磁性Fe_2O_3/Au/Ag复合纳米粒子的制备及其富集作用研究

Fabrication on Magnetic Fe_2O_3/Au/Ag Hybrid Nanostructures and Application for Magnetic Enrichment

利用种子生长法制备了磁性Fe2O3/Au/Ag复合纳米粒子,采用UV-vis和SEM对其光学性质以及表面结构的变化进行了表征.通过调节硝酸银的用量,制备了一系列具有不同Ag壳层厚度和表面结构的双金属外壳纳米粒子.以苯硫酚(TP)为探针分子,研究了不同Ag壳厚度的磁性纳米粒子的表面增强拉曼散射(SERS)活性.结果表明其SERS活性与表面结构的改变有关,在同时出现Ag和Au光学性质的Fe2O3/Au/Ag复合纳米粒子表面可观察到最强的SERS效应,这与表面的针孔效应以及Ag和Au之间的耦合增强作用有关.考察了Fe2O3/Au/Ag复合纳米粒子的磁富集作用,并利用SERS原位监测磁富集溶液中低浓度TP的能力,研究结果表明通过磁富集可提高SERS检测限,并且Fe2O3/Au/Ag的磁富集能力较Fe2O3/Au弱,但前者SERS信号较强.

A facile approach has been developed to synthesize multifunctional magnetic Fe2O3/Au/Ag hybrid nanoparticles.UV-vis and SEM were employed to characterize the optical properties and surface structures.By changing the amount of AgNO3,Fe2O3/Au/Ag hybrid nanoparticles with different Ag shell thicknesses and surface structures have been prepared.SERS activities of as-prepared nanoparticles with different Ag shell thicknesses were investigated by using thiophenol（TP） as probe.The results revealed that SERS activities were dependent on the changes in the surface structures.The maximum SERS effect was observed on the Fe2O3/Au/Ag hybrid nanoparticles which exhibited the optical absorbance of Ag and Au simultaneously.It might be associated with the pinhole effect and the coupling effect between Ag and Au.Moreover,the efficiency of the magnetic enrichment has been investigated by in-situ monitoring the changes in the SERS signal of the TP with low concentration.The results indicated that the limitation of SERS detection was increased by magnetic enrichment and the magnetic enrichment capacity of Fe2O3/Au/Ag was weaker than that of Fe2O3/Au,while the SERS signal of the former was stronger than the latter.