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Results for “FIBROIN”

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At least 307 records · Page 17Linked to original sources

PubMed2002

Visco-elastic properties of cartilage tissue regenerated with fibroin sponge.

The mechanical properties of regenerated cartilage tissue were measured to evaluate changes in their visco-elastic properties during cultivation. An indentation test and dynamic visco-elasticity measurements were carried out on cartilage tissue cultured with rabbit chondrocytes that had been inoculated into the fibroin sponge. A 1.5-mm-diameter porous indentor was used for the indentation test, in which time-dependent strain curves were derived from measurements taken under several loading conditions. Dynamic visco-elasticity measurements were performed under compressive loading to evaluate the load-bearing function of the articular cartilage. Although the amount of permanent deformation was not influenced by the duration of cartilage regeneration, the amount of creep deformation increased with longer cultivation. The E' value of the regenerated cartilage increased and the peak value of tan delta and the frequency at the peak became lower with longer cultivation. It is suggested that the changes in the time-dependent strain curves and dynamic visco-elastic properties of the regenerated cartilage were caused by maturation of the cultured cartilage tissue.

Animals↗

PubMed2006

Novel dermo-epidermal equivalents on silk fibroin-based formic acid-crosslinked three-dimensional nonwoven devices with prospective applications in human tissue engineering/regeneration/repair.

Biologically well-tolerated materials are at the core of intense research. In this study, we report both the intrinsic features of formic acid (FA)-crosslinked three-dimensional (3D) nonwoven scaffolds consisting of sericin-deprived, Bombyx mori silk fibroin (SF) in beta-sheet form and the long-term co-culture of adult human epidermal keratinocytes (HEKs) and dermal fibroblasts (HDFs) on them. The results of scanning electron microscopy, differential scanning calorimetry, and thermogravimetric and tensile strength studies showed that such scaffolds are made by a composite material, in which anisotropic SF fibres are enclosed within an isotropic matrix of SF in film form. Both fibres and films are firmly crosslinked by FA treatment and water-insoluble owing to their beta-sheet crystalline structure. Moreover, while a certain strength of the material in the dry state may favour its manufacturing, handling, and shaping, the dramatic loss of hardiness under wet conditions renders the scaffolds softer, mechanically more compliant and, hence, more apt for implantation. Normal HEKs and HDFs could be successfully co-cultured on such nonwovens for up to 75-95 days in vitro, thus forming a novel kind of dermo-epidermal equivalent, in which the cells were metabolically active and performed specific functions (e.g. the de novo production and assembly of collagen fibres), but never released urea nitrogen (an index of protein catabolism) or proinflammatory interleukin-1beta (IL-1beta). In keeping with the results of previous studies in animals (Dal Pra I, et al, Biomaterials 26: 1987-1989, 2005), these findings support the view that 3D SF-based nonwovens may be excellent candidates for beneficial applications in the field of human tissue engineering/regeneration/repair.

Animals↗

PubMed2006

Physical-chemical and biological characterization of silk fibroin-coated porous membranes for medical applications.

Membranes in artificial organs and scaffolds for tissue engineering are often coated with biomimetic molecules (e.g., collagen) to improve their biocompatibility and promote primary cell adhesion and differentiation. However, animal proteins are expensive and may be contaminated with prions. Silk fibroin (SF) made by Bombyx Mori silk worms, used as a scaffold or grafted to other polymers, reportedly promotes the adhesion and growth of many human cell types. This paper describes how commercial porous membranes were physically coated with SF, and their physical-chemical properties were characterized by SEM, AFM, tensile stress analysis and dynamic contact angle measurements. The effect of the SF coating on membrane biocompatibility and resistance to bacterial colonization is also examined. The proposed technique yields SF coats of different thickness that strengthen the membranes and make their surface remarkably more wettable. The SF coat is not cytotoxic, and promotes the adhesion and proliferation of an immortalized fibroblast cell line. Similarly to collagen, SF-coated membranes also exhibit a much better resistance to the adhesion of S. epidermidis bacteria than uncoated membranes. These preliminary results suggest that SF is a feasible alternative to collagen as a biomimetic coating for 3D scaffolds for tissue engineering or bioartificial (as well as artificial) prosthesis.

Chemical Phenomena↗

PubMed2004

Nano-scaled hydroxyapatite/polymer composite IV. Fabrication and cell adhesion properties of a three-dimensional scaffold made of composite material with a silk fibroin substrate to develop a percutaneous device.

Nano-scaled sintered hydroxyapatite (HAp) particles with an a-axis length of 87 +/- 23 nm, a c-axis length of 236 +/- 81 nm, and a mean aspect ratio ( c/ a) of 2.72 were covalently linked onto a silk fibroin (SF) substrate chemically modified by graft polymerization with gamma-methacryloxypropyl trimethoxysilane (MPTS). Graft polymerization with poly(MPTS) on SF was conducted by free-radical initiation in a water solvent with pentaethylene glycol dodecyl ether as a nonionic surfactant. The alkoxysilyl groups of the graft polymers avoided hydrolysis and maintained their activity in coupling with the hydroxyl groups on the HAp surface despite the use of water as the reaction solvent. The weight gain of poly(MPTS) on SF increased with increasing the reaction time, eventually reaching a plateau value of about 15 wt% after 50 min of reaction time. After HAp covalent coating, the particles separated or aggregated into several crystals, as shown by scanning electron microscopic observation. L929 fibroblast cells adhered more plentifully on HAp-coated SF compared to untreated SF and hydrolyzed poly(MPTS)-grafted SF during 24 h or 48 h of incubation. The cells adhered only on the HAp surface but not at all on the dehydrated grafted surface of SF without HAp. A button-shaped prototype for a percutaneous device was manufactured by transplantation of HAp-coated SF fibers of about 100 microm in length onto silicone moldings using an adhesive, and the device showed good cell adhesiveness.

Biocompatible Materials↗

PubMed1992

Characterization of low-temperature-plasma treated silk fibroin fabrics by ESCA and the use of the fabrics as an enzyme-immobilization support.

Bombyx mori silk fibroin fabrics were treated with low-temperature-plasma using various gases. Alkaline phosphatase was immobilized onto the fabrics using the CNBr method. The enzyme activity was much improved by plasma treatment, especially when both O2 and CF4 were used. Using the ESCA technique it was found that the activities of the immobilized enzyme were strongly correlated with the C1s peak intensities of the atomic group -C-O-CF3. The apparent Michaelis constant for the enzyme decreased with increasing amounts of -C-O-CF3.

Alkaline Phosphatase↗

PubMed1964