 (English)In: Ceramics International, ISSN 0272-8842, E-ISSN 1873-3956, Vol. 45, no 16, p. 20642-20655Article in journal (Refereed) Published
Abstract [en]

From a suite of advanced magic-angle spinning (MAS) NMR spectroscopy and powder X-ray diffraction (PXRD) experiments, we present a comprehensive structural analysis of pyrophosphate-bearing calcium phosphate cements that are investigated for bone-inductive biomedical implants. The cements consist mainly of poorly ordered monetite (CaHPO4), along with minor Ca orthophosphate phases, and two distinct pyrophosphate constituents: crystalline beta-Ca2P2O7 and amorphous calcium pyrophosphate (ACPP), the latter involving one water bearing portion and another anhydrous component. Independent 2D MAS NMR experiments evidenced close contacts between the amorphous pyrophosphates and the monetite phase, where ACPP is proposed to form a thin layer coating the monetite particles. Heteronuclear H-1-P-31 and homonuclear P-31-P-31 correlation NMR experimentation enabled us to detect, identify, and quantify even minor cement constituents (less than or similar to 2 mol%) that could not be ascertained by the Rietveld method. Quantitative phase analyses of the cements, as determined independently by P-31 NMR and PXRD, are contrasted and discussed.

Place, publisher, year, edition, pages
ELSEVIER SCI LTD, 2019
Keywords
Bioceramics, Monetite cement, DCPA, Amorphous calcium pyrophosphate, P-31 NMR, H-1 NMR, 2D homonuclear/heteronuclear correlation, NMR spectroscopy, Rietveld refinement, Cement structure
National Category
Ceramics
Identifiers
urn:nbn:se:uu:diva-395715 (URN)10.1016/j.ceramint.2019.07.047 (DOI)000488148100128 ()
Funder
Swedish Foundation for Strategic Research , RMA15-0110
Available from: 2019-10-25 Created: 2019-10-25 Last updated: 2019-10-25Bibliographically approved
Fowler, L., Janson, O., Engqvist, H., Norgren, S. & Öhman, C. (2019). Antibacterial investigation of titanium-copper alloys using luminescent Staphylococcus epidermidis in a direct contact test. Materials science & engineering. C, biomimetic materials, sensors and systems, 97, 707-714
Open this publication in new window or tab >>Antibacterial investigation of titanium-copper alloys using luminescent Staphylococcus epidermidis in a direct contact test
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2019 (English)In: Materials science & engineering. C, biomimetic materials, sensors and systems, ISSN 0928-4931, E-ISSN 1873-0191, Vol. 97, p. 707-714Article in journal (Refereed) Published
Abstract [en]

Commercially pure titanium (CP-Ti), used as oral implants, is often populated by various bacterial colonies in the oral cavity. These bacteria can cause Peri-implantitis, leading to loss of bone tissue and failure of implants. With the increased awareness of antibiotic resistance, research has been directed towards alternative solutions and recent findings have indicated titanium-copper (Ti-Cu) alloys as a promising antibacterial material. The aim of this study was to produce homogeneous Ti-Cu alloys, with various concentrations of copper, and to characterise their antibacterial properties through direct contact tests, using luminescent bacteria, in addition to traditional materials characterisation techniques. Samples of CP-Ti and four different Ti-Cu alloys (1, 2.5, 3 and 10 wt%Cu) were produced in an arc-furnace, heated treated and rapidly quenched. X-ray diffraction revealed that Ti2Cu, was present only in the 10 wt%Cu alloy, however, scanning electron microscopy (SEM) indicated precipitates at the grain boundaries of the 3 wt%Cu alloy, which were confirmed to be of a copper rich phase by energy dispersive x-ray spectroscopy (EDS) analysis. EDS line scans confirmed that the alloys were homogenous. After 6 h, a trend between copper content and antibacterial rate could be observed, with the 10 wt%Cu alloy having the highest rate. SEM confirmed fewer bacteria on the 3 wt%Cu and especially the 10 wt%Cu samples. Although the 10 wt%Cu alloy gave the best antibacterial results, it is desired that the Cu concentration is below similar to 3 wt%Cu to maintain similar mechanical and corrosive performance as CP-Ti. Therefore, it is proposed that future work focuses on the 3 wt%Cu alloy.

