以Au@Ag双金属纳米棒为核的热响应性核壳复合微凝胶的制备及性能表征

Fabrication and characterization of thermo-responsive composite microgels based on Au@Ag nanorod as core

本文采用种子沉淀聚合法将交联的聚(N-异丙基丙烯酰胺)(PNIPAM)包覆在单分散性良好的Au@Ag双金属纳米棒(Au@AgNR)表面,制得以Au@AgNR为核、交联PNIPAM为壳层的Au@AgNR@PNIPAM复合微凝胶。用透射电镜观察到复合微凝胶具有规整的核壳结构,动态激光光散射测试结果证实复合微凝胶存在热响应性。当环境温度从20℃升高到50℃,复合微凝胶中Au@AgNR的纵向局域表面等离子体共振波长从695nm红移到719nm,表明复合微凝胶内的Au@AgNRs的LSPR光学性能可利用温度来进行调节。以该复合微凝胶为SERS分析的基底,检测水溶液中痕量的难以吸附在金属粒子表面的1-萘酚(3×10-5M),结果发现复合微凝胶在发生体积相转变时对1-萘酚具有捕捉效应,因此可通过调节测试温度来达到提高待分析物的SERS的信号强度的目的。

The composite microgels based on Au@Ag bimetallic nanorod（Au@AgNR） as core and crosslinked poly（N-isopropylacrylamide）（PNIPAM） as shell（Au@AgNR @ PNIPAM composite microgels） were prepared by seed precipitation.The core-shell structure of the composite microgels was visualized by electron transmission microscopy,and their thermo-responsive property was identified by measuring their temperature dependent particle size using dynamic light scattering technique.As environmental temperature was raised from 20 to 50℃,the longitudinal localized surface plasmon resonance wavelength of Au@AgNR within the composite microgels measured by temperature variable ultraviolet visible near-infrared spectroscopy was red-shifted from 695 to 719 nm,indicating that their plasmonic property is temperature-tunable.When the composite microgels are used as SERS substrates for detection of 3×10-5M 1-naphthol in aqueous solution,it found that the composite microgels has entrappment effect for the analyte during their temperature triggered volume phase transition,and the SERS signal strength can be greatly enhanced as the temperature tuned.