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.