Biomimetic surface modification of poly (L-lactic acid) with gelatin and its effects on articular chondrocytes in vitro

Our objective in this study was to investigate the efficiency of two treatments for poly (L-lactic acid) (PLLA) surface modification with gelatin, via entrapment and coupling, using 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC) and N-hydroxysuccinimide (NHS). The properties of original PLLA, gelatin-entrapped, and coupled PLLA films were investigated by water contact angle measurement and electron spectroscopy for chemical analysis (ESCA). The water contact angle indicated that the incorporation of gelatin resulted in a change in hydrophilicity, and the ESCA data suggested that the modified PLLA films became enriched with nitrogen atoms. The cytocompatibility of modified PLLA films might be improved. Therefore, we examined the attachment and proliferation of bovine articular chondrocyte seeded on modified PLLA films and virgin films. A whole-cell enzyme-linked immunosorbent assay (cell ELISA) that detects 5-bromo-2'-deoxyuridine (BrdU) incorporation during DNA synthesis and collagen type II secretion was applied to evaluate the chondrocytes on different PLLA films and tissue culture plates (TCPS). Cell viability was estimated by the MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide] assay, and cell function was assessed by measuring glycosaminoglycan (GAG) secreted by chondrocytes. These results implied that gelatin used to modify the PLLA surface through entrapment and coupling could enhance chondrocyte adhesion, proliferation, and function.