Place, publisher, year, edition, pages
ELSEVIER SCIENCE BV, 2019
Keywords
Copper, Titanium, Antibacterial, S. epidermidis, Ti2Cu
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:uu:diva-378615 (URN)10.1016/j.msec.2018.12.050 (DOI)000457952800069 ()30678959 (PubMedID)
Available from: 2019-03-11 Created: 2019-03-11 Last updated: 2019-10-17Bibliographically approved
Zhu, W., Ma, Q., Borg, S., Öhman Mägi, C., Weng, X., Engqvist, H. & Xia, W. (2019). Cemented injectable multi-phased porous bone grafts for the treatment of femoral head necrosis. Journal of materials chemistry. B, 7(18), 2997-3006
Open this publication in new window or tab >>Cemented injectable multi-phased porous bone grafts for the treatment of femoral head necrosis
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2019 (English)In: Journal of materials chemistry. B, ISSN 2050-750X, E-ISSN 2050-7518, Vol. 7, no 18, p. 2997-3006Article in journal (Refereed) Published
Abstract [en]

Femoral head necrosis (FHN) can induce musculoskeletal disability. It presents a challenge from diagnostic and therapeutic points of view. Open surgery for the treatment of FHN is not an optimal route. To minimize the surgery window, an injectable material with a porous structure and bioactive nature is preferred. The fabrication of an injectable porous bone graft via a simple route was the aim of our study. Therefore, cemented multi-phased calcium phosphate porous granules have been studied with varied phase compositions, pore sizes and porosities, and degradation rates. Granules templated by PEG 100-600 mu m were chosen for cell toxicity and in vitro osteogenic potential testing. Rabbits, making up a femoral head necrosis model, were implanted with granule A. Mature cancellous bone tissue was observed in the femoral head defect after 2 months implantation. The results indicate that the newly formed injectable bioactive porous grafts could be a good candidate for the treatment of femoral head necrosis.

Place, publisher, year, edition, pages
ROYAL SOC CHEMISTRY, 2019
National Category
Orthopaedics
Identifiers
urn:nbn:se:uu:diva-390518 (URN)10.1039/c9tb00238c (DOI)000472921600011 ()
Available from: 2019-08-14 Created: 2019-08-14 Last updated: 2019-08-14Bibliographically approved
Sladkova, M., Cheng, J., Palmer, M., Chen, S., Lin, C., Xia, W., . . . de Peppo, G. M. (2019). Comparison of Decellularized Cow and Human Bone for Engineering Bone Grafts with Human Induced Pluripotent Stem Cells. Tissue Engineering. Part A, 25(3-4), 288-301
Open this publication in new window or tab >>Comparison of Decellularized Cow and Human Bone for Engineering Bone Grafts with Human Induced Pluripotent Stem Cells
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2019 (English)In: Tissue Engineering. Part A, ISSN 1937-3341, E-ISSN 1937-335X, Vol. 25, no 3-4, p. 288-301Article in journal (Refereed) Published
Abstract [en]

Bone engineering makes it possible to grow unlimited amounts of viable tissue products for basic and applied research, and for clinical applications. A common trend in tissue engineering is the use of decellularized tissue matrices as scaffolding materials, which display structural, mechanical, and biological attributes typical of the native tissue. Due to the limited availability and high cost of human samples, decellularized tissue matrices are typically derived from animal sources. It is unclear, however, whether interspecies differences in tissue parameters will influence the quality of tissue grafts that are engineered using human stem cells. In this study, decellularized cow and human bone scaffolds were compared for engineering bone grafts using human induced pluripotent stem cell-derived mesodermal progenitor cells. After seeding, the cell-scaffold constructs were cultured for 5 weeks in osteogenic medium under dynamic conditions in perfusion bioreactors. The architectural and chemical properties of the scaffolds were studied using microscopic, spectroscopic, and thermogravimetric techniques, while cell behavior and formation of mineralized tissue were assessed using a combination of molecular assays, histological methods, and imaging technologies. The results show that while scaffolds derived from cow and human bone differ somewhat in architecture and composition, both equally support cell viability, tissue growth, and formation of a mineralized bone matrix. Taken together, the results suggest that scaffolds derived from cow bone represent a suitable and convenient alternative to engineer human bone grafts for various biomedical applications.

