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Sökning: L773:1552 4973 OR L773:1552 4981

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1.
  • Abramo, Antonio, et al. (författare)
  • Osteotomy of distal radius fracture malunion using a fast remodeling bone substitute consisting of calcium sulphate and calcium phosphate.
  • 2010
  • Ingår i: Journal of biomedical materials research. Part B, Applied biomaterials. - : Wiley. - 1552-4981 .- 1552-4973. ; 92:1, s. 281-6
  • Tidskriftsartikel (refereegranskat)abstract
    • Malunion after a distal radius fracture can be treated with an osteotomy of the distal radius. Autologous iliac crest bone graft is often used to fill the gap, but the procedure is associated with donor site morbidity. In this study a novel fast resorbing biphasic bone substitute consisting of a mixture of calcium sulphate and calcium phosphate is used (Cerament BoneSupport AB, Sweden). Fifteen consecutive patients, with a mean age of 52 (27-71) years were included. All had a malunion after a distal radius fracture and underwent an osteotomy. A fragment specific fixation system, TriMed (TriMed, Valencia, CA), consisting of a Buttress Pin and a Radial Pin Plate were used for fixation and a calcium sulphate and calcium phosphate mixture as bone substitute. The patients were followed for 1 year. Grip strength increased from 61 (28-93)% of the contralateral hand to 85 (58-109)%, p < 0.001. DASH scores decreased from 37 (22-61) to 24 (2-49) p = 0.003. Radiographically all osteotomies healed. An increase of ulnar variance was noted during healing from 1.8 mm immediately postoperatively to 2.6 mm at final follow up. Osteotomy can increase grip strength and decease disability after a malunited fracture. In the present series the bone substitute was replaced by bone, but a minor loss of the achieved radiographic correction was noted in some patients during osteotomy healing. A more rigid fixation may improve the radiographic outcome with this kind of bone substitute.
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2.
  • Alenezi, Ali, et al. (författare)
  • Controlled release of Clarithromycin from PLGA microspheres enhances bone regeneration in rabbit calvaria defects
  • 2017
  • Ingår i: Journal of Biomedical Materials Research. Part B - Applied biomaterials. - : John Wiley & Sons. - 1552-4973 .- 1552-4981. ; 106:1, s. 201-208
  • Tidskriftsartikel (refereegranskat)abstract
    • Purpose: To evaluate the controlled release effect of Clarithromycin loaded in PLGA microspheres in a rabbit calvaria defect model. Methods: Clarithromycin-loaded PLGA microspheres (MSPs) were formulated by modified O/W single emulsion/solvent evaporation method. After characterization, in vivo animal experiment was conducted. Four critical size bone defects were created in the calvaria of New Zealand White rabbits (n=21, n=7/time point). The bone defects were randomly designated to 4 groups: Group 1: No augmentation (sham), Group 2: beta-Tricalcium phosphate (β-TCP), Group 3: beta-Tricalcium phosphate (β-TCP) with 0.12 µg clarithromycin, and Group 4: beta-Tricalcium phosphate (β-TCP) with 6.12 µg PLGA microspheres (loaded with 0.12 µg clarithromycin). After 2, 4 and 12 weeks of healing, the levels of bone regeneration were evaluated using micro- computed tomography and histology. Results: The average size of the PLGA microspheres was 26.38 μm that showed 94% encapsulation efficacy with clarithromycin. Clarithromycin release from PLGA microspheres revealed sustained release for around 4 weeks with approximately 50% release of clarithromycin during the first week. In the histological analysis, new bone formation was evident at 2 and 4 weeks of healing in all groups and bone formation increased as a function of healing time in vivo. At 12 weeks, Group 4 showed significantly higher amount of newly formed bone compared to Group 1 (p=0,002). Moreover, during the micro CT exam, Group 4 expressed significantly higher bone formation compared to Group 1 at all time points tested (p=0.00, 0.014, and 0.002 in 2, 4, and 12 weeks, respectively). Conclusions: PLGA microspheres demonstrated initial burst release of clarithromycin followed by a sustained release profile. The in vivo findings showed that β-TCP with clarithromycin-loaded microspheres can enhance bone formation in bone defects.
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3.
  • Apelgren, Peter, et al. (författare)
  • Long-term in vivo integrity and safety of3D-bioprinted cartilaginous constructs
  • 2021
  • Ingår i: Journal of Biomedical Materials Research Part B-Applied Biomaterials. - : Wiley. - 1552-4973 .- 1552-4981. ; 109:1, s. 126-136
  • Tidskriftsartikel (refereegranskat)abstract
    • Long-term stability and biological safety are crucial for translation of 3D-bioprinting technology into clinical applications. Here, we addressed the long-term safety and stability issues associated with 3D-bioprinted constructs comprising a cellulose scaffold and human cells (chondrocytes and stem cells) over a period of 10 months in nude mice. Our findings showed that increasing unconfined compression strength over time significantly improved the mechanical stability of the cell-containing constructs relative to cell-free scaffolds. Additionally, the cell-free constructs exhibited a mean compressive stress and stiffness (compressive modulus) of 0.04 +/- 0.05 MPa and 0.14 +/- 0.18 MPa, respectively, whereas these values for the cell-containing constructs were 0.11 +/- 0.08 MPa (p= .019) and 0.53 +/- 0.59 MPa (p= .012), respectively. Moreover, histomorphologic analysis revealed that cartilage formed from the cell-containing constructs harbored an abundance of proliferating chondrocytes in clusters, and after 10 months, resembled native cartilage. Furthermore, extension of the experiment over the complete lifecycle of the animal model revealed no signs of ossification, fibrosis, necrosis, or implant-related tumor development in the 3D-bioprinted constructs. These findings confirm the in vivo biological safety and mechanical stability of 3D-bioprinted cartilaginous tissues and support their potential translation into clinical applications.
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4.
  • Ardlin, Berit I., et al. (författare)
  • Corrosion of dental nickel-aluminum bronze with a minor gold content-mechanism and biological impact
  • 2009
  • Ingår i: Journal of Biomedical Materials Research. Part B - Applied biomaterials. - Malden : Wiley-Blackwell. - 1552-4973 .- 1552-4981. ; 88B:2, s. 465-473
  • Tidskriftsartikel (refereegranskat)abstract
    • Objectives: To study corrosion and to evaluate biological effects in vitro of corrosion products of a copper-aluminum-nickel alloy with 2% gold. Methods: The alloy NPGTM+2 with the nominal composition Cu:77.3; Al:7.8; Ni:4.3; Fe:3.0; Zn:2.7; Au:2.0; and Mn:1.7 was characterized. Static immersion in acidic saline, pH 2.2-2.4, was used to determine release of metallic elements in a milieu simulating the condition of plaque build-up in interproximal areas of the tooth. Corrosion and surface reactions in saline and artificial saliva were studied by electrochemical techniques including registration of open-circuit-potentials, polarization curves and impedance spectra. Extracts were made in cell culture media and acidic saline and used for MTT test for cytotoxicity and HET-CAM method for irritation. Results: The mean amount of elements released in the acidic saline were in g cm-2 : Cu:632; Al:210; Ni:144; Fe:122; Zn:48; Mn:52. No protective film was formed on the surface of the alloy, as extensive corrosion was observed in both saline and artificial saliva. The corrosion rate was higher in saline than in artificial saliva. Acidic extracts of the alloy diluted up to 64 times reduced cell viability with 80% or more. The extract induced coagulation of the blood vessels of the CAM and was rated as moderate irritant solution. Significance: The nickel-aluminum bronze showed high corrosion rate caused by an inability to create a protective surface layer. High levels of toxic elements were found after static immersion testing, and the corrosion products had a distinct adverse effect on the biological activity.
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5.
  • Arvidsson, Anna, 1973, et al. (författare)
  • Comparing and visualizing titanium implant integration in rat bone using 2D and 3D techniques
  • 2015
  • Ingår i: Journal of Biomedical Materials Research. Part B - Applied biomaterials. - : Wiley. - 1552-4973 .- 1552-4981. ; 103:1, s. 12-20
  • Tidskriftsartikel (refereegranskat)abstract
    • The aim was to compare the osseointegration of grit-blasted implants with and without a hydrogen fluoride treatment in rat tibia and femur, and to visualize bone formation using state-of-the-art 3D visualization techniques. Grit-blasted implants were inserted in femur and tibia of 10 Sprague-Dawley rats (4 implants/rat). Four weeks after insertion, bone implant samples were retrieved. Selected samples were imaged in 3D using Synchrotron Radiation-based CT (SRCT). The 3D data was quantified and visualized using two novel visualization techniques, thread fly-through and 2D unfolding. All samples were processed to cut and ground sections and 2D histomorphometrical comparisons of bone implant contact (BIC), bone area (BA), and mirror image area (MI) were performed. BA values were statistically significantly higher for test implants than controls (p<0.05), but BIC and MI data did not differ significantly. Thus, the results partly indicate improved bone formation at blasted and hydrogen fluoride treated implants, compared to blasted implants. The 3D analysis was a valuable complement to 2D analysis, facilitating improved visualization. However, further studies are required to evaluate aspects of 3D quantitative techniques, with relation to light microscopy that traditionally is used for osseointegration studies. (c) 2014 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 103B: 12-20, 2015.
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6.
