The objective of this study was to investigate the efficiency of two treatments for poly(l-lactic acid) (PLLA) surface modification with chitosan, via entrapment and coupling by using 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide and N-hydroxysuccinimide. The properties of original PLLA films, chitosan-entrapped and coupled PLLA films were investigated by water contact angle measurement and electron spectroscopy for chemical analysis (ESCA). The contact angle indicated the 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, the attachment and proliferation of bovine articular chondrocyte seeded on modified PLLA films and control one were examined. A whole cell enzyme-linked immunosorbent assay (Cell ELISA) that detects the BrdU incorporation during DNA synthesis and collagen type II secretion was applied to evaluate the chondrocytes on different PLLA films and tissue culture plates. Cell viability was estimated by the MTT assay and cell function were assessed by measuring sulfated glycosaminoglycan secreted by chondrocytes. These results implied that chitosan used to modify PLLA surface through entrapment and coupling could enhance the chondrocyte adhesion, proliferation and function.

In this study, L929 cell adhesion, proliferation and apoptosis were investigated on chitosan (CS) and chitosan-gelatin (CS-Gel) membranes having different degrees of deacetylation (DD). The mitochondrial activity [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide] assay results demonstrated that the DD played a key role in the L929 cell adhesion. Indeed, the higher the DD of a CS membrane, the stronger the cell adhesion. The cell cycle analysis showed that the CS surface inhibits most of the cells entering the cell cycle and the DD of CS had little effect on the cell cycle progression. On the other hand, this study also confirmed that CS, blended with Gel, induced L929 cells to enter the cell cycle, encouraged proliferation, decreased the degree of apoptosis on the CS membranes, and are comparable to the results from L929 cells on tissue culture plates. In brief, CS modified with Gel improves cytocompatibility by shielding the positively charged CS with a high charge density.

Chitosan-gelatin hybrid polymer network scaffolds were prepared via the freeze-drying technique by using the ice microparticle as a porogen. Monolayer and bilayer scaffolds were obtained by using different pre-freezing methods. The novel bilayer scaffolds were prepared via contact with 561C lyophilizing plate directly, then lyophilized. The properties of chitosan-gelatin scaffolds, such as microstructure, physical and mechanical and degradable properties, were studied. These results suggested that the porosity and pore size of the scaffolds could be modulated with thermodynamic and kinetic parameters of ice formation. The scaffolds prepared from chitosan and gelatin can be utilized as a promising matrix for tissue engineering.

The objective of the present studywas to investigate the properties of chitosan–gelatin membranes or scaffolds, which were modified byincorporation of hyaluronic acid in the surface or bulk phase through co-crosslinking with N;N-(3-dimethylaminopropyl)-N0-ethyl carbodiimide (EDC) and N-hydroxysuccinimide (NHS) in 2-morpholinoethane sulfonic acid (MES) buffer. The comparative studyon properties of surface modification (HA(S)) and polyblend membranes (HA(C)) revealed that gelatin was enriched on the surface of HA(C), while hyaluronic acid was enriched on the surface of the HA(S). The HA(S) membranes made by surface modification method had a characteristic surface morphology. The corresponding scaffolds were prepared through freezedrying. The incorporation of hyaluronic acid improved flexibility and fibroblasts adhesion, while slowing down the rate of biodegradation of chitosan-gelatin scaffold. Human fibroblasts adhered and proliferated well on the membranes or scaffolds in vitro.

The objective of this study was to modify the surface of poly(d,l-lactic acid) (PDLLA) with different molecular weight of silk fibroins, and assess the effects of the modified surfaces on the functions of rat osteoblasts cultured in vitro. The properties of the modified PDLLA surface and the control one were investigated by contact angle and electron spectroscopy for chemical analysis (ESCA). The former indicated the variation of hydrophilicity and the latter suggested that the modified PDLLA film using silk fibroin is enriched with nitrogen atoms. The biocompatibility of the PDLLA film may be altered and in turn affects the seeded cell functions Therefore, attachment and proliferation of osteoblasts seeded on the modified PDLLA films and the control one were examined. Cell morphologies on these films were studied by scanning electron microscopy (SEM) and cell viability was evaluated by MTT assay. In addition, differentiated cell function was assessed by measuring the alkaline phosphatase (ALP) activity. These results suggest that the silk fibroin-modified PDLLA surface can improve the interaction between osteoblasts and the PDLLA films.