Keywords
biomaterial scaffold, bone engineering, induced pluripotent stem cells, mesenchymal stem cells, osteogenic differentiation, tissue decellularization
National Category
Biomaterials Science
Identifiers
urn:nbn:se:uu:diva-369891 (URN)10.1089/ten.tea.2018.0149 (DOI)000448565100001 ()30129897 (PubMedID)
Funder
EU, FP7, Seventh Framework Programme
Note

De 2 första författarna delar förstaförfattarskapet.

Available from: 2018-12-19 Created: 2018-12-19 Last updated: 2019-12-10Bibliographically approved
Fowler, L., Masia, N., Cornish, L. A., Chown, L. H., Engqvist, H., Norgren, S. & Öhman-Mägi, C. (2019). Development of Antibacterial Ti-Cu-x Alloys for Dental Applications: Effects of Ageing for Alloys with Up to 10 wt% Cu. Materials, 12(23), Article ID 4017.
Open this publication in new window or tab >>Development of Antibacterial Ti-Cu-x Alloys for Dental Applications: Effects of Ageing for Alloys with Up to 10 wt% Cu
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2019 (English)In: Materials, ISSN 1996-1944, E-ISSN 1996-1944, Vol. 12, no 23, article id 4017Article in journal (Refereed) Published
Abstract [en]

Peri-implantitis, a disease caused by bacteria, affects dental implants in patients. It is widely treated with antibiotics, however, with growing antibiotic resistance new strategies are required. Titanium-copper alloys are prospective antibacterial biomaterials, with the potential to be a remedy against peri-implantitis and antibiotic resistance. The aim of this study was to investigate Ti-Cux alloys, exploring how Cu content (up to 10 wt%) and ageing affect the material properties. Electron microscopy, X-ray diffraction, hardness testing, bacteriological culture, and electrochemical testing were employed to characterize the materials. It was found that alloys with above 3 wt% Cu had two phases and ageing increased the volume fraction of Ti2Cu. An un-aged alloy of 5 wt% Cu showed what could be Ti3Cu, in addition to the α-Ti phase. The hardness gradually increased with increased Cu additions, while ageing only affected the alloy with 10 wt% Cu (due to changes in microstructure). Ageing resulted in faster passivation of the alloys. After two hours the aged 10 wt% Cu alloy was the only material with an antibacterial effect, while after six hours, bacteria killing occurred in all alloys with above 5 wt% Cu. In conclusion, it was possible to tune the material and antibacterial properties of Ti-Cux alloys by changing the Cu concentration and ageing, which makes further optimization towards an antibacterial material promising.

Place, publisher, year, edition, pages
Switzerland: MDPI, 2019
Keywords
titanium alloys, copper, Ti2Cu, Ti3Cu, biomaterial, antibacterial
National Category
Medical Materials
Identifiers
urn:nbn:se:uu:diva-395300 (URN)10.3390/ma12234017 (DOI)000510178700213 ()31816905 (PubMedID)
Funder
The Swedish Foundation for International Cooperation in Research and Higher Education (STINT), SA2017-7127
Available from: 2019-10-16 Created: 2019-10-16 Last updated: 2020-03-11Bibliographically approved
Fowler, L., Engqvist, H. & Öhman-Mägi, C. (2019). Effect of copper ion concentration on bacteria and cells. Materials, 12(22), Article ID 3798.
Open this publication in new window or tab >>Effect of copper ion concentration on bacteria and cells
2019 (English)In: Materials, ISSN 1996-1944, E-ISSN 1996-1944, Vol. 12, no 22, article id 3798Article in journal (Refereed) Published
Abstract [en]