  • Arvidsson, Anna, 1973, et al. (författare)
  • Early interactions between leukocytes and three different potentially bioactive titanium surface modifications
  • 2011
  • Ingår i: Journal of Biomedical Materials Research. Part B - Applied biomaterials. - : Wiley. - 1552-4973 .- 1552-4981. ; 97:2, s. 364-72
  • Tidskriftsartikel (refereegranskat)abstract
    • The aim of the present study was to compare the early interactions between leukocytes and three different surface modifications, suggested as bioactive. Blasted titanium discs were modified by alkali and heat treatment, sodium fluoride treatment, or hydroxyapatite coating. A number of these discs were also immersed in simulated body fluid (SBF) for a week, a treatment which yielded high levels of calcium and phosphate on each surface type. The specimens were exposed for human venous blood for 32 minutes and the respiratory burst response was measured in terms of reactive oxygen species with a luminometer, and coverage of viable cells with a fluorescence microscope after staining steps. The topography, morphology, and chemistry of the surfaces were evaluated with optical interferometry and scanning electron microscopy/energy dispersive X-ray analysis (SEM/EDX). A high respiratory burst response was found for HA coated titanium in comparison with the other surface groups (p < 0.0005). The SBF immersion resulted in an increased respiratory burst response (p < 0.0005) and removed statistically significant differences between the surface groups. Thus, the results in the present study indicate that different titanium surface modifications influence the early inflammatory response differently, and that calcium phosphate compounds increase the inflammatory response.
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7.
  • Asplund, Basse, et al. (författare)
  • In vitro degradation and in vivo biocompatibility study of a new linear poly(urethane urea)
  • 2008
  • Ingår i: Journal of biomedical materials research. Part B: Applied biomaterials. - : Wiley. - 1552-4973 .- 1552-4981. ; 86B:1, s. 45-55
  • Tidskriftsartikel (refereegranskat)abstract
    • Segmented poly(urethane urea)s (PUUs) with hard segments derived only from methyl 2,6-diisocyantohexanoate (LDI) without the use of a chain extender have previously been described. These materials, which contain hard segments with multiple urea linkages, show exceptionally high strain capability (1600-4700%). In the study reported here, the rate and effect of hydrolysis of these materials were determined for gamma-sterilized and nonsterilized samples. Materials investigated contained PCL, PTMC, P(TMC-co-CL), P(CL-co-DLLA), or P(TMC-co-DLLA) as soft segments and, as well as their mechanical properties, changes in mass, inherent viscosity (IN.), and thermal properties were studied over 20 weeks. Results showed that the degradation rate was dependant on the soft segment structure, with a higher rate of degradation for the polyester-dominating PUUs exhibiting a substantial loss in IN. A tendency of reduction of tensile strength and strain hardening was seen for all samples. Also, loss in elongation at break was detected, for PUU-P(CL-DLLA) it went from 1600% to 830% in 10 weeks. Gamma radiation caused an initial loss in I.V. and induced more rapid hydrolysis compared with nonsterilized samples, except for PUU-PTMC. A cytotoxicity test using human fibroblasts demonstrated that the material supports cell viability. In addition, an in vivo biocompatibility study showed a typical foreign body reaction after I and 6 weeks.
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8.
  • Atthoff, Björn, et al. (författare)
  • Polarized protein membrane for high cell seeding efficiency
  • 2007
  • Ingår i: Journal of Biomedical Materials Research - Part B Applied Biomaterials. - : Wiley. - 1552-4973 .- 1552-4981. ; 83:2, s. 472-480
  • Tidskriftsartikel (refereegranskat)abstract
    • A new type of scaffold for tissue engineering was developed to give enhanced cell seeding in three dimensions. A gradient of either collagen or fibrin protein was prepared, supported by a knitted poly(ethylene terephtalate) PET fabric. The membranes were, after hydrolysis and acetic acid wash, submerged in a protein solution for adsorption followed by immersion into a gelling agent. The immediate contact between the protein solution held by the fabric and the gelling agent resulted in a dense, fibrous protein network with pore sizes around 0.5 μm at the surface, and larger pores of 10-50 μm size throughout the interior of the fabric as observed by scanning electron microscopy. By separating the fabric double layers holding this network, a gradient porosity membrane was produced. To evaluate the fractions of cells trapped in the matrix upon seeding, i.e. the seeding efficiency, 500 μl 3T3 fibroblasts cell suspension containing one million cells was seeded by filtering through the gradient protein membrane. For both the collagen and fibrin membranes, the seeding efficiency was ∼93%, which was significantly higher than that of 28% from the corresponding PET fabric without protein immobilization. Attempt to seed cells from the dense side of the protein networks resulted in no cell penetration into the scaffold. Histology on subsequent culture of the cells in the scaffold demonstrated viability and proliferation in three dimensions throughout the scaffold. This new and simple way of producing scaffolds play an important role when the cells are precious or scarce and cell seeding in three dimensions is important.
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9.
  • Atthoff, Björn, et al. (författare)
  • Protein adsorption onto polyester surfaces : Is there a need for surface activation?
  • 2007
  • Ingår i: Journal of Biomedical Materials Research - Part B Applied Biomaterials. - : Wiley. - 1552-4973 .- 1552-4981. ; 80:1, s. 121-130
  • Tidskriftsartikel (refereegranskat)abstract
    • Surface hydrolysis of polyester scaffolds is a convenient technique suggested to promote protein adsorption for improving cell attachment. We have, therefore, investigated the effect of hydrolysis of polyester surfaces for protein adsorption to clarify the conditions needed. Three polyesters, poly(ethylene terephthalate) (PET), poly(lactic acid) (PLA), and poly(glycolic acid) (PGA), were selected. Adsorption was investigated by X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and quartz crystal microbalance (QCM). Hydrolyzed PET adsorbed significantly more proteins than nonhydrolyzed. Degradable polymers adsorbed at higher rates when the polymers were hydrolyzed prior to adsorption, but the same amount as noehydrolyzed, suggesting spontaneous hydrolysis during the adsorption. XPS shows that hydrolysis prior to absorption for PET results in a surface nitrogen composition of ∼14%, similar to pure protein (16%). Nonhydrolyzed PET surfaces showed only ∼7% nitrogen, indicating protein layers thinner than ∼10 nm. Adsorption to PLA and PGA shows nitrogen contents of 14-15% in both cases. SEM revealed striking differences in morphology of the protein coating. Hydrolyzed or spontaneously hydrolyzable surfaces display a pronounced fibrous structure while nonhydrolyzed surfaces give smooth structures. In combination, the results show that surface hydrolysis increase adsorption rate, but not the amount of proteins on polyesters that degrades in vivo. Surface treatment of nondegradable polyester increases the total amount of proteins and induces the formation of fibrous protein structures. Post hydrolysis treatment by acetic acid, replacing the counter-ion to a proton, further enhances protein attachment. Finally, cell attachment experiments verifies that protein adsorption increase the cell attachment to polyester surfaces.
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11.
  • Bang, Le T., et al. (författare)
  • Synthesis and assessment of metallic ion migration through a novel calcium carbonate coating for biomedical implants
  • 2020
  • Ingår i: Journal of Biomedical Materials Research. Part B - Applied biomaterials. - : Wiley. - 1552-4973 .- 1552-4981. ; 108:2, s. 429-438
  • Tidskriftsartikel (refereegranskat)abstract
    • Titanium (Ti) implants are commonly regarded as well accepted by the body. However, metal ion release is still a cause for concern. A small decrease in pH, which can be caused by inflammation, may produce a large increase in the corrosion rate of Ti implants. Coating the alloy with a buffer layer could have a significant protective effect. In this study, a calcium carbonate coating was developed on commercially pure Ti and a Ti-6Al-4V alloy through a hydrothermal treatment of previously NaOH-treated surfaces in calcium-citric acid chelate complexes. The results showed that a superstructured calcite coating layer formed on the Ti substrate after treatment at 170 degrees C for 3 hr. The coating was approx. 1 mu m thick and covered the substrate surface uniformly. When prolonging the hydrothermal treatment from 5 hr to 24 hr, the rhombohedral structure of calcite was observed in addition to the superstructure of calcite. Dissolution test results showed no significant differences in solution pH between the coated- and un-coated samples. However, the CaCO3 coating reduced by approx. 2-5 times the Ti and V ion release from the substrate as compared to the uncoated material, at pH 4. CaCO3 and hydroxyapatite (HA) coatings gave nonsignificant effects at neutral pH although the HA coating showed a trend for better results at the longer time points. The reduction in metal ion release from the substrate and the buffering ability of the CaCO3 coating encourage further studies on this coating for clinical applications.
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12.
  • Berglund, Ida S., et al. (författare)
  • Synthesis and characterization of Mg-Ca-Sr alloys for biodegradable orthopedic implant applications
  • 2012
  • Ingår i: Journal of Biomedical Materials Research. Part B - Applied biomaterials. - : Wiley. - 1552-4973 .- 1552-4981. ; 100B:6, s. 1524-1534
  • Tidskriftsartikel (refereegranskat)abstract
    • Magnesium has recently received an increased amount of interest due to its potential use in biodegradable implant applications. The rapid degradation of conventional Mg is, however, a major limitation that needs to be addressed in the design of these materials, along with consideration of toxicity in selection of alloying elements. In this study, five alloys in the Mg-xCa-ySr system (x = 0.57.0 wt %; y = 0.53.5 wt %) were prepared and characterized for their suitability as degradable orthopedic implant materials. The alloys were characterized using optical microscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction, degradation measurements in Hanks' solution at 37 degrees C, compression testing, and in vitro cytotoxicity testing with a mouse osteoblastic cell line. The results indicate that the Mg-1.0Ca-0.5Sr alloy is the most promising alloy for orthopedic implant applications since it showed the lowest degradation rate in Hanks' solution (0.01 mL cm-2 h-1) along with no significant toxicity to MC3T3-E1 osteoblasts and a compressive strength of 274 +/- 4 MPa.
