Au@SiO_2核壳纳米粒子的制备及其表面增强拉曼光谱

Preparation of Au@SiO_2 Core-shell Nanoparticles and Their Surface-Enhanced Raman Spectra

采用柠檬酸钠还原氯金酸法制备金溶胶,以正硅酸乙酯(TEOS)为硅源,氨水作催化剂,制备以金为核,二氧化硅为壳的核壳纳米粒子.金纳米粒子的粒径可以通过柠檬酸钠和氯金酸的比例控制,通过调节TEOS的量和反应的时间可以控制二氧化硅壳层的厚度.以苯硫酚为探针分子研究了核壳结构纳米粒子的表面增强拉曼散射(SERS)效应与二氧化硅壳层厚度之间的关系.研究结果表明,金内核电磁场增强效应随着二氧化硅壳层厚度的增加逐渐减弱,且其衰减速度比具有相同尺度的双金属核壳结构纳米粒子的慢.此外,探针分子主要以物理作用吸附在二氧化硅的表面,可通过洗涤方法将探针分子除去,从而可使该复合结构基底用于循环SERS分析.

Gold nanoparticles were prepared with chemical reduction method and the size was controlled via adjusting the molar ratio of citric acid to chloroauric acid. By measuring the TEOS and ammonia, the layer of SiO2 was attached onto gold nanoparticles with different thicknesses to produce Au@SiO2 core-shell nanoparticles. The relationship between the intensities of surface enhanced Raman spectroscopic （SERS） bands and the thickness of SiO2 was determined by employing thiophenol as the probe molecule. The results indicate that the electromagnetic enhancement（EM） was damped with the increase in the thickness of SiO2, and the damping effect was weaker that the dual-metal core-shell structure with the same size as the Au@SiO2. Moreover, the probe molecule was adsorbed onto the Au@SiO2 surface with physical interaction, and the probe was removed through the appropriate solvent for the cycle-SERS detection.