During the last decade, stimuli-responsible polymers based on poly(N-isopropylacrylamide) having conformational transition in the range of physiological temperature have been discussed as novel drug delivery nanosystems. A star-like copolymer with a dextran core and grafted poly(N-isopropylacrylamide) arms (D-g-PNIPAM) was synthesized, characterized, and used as a matrix for silver sol preparation. The comparative study of the behavior of individual D-g-PNIPAM and the nanohybrid system D-g-PNIPAM/silver nanoparticles has been done in the temperature range near the lower critical solution temperature (LCST). The methods of Dynamic Light Scattering, small angle X-ray scattering, and UV-VIS absorption spectroscopy have been used. The existence of single nanoparticles and aggregated nanoparticles located in a limited polymer macromolecular volume was established. The increase of the temperature leads to slight aggregation of the silver nanoparticles at the LCST transition. Single nanoparticles do not aggregate with the temperature increase. The thermally induced collapse of end-grafted poly(N-isopropylacrylamide) chains above the LCST do not affect significantly the size characteristics of silver nanoparticles incorporated into the polymer matrix.

中文翻译：

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葡聚糖-接枝-PNIPAM /嵌入式银纳米粒子混合体系中的温度驱动转化

在最近十年中，已经讨论了基于在生理温度范围内具有构象转变的聚（N-异丙基丙烯酰胺）的刺激负责的聚合物，作为新型药物递送纳米系统。合成了具有葡聚糖核心和接枝的聚（N-异丙基丙烯酰胺）臂的星形共聚物（Dg-PNIPAM），对其进行了表征，并将其用作制备银溶胶的基质。已经在接近较低临界溶液温度（LCST）的温度范围内对单个Dg-PNIPAM和纳米混合体系Dg-PNIPAM /银纳米粒子的行为进行了比较研究。已经使用了动态光散射，小角度X射线散射和UV-VIS吸收光谱的方法。建立了位于有限的聚合物大分子体积中的单个纳米颗粒和聚集纳米颗粒的存在。温度的升高导致在LCST转变时银纳米颗粒的轻微聚集。单个纳米颗粒不随温度升高而聚集。LCST上方热引发的末端接枝聚（N-异丙基丙烯酰胺）链塌陷不会显着影响掺入聚合物基质中的银纳米颗粒的尺寸特征。