title: Magnetically Assisted Surface-Enhanced Raman Spectroscopy for the Detection of Staphylococcus aureus Based on Aptamer Recognition.
abstract: 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.
authors: Beijing Institute of Radiation Medicine , Beijing 100850, PR China.|State Key Laboratory of Transducer Technology, Chinese Academy of Science , Shanghai 200050, PR China.
authors: Junfeng
authors: J
authors: Wang
authors: Xuezhong
authors: X
authors: Wu
authors: Beijing Institute of Radiation Medicine , Beijing 100850, PR China.|College of Life Sciences & Bio-Engineering, Beijing University of Technology , Beijing 100124, PR China.
authors: Chongwen
authors: C
authors: Wang
authors: Beijing Institute of Basic Medical Sciences , Beijing 100850, PR China.
authors: Ningsheng
authors: N
authors: Shao
authors: State Key Laboratory of Transducer Technology, Chinese Academy of Science , Shanghai 200050, PR China.
authors: Peitao
authors: P
authors: Dong
authors: Beijing Institute of Radiation Medicine , Beijing 100850, PR China.
authors: Rui
authors: R
authors: Xiao
authors: Beijing Institute of Radiation Medicine , Beijing 100850, PR China.
authors: Shengqi
authors: S
authors: Wang
mesh_terms: D052157:Aptamers, Nucleotide / Q000737:chemistry*; D015374:Biosensing Techniques; D060328:Magnetic Phenomena; D058185:Magnetite Nanoparticles / Q000737:chemistry / Q000648:ultrastructure; D018613:Microscopy, Confocal; D043942:Nanotubes / Q000648:ultrastructure; D012834:Silver / Q000494:pharmacology; D013059:Spectrum Analysis, Raman / Q000379:methods*; D013211:Staphylococcus aureus / Q000187:drug effects / Q000302:isolation & purification*; D014961:X-Ray Diffraction
chemical_list: D052157:Aptamers, Nucleotide; D058185:Magnetite Nanoparticles; D012834:Silver
keywords: Ag-coated magnetic nanoparticles; Staphylococcus aureus; aptamer; single-cell detection; surface-enhanced Raman spectroscopy