| Polycaprolactone is an important tissue engineering material, which is mainly synthesized through ring-opening polymerization catalyzed by metal complexes. The remaining toxic metal complexes in the reaction system made some adverse effects on the application of polycaprolactone. In addition, polycaprolactone has a strong hydrophobicity and poor cell affinity, which makes it unfavorable for cell adhesion and cell growth. In this paper, a glycosylated ?-polylysine which has specific sites for lipase-catalyzed reaction was first prepared through the Maillard reaction and the EDC method, respectively. Then, the two kinds of glycosylated ?-polylysine were used as initiators for the enzymatic ring-opening polymerization of ?-caprolactone to prepare the terminal functionalized polycaprolactone. The method could avoid the residual of metal ions and improve the cell affinity of the polycaprolactone.Firstly, the glycosylated ?-polylysine was successfully prepared by two different methods. In the Maillard reaction method, the effects of saccharides, ionic liquids, reaction time, temperature and reactant ratio on the Maillard reaction rate were investigated in detail. The results showed that 1-butyl-3-methylimidazolium chloride([Bmim]Cl) ionic liquid could effectively dissolve galactose and ?-polylysine, which was conducive to the Maillard reaction between them. And the optimum conditions were as follows: temperature 80?, time 6 h and reactant ratio 1:2. The results of FTIR, ~1H NMR and GPC confirmed that the Maillard reaction between ?-polylysine and galactose occurred successfully. In the EDC method, the results of FTIR and ~1H NMR showed that ?-polylysine was also successfully modified by lactobionic acid.Then, with the catalyzation of Novozyme-435 lipase, the synthesis and properties of the glycosylated ?-polylysine modified polycaprolactone were detailed studied. The results of FTIR confirmed that both two kinds of glycosylated ?-polylysine could successfully initiate the ring-opening polymerization of ?-caprolactone. The results of monomer conversion showed that the initiation rate was improved by the addition of glycosylated ?-polylysine. TGA tests showed that the decomposition temperature of the polycaprolactone chain was increased from 396? to 416? and 420?, respectively. The thermal stability of modified polycaprolactone was improved. The results of contact angle showed that the modified polycaprolactone had a good hydrophilicity. And XRD results showed that the crystallinity of the modified polycaprolactone decreased because of the introduction of glycosylated ?-polylysine. The results of solubility test indicated that the solubility of polycaprolactone in dichloromethane and acetone was significantly decreased after the terminal functionalization. The results of cytotoxicity test showed that NIH/3T3 had higher cell livability on the surface of the modified polycaprolactone, suggested that the addition of glycosylated polylysine could effectively improve the cell affinity of polycaprolactone. |
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