In the oral cavity, dental implants—most often made of commercially pure titanium—come in contact with bacteria, and antibacterial management has been researched extensively to improve patient care. With antibiotic resistance becoming increasingly prevalent, this has resulted in copper being investigated as an antibacterial element in alloys. In this study, the objective was to investigate the copper ion concentrations at which cyto-toxicity is avoided while bacterial inhibition is ensured, by comparing Cu ion effects on selected eukaryotes and prokaryotes. To determine relevant copper ion concentrations, ion release rates from copper and a 10 wt. % Cu Ti-alloy were investigated. Survival studies were performed on MC3T3 cells and Staphylococcus epidermidis bacteria, after exposure to Cu ions concentrations ranging from 9 × 10−3 to 9 × 10−12 g/mL. Cell survival increased from <10% to >90% after 24 h of exposure, by reducing Cu concentrations from 9 × 10−5 to 9 × 10−6 g/mL. Survival of bacteria also increased in the same range of Cu concentrations. The maximum bacteria growth was found at 9 × 10−7 g/mL, probably due to stress response. In conclusion, the minimum inhibitory concentrations of Cu ions for these prokaryotes and eukaryotes were found in the range from 9 × 10−5 to 9 × 10−6 g/mL. Interestingly, the Cu ion concentration correlating to the release rate of the 10 wt. % Cu alloy (9 × 10−8 g/mL) did not kill the bacteria, although this alloy has previously been found to be antibacterial. Further studies should investigate in depth the bacteria-killing mechanism of copper.

Place, publisher, year, edition, pages
Switzerland: MDPI, 2019
Keywords
Copper ion, Ion release, Antibacterial, S. Epidermidis, MC3T3
National Category
Other Materials Engineering
Identifiers
urn:nbn:se:uu:diva-395279 (URN)10.3390/ma12223798 (DOI)000502284400155 ()31752323 (PubMedID)
Available from: 2019-10-16 Created: 2019-10-16 Last updated: 2020-01-14Bibliographically approved
Janson, O., Sörensen, J. H., Strömme, M., Engqvist, H., Procter, P. & Welch, K. (2019). Evaluation of an alkali-treated and hydroxyapatite-coated orthopedic implant loaded with tobramycin. Journal of biomaterials applications, 34(5), 699-720, Article ID UNSP 0885328219867968.
Open this publication in new window or tab >>Evaluation of an alkali-treated and hydroxyapatite-coated orthopedic implant loaded with tobramycin
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2019 (English)In: Journal of biomaterials applications, ISSN 0885-3282, E-ISSN 1530-8022, Vol. 34, no 5, p. 699-720, article id UNSP 0885328219867968Article in journal (Refereed) Published
Abstract [en]

An approximately 1-µm thick hydroxyapatite coating was biomimetically deposited on an alkali-treated, commercially available orthopedic screw surface (type II anodized titanium). Tobramycin loaded into the coating via a simple soaking method was shown to provide a sustained release above the minimal inhibitory concentration 0.2 µg/µl for up to two days. Agar diffusion tests showed that the tobramycin-loaded coating was able to produce a zone of inhibition against Staphylococcus aureus for up to five days. Biocompatibility testing using outgrowth endothelial cells and primary osteoblasts suggested that good cell compatibility of the coating can be expected in vivo. A rabbit distal femur condyle model was used for in vivo evaluation of the antibacterial efficacy of the tobramycin-loaded coating, and this pilot study showed that the release of tobramycin was sufficient to locally eliminate very large amounts of bacteria in vivo (inoculation dose 104–105 CFU S. aureus/test site).

Keywords
Hydroxyapatite, antibacterial, orthopedic implant, tobramycin, fixation screw
National Category
Nano Technology
Research subject
Engineering Science with specialization in Nanotechnology and Functional Materials; Engineering Science with specialization in Materials Science
Identifiers
urn:nbn:se:uu:diva-390827 (URN)10.1177/0885328219867968 (DOI)000482810300001 ()31408413 (PubMedID)
Funder
EU, FP7, Seventh Framework Programme
Available from: 2019-08-14 Created: 2019-08-14 Last updated: 2019-10-30Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0001-9529-650X

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