In order to prepare a physically cross-linked thermo-sensitive hydrogel,in this paper,water-soluble glycol chitosan(GC)was selected as the matrix,the heptanoylated glycol chitosan(HAGC)with different degrees of heptanoylation(DS)were synthesized by acylation modification through amide coupling reaction between heptanoic anhydride and amino groups on the molecular chain of GC.The results show that the feed molar ratio of heptanoic anhydride to the amino group on GC is between 0.2 and 0.25,and DS is modulated from 26.4%to 31.5%.By the introduction of hydrophobic acetyl groups on the backbone of GC,it was not only found that such derivatiza-tion would improve the solubility in organic solvents and in vitro biodegradability of GC,but also import new at-tractive properties such as thermo-sensitive sol-gel transition properties.HAGC was physically cross-linked through intermolecular interactions,including hydrogen bonding and hydrophilic and hydrophobic interactions.Thus,HAGC could undergo sol-gel phase transition in response to ambient temperature changes.By changing the DS and solution concentration of HAGC,the sol-gel transition temperature of HAGC hydrogel was effectively adjusted between room temperature and human body temperature(25-37℃).The HAGC hydrogel had the three-dimensional porous structure.As the DS increase,the crosslink density of the HAGC hydrogel increased,the swell-ing ratio decreased,and the drug release rate slowed down.The HAGC hydrogel had a slow-release effect on the drug gemcitabine,and the drug release time could reach 5 days,and the drug release rate was up to 70%-91%.Therefore,HAGC hydrogel has important application value in biomedical fields such as drug injection and sustained-release carrier due to its excellent thermo-sensitive properties.
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