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Exposure of blood to biomaterial surfaces liberates substances that activate polymorphonuclear granulocytes
Karlsson, C., H. Nygren, et al. (1996), J Lab Clin Med 128(5): 496-505.
Abstract: Human whole blood, anticoagulated or not, was exposed to hydrophilic glass surfaces or methylated hydrophobic glass surfaces under saline cover. Platelet-poor plasma or serum was prepared after 10 minutes of exposure, measured in respect to complement activation, and transferred to a suspension of granulocytes, which acted as bioprobes. The granulocytes were prepared from blood, anticoagulated with ethylenediaminetetraacetic acid, and evaluated regarding intracellular Ca2+ concentration (Calcium Green-1 fluorescence), integrin expression (CD-11b immunohistochemistry), respiratory burst (chemiluminescence), and priming (increase in N-formyl-methionyl-leucyl-phenylalanine-induced respiratory burst). The results indicate that humoral factors formed during the surface exposure of blood were able to activate the probe granulocytes. The exposure to hydrophilic surfaces led to a calcium transient three times the magnitude of that of hydrophobic surfaces. This response could be blocked by the presence of heparin during the blood-surface exposure but was not affected by the addition of heparin to the probe granulocytes. Hirudin, a specific thrombin blocker, had no effect. The exposure to hydrophobic surfaces led to complement activation in serum that induced priming and respiratory burst of the probe granulocytes. In conclusion, the study provides evidence that hydrophilic-hydrophobic surface treatment significantly affects the immediate inflammatory response of a blood-biomaterial interaction that is moderated by the presence of heparin.

Exposure of orbital implants wrapped with polyester-urethane after enucleation for advanced retinoblastoma
Heimann, H., N. E. Bechrakis, et al. (2005), Ophthal Plast Reconstr Surg 21(2): 123-8.
Abstract: PURPOSE: Enucleation is the main form of treatment for advanced retinoblastoma. The major complication of this procedure is orbital implant exposure. Different implants and wrapping materials are currently in use. The aim of the current study was to analyze the complications associated with the use of polyester-urethane, an artificial dura substitute, as a wrapping material for enucleation in advanced retinoblastoma. METHODS: A retrospective review of 32 cases (28 patients), who were treated with enucleation for advanced retinoblastoma, was performed. The age of the patients ranged between 3 months and 6.7 years (median, 19 months). Additional chemotherapy was administered in 12 cases. The removed eyeball was replaced either with a silicone implant and polyester-urethane wrapping (13 cases) or hydroxyapatite, silicone-hydroxyapatite, or polyethylene implants without additional wrappings (19 cases). The follow-up period ranged from 7 months to 5.9 years (median, 22.4 months). Statistical analysis was performed using the Kaplan-Meier method. RESULTS: Single or multiple exposures occurred in 22% of cases (7/32). There were 6 exposures (46%, 6/13) in the group with polyester-urethane wrapping compared with only 1 exposure (5%, 1/19) in the implants without wrapping. This difference was statistically significant (p=0.0236). None of the other analyzed factors (additional chemotherapy, surgeon, age of the patient, or size of the implant) demonstrated a significant correlation to implant exposures. CONCLUSIONS: Wrapping of orbital implants with polyester-urethane resulted in a high rate of implant exposures after enucleation for advanced retinoblastoma. In this series, the best results were achieved with integrated implants without additional wrapping.

