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4-Aryl-1,2,3-triazole: a novel template for a reversible methionine aminopeptidase 2 inhibitor, optimized to inhibit angiogenesis in vivo
Kallander, L. S., Q. Lu, et al. (2005), J Med Chem 48(18): 5644-7.
Abstract: Inhibitors of human methionine aminopeptidase type 2 (hMetAP2) are of interest as potential treatments for cancer. A new class of small molecule reversible inhibitors of hMetAP2 was discovered and optimized, the 4-aryl-1,2,3-triazoles. Compound 24, a potent inhibitor of cobalt-activated hMetAP2, also inhibits human and mouse endothelial cell growth. Using a mouse matrigel model, this reversible hMetAP2 inhibitor was also shown to inhibit angiogenesis in vivo.

A "room-temperature" injection molding/particulate leaching approach for fabrication of biodegradable three-dimensional porous scaffolds
Wu, L., D. Jing, et al. (2006), Biomaterials 27(2): 185-91.
Abstract: A "room-temperature" injection molding approach combined with particulate leaching (RTIM/PL) has been, for the first time, developed in this work to fabricate three-dimensional porous scaffolds composed of biodegradable polyesters for tissue engineering. In this approach, a "wet" composite of particulate/polymer/solvent was used in processing, and thus the injection was not performed at melting state. Appropriate viscosity and flowability were facilely obtained at a certain solvent content so that the composite was able to be injected into a mould under low pressure at room temperature, which was very beneficial for avoiding thermal degradation of polyesters. As a demonstration, tubular and ear-shaped porous scaffolds were fabricated from biodegradable poly(D,L-lactide-co-glycolide) (PLGA) by this technology. Porosities of the resulting scaffolds were as high as 94%. The pores were well interconnected. Besides the well-known characteristics of injection molding to be suitable for automatization of a fabrication process with high repeatability and precision, this RTIM/PL approach is much suitable for tailoring highly porous foams with its advantages flexible for shaping complicated scaffolds, free of thermal degradation and high-pressure machine, etc.

A 10-year follow-up study of titanium dioxide-blasted implants
Rasmusson, L., J. Roos, et al. (2005), Clin Implant Dent Relat Res 7(1): 36-42.
Abstract: BACKGROUND: Dental implants with moderately rough surfaces are commonly used in the treatment of edentulous patients. However, long-term data on survival rates and marginal bone conditions are lacking. PURPOSE: This prospective study evaluated the cumulative survival rate of the TiOblast implant (Astra Tech AB, Molndal, Sweden) after 10 years of prosthetic loading. Materials and Methods: A total of 199 TiOblast implants were placed in 36 consecutive edentulous patients (23 males and 13 females). All patients were treated at one clinic and by the same team. The patients were edentulous in either the maxilla (n = 16) or the mandible (n = 20). The average age of the patients at the start of the trial was 64 years (range, 59-82 years). Of the 199 implants inserted 108 were in the mandible and 91 were in the maxilla. Clinical evaluations were undertaken after completion of the prosthetic superstructure (baseline) and after 6 months, 1 year, 3 years, 5 years, 7 years, and 10 years. Mean marginal bone level was evaluated for the first 100 placed implants for up to 7 years. RESULTS: Six implants failed during the study (3 in the mandible and 3 in the maxilla). All failures occurred within the first year, giving a cumulative survival rate of 96.9% (96.6 % in the maxilla and 97.2 % in the mandible) after 10 years of follow-up. The survival rate for the superstructures was 100%. The mean marginal bone level in the measured sample was 0.2 mm (standard deviation [SD], 0.31) below the reference point at baseline, 0.28 mm (SD, 0.20) and 1.27 mm (SD, 1.15) below the same point 7 years later (mean, 0.15 mm per year). CONCLUSION: This study showed that titanium dioxide-blasted implants offer predictable long-term results as supports for fixed prostheses in both the maxilla and mandible.

A 13C NMR study of the molecular dynamics and phase transition of confined benzene inside titanate nanotubes
Tang, X. P., J. C. Wang, et al. (2005), J Am Chem Soc 127(25): 9255-9.
Abstract: This work investigated the nanoconfinement effect on the molecular dynamics and phase transition of confined benzene inside titanate nanotubes with a uniform inner diameter of approximately 5.3 nm. For 13C-enriched organics, the 13C nuclear spin-spin relaxation was demonstrated as a sensitive tool to differentiate molecular translational motion and reorientation and, thus, was shown to be advantageous over the commonly employed 1H and 2H NMR for studying complex phase diagram, specifically, for separating the phase behavior of translational motion and the phase behavior of molecular reorientation. In such an approach, the melting of translational motion of confined benzene was explicitly observed to take place in a broad temperature range below the bulk melting temperature. The abrupt change of the 13C nuclear spin-spin relaxation time of the confined liquid benzene at about 260 K suggested that nanoconfinement induced two topologically distinct liquid phases.

