Wang Junfeng, Wu Xuezhong, Wang Chongwen, Shao Ningsheng, Dong Peitao, Xiao Rui, Wang Shengqi
Beijing Institute of Radiation Medicine , Beijing 100850, PR China.
State Key Laboratory of Transducer Technology, Chinese Academy of Science , Shanghai 200050, PR China.
ACS Appl Mater Interfaces. 2015 Sep 23;7(37):20919-29. doi: 10.1021/acsami.5b06446. Epub 2015 Sep 9.
A magnetically assisted surface-enhanced Raman scattering (SERS) biosensor for single-cell detection of S. aureus on the basis of aptamer recognition is reported for the first time. The biosensor consists of two basic elements including a SERS substrate (Ag-coated magnetic nanoparticles, AgMNPs) and a novel SERS tag (AuNR-DTNB@Ag-DTNB core-shell plasmonic NPs or DTNB-labeled inside-and-outside plasmonic NPs, DioPNPs). Uniform, monodisperse, and superparamagnetic AgMNPs with favorable SERS activity and magnetic responsiveness are synthesized by using polymer polyethylenimine. AgMNPs use magnetic enrichment instead of repeated centrifugation to prevent sample sedimentation. DioPNPs are designed and synthesized as a novel SERS tag. The Raman signal of DioPNPs is 10 times stronger than that of the commonly used SERS tag AuNR-DTNB because of the double-layer DTNB and the LSPR position adjustment to match the given laser excitation wavelength. Consequently, a strong SERS enhancement is achieved. Under the optimized aptamer density and linker length, capture by aptamer-modified AgMNPs can achieve favorable bacteria arrest (up to 75%). With the conventional Raman spectroscopy, the limit of detection (LOD) is 10 cells/mL for S. aureus detection, and a good linear relationship is also observed between the SERS intensity at Raman peak 1331 cm(-1) and the logarithm of bacteria concentrations ranging from 10(1) to 10(5) cells/mL. With the help of the newly developed SERS mapping technique, single-cell detection of S. aureus is easily achieved.
首次报道了一种基于适体识别的用于金黄色葡萄球菌单细胞检测的磁辅助表面增强拉曼散射（SERS）生物传感器。该生物传感器由两个基本元件组成，包括一个SERS基底（银包覆磁性纳米颗粒，AgMNPs）和一种新型SERS标签（金纳米棒 - 二硫代硝基苯甲酸@银 - 二硫代硝基苯甲酸核壳等离子体纳米颗粒或二硫代硝基苯甲酸标记的内外等离子体纳米颗粒，DioPNPs）。通过使用聚合物聚乙烯亚胺合成具有良好SERS活性和磁响应性的均匀、单分散且超顺磁性的AgMNPs。AgMNPs使用磁富集而非反复离心来防止样品沉淀。DioPNPs被设计并合成为一种新型SERS标签。由于双层二硫代硝基苯甲酸以及局域表面等离子体共振（LSPR）位置调整以匹配给定的激光激发波长，DioPNPs的拉曼信号比常用的SERS标签金纳米棒 - 二硫代硝基苯甲酸强10倍。因此，实现了强烈的SERS增强。在优化的适体密度和连接子长度下，经适体修饰的AgMNPs捕获可实现良好的细菌捕获率（高达75%）。使用传统拉曼光谱法，金黄色葡萄球菌检测的检测限（LOD）为10个细胞/mL，并且在拉曼峰1331 cm⁻¹处的SERS强度与10¹至10⁵个细胞/mL的细菌浓度对数之间也观察到良好的线性关系。借助新开发的SERS映射技术，很容易实现金黄色葡萄球菌的单细胞检测。
