中文摘要：

以具有核壳结构的Au@SiO2纳米颗粒为基底,建立了一种以表面增强拉曼（SERS）原位、快速检测食品中非法添加剂酸性橙Ⅱ的新方法.研究了活性硅加入量对所形成的Au@SiO2纳米颗粒的SERS活性的影响,制备了具有最佳SERS活性的Au@SiO2,并以此为SERS基底建立了酸性橙Ⅱ的分析方法,可实现0.17 mg/L酸性橙Ⅱ的SERS检测.将合成的Au@SiO2滴加到瓜子表面后,可以实现对瓜子表面酸性橙Ⅱ浓度为0.01 mg/g时的SERS检测,能够满足食品中酸性橙Ⅱ的测定要求,有望用于瓜子及其它可能被非法添加该物质的食品的现场、快速检测.

英文摘要：

As a strong carcinogen to humans,acid orange Ⅱ is forbidden to be added as an additive into foodstuff.Because the foods colored with acid orange Ⅱ showed stable and colorful appearance,acid orange Ⅱ is broadly utilized by illegally producers for their low costing.Currently available analytical methods for acid orange Ⅱ are mainly based on fluorescence and liquid chromatography,which are time-consuming and tedious as acid orange Ⅱ has to be extracted from the samples before determination.For efficient detection and insurance of food safety,it is urgent to develop fast and low-cost in situ assay methods for field detection of acid orange Ⅱ on foods.In this study,shell-isolated Au@SiO2 nanoparticles is prepared for detecting acid orange Ⅱ on food.Gold colloidal solution with good size distribution（50 nm） is prepared using the standard sodium citrate reduction method,followed by coating a thin layer of SiO2on Au nanoparticle surface.This shell-isolated Au@SiO2 is obtained by the addition of active silica to the gold colloidal solution,with the（3-aminopropyl）trimethoxysilane（APTMS） as the coupling agent at pH 8.5.By regulating the amount of the active silica,the Au@SiO2 with different silica shell thickness is synthesized.Ultraviolet-visible spectroscopy（UV-Vis） and transmission electron microscope（TEM） are employed to characterize the optical property and morphology of the as-synthesized Au@SiO2 nanoparticles.The amount of the active silica added in preparation of the Au@SiO2is optimized through comparing the surface enhanced Raman scattering（SERS） intensity of acid orange Ⅱ,using the synthetic Au@SiO2 structure as the SERS substrate.Under the optimized experimental conditions,acid orange Ⅱ on the Si wafer can be detected at concentrations below 0.17 mg/L.The feasibility of the proposed method for detecting acid orange Ⅱ in real samples is verified by spreading the Au@SiO2 nanoparticles on the surface of the watermelon seeds stained with acid orange Ⅱ.Results showed that