Expression and activity of vascular endothelial growth factor and metalloproteinases in alveolar and embryonal rhabdomyosarcoma cell lines
Onisto, M., M. L. Slongo, et al. (2005), Int J Oncol 27(3): 791-8.
Abstract: Rhabdomyosarcoma (RMS) is a malignant tumour of skeletal muscle origin which includes two major histological subtypes: alveolar rhabdomyosarcoma (ARMS), the more aggressive, and embryonal rhabdomyosarcoma (ERMS). In order to establish whether the higher metastatic potential of ARMS cells may depend on differential expression of specific matrix metalloproteinases (MMPs) and angiogenesis-related factors, we studied the expression of MMP-2, MT1-MMP, TIMP-2, VEGF and VEGF receptors in four ARMS (RH30, RH4, RH18, RH28), three ERMS (RD, RH36, SMS-CTR) and one undifferentiated sarcoma cell line (A204). Semi-quantitative analysis of MMP-2 revealed high levels of expression in 3 out of 4 ARMS cell lines whereas, among ERMS, only RH36 showed comparable levels of the protease. TIMP-2 and MT1-MMP showed no significant differences among cell lines. in vitro invasiveness was also evaluated. The MMP-2-overexpressing RH30 cells were more invasive than RD cells, which expressed low levels of MMP-2. Exogenous expression of the ARMS specific PAX3-FKHR chimeric protein in RD cells increased MMP-2 activity and invasiveness. Of the three main VEGF isoforms only VEGF165 and VEGF121 were detected in RMS lines: ARMS expressed both isoforms, whereas the ERMS cell line SMS-CTR and the undifferentiated sarcoma cell line A204 showed the VEGF121 isoform only. All RMS cell lines expressed VEGFR-1 at mRNA as well as at protein level. The VEGFR-2, on the contrary, was undetectable with the sole exception of the RH28 cell line. Overall, our data suggest that a high level of MMP-2 protein and VEGF/VEGFR expression may contribute to the metastatic phenotype of ARMS cells and that exogenously induced PAX3-FKHR expression increases MMP-2 secretion and invasive capability of RMS cells.

Expression of cell adhesion complexes in epithelial cells seeded on biomaterial surfaces
Raisanen, L., M. Kononen, et al. (2000), J Biomed Mater Res 49(1): 79-87.
Abstract: Clinical studies indicate that soft tissue responses around dental implants vary, depending on the material used. It is therefore also possible that there are differences in how epithelial cells attach to various biomaterial surfaces. We studied the adhesion of cultured epithelial cells to five different dental material surfaces and to glass. The efficacy of adhesion was evaluated by using scanning electron microscopy (SEM) and immunofluorescence microscopy (IF) with antibodies to vinculin and alpha(6)beta(4) integrin, two cell surface molecules that are functional in epithelial cell adhesion. Our results indicate that epithelial cells adhere and spread more avidly on metallic surfaces (titanium, Ti(6)Al(4)V titanium alloy, dental gold alloy) than on ceramic surfaces (dental porcelain, aluminum oxide). As revealed by SEM, cells on metallic surfaces had a flattened morphology and formed multicellular islands. On porcelain and aluminum oxide most cells were round and adhesion occurred as single cells. Surface coverage was over twofold on metallic surfaces as compared to ceramic surfaces. IF of cells grown on metallic surfaces revealed vinculin in well-organized focal contacts and alpha(6)beta(4) integrin in punctate patterns typical of prehemidesmosomes. On porcelain and aluminum oxide surfaces the cells were mostly round and showed less well-organized adhesion complexes. Our results indicate that smooth metallic biomaterial surfaces are optimal for epithelial cell adhesion and spreading. These findings may have clinical implications in the design of transgingival implant structures.

