Synthesis Of Collagenase Sensitive Poly (α-hydroxy Acid)s

Poly(lactic acid) or polylactides (PLA) was widely used in biomedical engineering due to its biocompatibility, biodegradability, as well as mechanical, machining and antiseptic properties. In order to match the degradation rate of polylactides and formation rate of engineered tissue, a great number of experiments based on copolymerization, blending and composite were studied. However, the characteristics and mechanism of degradation of polylactides did not change anymore. To match the rate of material degradation and engineerd tissue formation, biomimetic should be the most effective solution.In this thesis, oligomers of dihydroxyl-terminated polylactides was prepared by ring-opening polymerization of D,L-lactide(LA) with lysine and collagenase-sensitive peptide as initiators. The obtained oligomers were characterized with UV-vis spectrophotometer, Fourier infrared transform spectrometry(FTIR), Hydrogen nuclear magnetic resonance (1H-NMR), and chemical analysis methods. The main works and conclusions were summarized as follows:Firstly, polylactides oligomers can be obtained by ring-opening polymerization of D,L-lactide with stannous octoate as catalyst and lysine as initiator, and the obtained oligomers were dihydroxyl-terminated PLA(HO-PLA-Lys-PLA-OH).Secondly, the experimental conditions, ring-opening polymerization of lactide with lysine as initiator, were optimized through the orthogonal experiment. When experimental conditions were polymerization temperature 110℃, reaction time 60h, stannous octoate 1.25wt% of D,L-lactide, molar ratio of lactide and lysine 41,the molecular weight of HO-PLA-Lys-PLA-OH(5618g·mol-1)was most close to the designed theoretical molecular weight.Finally, based on the similar molecular structure and double-end amino functional groups of polypeptide (GGGLGPAGGK) and lysine, the optimized conditions of ring-openning polymerization with lysine was applied to collagenase-sensitive peptide, and the oligomer of collagenase-sensitive peptide-polylactides (HO-PLA-GGGLGPAGGK-PLA-OH) can be obtained by ring-opening polymerization of D,L-lactide with collagenase-sensitive peptide as initiator, which was good enough to synthesize biomimetic materials of collagenase-sensitive poly(lactic acid) with high molecular weight through chain extension.