聚吡咯基温敏凝胶的制备及性能研究

Preparation and properties of polypyrrole-based thermosensitive gels

为了明确纳米温敏凝胶在光控药物释放和光热治疗等方面的应用价值,通过无皂乳液聚合法,使用单体N-异丙基丙烯酰胺(N-isopropylacrylamide,NIPAM)与壳聚糖(chitosan,CS)合成了体积相转变温度为38.5℃,并具有明显的温敏性的PNIPAM/CS复合温敏凝胶;利用原位吸附法在PNIPAM/CS凝胶颗粒表面生长聚吡咯(polypyrrole,PPy)光响应层,获得结构为球形,尺寸分布为100~200 nm的PNIPAM/CS@PPy纳米凝胶。当温度从20℃增加到42℃时,凝胶颗粒的水合粒径从250 nm下降到140 nm,表现出温度变化驱动的体积收缩性能。研究结果表明:纳米凝胶颗粒具有较强的吸收近红外光功能;在808 nm激光照射下,纳米凝胶具有强光热转换性能,其光热升温随着浓度的增加而增强;PNIPAM/CS@PPy在温控药物释放和光热治疗等方面具有潜在的应用价值。

PNIPAM/CS composite thermosensitive gels were synthesized by using N-isopropyl acrylamide(NIPAM)and chitosan(CS)through the soap-free emulsion polymerization.PNIPAM/CS gels exhibit obvious thermal sensitivity with the volume phase transition temperature(VPTT)at 38.5℃.Subsequently,the photoresponsive polypyrrole(PPy)layer was grown on the surface of PNIPAM/CS by the in-situ adsorption method,resulting in PNIPAM/CS@PPy nanogels.PNIPAM/CS@PPy nanogels are spherical with a size range of 100 to 200 nm.When the temperature increases from 20 to 42℃,the nanogels show an obvious reduction of hydrodynamic size from 250 nm to 140 nm,indicating the volume shrinkage driven by temperature change.The results verify that the nanogels have strong absorbance in the near-infrared light region and show strong photothermal effects under irradiation of 808 nm laser,and the temperature elevation increases with gel concentrations.PNIPAM/CS@PPy nanogels have potential applications in thermosensitive drug release and photothermal therapy.