Expression of contact allergy in undergoing prosthodontic therapy patients with oral diseases
Mehulic, M., K. Mehulic, et al. (2005), Minerva Stomatol 54(5): 303-9.
Abstract: AIM: Contact allergy is a postponed reaction of hypersensitivity where a localised cutaneous or mucosal lesion occurs due to a recurrent contact with an allergen. Placement of a fixed or removable prosthetic replacement into the oral cavity causes corrosive processes on the surface of the restoration and discharge of ions, which as haptens can induce allergic reactions. The purpose of this study was to examine occurrence of allergies to basic and auxiliary restorative dental materials in patients with lichen, stomatitis and stomatopyrosis by means of an epicutaneous allergy test. METHODS: The study included 32 patients with a fixed and/or removable replacement and 7 patients with one of the mentioned diagnoses, but without any replacement. Testing was conducted using a standard method (patch test), and hypersensitivity to 13 most common allergens in prosthodontics was examined. RESULTS: The research results revealed higher frequency of positive allergic reactions in persons with the mentioned diseases and with a restoration. Patients with lichen indicated positive patch test in the majority of cases. The allergens of nickel, cobalt and chromium demonstrated the highest score of positive results, and negative score was found for dibutylphthalate and HH mix. Stomatopyrosis was more common in persons with hypersensitivity to chromium. A lower incidence of positive allergic reactions to epoxide resins was found in female than in male subjects. CONCLUSIONS: The epicutaneous (patch) test performed in the subjects examined in this study, showed that the majority of positive reactions was caused by mixes of nickel, cobalt and chromium; however, unwanted reactions also to other auxiliary materials used in dental practice should also be considered.

Expression of functional recombinant mussel adhesive protein type 3A in Escherichia coli
Hwang, D. S., Y. Gim, et al. (2005), Biotechnol Prog 21(3): 965-70.
Abstract: Mussel adhesive proteins, including the 20-plus variants of foot protein type 3 (fp-3), have been suggested as potential environmentally friendly adhesives for use in aqueous conditions and in medicine. Here we report the novel production of a recombinant Mytilus galloprovincialis foot protein type 3 variant A (Mgfp-3A) fused with a hexahistidine affinity ligand in Escherichia coli and its approximately 99% purification with affinity chromatography. Recombinant Mgfp-3A showed a superior purification yield and better apparent solubility in 5% acetic acid (prerequisites for large-scale production and practical use) compared to those of the previously reported recombinant M. galloprovincialis foot protein type 5 (Mgfp-5). The adsorption abilities and adhesion forces of purified recombinant Mgfp-3A were compared with those of Cell-Tak (a commercial mussel extract adhesive) and recombinant Mgfp-5 using quartz crystal microbalance analysis and modified atomic force microscopy, respectively. These assays showed that the adhesive ability of recombinant Mgfp-3A was comparable to that of Cell-Tak but lower than that of recombinant Mgfp-5. Collectively, these results indicate that recombinant Mgfp-3A may be useful as a commercial bioadhesive or an adhesive ingredient in medical or underwater environments.

Expression of MMPs and TIMPs in primary epithelial cell cultures of the upper aerodigestive tract seeded on the surface of a novel polymeric biomaterial
Rickert, D., A. Lendlein, et al. (2005), Clin Hemorheol Microcirc 32(2): 117-28.
Abstract: INTRODUCTION: Using standard cell biological and biochemical experimental approaches we were able to test the ability of a particular polymer construct to support the adhesion, proliferation, and the cellular acitivity of pharyngeal cells. The delicate balance between Matrix Metalloproteinases (MMPs) and their endogenous inhibitors (Tissue Inhibitor of MMPs, TIMPs) have a decisive function in the remodeling of the extracellular matrix during cellular ingrowth. Novel polymeric biomaterials may be useful to develop new therapeutic options in head and neck surgery. METHODS: Primary cell cultures of the pharynx of Sprague-Dawley rats were seeded on the surface of a thermoplastic multi-block copolymer and on a polystyrene surface as control. Conditioned media of the primary cells was analyzed for MMPs and TIMPs. The MMP and TIMP expression was analysed by zymography and a radiometric enzyme assay. RESULTS: No statistically significant differences in the levels of MMP-1, MMP-2, MMP-9 and TIMPs were detected between cells grown on the novel polymer surface versus control. CONCLUSION: An appropriate understanding of the molecular machinery that regulates gene expression and cellular growth in tissue engineered constructs is the requirement for an optimal adaptation of biodegradable biomaterials to develop new therapeutic options in otolaryngology and head and neck surgery.

