Papers by Keyword: Biological Property

Abstract: To investigate the influence of initial copolymer compositions of poly (lactic-co-glycolic acid) (PLGA) on mechanical properties, degradation behavior and biological properties of the scaffolds, porous PLGA scaffolds with different initial copolymer compositions (lactide/glycolide (PLA/PGA) molar ratio: 50:50, 70:30 and 80:20) were prepared by solvent casting/particulate leaching method. Mechanical properties were measured by testing the tensile strength and degradation rate was detected by soaking the scaffolds in phosphate buffered solution at 37 °C for various time points. Human dermal fibroblasts were seeded on PLGA scaffolds with different copolymer compositions. The morphology, adhesion efficiency, proliferation rate, and total collagen contents of cells on the scaffolds were analyzed. The results showed that the ratio of PLA/PGA is one important factor which influences the degradation of scaffolds. The mechanical strength of PLGA scaffolds with the ratio of 70:30 and 80:20, was higher than that of PLGA scaffolds with the ratio of 50:50.. Compared to 70:30 and 80:20 PLGA scaffolds, 50:50 PLGA had a quicker degradation. The three PLGA scaffolds had no obvious difference for cell response and all of them had excellent cytocompatibility, indicated by their high efficiency for human dermal fibroblast adhesion, fast proliferation rate and stretched cell morphology. A large amount of extracellular matrix was secreted and after 7 days of culture, and cell nearly covered the entire surface of the scaffolds. Overall, our results indicate that the copolymer compositions of PLGA have important effect on degradation and mechanical strength, but have no obvious effect on the biological properties of the scaffolds.

Abstract: Silk fibers were introduced into hydroxyapatite(HA)/chitosan(CS) matrix to prepare scaffold materials of bone tissue engineering with the adequate initial strength and improved cellular affinity using combination of in situ synthesis and freeze-drying technique. Chemical component was investigated using X rays diffraction (XRD) and Fourier transform infrared spectrum (FTIR). Structure and morphology of the composites were observed by scanning electron microscope (SEM). Porosity was tested by liquid substitution method. The mechanical properties of the composites were also measured. The simulated body fluid (SBF) and the cell culture experiments were conducted to assess biological properties of the composites. Results show that the composites with a pore size of 100~250μm have a porosity of 75%~90%and the maximum compressive strength of 5.7 MPa. The compressive strength of the composite is greatly improved in comparison with that of HA/CS matrix (4.6 MPa). In the SBF tests, a layer of randomly oriented apatite crystals form on the scaffold surface after sample immersion in SBF. The cell culture experiments show that the osteoblast cells are attached and proliferated on the surface of the composite, which suggests good bioactivity and cellular compatibility of the composite material. It is concluded that the composites have a promising prospect as bone tissue engineering materials.

Abstract: UNCD/a-C composite films have been deposited by microwave plasma chemical vapour deposition from methane/nitrogen mixtures with 17% CH4 in the temperature range 500-770°C on various substrates such as monocrystalline silicon wafers, polycrystalline diamond, c-BN, TiN, GaAs, and other materials of technological interest. The resulting films have been thoroughly characterized with respect to their morphology, crystallinity, composition, and bonding structure. It was found that they are composed of diamond nanocrystallites (3-5 nm in diameter) surrounded by 1-1.5 nm amorphous carbon grain boundary material; the ratio of the volume fractions of crystalline and amorphous phase is close to unity. The investigations of the application-relevant properties of the UNCD/a-C films revealed that they are attractive for a number of mechanical, tribological, structural, and biomedical applications.

Abstract: Hydroxyapatite (HAp) has unique properties for biomaterials such as hard-tissue-compatible material for bone and tooth and also soft-tissue-compatible materials for skin tissue. However, the hard and brittle nature of HAp limits spreading many medical devices. Recently, a unique composite of sintered HAp nano-crystals -- ceramics -- covalently coupled to polymer substrates was developed -- Nano-Ceramic Coating --. The development was depended on the two original technologies: (1) control of size/morphology of high-dispersed sintered nano-HAp, (2) donation of covalent bonding between nano-HAp and substrates to coat strongly on the surface. The nano-composite material holds not only the mechanical properties of the substrate but also biological properties of the ceramics coated on the surface. In this report, the method of synthesis of high-dispersed nano-HAp, the preparation of the nano-composite, the biological properties with cells or animal tissue, and especially, the development of medical devices, such as percutaneous device or blood vessel and so on, made of the composite will be presented.