A 1-year study of hydroxyapatite-derived biomaterials in an adult sheep model: III. Comparison with autogenous bone graft for facial augmentation
Gosain, A. K., P. A. Riordan, et al. (2005), Plast Reconstr Surg 116(4): 1044-52.
Abstract: BACKGROUND: The present study investigates onlay bone grafts and implants in a large-animal (sheep) model to determine whether there are composite biomaterials that can maximize long-term facial augmentation when compared with conventional bone grafts. METHODS: Facial augmentation was performed in 10 adult sheep. First, 16.8 x 5-mm disks were prepared from autogenous calvarial bone, hydroxyapatite ceramic, ceramic composite of 60 percent hydroxyapatite and 40 percent beta-tricalcium phosphate (60 percent hydroxyapatite ceramic), and hydroxyapatite cement paste. Facial recipient sites were the body of the mandible (depository), the maxillary region (resorptive), and the frontal bone (depository). The volume of all bone grafts and implants was determined using computed tomographic scans, and the amount of bone formation was measured by means of backscatter electron microscopy 1 year postimplantation. RESULTS: Cranial bone graft demonstrated a highly significant reduction in volume in all sites studied. Other than a slight decrease in volume of hydroxyapatite cement paste disks applied to the maxillary region, there was no significant change in volume of the biomaterials implanted in any of the remaining recipient sites. Bone replacement was greatest in hydroxyapatite ceramic (23.9 percent) followed by 60 percent hydroxyapatite ceramic (16.4 percent) and least with hydroxyapatite cement paste (4.2 percent). Minimal differences in bone replacement were noted between recipient sites. CONCLUSIONS: This study demonstrates that the volume maintenance of onlay hydroxyapatite composites is highly predictable, whereas that of cranial bone graft is unpredictable. Minimal differences were seen in bone replacement within biomaterials between "depository" and "resorptive" facial recipient sites. Ceramic forms of onlay hydroxyapatite implants demonstrated significantly greater bone replacement than did the cement paste forms of hydroxyapatite.

A 1-year study of osteoinduction in hydroxyapatite-derived biomaterials in an adult sheep model: part I
Gosain, A. K., L. Song, et al. (2002), Plast Reconstr Surg 109(2): 619-30.
Abstract: The study presented here investigated hydroxyapatite biomaterials implanted in soft-tissue sites in adult sheep to determine whether these materials are osteoinductive and whether the rate of osteoinduction can be increased by manipulating the composition and porosity of the implants. For the study, 16.8-mm x 5-mm discs were prepared from mixtures of hydroxyapatite and beta-tricalcium phosphate. Five mixtures of hydroxyapatite-ceramic and hydroxyapatite-cement paste forms were studied: 100 percent hydroxyapatite-ceramic (Interpore), 60 percent hydroxyapatite-ceramic, 100 percent hydroxyapatite-cement paste, 60 percent hydroxyapatite-cement paste, and 20 percent hydroxyapatite-cement paste. Biomaterials were implanted in subcutaneous and intramuscular soft-tissue pockets in 10 adult sheep. Cranial bone grafts of equal dimension were implanted as controls. One year after implantation, the volume of all biomaterials and bone grafts was determined from a computed tomographic scan, and porosity and bone formation were determined using backscatter electron microscopy. Cranial bone and the 20 percent hydroxyapatite-cement paste implants demonstrated significant volume reduction in all sites after 1 year (p < 0.001). No significant difference in volume of the remaining four biomaterials was found. There was no significant change in pore size in the ceramic implants (range, 200 to 300 micro) and in the cement-paste implants containing 60 percent hydroxyapatite or more (range, 3 to 5 nm). Pore size in the cement-paste implants containing 20 percent hydroxyapatite increased significantly with resorption of the tricalcium-phosphate component, reaching a maximum of 200 to 300 micro in the periphery, where the greatest tricalcium-phosphate resorption had occurred. Both ceramic biomaterials demonstrated lamellar bone deposition within well-formed haversian systems through the entire depth of the implants, ranging from a mean of 6.6 percent to 11.7 percent. There was minimal bone formation in the cement-paste implants containing 60 percent hydroxyapatite or more. In contrast, cement-paste implants containing 20 percent hydroxyapatite demonstrated up to 10 percent bone replacement, which was greatest in the periphery of the implants where the greatest tricalcium-phosphate resorption had occurred. This study confirms the occurrence of true osteoinduction within hydroxyapatite-derived biomaterials, when examined using backscatter techniques. In this study, the rate of osteoinduction was greatest when a porous architecture was maintained, which was best achieved in ceramic rather than cement-paste forms of hydroxyapatite. Porosity and resultant bone formation in cement-paste implants can be improved by combining hydroxyapatite with a rapidly resorbing component, such as tricalcium phosphate.

