NIR光响应型PNIPAM-co-AA/GO复合体系的制备及药物释放

Preparation and drug release of NIR photosensitive PNIPAM-co-AA/GO composite system

采用乳液聚合法将N-异丙基丙烯酰胺(NIPAM)与丙烯酸(AA)聚合为PNIPAM-co-AA微凝胶,并进一步与氧化石墨烯(GO)超声共混得到PNIPAM-co-AA/GO复合体系,将其应用于药物释放研究。采用FTIR、TEM、DLS、UV-Vis对微凝胶及复合体系的结构和性能进行了表征与测试。结果表明,PNIPAM-co-AA微凝胶的粒径为458.7nm,最低临界相转变温度(LCST)为40℃,具有温度敏感性和pH敏感性。GO的存在将PNIPAM-co-AA/GO复合体系的温度响应控制转化成了近红外(NIR)响应。复合体系受到NIR光照射,可在3 min内将NIR光能转化为热能达到微凝胶的LCST,多次循环后光热转化性能稳定。药物释放实验结果表明,有NIR、pH 7.4,25℃条件下,PNIPAM-co-AA/GO[AA含量为5%(以NIPAM、BIS和SDS物质的量之和为基准,下同),GO含量为5%(以PNIPAM-co-AA质量为基准,下同)]对5-氟尿嘧啶(5-FU)在24h的累积释放率为77.24%。

PNIPAM-co-AA/GO composite system was synthesized by ultrasonic blending of GO and PNIPAM-co-AA microgels which were prepared via emulsion polymerization of N-isopropylacrylamide(NIPAM)and acrylic acid(AA),and its in vitro drug release performances were investigated.Meanwhile,the microstructure and properties of PNIPAM-co-AA microgels and PNIPAM-co-AA/GO composite system were characterized by FTIR,TEM,DLS and UV-Vis.The results showed that the PNIPAM-co-AA microgels exhibited a particle size of 458.7 nm,lower critical solution temperature(LCST)of 40℃,as well as temperature and pH sensitivity.The presence of GO transformed the temperature response control of PNIPAM-co-AA composite system into near infra-red(NIR)response.When irradiated by NIR light,the composite system,converting the NIR light energy into heat energy,could obtain the LCST of microgel within just 3 min,and the photothermal conversion performance was stable after several cycles.The drug release study revealed that under the conditions of NIR irradiation and pH 7.4,25℃,the cumulative release rate of PNIPAM-co-AA/GO[5%AA(based on the total mole of NIPAM,BIS and SDS),5%GO(based on the mass of PNIPAM-co-AA)]to 5-fluorouracil(5-FU)within 24 h reached up to 77.24%.