Expression pattern of the chromosome 21 transcription factor Ets2 in cell-seeded three-dimensional bone constructs
Turhani, D., E. Watzinger, et al. (2005), J Biomed Mater Res A 73(4): 445-55.
Abstract: The ability to generate new bone for reconstructive surgery use is a major clinical need. Tissue engineering with osteoprogenitor cells isolated from the patient's periosteum and seeded into bioresorbable scaffolds offers a promising approach to the generation of skeletal tissue. To our knowledge, there is no description about the expression of Ets2 in tissue engineered "bone neotissue." The aim of our study was to manufacture cell-seeded three-dimensional bone constructs with human periosteal cells on poly (lactic-co-glycolic acid) polymer fleeces to describe the expression pattern of Ets2 and its target genes osteocalcin and osteopontin; expression analysis of type I collagen, core-binding factor-1, alkaline phosphatase, and osteonectin; the ability of matrix mineralization and ALP enzymatic activity showed the osteogenic character of the constructs. A significant correlation between the expression of Ets2 and osteopontin mRNA (r = -0.70; p < 0.05) could be shown. A 1.35-fold increase of Ets2 expression from days 1 to 9 was detected, followed by a slight decrease from days 11 to 15. Until the end of the culture period, the expression of Ets2 reached a comparable high level as detected on day 9. In contrast, the expression level of osteopontin mRNA reached a maximum at day 7, followed by a progressive 3.04-fold decrease until day 21. This study shows for the first time that Ets2 gene and its transcriptional target genes are expressed in tissue-engineered bone constructs. These findings have the potential to provide much-needed information about the role and function of Ets2 in human osteogenesis processes and creation of "bone neotissue."

Extensive H(+) release by bone substitutes affects biocompatibility in vitro testing
Jager, M., J. Fischer, et al. (2006), J Biomed Mater Res A 76(2): 310-22.
Abstract: Bone substitutes are widespread in orthopedic and trauma surgery to restore critical bony defects and/or promote local bone healing. Cell culture systems have been used for many years to screen biomaterials for their toxicity and biocompatibility. This study applies a human bone marrow cell culture system to evaluate the toxic in vitro effects of soluble components of different bone substitutes, which are already in clinical use. Different specimens of tricalcium phosphates (TCP) (Vitosstrade mark, Cerasorbtrade mark), nondecalcified bovine bone (Lubboctrade mark), demineralized human bone matrices (DBM) (Graftontrade mark Flex/Putty), and collagen I/III matrix (ACI-Maixtrade mark) were tested in Dulbecco's modified Eagle's medium (DMEM) and Mesenculttrade mark culture solution and compared with a biomaterial-free cell culture. Biocompatibility parameters were cell viability evaluated by phase-contrast microscopy and laser flow cytometry, morphology, and the local H(+) release by bone substitutes. There were significant differences (p < 0.05) between the tested biomaterials and culture solutions. Collagen I/III, nondemineralized bovine bone, and TCP materials showed advantages for cell survival over other tested biomaterials (average values of vital cells/mL MesenCulttrade mark/DMEM: Collagen I/III: 1090/1083; Vitosstrade mark: 893/483; Cerasorbtrade mark: 471/523; Lubboctrade mark: 815/410; Graftontrade mark Putty: 61/44; Graftontrade mark Flex: 149/57). Especially the DBM materials lead to a significant decrease of pH, which is considered to be a major factor for cell death. DMEM culture solution supports cell survival for those bone substitutes that induce an alkaline reaction, whereas MesenCulttrade mark media promotes cell vitality in biomaterials, which leads to an acidification of culture solution. (c) 2005 Wiley Periodicals, Inc. J Biomed Mater Res, 2006.

Extensively porous coated stems: Res Ipsa Loquitur
Moreland, J. R. (2005), Orthopedics 28(9): 965-6.