A 1-year study of osteoinduction in hydroxyapatite-derived biomaterials in an adult sheep model: part II. Bioengineering implants to optimize bone replacement in reconstruction of cranial defects
Gosain, A. K., P. A. Riordan, et al. (2004), Plast Reconstr Surg 114(5): 1155-63; discussion 1164-5.
Abstract: The present study investigated hydroxyapatite biomaterials implanted in critical-size defects in the calvaria of adult sheep to determine the optimal bioengineering of hydroxyapatite composites to facilitate bone ingrowth into these materials. Five calvarial defects measuring 16.8 mm in diameter were made in each of 10 adult sheep. Three defects were filled with cement paste composites of hydroxyapatite and beta-tricalcium phosphate as follows: (1) 100 percent hydroxyapatite-cement paste, (2) 60 percent hydroxyapatite-cement paste, and (3) 20 percent hydroxyapatite-cement paste. One defect was filled with a ceramic composite containing 60 percent hydroxyapatite-ceramic, and the fifth defect remained unfilled. One year after implantation, the volume of all biomaterials was determined by computed tomography, and porosity and bone replacement were determined using backscatter electron microscopy. Computed tomography-based volumetric assessment 1 year after implantation demonstrated that none of the unfilled cranial defects closed over the 1-year period, confirming that these were critical-size defects. There was a significant increase in volume in both the cement paste and ceramic implants containing 60 percent hydroxyapatite (p < 0.01). There was no significant change in volume of the remaining cement paste biomaterials. Analysis of specimens by backscatter electron microscopy demonstrated mean bone replacement of 4.8 +/- 1.4 percent (mean +/- SEM) in 100 percent hydroxyapatite-cement paste, 11.2 +/- 2.3 percent in 60 percent hydroxyapatite-cement paste, and 28.5 +/- 4.5 percent in 20 percent hydroxyapatite-cement paste. There was an inverse correlation between the concentration of hydroxyapatite and the amount of bone replacement in the cement paste for each composite tested (p < 0.01). Bone replacement in 60 percent hydroxyapatite-ceramic composite (13.6 +/- 2.0 percent) was not significantly different from that in 60 percent hydroxyapatite-cement paste. Of note is that the ceramic composite contained macropores (200 to 300 microm) that did not change in size over the 1-year period. All cement paste composites initially contained micropores (3 to 5 nm), which remained unchanged in 100 percent hydroxyapatite-cement paste. Cement paste implants containing increased tricalcium phosphate demonstrated a corresponding increase in macropores following resorption of the tricalcium phosphate component. Bone replacement occurred within the macropores of these implants. In conclusion, there was no significant bone ingrowth into pure hydroxyapatite-cement paste (Bone Source, Stryker-Leibinger Inc., Dallas, Texas) in the present study. The introduction of macropores in a biomaterial can optimize bone ingrowth for reconstruction of critical-size defects in calvaria. This was demonstrated in both the ceramic composite of hydroxyapatite tested and the cement paste composites of hydroxyapatite by increasing the composition of a rapidly resorbing component such as beta-tricalcium phosphate.

A bibliography of monographic works on biomaterials and biocompatibility
Bush, R. B. (1993), J Appl Biomater 4(2): 195-209.
Abstract: Organizing and accessing biomaterials-related information is problematic because of the interdisciplinary nature of the field. Relevant information appears in the literature of numerous science and technology subdisciplines and there is no one index or database that covers all of the related publications. An additional barrier to information retrieval is the lack of a thesaurus for the field. Multiple terms representing the same concepts are currently employed and it is not always readily apparent which terms to use in a literature search. As an aid for students and researchers in the discipline, the author provides an indexed bibliography of English language monographic works on biomaterials and biocompatibility published after 1973.

