Magnetically Assisted Surface-Enhanced Raman Spectroscopy for the Detection of Staphylococcus aureus Based on Aptamer Recognition

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• 作者：Junfeng Wang ; Xuezhong Wu ; Chongwen Wang ; Ningsheng Shao ; Peitao Dong ; Rui Xiao ; Shengqi Wang
• 刊名：ACS Applied Materials & Interfaces
• 出版年：2015
• 出版时间：September 23, 2015
• 年：2015
• 卷：7
• 期：37
• 页码：20919-20929
• 全文大小：551K
• ISSN：1944-8252

文摘

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鈥揇TNB@Ag鈥揇TNB core鈥搒hell 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鈥揇TNB 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^鈥? and the logarithm of bacteria concentrations ranging from 10¹ to 10⁵ cells/mL. With the help of the newly developed SERS mapping technique, single-cell detection of S. aureus is easily achieved.