基于Ag包覆聚苯乙烯球(PS@Ag)纳米探针和Ag覆盖硅金字塔结构(Si@Ag)阵列基底构建“三明治”免疫结构, 开展表面增强拉曼散射(SERS)特性研究, 实现了肝癌肿瘤标志物甲胎蛋白(AFP)的高灵敏、高特异性的检测.通过硝酸银原位还原生成PS@Ag纳米粒子, 再依次链接4-巯基苯甲酸(4-MBA)及甲胎蛋白抗体(Anti-AFP) 制备得到PS@Ag免疫探针.采用Langmiur-Bloggt膜技术、等离子体刻蚀和湿法刻蚀技术, 以PS球阵列为模版, 刻蚀大面积硅金字塔结构, 再依次沉积Ag膜和链接Anti-AFP制备得到免疫基底.结果表明, 基于“三明治”免疫结构的SERS检测方案具有高灵敏度(检测极限为1.75 fg·mL－1)和宽的动态范围(2 fg·mL－1~200 ng·mL－1).此外, 对临床人体血清样品进行SERS免疫检测, 得到了与化学免疫发光法一致的结果, 而且具有更高的灵敏度, 可应用于肝癌的早期检测与诊断.

A super-sensitive, high-specific immunoassay of tumor marker based on Surface Enhanced Raman Scattering (SERS) was developed with the sandwich-type immune structure consisted of Ag-covered polystyrene sphere (PS@Ag) probes and Ag-deposited Si pyramid array (Si@Ag) substrate. The PS@Ag immune probe was prepared by successively immobilizing 4-Mercaptobenzoic acid (4-MBA) and Anti-AFP antibodies on the surface of in-situ reduced PS@Ag nanoparticles. The Si pyramid array was fabricated using PS spheres as a template, combining with Langmiur-Bloggt method, reactive ion etching and wet chemical etching techniques. Then, Si @Ag immune substrate was prepared by successively depositing Ag film and immobilizing Anti-AFP antibodies on the surface of Si pyramid array. The results demonstrate that the constructed immunoassay platform exhibits high sensitivity with the limit of detection of 1.75 fg·mL－1 and wide linear range from 2 fg·mL－1 to 200 ng·mL－1. In addition, the detections of serum sample show the SERS-based platform is not only well-consistent with that of chemiluminescent immunoassay but also more sensitive, which could be potentially applied in the practical clinical diagnoses of cancer.