A bibliography of monographic works on biomaterials and biocompatibility: update
Bush, R. B. (1996), J Biomed Mater Res 33(2): 107-13.

A bibliography of monographic works on biomaterials and biocompatibility: update II
Bush, R. B. (1999), J Biomed Mater Res 48(3): 335-41.
Abstract: This bibliography includes monographs published from 1996 to 1998 and serves to update two previous bibliographies by the same title that together covered the years 1973 to 1995. All three bibliographies are indexed as a combined work by conference titles, series titles, and names of associated corporate bodies including professional society, research institute, and government agency names.

A biomaterial based approach for arsenic removal from water
Al Rmalli, S. W., C. F. Harrington, et al. (2005), J Environ Monit 7(4): 279-82.
Abstract: We demonstrate that the non-living, dried roots of the water hyacinth plant [Eichhornia crassipes(Mart.) Solms] can rapidly remove arsenic from water. Atomic absorption spectrometry was used to demonstrate that more than 93% of arsenite (As(iii)) and 95% of arsenate (As(v)) were removed from a solution containing 200 microg As l(-1) within 60 minutes of exposure to a powder produced from dried roots. No difference in removal efficiency was observed between the two oxidation states of As studied. The amount of arsenic remaining in solution was found to be less than 10 microg l(-1) which is the WHO guideline limit value for As in drinking water. The presence of arsenic in drinking water in a number of countries in the developing world has been found to be much higher than the WHO level, affecting the health of millions of people. In this paper, we show that a biomaterial produced from dried water hyacinth roots, a plant that is found in abundant supply in many parts of the world, can provide a simple, effective and yet cheap method for removing arsenic from contaminated water.

A central role for plasminogen in the inflammatory response to biomaterials
Busuttil, S. J., V. A. Ploplis, et al. (2004), J Thromb Haemost 2(10): 1798-805.
Abstract: The inflammatory response to implanted biomaterials severely limits their deployment in patients. Plasminogen has been shown to play a central role in cell migration, and therefore could regulate this inflammatory response. We sought to determine if plasminogen influences recruitment of inflammatory cells to a biomaterial implanted into plasminogen-deficient (Plg(-/-)) mice. Small disks of polyethylene terephthalate, a material used in vascular grafts, were surgically implanted into the peritoneum of wild-type and Plg(-/-) mice. Recruitment of neutrophils and monocytes/macrophages into the peritoneum and onto the disks was measured, primarily at 18 h. Monocyte/macrophage recruitment was markedly blunted in Plg(-/-) mice compared with wild-type mice. Unexpectedly, neutrophil recruitment was also markedly decreased in the Plg(-/-) mice. While recruitment of leukocytes into the peritoneum was plasminogen-dependent, the adhesion of the emigrating cells to the implants was not. In contrast, adhesion but not recruitment was reduced in fibrinogen-deficient mice. Reconstitution of Plg(-/-) mice with intravenous or intraperitoneal plasminogen differentially restored monocyte/macrophage and neutrophil recruitment. Tranexamic acid, an inhibitor of the lysine binding sites of plasminogen, suppressed leukocyte recruitment in wild-type mice, but aprotinin, a plasmin inhibitor, did not. Plasminogen exerts a marked influence on both neutrophil and monocyte/macrophage recruitment to implanted biomaterials. This role is distinct from that of fibrinogen, and the two inflammatory cell types use plasminogen in different ways. Plasminogen represents a therapeutic target for controlling the inflammatory response to implanted materials.

A centrifugation cell adhesion assay for high-throughput screening of biomaterial surfaces
Reyes, C. D. and A. J. Garcia (2003), J Biomed Mater Res A 67(1): 328-33.
Abstract: A quantitative analysis of cell adhesion is essential in understanding physiological phenomena and designing biomaterials, implant surfaces, and tissue-engineering scaffolds. The most common cell adhesion assays used to evaluate biomaterial surfaces lack sensitivity and reproducibility and/or require specialized equipment and skill-intensive operation. We describe a modified centrifugation cell adhesion assay that uses simple and convenient techniques with standard laboratory equipment and provides reliable, quantitative measurements of cell adhesion. This centrifugation assay applies controlled and uniform detachment forces to a large population of adherent cells, providing robust statistics for quantifying cell adhesion. The applicability of this system to the design and characterization of biomaterial surfaces is shown by evaluating cell adhesion on substrates using different coating proteins, cell types, seeding times, and relative centrifugal forces (RCF). Results verify that this centrifugation cell adhesion assay represents a simple, convenient, and standard method for high-throughput characterization of a variety of biomaterial surfaces and conditions.