Extracellular carbohydrate-containing polymers of a model biofilm-producing strain, Staphylococcus epidermidis RP62A
Sadovskaya, I., E. Vinogradov, et al. (2005), Infect Immun 73(5): 3007-17.
Abstract: Staphylococcus aureus and coagulase-negative staphylococci, primarily Staphylococcus epidermidis, are recognized as a major cause of nosocomial infections associated with the use of implanted medical devices. It has been established that clinical isolates often produce a biofilm, which is involved in adherence to biomaterials and provides enhanced resistance of bacteria against host defenses and antibiotic treatments. It has been thought that the staphylococcal biofilm contains two polysaccharides, one responsible for primary cell adherence to biomaterials (polysaccharide/adhesin [PS/A]) and an antigen that mediates bacterial aggregation (polysaccharide intercellular adhesin [PIA]). In the present paper we present an improved procedure for preparation of PIA that conserves its labile substituents and avoids contamination with by-products. Based on structural analysis of the polysaccharide antigens and a thorough overview of the previously published data, we concluded that PIA from S. epidermidis is structurally identical to the recently described poly-beta-(1-->6)-N-acetylglucosamine from PS/A-overproducing strain S. aureus MN8m. We also show that another carbohydrate-containing polymer, extracellular teichoic acid (EC TA), is an essential component of S. epidermidis RP62A biofilms. We demonstrate that the relative amounts of extracellular PIA and EC TA produced depend on the growth conditions. Moderate shaking or static culture in tryptic soy broth favors PIA production, while more EC TA is produced in brain heart infusion medium.

Extracellular matrix covered biomaterials for human endothelial cell growth
Desgranges, P., M. Tardieu, et al. (1992), Int J Artif Organs 15(12): 722-6.
Abstract: The aim of this study is to optimize conditions for growing endothelial cells on vascular biomaterials. Bovine cornea endothelial cells (BCEC), stimulated by basic Fibroblast Growth Factor (bFGF) secrete an extracellular matrix (ECM) similar to the Descemet membrane produced in vivo by these cells. This ECM, obtained by removing BCEC with an hypotonic shock can be used as a substratum for other endothelial cell growth. Human endothelial cells (HEC) were purified from omentum that was digested with a solution of collagenase-dispase, then filtered through nylon meshes. The cells were further purified by centrifugation onto a Percoll gradient. A comparative study on the attachment and growth of HEC on various coatings (laminin, poly-L-lysine, fibronectin or ECM) indicates that ECM is the most performing substratum. The quality of this endothelium was confirmed by the presence of factor VIII, and MHC class I and the absence of class II antigens.

Extracellular matrix-enriched polymeric scaffolds as a substrate for hepatocyte cultures: in vitro and in vivo studies
Zavan, B., P. Brun, et al. (2005), Biomaterials 26(34): 7038-45.
Abstract: Tissue engineering is a promising approach to developing hepatic tissue suitable for the functional replacement of a failing liver. The aim of the present study was to investigate whether an extracellular cell matrix obtained from fibroblasts-cultured within scaffolds of hyaluronic acid (HYAFF) could influence the proliferation rate and survival of rat hepatocytes both during long-term culture and after in vivo transplantation. Cultures were evaluated by histological and morphological analysis, a proliferation assay and metabolic activity (albumin secretion). Hepatocytes cultured in extracellular matrix-enriched scaffolds exhibited a round cellular morphology and re-established cell-cell contacts, growing into aggregates of several cells along and/or among fibers in the fabric. Hepatocytes were able to secrete albumin up to 14 days in culture. In vivo results demonstrated the biocompatibility of HYAFF-11 implanted in nude mice, in which hepatocytes maintained small well-organised aggregates until the 35th day. In conclusion, the presence of a fibroblast-secreted extracellular matrix improved the biological properties of the hyaluronan scaffold, favoring the survival and morphological integrity of hepatocytes in vitro and in vivo.

