型胶原在聚-L-乳酸(PLLA)表面的化学接枝和涂层及其对软骨细胞生长的促进作用

Grafting and Coating of Collagen Type Ⅰ on Poly-L-lactic Acid (PLLA) Membrane Surface to Enhance the Growth of Chondrocytes

采用接枝 -涂层技术在聚 -L-乳酸 ( PLLA)膜表面接枝聚甲基丙烯酸 ( PMAA)得到稳定的 PLLA-g-PMAA胶原涂层 .利用水溶性碳化二亚胺作为缩合剂 ,使 PLLA-g-PMAA表面的羧基和胶原分子中的氨基发生缩合反应 ,从而将 型胶原接枝在 PLLA表面 ;同时保留材料表面物理涂层的胶原溶液 ,获得了稳定的胶原涂层 . XPS谱图证实了接枝反应的发生 .分别用比色法和茚三酮法测定了 PLLA-g-PMAA表面的羧基密度和 PLLA膜表面胶原的接枝量和涂层量 .细胞培养结果表明 ,改性后的 PLLA膜表面软骨细胞的铺展性能和增长速度明显改善 .

Stable type Ⅰ collagen layer was formed on PLLA membrane surface by using the grafting-coating method. First, polymethacrylic acid (PMAA) was grafted on the PLLA membrane to yield carboxyl groups on the PLLA surface. Then, water-soluble carbodiimide was used as condensing agent to catalyze the reaction between the carboxyl groups and the amino groups to graft the collagen covalently on the PLLA-g-PMAA surface. Meanwhile, the collagen solution physically coated on the PLLA membrane surface was preserved to form coated collagen layer. XPS spectroscopy was used to verify the occurrence of the grafting reaction. The density of the carboxyl groups on the PLLA-g-PMAA surface was determined by colorimetric method. The surface density of the collagen coated on the PLLA surface was determined by ninhydrin method. The stability of the collagen layer was studied by incubating the collagen-coated membrane in phosphate buffer saline (PBS, pH=7.4). The surface density of the collagen decreased very slightly after the incubation, indicating the good stability of the coated collagen layer. The cell culture results showed that the growth rate of chondrocytes increased significantly on the collagen-coated PLLA membrane compared with that under the control. On the control of PLLA membrane, the cells were round shaped and easy to accumulate with each other, while on the collagen-coated PLLA membrane, the cells were spread out and evenly distributed. In conclusion, using grafting-coating method, stable collagen layer can be produced on the hydrophobic PLLA surface to improve the cytocompatibility obviously.