A chemical surface modification of chitosan by glycoconjugates to enhance the cell-biomaterial interaction
Wang, Y. C., S. H. Kao, et al. (2003), Biomacromolecules 4(2): 224-31.
Abstract: The use of wheat germ agglutinin (WGA), a lectin molecule, to modify chitosan and enhance the cell-biomaterial interaction was examined. The percentage of living fibroblast cells on the surfaces of tissue culture polystyrene (TCPS) control, WGA-modified chitosan, and unmodified chitosan films increased to 99%, 99%, and 85%, respectively, after seeding for 48 h. DNA staining revealed that a portion of fibroblasts cultivated on chitosan filmswere undergoing apoptosis. In contrast, fibroblasts growing on WGA-modified chitosan film surfaces did not show any indication of apoptosis. The number of fibroblast cells was the highest on the WGA-modified chitosan surfaces, followed by the TCPS and unmodified chitosan surfaces. This WGA-mediated enhancement on the fibroblast cell-biomaterial interaction was cell type dependent. Other types of cells may need different lectin molecules for enhanced interaction with biomaterials. Further, the evaluation of the heat shock protein (HSP) mRNA expression indicated that HSP 90 expression was increased in the fibroblast cells cultivated on chitosan films and decreased to basal levels on the WGA-modified chitosan films. Taken together, our data suggest that the use of WGA and other lectin molecules to enhance the cell-biomaterial interaction via oligosaccharide-mediated cell adhesion is a promising way to improve cell adhesion and proliferation, the two key issues in tissue engineering.

A chemically defined surface for the co-culture of melanocytes and keratinocytes
Eves, P. C., A. J. Beck, et al. (2005), Biomaterials 26(34): 7068-81.
Abstract: Patients with stable vitiligo can be helped surgically using transplantation of autologous cultured melanocytes, but there is a need for a culture methodology that is free from xenobiotic agents and for a simple way of delivering cultured melanocytes to the patient to achieve pigmentation with good wound healing. The aim of this study was to develop a chemically defined surface, suitable for the co-culture of melanocytes and keratinocytes which could be used in the future for the treatment vitiligo patients to achieve both restoration of pigmentation and good wound healing. Two keratinocyte growth media and two melanocyte growth media were compared; two of these were serum free. Cells were seeded on a range of chemically defined substrates (produced by plasma polymerisation of acrylic acid, allylamine or a mixture of these monomers) either as mono- or co-cultures. Melanocytes and keratinocytes attached and proliferated on both acid and amine substrates (without significant preferences), and co-cultures of cells proliferated more successfully than individual cultures. One media, M2, which is serum free, supported expansion of melanocytes and to a lesser extent keratinocytes on several plasma polymer substrates. In conclusion, these data indicate that a combination of a chemically defined substrate with M2 media allows serum-free co-culture of melanocytes and keratinocytes.

A chitosan-arginine conjugate as a novel anticoagulation biomaterial
Liu, W. G., J. R. Zhang, et al. (2004), J Mater Sci Mater Med 15(11): 1199-203.
Abstract: Chitosan (CS) was modified with arginine using 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) and N-hydroxysuccinimide (NHS) as coupling agents. FTIR and 13C NMR spectra showed that arginine was chemically coupled to CS to form a chitosan-arginine conjugate (CS-ArgC). The substitution degree of arginine in CS estimated from elemental analysis was 20.1%. The circular dichroism spectra indicated that the incorporation of arginine significantly altered the conformation of thrombin; while no obvious variation in the conformation of thrombin was observed with the addition of CS. The anticoagulation activity of glucose aldehyde crosslinked CS-ArgC and CS membranes was evaluated by assaying prothrombin time (PT), thrombin time (TT) and activated partial thromboplastin time (APTT). The APTT of CS-ArgC membrane was prolonged two times as that of CS counterpart, suggesting that the CS-ArgC is a promising candidate as an anticoagulation biomaterial.

A chronic arteriovenous shunt for the testing of biomaterials and devices in dogs
Zingg, W., W. F. Ip, et al. (1986), Life Support Syst 4(3): 221-9.
Abstract: A technique is described for an extracorporeal arteriovenous shunt in dogs which allows the testing of biomaterials in the shunt for several months in the same animal. The details of the preparation of the tubes and of the surgical technique are given. In contrast to other techniques, encircling ligatures are not placed around the cannulated blood vessels.