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13.
  • Björling, Gunilla, et al. (författare)
  • Evaluation of central venous catheters coated with a noble metal alloy - A randomized clinical pilot study of coating durability, performance and tolerability
  • 2018
  • Ingår i: Journal of Biomedical Materials Research. Part B - Applied biomaterials. - : John Wiley & Sons. - 1552-4973 .- 1552-4981. ; 106:6, s. 2337-2344
  • Tidskriftsartikel (refereegranskat)abstract
    • The use of Central Venous Catheters (CVCs) commonly results in complications. Coatings with silver or metal alloys can reduce the risk associated with the use of CVC. We have evaluated the durability of a noble metal coated CVC (the Bactiguard Infectious Protection, BIP CVC) and compared with an uncoated CVC for clinical tolerability (Adverse Events, AEs) and performance, in order to create a baseline for a large future study. Patients undergoing major surgery, randomised at a 2:1 ratio to BIP CVC (n = 22) or standard CVC (n = 12), were catheterized 9 - 12 days, respectively. Adverse events, microbial colonization and metal release were measured.FINDINGS: There were no AEs in the BIP CVC-group, but 5 AEs occurred in 4 patients (1 patient had 2 AEs) in the standard CVC-group, p = 0.011 (whereof 3 were catheter related). The BIP CVC showed an initial release of coating metals in blood (gold, silver and palladium), which rapidly decreased and were far below Permitted Paily Exposure (PDE) for chronical use. The levels of silver concentration were far below those needed to develop microbial resistance. The performance was equal, and there was no difference concerning microbial colonization, for the two CVCs.CONCLUSION: In this pilot study the BIP CVC had significantly lower AEs and showed a comparable performance to the standard CVC. The coating was durable throughout the study length (up to 16 days) and toxicological evaluation showed good safety margins. Larger studies are needed.
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14.
  • Cai, Yanling, et al. (författare)
  • Photocatalytic inactivation of biofilms on bioactive dental adhesives
  • 2014
  • Ingår i: Journal of Biomedical Materials Research. Part B - Applied biomaterials. - : Wiley. - 1552-4973 .- 1552-4981. ; 102:1, s. 62-67
  • Tidskriftsartikel (refereegranskat)abstract
    • Biofilms are the most prevalent mode of microbial life in nature and are 10-1000 times more resistant to antibiotics than planktonic bacteria. Persistent biofilm growth associated at the margin of a dental restoration often leads to secondary caries, which remains a challenge in restorative dentistry. In this work, we present the first in vitro evaluation of on-demand photocatalytic inactivation of biofilm on a novel dental adhesive containing TiO2 nanoparticles. Streptococcus mutans biofilm was cultured on this photocatalytic surface for 16 h before photocatalytic treatment with ultraviolet-A (UV-A) light. UV-A doses ranging from 3 to 43 J/cm(2) were applied to the surface and the resulting viability of biofilms was evaluated with a metabolic activity assay incorporating phenol red that provided a quantitative measure of the reduction in viability due to the photocatalytic treatments. We show that an UV-A irradiation dose of 8.4 J/cm(2) leads to one order of magnitude reduction in the number of biofilm bacteria on the surface of the dental adhesives while as much as 5-6 orders of magnitude reduction in the corresponding number can be achieved with a dose of 43 J/cm(2). This material maintains its functional properties as an adhesive in restorative dentistry while offering the possibility of a novel dental procedure in the treatment or prevention of bacterial infections via on-demand UV-A irradiation. Similar materials could be developed for the treatment of additional indications such as peri-implantits.
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15.
  • Camire, Christopher, et al. (författare)
  • Material characterization and in vivo behavior of silicon substituted alpha-tricalcium phosphate cement.
  • 2006
  • Ingår i: Journal of Biomedical Materials Research. Part B - Applied Biomaterials. - : Wiley. - 1552-4981 .- 1552-4973. ; 76B:2, s. 424-431
  • Tidskriftsartikel (refereegranskat)abstract
    • The possibility and biological effects of substituting silicon in a-tricalcium phosphate (alpha-TCP) by way of solid-state reaction have been evaluated. a-TCP powders with varying substitution amounts (1 and 5 mol % Ca2SiO4) were synthesized by reacting mixtures of CaCO3, Ca(2)P(2)O7, and SiO2, at a rate of 4 degrees C(min)(-1) to 1100 degrees C, left to dwell for 2 h and then heated to 1325 degrees C at 4 degrees C(min)(-1) and left to dwell for a period of 4 h. The powders were then rapidly quenched in air. Si incorporation could be verified by X-ray diffraction analysis, indicating an increase of the lattice volume with increasing Si content from 4284.1(8) to 4334(1) angstrom(3) for pure alpha-TCP and alpha-Si5%TCP, respectively. The hydrolysis of milled alpha-SiTCP powders was monitored by isothermal calorimetry, and the compressive strength of set cements was tested. The results showed changes in speed and amount of heat released during reactivity tests and a decrease in mechanical strength (60, 50, and 5 MPa) with increasing Si content. In vitro bioactivity of the set cements after soaking in simulated body fluid for 4 weeks was also tested. The formation of a bonelike apatite layer on the surface of the set cements could be observed and was thickest for 1% Si (20 mu m). These results were in good agreement with the in vivo studies performed, which showed strong evidence that the cement containing 1% silicon doped alpha-TCP enhanced mesenchymal cell differentiation and increased osteoblast activity compared with alpha-TCP. (c) 2005 Wiley Periodicals, Inc.
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16.
  • Camire, Christopher, et al. (författare)
  • The effect of crystallinity on strength development of alpha-TCP bone substitutes.
  • 2006
  • Ingår i: Journal of Biomedical Materials Research. Part B - Applied Biomaterials. - : Wiley. - 1552-4981 .- 1552-4973. ; 79B:1, s. 159-165
  • Tidskriftsartikel (refereegranskat)abstract
    • Alpha phase tricalcium phosphates (alpha-TCP) were produced using a solid-state reaction method and milled for various periods of time. The resulting four materials were alpha-TCPs, ranging in crystalline content. Powders were exposed to X-ray diffraction for material identification as well as for use in crystallinity and purity calculations. Powder particle size was investigated using laser diffraction. Materials were mixed with 2.5% Na2HPO4 solution to initiate the hydration of alpha-TCP to calcium-deficient hydroxyapatite (CDHA). Isothermal calorimetry was performed to observe thermal response of the powders over a period of time. During the reaction process, at various time points up to 216 h, the material was compression tested to observe strength development. Materials proved to be predominantly alpha phase, while amorphous content determined by XRD varied. Reactivity, as measured by isothermal calorimetry, varied with crystallinity of the alpha-TCP powder. Speed of strength development did not change except for the most finely ground powder. In addition, crystal size of the CDHA was changed only in the product formed from the most highly ground material. It is proposed that increasing reactivity of alpha-TCP cements does not result in a corresponding increase in rate of strength development until there is sufficient supersaturation to produce significant crystal nucleation.
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17.
  • Coelho, Paulo G., et al. (författare)
  • The in vivo effect of P-15 coating on early osseointegration
  • 2014
  • Ingår i: Journal of Biomedical Materials Research. Part B - Applied biomaterials. - : John Wiley & Sons. - 1552-4973 .- 1552-4981. ; 102:3, s. 430-440
  • Tidskriftsartikel (refereegranskat)abstract
    • The aim of this study was to evaluate mechanically and morphologically the effect of a specific peptide sequence P-15, when incorporated into implant surfaces. Three types of implants were used for the study: Group A: commercially pure titanium implant (blasted and acid etched) + electrochemical thin calcium phosphate deposition, Group B: commercially pure titanium implant (blasted and acid etched) + electrochemical thin calcium phosphate deposition + P-15 incorporation, and as control, Group C: commercially pure titanium implant (blasted and acid etched). After a topographical characterization, transcortical osteotomies were made, and all implant groups (102 implants per group) were randomly placed bilaterally in the tibiae of adult beagle dogs (n = 24). At, 1, 2, and 4 weeks post-surgery, the animals were sacrificed and the samples were retrieved for removal torque tests, for nano indentation, and for histomorphometrical analysis. The results (mean +/- 95% CI) showed that Group B (34.4 +/- 8.7%) presented statistically higher bone-to-implant contact than the other groups (A = 23.9 +/- 7.8%; C = 21.7 +/- 8.3%) at 1 week, indicating an enhanced osteogenesis due to the peptide incorporation. The results suggested that the incorporation of P-15 to implant surfaces increased its bioactivity and the effects were notable especially in the early stages of the healing process. (c) 2013 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 102B: 430-440, 2014.
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18.
