基于含苯硼酸三嵌段共聚物的糖响应性水凝胶

Glucose-responsive Hydrogels Based on ABA Triblock Copolymers Containing Phenylboronic Acid

设计合成了一类新型结构的聚环氧乙烷(PEO)大分子链转移剂,调控3-丙烯酰胺基苯硼酸(AAPBA)的可逆加成断裂-链转移(RAFT)自由基聚合,合成得到3种PAAPBA链段长度不同的PAAPBA-bPEO-b-PAABPA3嵌段共聚物.研究了3种聚合物在生理pH值下的凝胶化行为,证明凝胶的形成与PAABPA的长度有关,当该链段较长时,由于PAABPA链段疏水性太强,不能形成稳定的水凝胶.详细研究了聚合物浓度、温度、葡萄糖浓度对凝胶流变行为的影响,证明共聚物浓度越高,形成的凝胶的强度更大,性质上更接近于固体,浓度较高条件下形成的凝胶的转变温度较高.凝胶表现出葡萄糖敏感性,当高葡萄糖存在时,随时间延长,凝胶会发生崩解直至最后溶解.凝胶亲水微区能包载蛋白质FITC-BSA,加入葡萄糖后,FITC-BSA的释放加快.

A new type of poly（ethylene oxide） （PEO） chain transfer reagent was synthesized and used to mediate the reversible addition fragmentation chain transfer （RAFT） polymerization of 3-（acrylamino） phenylboronic acid （AAPBA） to get three types of PAAPBA-b-PEO-b-PAABPA triblock copolymers with different PAAPBA lengths. The gelation of these copolymers at physiological pH was examined. It was found that hydrogel formation was dependent on the PAABPA block chain length, when the block was too long, no stable gel can be obtained due to the high hydrophobicity of the PAABPA segment. The effects of temperature, polymer concentration and glucose on the rheological properties of the gel were investigated in detail. The results indicated that the formed hydrogels possess solid-like behavior, at high polymer concentrations, gels with high strength and high phase transfer temperature could be obtained. In the presence of high concentration of glucose,interaction of glucose with the PAAPBA block can lead to the increase of the hydrophilicity of the PAAPBA block,thus leading to the break of the hydrogel network with time and finally the gel dissolved in about 1.5 h. Finally, the hydrogels could load FITC-BSA in the hydrophilic regions, and the release profile of FITC-BSA was accelerated in the presence of glucose.