Biomimetic Design Of Biomaterials

For bioactivating biomaterials surface, surface modification of 2D polystyrene (PS) with protein was studied. Firstly gelatin, collagen and Arginine-glycine-aspartic acid (RGD) peptide adsorbed to PS surfaces with physical reaction. XPS proved the increase of nitrogen content on the modified surfaces. Quantitative analysis of protein adsorption was done by Bradford method. Secondly, PS surfaces were carboxylated by permanganate oxidation in diluted sulfuric acid, and the carboxyls were activated with water-soluble carbodiimide to graft with gelatin, collagen and RGD peptide. XPS method confirmed the existence of nitrogen element from protein molecules. Further more, this paper parsed C1s charts. The results showed the presence of amido link (-CONH-) and covalently binding of proteins to PS surfaces. Dynamic contact angle measurement indicated hydrophilicity of PS surfaces was improved obviously after grafting modification. Thirdly, evaluated by epidermal cell culture, cell adhesion and proliferation was better on modified surfaces than the initial. This paper also compared the effect of these different protein molecules to cell behavior. Mechanical intension and biocompatibility are important factors of biomaterials used in Tissue Engineering. Chitosan-poly(lactic acid) copolymer (CS-LA, CL) was synthesized by thermal condensation polymerization. Main body was chitosan, and grafting phase was oligomer of lactic acid (PLA). IR and NMR spectra verified the occurrence of LA grafting in CL. XPS indicated that the length of PLA segments in CL structure increased with LA content. The change of CL conformation in water was analyzed with dynamic contact angle measurement. Mechanical properties of CL membranes were also done. In contrast of chitosan, intension and extension property of CL membranes were all improved due to PLA segment physical cross-linkage. Epidermal cell culture was performed to evaluate cytocompatibility of membranes. The results showed that cell adhesion and proliferation was effective on the surface of CL membranes especially CL-1.5. To improve CL's cytocompatibility further, gelatin and RGD peptide were immobilized to CL by entrapment method. MSCs, cultured on the modified CL membranes, grew well and spread sufficiently especially the gelatin-modified.