  • Dehestani, M., et al. (författare)
  • Enhancing the bioactivity of zirconia and zirconia composites by surface modification
  • 2012
  • Ingår i: Journal of Biomedical Materials Research - Part B Applied Biomaterials. - : Wiley. - 1552-4981 .- 1552-4973. ; 100B:3, s. 832-840
  • Tidskriftsartikel (refereegranskat)abstract
    • Among bioceramics, zirconia (ZrO2) and alumina (Al2O3) possess exceptional mechanical properties suitable for load-bearing and wear-resistant applications but the poor bioactivity of these materials is the major concern when bonding and integration to the living bone are desired. This article investigates two different approaches and their underlying mechanisms to improve the bioactivity of zirconia (3Y-TZP) and a zirconia composite with alumina (10Ce-TZP/Al2O3). Chemical treatment approach applied on 3Y-TZP where the substrates were soaked in 5M H3PO4 to create chemically functional groups on the surface for inducing apatite nucleation. X-ray photoelectron spectroscopy (XPS) was used to detect chemical changes and X-ray diffraction (XRD) to monitor phase changes on the surface before and after acid treatment. Alternate soaking approach applied on 10Ce-TZP/Al2O3 consisted of soaking the composite substrates in CaCl2 and Na2HPO4 solutions alternately to make a precursor for apatite formation. The bioactivity was evaluated by apatite-forming ability of surface-treated materials in simulated body fluid (SBF). Both methods resulted in the formation of hydroxyapatite on the surface of materials; however, alternate soaking approach showed to be a simpler, faster, and more effective method than the chemical treatment approach for enhancing the bioactivity of zirconia materials.
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19.
  • Eick, Sigrun, et al. (författare)
  • Gingipains impair attachment of epithelial cell to dental titanium abutment surfaces
  • 2019
  • Ingår i: Journal of Biomedical Materials Research. Part B - Applied biomaterials. - : John Wiley & Sons. - 1552-4973 .- 1552-4981. ; 107:8, s. 2549-2556
  • Tidskriftsartikel (refereegranskat)abstract
    • The study investigated in vitro the effect of Porphyromonas gingivalis and its cysteine proteases (gingipains) on epithelial cell adhesion to titanium-zirconium alloy surfaces. Titanium-zirconium discs with a standard machined (M) or chemically modified hydrophilic surface (modM) were coated with lamin-5 and incubated with telomerase-inactivated gingival keratinocytes (TIGK). Three P. gingivalis strains or gingipains were either added simultaneously with TIGK or after TIGK cells were already attached to the disks. Adhered TIGK cells were counted at 24 h. All P. gingivalis strains clearly inhibited adhesion of TIGK cells to M and modM surfaces. Compared with bacteria/gingipain-free TIGK cell cultures, the number of attached TIGK cells was reduced by about 80% and 60% when P. gingivalis was added simultaneously or after TIGK cells were already attached to the disks (each p < 0.01), respectively. Counts of attached cells were similarly reduced when only gingipains were used. Adhesion molecules of TIGK cells, in particular E-cadherin, were cleaved by P. gingivalis. In conclusion, P. gingivalis and gingipains interfere with the adhesion of epithelial cells to titanium-zirconium alloy surfaces by cleaving adhesion molecules, while a chemically modified hydrophilic titanium-zirconium alloy surface did not yield any protection. (c) 2019 Wiley Periodicals, Inc. J Biomed Mater Res B Part B, 2019.
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20.
  • Engstrand Unosson, Johanna, et al. (författare)
  • An evaluation of methods to determine the porosity of calcium phosphate cements
  • 2015
  • Ingår i: Journal of Biomedical Materials Research. Part B - Applied biomaterials. - : Wiley. - 1552-4973 .- 1552-4981. ; 103:1, s. 62-71
  • Tidskriftsartikel (refereegranskat)abstract
    • The porosity of a material can be determined using a diversity of methods; however, the results from these methods have so far not been compared and analyzed for calcium phosphate cements (CPCs). The aim of this study was to compare a fast and easy method for porosity measurements with some commonly used porosity methods for CPCs. The investigated method is based on the assumption that when a wet cement sample is dried, the volume of the evaporated water is equal to the volume of pores within the cement. Moreover, different methods of drying the cements were evaluated for acidic CPCs. The results showed that drying at room temperature (22°C ±1°C) is preferable, since a phase transformation was observed at higher temperatures. The results also showed that drying for 24 hours in vacuum was sufficient to achieve water free cements. The porosity measured was found to vary between the porosity methods evaluated herein, and to get a complete picture of a cement’s porosity more than one method is recommended. Water evaporation, is, however, a fast and easy method to estimate the porosity of CPCs and could simplify porosity measurements in the future.
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21.
  • Galli, Silvia, et al. (författare)
  • Magnesium release from mesoporous carriers on endosseus implants does not influence bone maturation at 6 weeks in rabbit bone
  • 2017
  • Ingår i: Journal of Biomedical Materials Research - Part B Applied Biomaterials. - : Wiley. - 1552-4981 .- 1552-4973. ; 105:7, s. 2118-2125
  • Tidskriftsartikel (refereegranskat)abstract
    • ObjectivesThe release of magnesium ions (Mg2+) from titanium surfaces has been shown to boost the initial biological response of peri-implant bone and to increase the biomechanical strength of osseointegration. The objective of the present paper was to investigate if the initial improvement in osseointegration would influence the bone remodeling also during the maturation stage of bone healing. Methods: Titanium implants were coated with mesoporous titania layers and either loaded with Mg2+ (test group) or left untreated (control group). The implants were inserted in the tibiae of 10 New Zealand White rabbits. Osseointegration was assessed after 6 weeks by means of biomechanical testing (RTQ), non-decalcified histology and histomorphometry (BIC%, BA%, NBA%). The expression of genes involved in the bone formation and remodeling was quantified using qPCR. Results: Mg2+ releasing mesoporous titania coatings showed, on average, higher removal torques and histomorphometrical outcomes (RTQ: 17.2 Ncm vs. 15 Ncm; BIC: 38.8% vs. 32.1%; BA%: 71.6% vs. 64%; NBA% 62.5% vs. 54% for the tests vs the controls); however, the differences were not statistically significant. Three osteogenic markers, osteocalcin (OC), collagen 1 alpha 1 (COL1A1), and alkalin phosphatase (ALPL), were respectively 2-fold, 1.53-fold, and 1.13-fold up-regulated in the control group compared to the test. The expression of COL1A1 was particularly high in both groups, while the biomarkers for remodeling and inflammation showed a low expression in both groups. Significance: The results suggested that the initial enhancement in osseointegration induced by magnesium release from mesoporous titania coatings has no detrimental effects during bone maturation.
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22.
  • Gil, Luiz F., et al. (författare)
  • Progressive plateau root form dental implant osseointegration : a human retrieval study
  • 2015
  • Ingår i: Journal of Biomedical Materials Research. Part B - Applied biomaterials. - : John Wiley & Sons. - 1552-4973 .- 1552-4981. ; 103:6, s. 1328-1332
  • Tidskriftsartikel (refereegranskat)abstract
    • Although preclinical and sparse human histology retrieval studies have shown that the interface between implant and bone is constantly remodeling, no human retrieval database has been developed to determine the effect of functional loading time and other clinical/implant design variables on osseointegration. The present study tested the hypothesis that bone-to-implant contact (BIC) and bone area fraction occupancy (BAFO) increase over functional loading time around dental implants. Due to prosthetic retreatment reasons, 93 human implant retrievals from the same manufacturer (Bicon LLC, Boston, MA, USA) were obtained over a period of approximately 15 years. The retrieved implants were under functional loading from 120 days to approximate to 18 years and were histomorphologic/metrically evaluated. BIC/BAFO were assessed as a function of multiple independent variables: implant surface type, diameter, length, jaw (maxilla/mandible), region (anterior/posterior), and time of functional loading. The results showed that both BIC and BAFO increased over time independently of implant design/clinical variables, supporting the postulated hypothesis. (c) 2014 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 103B: 1328-1332, 2015.
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23.
  • Gotfredsen, Klaus, et al. (författare)
  • Does Longstanding Nicotine Exposure Impair Bone Healing and Osseointegration? An Experimental Study in Rabbits
  • 2009
  • Ingår i: Journal of Biomedical Materials Research. Part B - Applied Biomaterials. - : Wiley. - 1552-4981 .- 1552-4973. ; 91B:2, s. 918-923
  • Tidskriftsartikel (refereegranskat)abstract
    • Objectives: The aim of this study was to analyze the effect of longstanding nicotine exposure on bone healing and osseointegration of titanium implants. Materials and Methods: 20 female rabbits received either nicotine (n = 10) or saline (n = 10) administered subcutaneously via mini-osmotic pumps for 32 weeks. The pump delivered 6 mu g/kg/min of nicotine for the animals in the test group. Blood samples were collected and plasma cotinine levels were measured monthly. Six months after the commencement of nicotine or saline administration three osteotomy preparations, one in right, femoral condyle and two in the right tibia were made. One experimental implant was placed in the femur site and one in the most distal preparation of the tibia. The remaining site in the tibia was left empty. The osteotomy preparation and implant installation procedure was repeated in the left leg of the rabbits after 2 weeks. The implants in the tibial site were subjected to removal torque test (RMT) 2 weeks later. Block biopsies of the two other osteotomy sites were prepared for histological analysis. Results: Although no differences in RMT values were found between test and control groups, there was a significant increase in RMT between 2 and 4 weeks within each group. The histomorphometric analysis of bone-to-implant contact and bone density in the bone defects revealed no differences between the test and the control group after 2 or 4 weeks of healing. Conclusion: Longstanding (6 months) nicotine exposure did not impair bone healing and osseointegration of titanium implants. (C) 2009 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 91B: 918-923, 2009
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24.
