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报道了一种在壳聚糖重复单元C6位用聚乙二醇化学选择性修饰的新方法,主要以壳聚糖(CS)和单甲氧基聚乙二醇(mPEG)为原料,先用邻苯二甲酸酐保护壳聚糖C2-氨基,然后利用N-溴琥珀酰亚胺和三苯基膦将壳聚糖C6-伯羟基取代成溴,得到6-溴-N-邻苯二甲酰壳聚糖,将其与活化的mPEG反应,再用水合肼脱保护,即得到壳聚糖C6-聚乙二醇(mPEG-CS)。用红外光谱(IR)、核磁共振波谱(NMR)和溶解实验对产物的结构和性能进行表征分析。由1 H-NMR谱得到mPEG-CS的接枝率为15.0%,并用碱量法对接枝率结果进行确证。与壳聚糖相比,该接枝共聚物在较宽pH值范围的水溶液中均有良好的溶解性,并保留了氨基活性基团。
A new method for the chemical selective modification of polyethylene glycol with chitosan at the C6 position was reported. Chitosan (CS) and monomethoxy polyethylene glycol (mPEG) Phthalic anhydride protects the chitosan C2-amino group, and then the C6-primary hydroxyl group of chitosan is substituted with bromine using N-bromosuccinimide and triphenylphosphine to give 6-bromo-N- Chitosan, which is reacted with activated mPEG, deprotected with hydrazine hydrate to obtain chitosan C6-polyethylene glycol (mPEG-CS). The structure and properties of the product were characterized by IR, NMR and dissolution experiments. The graft rate of mPEG-CS was 15.0% from1H-NMR spectrum, and the result of grafting degree was confirmed by alkali method. Compared with chitosan, the graft copolymer has good solubility in aqueous solution over a wide range of pH, and retains amino reactive groups.