Extracellular stimulation in tissue engineering
Seliktar, D. (2005), Ann N Y Acad Sci 1047: 386-94.
Abstract: The field of tissue engineering has created a need for biomaterials that are capable of providing biofunctional and structural support for living cells outside of the body. Most of the commonly used biomaterials in tissue engineering are designed based on their physicochemical properties, thus achieving precise control over mechanical strength, compliance, porosity, and degradation kinetics. Biofunctional signals are added to the scaffold by tethering, immobilizing, or supplementing biofunctional macromolecules, such as growth factors, directly to the scaffold material. The challenge in tissue engineering remains to find the correct balance between the biofunctional and the physical properties of the scaffold material for each application. Moreover, the ability to modulate communication between cells and the extracellular environment using the engineered scaffold as the actuator can provide a significant advantage in tissue engineering. In this study, a unique scaffold material is presented. The material interchangeably combines biofunctional and structural molecules by fusing the two into a single backbone macromolecule. This integration provides the basis for practical, effective, and high-resolution control of both the biofunctional and the physical properties of the scaffold material. This new scaffold material has proven effective with smooth muscle, cardiac, cartilage, and human embryonic stem cell cultures. The advantages of this approach as well as the potential applications of this unique scaffold material are discussed.

Extracorporeal circulation, hemocompatibility, and biomaterials
Janvier, G., C. Baquey, et al. (1996), Ann Thorac Surg 62(6): 1926-34.
Abstract: BACKGROUND: Performance of a majority of cardiac surgical procedures requires the use of extracorporeal circulation. Contact of the patients' blood with the nonendothelial surface of the cardiopulmonary bypass circuit is responsible for several, potentially harmful systemic reactions. METHODS: The patients' response to extracorporeal circulation is reviewed briefly. The interactions between patient and circuit are discussed not only as they relate to blood-material contact, but also from a mechanical and rheologic standpoint. The theoretic benefits of the newer, more hemocompatible materials are presented, along with a review of published clinical experience with heparinized cardiopulmonary bypass circuits. RESULTS: The response to extracorporeal circulation extends far beyond a simple derangement of hemostasis. This inflammatory response is strongly influenced by the rheologic design of the circuit and by the physical and chemical properties of the surface. Heparinized circuits decrease inflammation, but the clinical benefits of this reduction remain unclear, except for extended cardiopulmonary support. The safe use of these circuits requires full heparinization and does not reduce allogeneic transfusions. CONCLUSIONS: Clinicians are still in the search of the ideal material and the ideal extracorporeal circuit design. Newer, heparinized materials offer real but limited clinical benefits.

Extraction, bone graft, and immediate placement of a 6-unit fixed bridge
Groba, R. E. (2005), Dent Today 24(7): 118-9.

Extramucosal hepaticojejunostomy
Sutherland, F. and E. Dixon (2005), Am J Surg 189(6): 667-9.
Abstract: BACKGROUND: The creation of a secure hepaticojejunostomy is an essential skill for any hepatobiliary surgeon. METHODS: We describe a refined technique of sewing the end of the common hepatic duct to the side of the jejunum. The sutures are placed to include all layers of the bowel wall except mucosa. RESULTS: One hundred eighty-five anastomoses were performed over a 6-year period. There were 3 documented leaks, 1 significant anastomotic bleed, and 2 postoperative strictures. There were no deaths. CONCLUSION: This refined technique facilitates accurate placement of sutures by improving vision and results in a well-vascularized watertight connection.