  • Hedberg, Yolanda, et al. (författare)
  • Metal release and speciation of released chromium from a biomedical CoCrMo alloy into simulated physiologically relevant solutions
  • 2014
  • Ingår i: Journal of Biomedical Materials Research. Part B - Applied biomaterials. - : Wiley. - 1552-4973 .- 1552-4981. ; 102:4, s. 693-699
  • Tidskriftsartikel (refereegranskat)abstract
    • The objective of this study was to investigate the extent of released Co, Cr(III), Cr(VI), and Mo from a biomedical high-carbon CoCrMo alloy exposed in phosphate-buffered saline (PBS), without and with the addition of 10 mu M H2O2 (PBS + H2O2), and 10 g L-1 bovine serum albumin (PBS + BSA) for time periods up to 28 days. Comparative studies were made on AISI 316L for the longest time period. No Cr(VI) release was observed for any of the alloys in either PBS or PBS + H2O2 at open-circuit potential (no applied potential). However, at applied potentials (0.7 V vs. Ag/AgCl), Cr was primarily released as Cr(VI). Co was preferentially released from the CoCrMo alloy at no applied potential. As a consequence, Cr was enriched in the utmost surface oxide reducing the extent of metal release over time. This passivation effect was accelerated in PBS + H2O2. As previously reported for 316L, BSA may also enhance metal release from CoCrMo. However, this was not possible to verify due to the precipitation of metal-protein complexes with reduced metal concentrations in solution as a consequence. This was particularly important for Co-BSA complexes after sufficient time and resulted in an underestimation of metals in solution.
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25.
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26.
  • Ichioka, Yuki, et al. (författare)
  • Mechanical removal of biofilm on titanium discs: An in vitro study
  • 2022
  • Ingår i: Journal of Biomedical Materials Research Part B-Applied Biomaterials. - : Wiley. - 1552-4973 .- 1552-4981. ; 110:5, s. 1044-1055
  • Tidskriftsartikel (refereegranskat)abstract
    • The objective of this in vitro study was to evaluate surface cleanness and cytocompatibility following mechanical instrumentation of biofilm-contaminated titanium surfaces. Titanium discs (non-modified [Ti(s)] and shot-blasted surfaces [Ti(r)]) contaminated with Streptococcus gordonii were instrumented using four different techniques: (i) gauze soaked in saline (GS), (ii) ultra-sonic device (US), (iii) rotating nickel-titanium brush (TiB), or (iv) air-polishing device (AP). Non-contaminated, untreated titanium disks were used as controls (C). Residual deposits and cytocompatibility for osteoblast-like cells were evaluated using scanning electron microscopy, immunofluorescence, and reverse transcriptase polymerase chain reaction. While the number of residual bacteria on Ti(s) discs was close to 0 in all treatment groups, significantly higher mean numbers of residual bacteria were observed on Ti(r) discs for GS (152.7 +/- 75.7) and TiB (33.5 +/- 22.2) than for US (0) and AP (0). Instrumentation with US resulted in deposition of foreign material (mean area% of foreign material: 3.0 +/- 3.6% and 10.8 +/- 9.6% for Ti(s) and Ti(r) discs, respectively). AP was the most effective decontamination procedure in reducing bacteria without depositing residual foreign material on Ti(r) discs. TiB and AP were superior methods in restoring cytocompatibility, although no method of mechanical decontamination resulted in pristine levels of cytocompatibility.
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27.
  • Jimbo, Ryo, et al. (författare)
  • Regeneration of the cementum and periodontal ligament using local BDNF delivery in class II furcation defects
  • 2018
  • Ingår i: Journal of Biomedical Materials Research. Part B - Applied biomaterials. - : John Wiley & Sons. - 1552-4973 .- 1552-4981. ; 106:4, s. 1611-1617
  • Tidskriftsartikel (refereegranskat)abstract
    • Periodontal furcation defects are usually addressed by the placement of a physical barrier which may limit the regenerative potential of periodontal wounds. This study morphometrically quantified the regenerative effect of brain-derived neurotrophic factor (BDNF) in furcation defects in a non-human primate model. Grade II furcation defects (with and without induced inflammation prior to surgery) were created on the first and second molars of eight non-human primates. Defects were treated with open flap debridement and subsequently filled with either: Group A; BDNF (500 µg mL−1) in high-molecular weight-hyaluronic acid (HMW-HA), Group B; BDNF (50 µg mL−1) in HMW-HA, Group C; HMW-HA acid only, Group D; unfilled defect, or Group E; BDNF (500 µg mL−1) in saline. Periodontal wound healing was observed every 2 weeks by computed-tomography. At 11 weeks all animals were sacrificed and maxillary and mandibular block biopsies were referred for nondecalcified histology. Linear measurements of new cementum (cellular and acellular) and periodontal ligament (PDL) formation were performed. Computerized-tomography reconstruction and software quantification demonstrated successful bone fill for all groups. However, histometric assessment demonstrated significantly higher level of total periodontal regeneration for the 500 µg mL−1 BDNF HMW-HA relative to all other groups. No significant differences in cementogenesis were observed among groups. Significantly higher acellular cementum formation was observed for sites where inflammation was not induced prior to surgical procedures. While all groups experienced similar bone fill and cementogenesis, the 500 µg mL−1 BDNF HMW-HA appeared to most effectively repair PDL (minimum increase of ∼22% relative to all groups; over 200% relative to unfilled defects).
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28.
  • Johansson, Martin L, et al. (författare)
  • Integration between a percutaneous implant and the porcine small bowel.
  • 2011
  • Ingår i: Journal of biomedical materials research. Part B, Applied biomaterials. - : Wiley. - 1552-4981 .- 1552-4973. ; 98:1, s. 101-9
  • Tidskriftsartikel (refereegranskat)abstract
    • Inflammatory bowel diseases, cancer or trauma may require removal of all or part of the intestines, leaving the patient with a need to wear external stoma appliances for collection of bowel contents. By connecting the small bowel to a percutaneous port, equipped with a sealing lid, a fully continent and leak proof stoma can be created without a need for permanently wearing stoma appliance. The prerequisites for a connection between a permanent, transabdominal implant and a visceral organ are largely unexplored. Stoma ports made of titanium were implanted in the abdominal wall of domestic pigs and a branch of distal ileum was inserted through the ports. After being followed for 1-3 weeks, the ports were removed and subjected to histological evaluation to study the influence of their shape, structure, and position on the tissue response. Particular focus was attended to the attachment of the ileal serosal surface to the implants inner structure consisting of a titanium mesh. Macroscopic examination revealed fistulas and formation of abscesses in 4 of 11 the retrieved implants. Histological examination revealed regenerated and well-vascularized collagenous tissue around the mesh structure inside the implant. The integration was complete or partial for 10 of 11 ports. Despite various degrees of inflammation and tissue ingrowth, it was demonstrated for the first time that the serosal surface of ileum was firmly attached to the internal structure of the implant. These experiments provide a basis for optimization of the implant and surgical procedure before long-term functional animal experiments.
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29.
  • Kjellson, Fred, et al. (författare)
  • Bone cement X-ray contrast media: A clinically relevant method of measuring their efficacy.
  • 2004
  • Ingår i: Journal of Biomedical Materials Research. Part B - Applied Biomaterials. - : Wiley. - 1552-4981 .- 1552-4973. ; 70B:2, s. 354-361
  • Tidskriftsartikel (refereegranskat)abstract
    • It is important to compare different contrast media used in bone cement according to their ability to attenuate X-rays and thereby produce image contrast between bone cement and its surroundings in clinical applications. The radiopacity of bone cement is often evaluated by making radiographs of cement in air at an X-ray tube voltage of 40 kV. We have developed a method for ranking contrast media in bone cement simulating the clinical situation, by (1) choosing the same X-ray tube voltage as used in clinical work, and (2) using a water phantom to imitate the effects of the patients' soft tissue on the X-ray photons. In clinical work it is desirable to have low radiation dose, but high image contrast. The voltage chosen is a compromise, because both dose and image contrast decrease with higher voltage. Three contrast media (ZrO2, BaSO4, and Iodixanol) have been compared for degree of "image contrast." Comparing 10 wt % contrast media samples at an X-ray tube voltage of 40 kV, ZrO2 produced higher image contrast than the other media. However, at 80 kV, using a water phantom, the results were reversed, ZrO2 produced lower image contrast than both BaSO4 and Iodixanol. We conclude that evaluations of contrast media should be made with voltages and phantoms imitating the clinical application. (C) 2004 Wiley Periodicals, Inc.
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30.
  • Kou, Wen, et al. (författare)
  • A 3D numerical simulation of stress distribution and fracture process in a zirconia-based FPD framework
  • 2011
  • Ingår i: Journal of Biomedical Materials Research. Part B - Applied biomaterials. - : John Wiley & Sons. - 1552-4973 .- 1552-4981. ; 96B:2, s. 376-385
  • Tidskriftsartikel (refereegranskat)abstract
    • In this study, a numerical approach to the fracture behavior in a three-unit zirconia-based fixed partial denture (FPD) framework was made under mechanical loading using a newly developed three-dimensional (3D) numerical modeling code. All the materials studied were treated heterogeneously and Weibull distribution law was applied to describe the heterogeneity. The Mohr-Coulomb failure criterion with tensile strength cut-off was utilized to judge whether the material was in an elastic or failed state. For validation, the fracture pattern obtained from the numerical modeling was compared with a laboratory test; they largely correlated with each other. Similar fracture initiation sites were detected both in the numerical simulation and in an earlier fractographic analysis. The numerical simulation applied in this study clearly described the stress distribution and fracture process of zirconia-based FPD frameworks, information that could not be gained from the laboratory tests alone. Thus, the newly developed 3D numerical modeling code seems to be an efficient tool for prediction of the fracture process in ceramic FPD frameworks.
