基于PS@Ag纳米探针和Si@Ag阵列基底的表面增强拉曼散射特性的肿瘤标志物免疫检测

Surface Enhanced Raman Scattering-based Tumor Immunoassay Using PS@Ag Nano-probes and Si@Ag Array Substrate

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1.75fg·mL^(-1))和宽的动态范围(2fg·mL^(-1)～200ng·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.