单模微波辐照下壳聚糖-左旋聚乳酸接枝共聚物的酶催化合成

以猪胰脂肪酶(PPL)代替传统的有机金属作为催化剂,在单模微波辐照下利用左旋丙交酯(L-LA)的开环聚合制备壳聚糖-左旋聚乳酸(CS-g-PLLA)接枝共聚物.考察了反应温度及酶用量对接枝率的影响.以此为基础,利用DTG、XRD和3T3成纤维细胞培养对产物的物理性能及细胞相容性进行分析.结果显示,猪胰酶可有效催化接枝反应的进行.反应温度和酶用量对产物的接枝率有较大影响.在单模微波作用下,较低的反应温度(50℃)可获得具有较高接枝率(178.8%)的接枝产物.与纯壳聚糖相比,接枝产物的结晶度和热稳定性降低,说明PLLA的引入破坏了壳聚糖的高结晶性.产物具有良好的细胞相容性,可作为优良的组织工程支架材料.

ENZYMATIC SYNTHISIS OF CHITOSAN-GRAFT-POLY(L-LACTIDE) COPOLYMERS UNDER SINGLE-MODE MICROWAVE IRRADIATION

The porcine pancreatic lipase(PPL) was used to replace the traditional catalysts to catalyze L-lactide(L-LA) graft copolymerization onto chitosan under single-mode microwave irradiation,in order to prepare chitosan-graft-poly(L-lactide) copolymers(CS-g-PLLA).The effects of reaction temperature and catalyst dosage on the reaction were investigated.The physical properties and cell affinity of the copolymer were further discussed by differential thermogravimetry(DTG),X-ray diffraction(XRD) and 3T3 fibroblast incubation,taking pure chitosan as references.The results showed that the grafting reaction could be carried out by PPL catalyzing under normal atmospheric pressure.The reaction temperature and amount of PPL influenced the grafting degree greatly.The copolymer with high grafting degree(178.8%) could be achieved at low reaction temperature(50℃) under single-mode microwave radiation.Compared with pure chitosan,the thermal stability and crystallinity of copolymers decreased because grafting PLLA would destroy the high crystallinity of chitosan.The copolymer offered an excellent substrate for cell adhesion and proliferation,demonstrating that it could be applied as scaffold material in tissue engineering.The above results proved that the enzyme might be an ideal catalyst to prepare derivates of polysaccharose for application in biomaterials.