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.

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.

Glucose was oxidized to generate a glucose dialdehyde and chitosan (CS) was hydrophobically modified with butyl bromide, octyl bromide and dexyl bromide. The analysis of IR and X-ray diffraction results of CS derivatives confirms that the hydrogen bonds and crystallinity were weakened by the incorporation of pendant alkyl. The permeability coefficient P and diffusion coefficient D for model drug vitamin B2 through oxidized glucose-crosslinked alkylated CS membrane were determined under different pH media. The results show that for the same alkylated CS in different pH media, P and D decrease withan increase in pH; for different alkylated CSs in acidic media, P and D diminish with the increase in the length of alkyl side, which is supposedly originated from the enhancement of hydrophobicity. In alkali medium, P and D show a rising trend with the increase in the length of alkyl chain, which might be related to the loose stacking of network as it occurs to shrink in alkali medium. The preliminary cytotoxicity assay indicates that oxidized glucose-crosslinked alkylate CS membrane is non-toxic in vitro.

The objective of this study was to investigate the efficiency of two treatments for poly(d,l-lactic acid) (PDLLA) surface modification using silk fibroin, one chemical treatment and one physical treatment: 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide (WSC) and entrapment. The properties of control films, WSC-modified and entrapment-treated PDLLA films were investigated by water contact angle measurement and electron spectroscopy for chemical analysis (ESCA). The water-contact angle measurement indicated the change of hydrophilicity and the ESCA analysis suggested that the modified PDLLA film using silk fibroin became enriched with nitrogen atoms. The biocompatibility of PDLLA film might be altered, which in turn would affect the functions of cells that were seeded on it. Therefore, attachment and proliferation of osteoblasts that were seeded on modified PDLLA films and control films were examined. Cell viability was evaluated by the MTT assay and differentiated cell function was assessed by measuring alkaline phosphatase activity. These results suggested that silk fibroin was used to modify PDLLA surface via WSC and that entrapment could improve the interactions between osteoblasts and PDLLA films. The entrapment treatment was more effective than WSC treatment to accomplish the goal of surface modification.