Fabrication and characterization of DTBP-crosslinked chitosan scaffolds for skin tissue engineering
Adekogbe, I. and A. Ghanem (2005), Biomaterials 26(35): 7241-50.
Abstract: Chitosan, the deacetylated derivative of chitin, is a promising scaffold material for skin tissue engineering applications. It is biocompatible and biodegradable, and the degradation products are resorbable. However, the rapid degradation of chitosan and its low mechanical strength are concerns that may limit its use. In this study, chitosan with 80%, 90% and 100% degree of deacetylation (DDA) was crosslinked with dimethyl 3-3, dithio bis' propionimidate (DTBP) and compared to uncrosslinked scaffolds. The scaffolds were characterized with respect to important tissue engineering properties. The tensile strength of scaffolds made from 100% DDA chitosan was significantly higher than for scaffolds made from 80% and 90% DDA chitosan. Crosslinking of scaffolds with DTBP increased the tensile strength. Crosslinking with DTBP had no significant effect on water vapour transmission rate (WVTR) or water absorption but had significant effect on the pore size and porosity of the samples. All samples showed a WVTR and pore size distribution suitable for skin tissue engineering; however, the water absorption and porosity were lower than the optimal values for skin tissue engineering. The biodegradation rate of scaffolds crosslinked with DTBP and glutaraldehyde (GTA) were reduced while no significant effect was observed in biodegradation of the samples made from 100% DDA chitosan whether crosslinked or uncrosslinked after 24 days of degradation.

Fabrication and characterization of porous alginate/polyvinyl alcohol hybrid scaffolds for 3D cell culture
Cho, S. H., S. H. Oh, et al. (2005), J Biomater Sci Polym Ed 16(8): 933-47.
Abstract: Porous alginate/polyvinyl alcohol (PVA) hybrid scaffolds as bioartificial cell scaffolds were fabricated to improve cell compatibility as well as flexibility of the scaffolds. The alginate/PVA hybrid scaffolds with different PVA compositions up to 50 wt% were fabricated by a modified freeze-drying method including the physical cross-linking of PVA and the following chemical cross-linking of alginate. The prepared alginate/PVA hybrid scaffolds were characterized by morphology observations using scanning electron microscopy (SEM), the measurements of porosity and average pore sizes and the measurements of compressive strength and modulus. The scaffolds exhibited highly porous, open-cellular pore structures with almost the same surface and cross-sectional porosities (total porosities about 85%, regardless of PVA composition) and the pore sizes from about 290 microm to about 190 microm with increasing PVA composition. The alginate/PVA hybrid scaffolds were more soft and elastic than the control alginate scaffold without significant changes of mechanical strength. The scaffolds were examined for their in vitro cell compatibility by the culture of chondrocytes (human chondrocyte cell line) in the scaffolds and the following analyses by MTT assay and SEM observation. It was observed that the alginate/PVA scaffolds had better cell adhesion and faster growth than the control alginate scaffold. It seems that 30 wt% addition of PVA to alginate in the fabrication of the hybrid scaffolds is desirable for improving their flexibility and cell compatibility.

Fabrication and characterization of three-dimensional poly(ether- ether- ketone)/-hydroxyapatite biocomposite scaffolds using laser sintering
Tan, K. H., C. K. Chua, et al. (2005), Proc Inst Mech Eng [H] 219(3): 183-94.
Abstract: The ability to have precise control over porosity, scaffold shape, and internal pore architecture is critical in tissue engineering. For anchorage-dependent cells, the presence of three-dimensional scaffolds with interconnected pore networks is crucial to aid in the proliferation and reorganization of cells. This research explored the potential of rapid prototyping techniques such as selective laser sintering to fabricate solvent-free porous composite polymeric scaffolds comprising of different blends of poly(ether-ether-ketone) (PEEK) and hydroxyapatite (HA). The architecture of the scaffolds was created with a scaffold library of cellular units and a corresponding algorithm to generate the structure. Test specimens were produced and characterized by varying the weight percentage, starting with 10 wt% HA to 40 wt% HA, of physically mixed PEEK-HA powder blends. Characterization analyses including porosity, microstructure, composition of the scaffolds, bioactivity, and in vitro cell viability of the scaffolds were conducted. The results obtained showed a promising approach in fabricating scaffolds which can produce controlled microarchitecture and higher consistency.

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Last Modified: 8 February 2006