基于超支化温敏聚合物制备温敏金纳米粒子

Thermoresponsive Gold Nanoparticles Based on the Hyperbranched Thermoresponsive Polymers

通过对不同分子量的超支化聚乙烯亚胺（hyperbranched polyethyleni mine,HPEI）的端基进行部分或完全异丁酰胺（isobutyric amide,IBAm）化,可以制备一系列具有不同低临界溶解温度（Lower Critical SolutionTemperature,LCST）的超支化温敏聚合物HPEI-IBAm。通过离子键或氢键之间的相互作用,所得超支化温敏聚合物可以吸附于柠檬酸钠还原并稳定的14nm的金纳米粒子（AuNP）的表面,从而得到具有温敏性质的金纳米粒子。所得温敏金的LCST都低于其相应的温敏聚合物,其差值在0.8至6℃之间。在pH值为9.18的缓冲溶液中,通过改变所用聚合物的分子量以及异丁酰胺基团的取代度,所得温敏金的LCST可控制在21.7~48.2℃之间。此外,所得温敏金的LCST也是pH值敏感的,通过溶液pH值的改变,所得温敏金的LCST值可以在更宽的范围内调节。增加溶液的碱性,LCST可能变化不大或降低,减小溶液的碱性会使LCST升高,直到消失。在偏酸的条件下,所得金复合物通常发生聚集,变得不稳定。此外,溶液中的盐度对所得温敏金的LCST也有影响,氯化钠和硫酸钠会降低其LCST,尤其是硫酸钠的效果更显著。

A series of thermoresponsive gold nanoparticles were prepared by capping the surface of the citrate-protected 14 nm diameter gold nanoparticles with the hyperbranched thermoresponsive polymer,isobutyric amide group terminated hyperbranched polyethylenimine（HPEI-IBAm）.The lower critical solution temperatures（LCST） of the obtained gold composites were lower about 0.8~6℃ than those of their capping polymers in the buffer solution with pH=9.18.The LCST of the thermoresponsive gold composites could be adjusted in the range of 21.7-48.2℃ by changing the molecular weight or the degree of substitution of IBAm groups of the capping polymers.By varying the pH value of the aqueous solution,the LCST of the gold composites could be tuned in much wide range.Moreover,the addition of small amount of salts also had influence in the LCST of the gold composites.Both sodium chloride and sodium sulfate lowered the LCST;however,the influence of sodium sulfate was much significant.