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31.
  • Krontiras, P., et al. (författare)
  • Adipogenic differentiation of stem cells in three-dimensional porous bacterial nanocellulose scaffolds
  • 2015
  • Ingår i: Journal of Biomedical Materials Research - Part B Applied Biomaterials. - : Wiley. - 1552-4981 .- 1552-4973. ; 103:1, s. 195-203
  • Tidskriftsartikel (refereegranskat)abstract
    • There is an increased interest in developing adipose tissue for in vitro and in vivo applications. Current two-dimensional (2D) cell-culture systems of adipocytes are limited, and new methods to culture adipocytes in three-dimensional (3D) are warranted as a more life-like model to study metabolic diseases such as obesity and diabetes. In this study, we have evaluated different porous bacterial nanocellulose scaffolds for 3D adipose tissue. In an initial pilot study, we compared adipogenic differentiation of mice mesenchymal stem cells from a cell line on 2D and 3D scaffolds of bacterial nanocellulose. The 3D scaffolds were engineered by crosslinking homogenized cellulose fibrils using alginate and freeze drying the mixture to obtain a porous structure. Quenching the scaffolds in liquid nitrogen resulted in smaller pores compared to slower freezing using isopropanol. We found that on 2D surfaces, the cells were scarcely distributed and showed limited formation of lipid droplets, whereas cells grown in macroporous 3D scaffolds contained more cells growing in clusters, containing large lipid droplets. All four types of scaffolds contained a lot of adipocytes, but scaffolds with smaller pores contained larger cell clusters than scaffolds with bigger pores, with viable adipocytes present even 4 weeks after differentiation. Scaffolds with lower alginate fractions retained their pore integrity better. We conclude that 3D culturing of adipocytes in bacterial nanocellulose macroporous scaffolds is a promising method for fabrication of adipose tissue as an in vitro model for adipose biology and metabolic disease.
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32.
  • La Spina, Rita, et al. (författare)
  • Chemically modified poly(2-hydroxyethyl methacrylate) cryogel for the adsorption of heparin.
  • 2014
  • Ingår i: Journal of Biomedical Materials Research. Part B - Applied Biomaterials. - : Wiley. - 1552-4981 .- 1552-4973. ; 102:6, s. 1207-1216
  • Tidskriftsartikel (refereegranskat)abstract
    • Various clinical procedures, such as cardiovascular surgery or extracorporeal blood purification, involve systemic anticoagulation using heparin. High concentrations of circulating heparin require neutralization due to possible serious bleeding complications. The intravenous administration of the heparin antagonist protamine sulfate is routinely clinically performed, but is frequently associated with adverse reactions. Therefore, there is a need for a valid and safe alternative to achieve extracorporeal heparin removal from blood or plasma, such as a filter, a matrix, or an adsorbent. Here, we describe the development of a macroporous poly(2-hydroxyethyl methacrylate)-based monolithic cryogel functionalized with l-lysine (pHEMA-lys) and the characterization of its selective heparin adsorption. The maximum binding capacity was quantified in vitro using aqueous and serum solutions under static and dynamic conditions, and fresh human plasma under static conditions. The pHEMA-lys bound 40,500 IU and 32,500 IU heparin/g cryogel at the equilibrium in aqueous solution and 50% serum, respectively. In human plasma spiked with 100 IU/mL of heparin, the binding was still highly efficient (4330 IU/g cryogel after 30 min, i.e., 87% of the initial concentration). The cryogels showed good blood compatibility, as indicated by negligible adsorption of albumin, antithrombin III, and total protein, and may thus be suitable for extracorporeal heparin removal. © 2014 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2014.
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33.
  • Lahens, Bradley, et al. (författare)
  • The effect of osseodensification drilling for endosteal implants with different surface treatments : A study in sheep.
  • 2019
  • Ingår i: Journal of Biomedical Materials Research. Part B - Applied biomaterials. - : John Wiley & Sons. - 1552-4973 .- 1552-4981. ; 107:3, s. 615-623
  • Tidskriftsartikel (refereegranskat)abstract
    • This study investigated the effects of osseodensification drilling on the stability and osseointegration of machine-cut and acid-etched endosteal implants in low-density bone. Twelve sheep received six implants inserted into the ilium, bilaterally (n = 36 acid-etched, and n = 36 as-machined). Individual animals received three implants of each surface, placed via different surgical techniques: (1) subtractive regular-drilling (R): 2.0 mm pilot, 3.2 and 3.8 mm twist drills); (2) osseodensification clockwise-drilling (CW): Densah Bur (Versah, Jackson, MI) 2.0 mm pilot, 2.8, and 3.8 mm multifluted tapered burs; and (3) osseodensification counterclockwise-drilling (CCW) Densah Bur 2.0 mm pilot, 2.8 mm, and 3.8 mm multifluted tapered burs. Insertion torque was higher in the CCW and CW-drilling compared to the R-drilling (p < 0.001). Bone-to-implant contact (BIC) was significantly higher for CW (p = 0.024) and CCW-drilling (p = 0.006) compared to the R-drilling technique. For CCW-osseodensification-drilling, no statistical difference between the acid-etched and machine-cut implants at both time points was observed for BIC and BAFO (bone-area-fraction-occupancy). Resorbed bone and bone forming precursors, preosteoblasts, were observed at 3-weeks. At 12-weeks, new bone formation was observed in all groups extending to the trabecular region. In low-density bone, endosteal implants inserted via osseodensification-drilling presented higher stability and no osseointegration impairments compared to subtractive regular-drilling technique, regardless of evaluation time or implant surface. (c) 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 00B: 000-000, 2018.
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34.
  • Larsson, Lena, 1969, et al. (författare)
  • When epigenetics meets bioengineering-A material characteristics and surface topography perspective
  • 2018
  • Ingår i: Journal of Biomedical Materials Research - Part B Applied Biomaterials. - : Wiley. - 1552-4973 .- 1552-4981. ; 106:5, s. 2065-2071
  • Forskningsöversikt (refereegranskat)abstract
    • © 2017 Wiley Periodicals, Inc. The field of tissue engineering and regenerative medicine (TE/RM) involves regeneration of tissues and organs using implantable biomaterials. The term epigenetics refers to changes in gene expression that are not encoded in the DNA sequence, leading to remodeling of the chromatin and activation or inactivation of gene expression. Recently, studies have demonstrated that these modifications are influenced not only by biological cues but also by mechanical and topographical signals. This review highlights the current knowledge on emerging approaches in TE/RM with a focus on the effect of materials and topography on the epigenetic expression pattern in cells with potential impacts on modulating regenerative biology.
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35.
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36.
  • Leino, Mattias, et al. (författare)
  • Human embryonic stem cell dispersion in electrospun PCL fiber scaffolds by coating with laminin-521 and E-cadherin-Fc
  • 2018
  • Ingår i: Journal of Biomedical Materials Research. Part B - Applied biomaterials. - : Wiley. - 1552-4973 .- 1552-4981. ; 106:3, s. 1226-1236
  • Tidskriftsartikel (refereegranskat)abstract
    • Advances in human pluripotent cell cultivation and differentiation protocols have led to production of stem cell-derived progenitors as a promising cell source for replacement therapy. Three-dimensional (3-D) culture is a better mimic of the natural niche for stem cells and is widely used for disease modeling. Here, we describe a nonaggregate culture system of human embryonic stem cells inside electrospun polycaprolactone (PCL) fiber scaffolds combined with defined extracellular proteins naturally occurring in the stem cell niche. PCL fiber scaffolds coated with recombinant human laminin-521 readily supported initial stem cell attachment and growth from a single-cell suspension. The combination of recombinant E-cadherin-Fc and laminin-521 further improved cell dispersion rendering a uniform cell population. Finally, we showed that the cells cultured in E-cadherin-Fc- and laminin-521-coated PCL scaffolds could differentiate into all three germ layers. Importantly, we provided a chemically defined 3-D system in which pluripotent stem cells grown and differentiated avoiding the formation of cell aggregates.
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37.
  • Lilja, Mirjam, et al. (författare)
  • Effect of deposition parameters on the photocatalytic activity and bioactivity of TiO(2) thin films deposited by vacuum arc on Ti-6Al-4V substrates
  • 2012
  • Ingår i: Journal of Biomedical Materials Research. Part B - Applied biomaterials. - : Wiley. - 1552-4973 .- 1552-4981. ; 100B:4, s. 1078-1085
  • Tidskriftsartikel (refereegranskat)abstract
    • This article evaluates the influence of the main parameters in a cathodic arc deposition process on the microstructure of titanium dioxide thin coatings and correlates these to the photocatalytic activity (PCA) and in vitro bioactivity of the coatings. Bioactivity of all as deposited coatings was confirmed by the growth of uniform layers of hydroxyapatite (HA) after 7 days in phosphate buffered saline at 37°C. Comparison of the HA growth after 24 h indicated enhanced HA formation on coatings with small titanium dioxide grains of rutile and anatase phase. The results from the PCA studies showed that coatings containing a mixed microstructure of both anatase and rutile phases, with small grain sizes in the range of 26-30 nm and with a coating thickness of about 250 nm, exhibited enhanced activity as compared with other microstructures and higher coating thickness. The results of this study should be valuable for the development of new bioactive implant coatings with photocatalytically induced on-demand antibacterial properties.
