聚乳酸的层层自组装修饰及其内皮细胞相容性研究

通过胺解反应在生物降解聚(L-乳酸)表面引入带有正电荷的自由氨基,并通过静电吸引层层(Layer-by-layer,LBL)自组装技术将具有良好生物相容性的硫酸软骨素(CS)和细胞外基质成分型胶原组装到该PLLA材料表面.通过反应性荧光探针标记、紫外-可见吸收光谱以及荧光能量转移等测试技术跟踪并表征了自组装过程的进行.组装层的厚度开始随组装层数的增加而线性增加,而后增加变缓.内皮细胞的体外培养证明,表面组装CS和胶原(以胶原为最外层)以后,细胞的增殖率和细胞活性显著提高,材料的细胞相容性得到明显改善.细胞体现了充分铺展的多角形内皮细胞形貌,而且局部已融合形成了一单层内皮细胞层.

LBL Self-assembly of Chondroitin Sulfate and Collagen onto Poly(L-lactic acid) Surface for Improving Its Cytocompatibility with Endothelial Cells

Amino groups were covalently introduced onto poly(L-lactic acid)(PLLA) surface by the aminolyzing reaction between 1,6-hexanediamine and the ester groups of PLLA. The amino groups provides the possibility to modify PLLA surface using technology of layer-by-layer (LBL) self-assembly, because these aminolyzed polyesters can be used as the polycationic substrate. Biocompatible chondroitin sulfate A (CS) and collagen type Ⅰ were chosen to be deposited alternately onto the aminolyzed PLLA membrane surface. The deposition process was monitored by UV-Vis absorbance spectroscopy and energy transfer by fluorescence spectroscopy after the polyelectrolytes were labeled by fluorescein isothiocyanate (FITC) and rhodamine isothiocyanate, respectively. The layer thickness increased linearly at first with the increase of the deposited layers, and then increased slowly due to the layer interpenetration. The existed collagen improved the cytocompatibility of PLLA to human endothelial cells. The cell attachment, activity and proliferation increased greatly on the PLLA membranes assembled with only one bilayers of CS/collagen (with collagen as the outermost layer). Cells also showed morphology of flat endothelium, and a confluent cell layer was reached after being cultured for 4 d. Due to the advantages of those traditional methods, LBL self-assembly technique will attract many attentions in scaffold modification in tissue engineering.