A clinical, renal and immunological assessment of surface modifying additive treated (SMART) cardiopulmonary bypass circuits
Allen, S., W. T. McBride, et al. (2005), Perfusion 20(5): 255-62.
Abstract: Biocompatible cardiopulmonary bypass (CPB) circuits aim to reduce contact activation and its physiological consequences. We investigated the hypothesis that use of Surface Modifying Additive (SMA)-treated circuits (Sorin Group Ltd) compared with non-SMA circuits would be associated with preservation of blood pressure during CPB and modulation of perioperative subclinical renal function (urinary alpha-1-microglobulin (alpha-1-m)) and plasma and urinary cytokine changes. In a study of low-risk CABG patients (n=40), randomized to SMA (n=20) versus non-SMA circuits (n=20), we found better preserved blood pressure at CPB initiation in SMA patients (p <0.05), particularly in ACE-inhibited SMA patients (n =11) versus ACE-inhibited non-SMA patients (n =10) (p <0.05). Plasma anti-inflammatory IL-10, as well as urinary alpha-1-m, were elevated 48 hours postoperatively (p <0.05). SMA patients also had lower blood loss (p <0.05). SMA circuits have some clinical benefit, especially in ACE-inhibited patients.

A collagen-glycosaminoglycan co-culture model for heart valve tissue engineering applications
Flanagan, T. C., B. Wilkins, et al. (2006), Biomaterials 27(10): 2233-46.
Abstract: In order to develop efficient design strategies for a tissue-engineered heart valve, in vivo and in vitro models of valvular structure and cellular function require extensive characterisation. Collagen and glycosaminoglycans (GAGs) provide unique functional characteristics to the heart valve structure. In the current study, type I collagen-GAG hydrogels were investigated as biomaterials for the creation of mitral valve tissue. Porcine mitral valve interstitial cells (VICs) and endothelial cells (VECs) were isolated and co-cultured for 4 weeks in hydrogel constructs composed of type I collagen. The metabolic activity and tissue organisation of mitral valve tissue constructs was evaluated in the presence and absence of chondroitin sulphate (CS) GAG, and comparisons were made with normal mitral valve tissue. Both collagen and collagen-CS mitral valve constructs contracted to form tissue-like structures in vitro. Biochemical assay demonstrated that over 75% of CS was retained within collagen-CS constructs. Morphological examination demonstrated enhanced VEC surface coverage in collagen-CS constructs compared to collagen constructs. Ultrastructural analysis revealed basement membrane synthesis and cell junction formation by construct VECs, with an increased matrix porosity observed in collagen-CS constructs. Immunohistochemical analyses demonstrated enhanced extracellular matrix production in collagen-CS constructs, including expression of elastin and laminin by VICs. Both native valve and collagen-CS construct VECs also expressed the vasoactive molecule, eNOS, which was absent from collagen construct VECs. The present study demonstrates that collagen gels can be used as matrices for the in vitro synthesis of tissue structures resembling mitral valve tissue. Addition of CS resulting in a more porous model was shown to positively influence the bioactivity of seeded valve cells and tissue remodelling. Collagen-GAG matrices may hold promise for a potential use in heart valve tissue engineering and improved understanding of heart valve biology.

A comparative study of calcium phosphate formation on bioceramics in vitro and in vivo
Xin, R., Y. Leng, et al. (2005), Biomaterials 26(33): 6477-86.
Abstract: Formation of calcium phosphate (Ca-P) on various bioceramic surfaces in simulated body fluid (SBF) and in rabbit muscle sites was investigated. The bioceramics were sintered porous solids, including bioglass, glass-ceramics, hydroxyapatite, alpha-tricalcium phosphate and beta-tricalcium phosphate. The ability of inducing Ca-P formation was compared among the bioceramics. The Ca-P crystal structures were identified using single-crystal diffraction patterns in transmission electron microscopy. The examination results show that ability of inducing Ca-P formation in SBF was similar among bioceramics, but considerably varied among bioceramics in vivo. Sintered beta-tricalcium phosphate exhibited a poor ability of inducing Ca-P formation both in vitro and in vivo. Octacalcium phosphate (OCP) formed on the surfaces of bioglass, A-W, hydroxyapatite and alpha-tricalcium phosphate in vitro and in vivo. Apatite formation in physiological environments cannot be confirmed as a common feature of bioceramics.

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