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38.
  • López, Alejandro, et al. (författare)
  • Calcium phosphate cements with strontium halides as radiopacifiers
  • 2014
  • Ingår i: Journal of Biomedical Materials Research. Part B - Applied biomaterials. - : Wiley. - 1552-4973 .- 1552-4981. ; 102:2, s. 250-259
  • Tidskriftsartikel (refereegranskat)abstract
    • High radiopacity is required to monitor the delivery and positioning of injectable implants. Inorganic nonsoluble radiopacifiers are typically used in nondegradable bone cements; however, their usefulness in resorbable cements is limited due to their low solubility. Strontium halides, except strontium fluoride, are ionic water-soluble compounds that possess potential as radiopacifiers. In this study, we compare the radiopacity, mechanical properties, composition, and cytotoxicity of radiopaque brushite cements prepared with strontium fluoride (SrF2), strontium chloride (SrCl2·6H2O), strontium bromide (SrBr2), or strontium iodide (SrI2). Brushite cements containing 10 wt % SrCl2·6H2O, SrBr2, or SrI2 exhibited equal to or higher radiopacity than commercial radiopaque cements. Furthermore, the brushite crystal lattice in cements that contained the ionic radiopacifiers was larger than in unmodified cements and in cements that contained SrF2, indicating strontium substitution. Despite the fact that the strontium halides increased the solubility of the cements and affected their mechanical properties, calcium phosphate cements containing SrCl2·6H2O, SrBr2, and SrI2 showed no significant differences in Saos-2 cell viability and proliferation with respect to the control. Strontium halides: SrCl2·6H2O, SrBr2, and SrI2 may be potential candidates as radiopacifiers in resorbable biomaterials although their in vivo biocompatibility, when incorporated into injectable implants, is yet to be assessed.
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39.
  • López, Alejandro, 1983-, et al. (författare)
  • Synthesis and characterization of injectable composites of poly[D,L-lactide-co-(ε-caprolactone)] reinforced with β-TCP and CaCO3 for intervertebral disk augmentation.
  • 2010
  • Ingår i: Journal of biomedical materials research. Part B, Applied biomaterials. - : Wiley. - 1552-4981 .- 1552-4973. ; 95:1, s. 75-83
  • Tidskriftsartikel (refereegranskat)abstract
    • Degeneration of the intervertebral disk constitutes one of the major causes of low back pain in adults aged 20-50 years old. In this study, injectable, in situ setting, degradable composites aimed for intervertebral disk replacement were prepared. β-TCP and calcium carbonate particles were mixed into acrylic-terminated oligo[D,L-lactide-co-(ε-caprolactone)], which were crosslinked at room temperature. The structure of the oligomers was confirmed by 1H-NMR spectroscopy. The composites were examined via SEM, and the mechanical properties of the crosslinked networks were determined. The porous β-TCP particles showed good mechanical anchorage to the matrix due to polymer penetration into the pores. In vitro degradation tests showed that the composites containing β-TCP slowly degraded, whereas the composites containing CaCO3 exhibited apatite formation capacity. It was concluded that the surface area, morphology, and solubility of the fillers might be used to control the degradation properties. The incorporation of fillers also increased both the elastic modulus and the maximum compression strength of the composites, properties that were similar to those of the physiological disk. These materials have potential for long-term intervertebral disk replacement and regenerative scaffolds because of their low degradation rates, bioactivity, and mechanical properties.
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40.
  • Löberg, Johanna, 1981, et al. (författare)
  • Electronic properties of anodized TiO2 electrodes and the effect on the in-vitro response
  • 2014
  • Ingår i: Journal of Biomedical Materials Research. Part B - Applied biomaterials. - : Wiley. - 1552-4973 .- 1552-4981. ; 102:4, s. 826-839
  • Tidskriftsartikel (refereegranskat)abstract
    • For dental implants, improved osseointegration is obtained by modifying the surface roughness as well as oxide morphology and composition. A combination of different effects contributes to enhanced performance, but with surface roughness as the dominant factor. In order to single out the effect of oxide conductivity on biological response, oxide films with similar thickness and surface roughness but different electronic properties were formed using galvanostatic anodization. Three different current densities were used, 2.4, 4.8 and 11.9 mAcm-2, which resulted in growth rates ranging from 0.2 to 2.5 V/s. The electronic properties were evaluated using cyclic voltammetry and impedance spectroscopy, while the biological response was studied by cell activity and apatite formation. The number of charge carrier in the oxide film close to the oxide/solution interface decreased from 5.810-19 to 3.210-19 cm-2 with increasing growth rate, i.e. the conductivity decreased correspondingly. Cell response of the different surfaces was tested in-vitro using human osteoblast-like cells (MG-63). The results clearly show decreased osteoblast proliferation and adhesion but higher mineralisation activity for the oxide with lower conductivity at the oxide/solution interface. The apatite-forming ability was examined by immersion in simulated body fluid. At short times the apatite coverage was 26% for the anodized surfaces, significantly larger than for the reference with only 3% coverage. After one week of immersion the apatite coverage ranged from 73% to 56% and a slight differentiation between the anodized surfaces was obtained with less apatite formation on the surface with lower conductivity, in line with the cell culture results.
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41.
  • Melin Svanborg, Lory, et al. (författare)
  • Surface characterization of commercial oral implants on the nanometer level
  • 2009
  • Ingår i: Journal of Biomedical Materials Research. Part B - Applied biomaterials. - : John Wiley & Sons. - 1552-4973 .- 1552-4981. ; 92:2, s. 462-469
  • Tidskriftsartikel (refereegranskat)abstract
    • Lately, there has been a growing interest in how the presence of nanometer structures on a bone integrated implant surface influences the healing process. Recent in vitro studies have revealed an increased osteoblast response to different nanophase surfaces. Some commercial implant brands claim their implants have nanometer structures. However, at present, there are no studies where the nano topography of today's commercially available oral implants has been investigated. The aim of this study was to characterize commercial oral implants on the nanometer level and to investigate whether or not the nanometer surface roughness was correlated to the more well-known micrometer roughness on the implants. Twelve different commercial screw-shaped oral implants with various surface modifications were examined using scanning electron microscopy and a white light interferometer. The interferometer is suitable for detection of nanoscale roughness in the vertical dimension; however, limitation exists on the horizontal due to the wavelength of the light. A 1 x 1 microm Gaussian filter was found to be useful for identifying nm roughness with respect to height deviation. The results demonstrated that an implant that was smooth on the micrometer level was not necessarily smooth on the nanometer level. Different structures in the nanometer scale was found on some of the implants, indicating that to fully understand the relationship between the properties of an implant surface and its osseointegration behavior, a characterization at the nanometer scale might be relevant.
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42.
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43.
  • Palmquist, Anders, 1977, et al. (författare)
  • Biomechanical, histological and ultrastructural analyses of laser micro- and nano-structured titanium implant after 6 months in rabbit.
  • 2011
  • Ingår i: Journal of biomedical materials research. Part B, Applied biomaterials. - : Wiley. - 1552-4981 .- 1552-4973. ; 97:2, s. 289-98
  • Tidskriftsartikel (refereegranskat)abstract
    • Short-term, experimental studies of partly laser-modified implants with nano-scale surface topographical features have recently shown a considerable increase in the biomechanical anchorage to bone. The aim of this study is to evaluate the biomechanical and bone-bonding ability of partly laser-modified implants compared with machined implants after a healing period of 6 months in a rabbit model. The results showed a 170% increase in removal torque. Histology and scanning electron microscopy demonstrated osseointegration for both implant types, but also revealed a different fracture pattern at the interface and in the bone. Transmission electron microscopy and chemical analysis showed coalescence between mineralized tissue and the nano-structured surface of the laser modified implant. Taken together, the results indicate that nano-structured surfaces promote in vivo long-term bone bonding and interface strength.
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44.
  • Palmquist, Anders, 1977, et al. (författare)
  • Calcium Aluminate Coated and Uncoated Free Form Fabricated CoCr Implants : A Comparative Study in Rabbit
  • 2009
  • Ingår i: Journal of Biomedical Materials Research - Part B Applied Biomaterials. - : Wiley. - 1552-4973 .- 1552-4981. ; 91B:1, s. 122-127
  • Tidskriftsartikel (refereegranskat)abstract
    • The purpose of this study was to compare the integration in bone of uncoated free form fabricated cobalt chromium (CoCr) implants to the same implant with a calcium aluminate coating. The implants of cylindrical design with a pyramidal surface structure were press-fit into the limbs of New Zealand white rabbits. After 6 weeks, the rabbits were sacrificed, and samples were retrieved and embedded. Ground sections were subjected to histological analysis and histomorphometry. The section counter part was used for preparing an electron transparent transmission electron microscopy sample by focused ion beam milling. Calcium aluminate dip coating provided a significantly greater degree of bone contact than that of the native CoCr. The gibbsite hydrate formed in the hardening reaction of the calcium aluminate was found to be the exclusive crystalline phase material in direct contact with bone.
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45.
  • Palmquist, Anders, 1977, et al. (författare)
  • Morphological studies on machined implants of commercially pure titanium and titanium alloy (Ti6Al4V) in the rabbit.
  • 2009
  • Ingår i: Journal of biomedical materials research. Part B, Applied biomaterials. - : Wiley. - 1552-4981 .- 1552-4973. ; 91:1, s. 309-19
  • Tidskriftsartikel (refereegranskat)abstract
    • The aim of this study was to evaluate the bone response to commercially pure titanium grade I and titanium alloy grade V (90% Ti, 6% Al, and 4% V, depicted Ti6Al4V) after 8 weeks in rabbit tibia. Interference microscopy and scanning electron microscopy were used for surface analyses. Transmission electron microscopy (TEM) was used for evaluation of surface crystallinity and chemistry after preparation of ultrathin sections using focused ion beam (FIB) microscopy. Three different embedding resins commonly used for histological preparation were evaluated with respect to adaptation to a turned implant surface. Epoxy Agar 100 resin and acrylic Technovit 7200 resin showed low separation while acrylic LR White resin showed large separation at the interface. The retrieved specimens were embedded in acrylic Technovit 7200 resin after fixation and dehydration. The histological evaluation revealed osseointegration for both c.p. titanium grade I and Ti6Al4V alloy, but no quantitative differences in bone contact and bone area were detected. Because a separation of implant and tissue occurred in the interface between implant and bone embedded in acrylic Technovit 7200 resin, additional factors related to implant surface properties and technical procedures are likely to influence the possibilities to prepare ultrathin sections by FIB.
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46.
  • Papia, Evaggelia, et al. (författare)
  • Bonding between oxide based ceramics and adhesive cement systems : a systematic review
  • 2014
  • Ingår i: Journal of Biomedical Materials Research. Part B - Applied biomaterials. - : Wiley-Blackwell. - 1552-4973 .- 1552-4981. ; 102:2, s. 395-413
  • Forskningsöversikt (refereegranskat)abstract
    • The following aims were set for this systematic literature review: (a) to make an inventory of existing methods to achieve bondable surfaces on oxide ceramics and (b) to evaluate which methods might provide sufficient bond strength. Current literature of in vitro studies regarding bond strength achieved using different surface treatments on oxide ceramics in combination with adhesive cement systems was selected from PubMed and systematically analyzed and completed with reference tracking. The total number of publications included for aim a was 127 studies, 23 of which were used for aim b. The surface treatments are divided into seven main groups: as-produced, grinding/polishing, airborne particle abrasion, surface coating, laser treatment, acid treatment, and primer treatment. There are large variations, making comparison of the studies difficult. An as-produced surface of oxide ceramic needs to be surface treated to achieve durable bond strength. Abrasive surface treatment and/or silica-coating treatment with the use of primer treatment can provide sufficient bond strength for bonding oxide ceramics. This conclusion, however, needs to be confirmed by clinical studies. There is no universal surface treatment. Consideration should be given to the specific materials to be cemented and to the adhesive cement system to be used.
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47.
  • Papia, Evaggelia, et al. (författare)
  • Impaction-modified densely sintered yttria-stabilized tetragonal zirconium dioxide : methodology, surface structure, and bond strength
  • 2012
  • Ingår i: Journal of Biomedical Materials Research. Part B - Applied biomaterials. - : John Wiley & Sons. - 1552-4973 .- 1552-4981. ; 100:3, s. 677-684
  • Tidskriftsartikel (refereegranskat)abstract
    • The objectives of the study were to describe a novel method for producing zirconium dioxide specimens with a cementation surface that allows adhesive cementation techniques, to describe the surface structure and to evaluate the bond strength. Forty-eight pairs of specimens were fabricated and adhesively luted together. Three different surfaces were tested: impaction-modified surfaces created by using glass granules (G), impaction-modified surfaces created by using polymer granules (P) and a nonmodified control surface (C). Two bonding systems were used, Variolink(®)II (VA) or Panavia™F 2.0 (PA). During the different fabrication steps, the surfaces were examined under light microscope and analyzed with an optical interferometer. All groups were thermocycled and subjected to shear bond strength test. The groups with modified cementation surfaces showed significantly higher shear bond strength: 34.9 MPa (VA-G), 30.9 MPa (VA-P), 29.6 MPa (PA-P), and 26.1 MPa (PA-G) compared with the relevant control group: 20.5 MPa (VA-C) and 17.8 MPa (PA-C). The groups with surface modification showed a rougher surface structure and significantly fewer fractures between the cement and the zirconium dioxide surfaces compared to the control groups where all failures were adhesive. Impaction modification with an impaction medium pressed into the cementation surface of zirconium dioxide-based reconstructions can be used in combination with an additive production technique to increase bond strength. Both modification techniques described in the study result in a rougher surface structure and higher shear bond strength compared to the control groups.
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48.
  • Peeters, Elien, et al. (författare)
  • An antibiofilm coating of 5-aryl-2-aminoimidazole covalently attached to a titanium surface
  • 2019
  • Ingår i: Journal of Biomedical Materials Research. Part B - Applied biomaterials. - : Wiley. - 1552-4973 .- 1552-4981. ; 107:6, s. 1908-1919
  • Tidskriftsartikel (refereegranskat)abstract
    • Biofilms, especially those formed by Staphylococcus aureus, play a key role in the development of orthopedic implant infections. Eradication of these infections is challenging due to the elevated tolerance of biofilm cells against antimicrobial agents. In this study, we developed an antibiofilm coating consisting of 5-(4-bromophenyl)-N-cyclopentyl-1-octyl-1H-imidazol-2-amine, designated as LC0024, covalently bound to a titanium implant surface (LC0024-Ti). We showed in vitro that the LC0024-Ti surface reduces biofilm formation of S. aureus in a specific manner without reducing the planktonic cells above the biofilm, as evaluated by plate counting and fluorescence microscopy. The advantage of compounds that only inhibit biofilm formation without affecting the viability of the planktonic cells, is that reduced development of bacterial resistance is expected. To determine the antibiofilm activity of LC0024-Ti surfaces in vivo, a biomaterial-associated murine infection model was used. The results indicated a significant reduction in S. aureus biofilm formation (up to 96%) on the LC0024-Ti substrates compared to pristine titanium controls. Additionally, we found that the LC0024-Ti substrates did not affect the attachment and proliferation of human cells involved in osseointegration and bone repair. In summary, our results emphasize the clinical potential of covalent coatings of LC0024 on titanium implant surfaces to reduce the risk of orthopedic implant infections.
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49.
  • Pihl, Maria, 1978, et al. (författare)
  • Osseointegration and antibacterial effect of an antimicrobial peptide releasing mesoporous titania implant
  • 2021
  • Ingår i: Journal of Biomedical Materials Research - Part B Applied Biomaterials. - : Wiley. - 1552-4981 .- 1552-4973. ; 109:11, s. 1787-1795
  • Tidskriftsartikel (refereegranskat)abstract
    • Medical devices such as orthopedic and dental implants may get infected by bacteria, which results in treatment using antibiotics. Since antibiotic resistance is increasing in society there is a need of finding alternative strategies for infection control. One potential strategy is the use of antimicrobial peptides, AMPs. In this study, we investigated the antibiofilm effect of the AMP, RRP9W4N, using a local drug-delivery system based on mesoporous titania covered titanium implants. Biofilm formation was studied in vitro using a safranine biofilm assay and LIVE/DEAD staining. Moreover, we investigated what effect the AMP had on osseointegration of commercially available titanium implants in vivo, using a rabbit tibia model. The results showed a sustained release of AMP with equal or even better antibiofilm properties than the traditionally used antibiotic Cloxacillin. In addition, no negative effects on osseointegration in vivo was observed. These combined results demonstrate the potential of using mesoporous titania as an AMP delivery system and the potential use of the AMP RRP9W4N for infection control of osseointegrating implants.
  •  
50.
  • Piskounova, Sonya, et al. (författare)
  • In vitro characterization of bioactive titanium dioxide/hydroxyapatite surfaces functionalized with BMP-2
  • 2009
  • Ingår i: Journal of biomedical materials research. Part B, Applied biomaterials. - : Wiley. - 1552-4981 .- 1552-4973. ; 91B:2, s. 780-787
  • Tidskriftsartikel (refereegranskat)abstract
    • Poor implant fixation and bone resorption are two of the major challenges in modern orthopedics and are caused by poor bone/implant integration. In this work, bioactive crystalline titanium dioxide (TiO(2))/hydroxyapatite (HA) surfaces, functionalized with bone morphogenetic protein 2 (BMP-2), were evaluated as potential implant coatings for improved osseointegration. The outer layer consisted of HA, which is known to be osteoconductive, and may promote improved initial bone attachment when functionalized with active molecules such as BMP-2 in a soaking process. The inner layer of crystalline TiO(2) is bioactive and ensures long-term fixation of the implant, once the hydroxyapatite has been resorbed. The in vitro response of mesenchymal stem cells on bioactive crystalline TiO(2)/HA surfaces functionalized with BMP-2 was examined and compared with the cell behavior on nonfunctionalized HA layers, crystalline TiO(2) surfaces, and native titanium oxide surfaces. The crystalline TiO(2) and the HA surfaces showed to be more favorable than the native titanium oxide surface in terms of cell viability and cell morphology as well as initial cell differentiation. Furthermore, cell differentiation on BMP-2-functionalized HA surfaces was found to be significantly higher than on the other surfaces indicating that the simple soaking process can be used for incorporating active molecules, promoting fast bone osseointegration to HA layers.
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