Plasmon-coupled microcavity aptasensors for visual and ultra-sensitive simultaneous detection of Staphylococcus aureus a
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RESEARCH PAPER
Plasmon-coupled microcavity aptasensors for visual and ultra-sensitive simultaneous detection of Staphylococcus aureus and Escherichia coli Milan Lei 1 & Chunxiang Xu 1 & Yaqi Shan 1 & Chuansheng Xia 1 & Ru Wang 1 & Huan-Huan Ran 1 & Fu-Gen Wu 1 & Ruipeng Chen 1 & Xiangwei Zhao 1 & Qiannan Cui 1 Received: 11 June 2020 / Revised: 31 August 2020 / Accepted: 4 September 2020 # Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract Septicemia and bacteremia are serious infections in the bloodstream. Thus, time-saving and ultra-sensitive pathogenic bacteria detection is highly required. Herein, we constructed gold nanoparticle-modified polystyrene microspheres (Au/PS) as plasmoncoupled microcavities to realize simultaneous detection of Staphylococcus aureus and Escherichia coli based on a fluorescence and surface-enhanced Raman spectroscopy (SERS) dual-mode method. Fluorescence imaging, serving as a means for assistant validation and rapid screening, was carried out to achieve qualitative and semi-quantitative determination, which gave us visual information of the existence and distribution of the target bacteria. Meanwhile, SERS test was conducted to realize ultra-sensitive quantitative detection. The evanescent wave aroused from total internal reflection in PS microcavities coupled with the localized electromagnetic field from surface plasmons of gold nanoparticles to improve light-matter interaction synergistically, leading to an enhancement factor of 2.25 × 1011 for SERS sensing. The whole measurement was carried out in a typical sandwich assay of “capture probe-target bacteria-signal probe.” As a result, calibrated concentration response curves demonstrated the sensitive quantitative detection with the limit of detection (LOD) of 3 cfu/mL for S. aureus and 2 cfu/mL for E. coli. This rapid, ultrasensitive, and visual sensing method was further developed for dual-bacteria detection in the whole blood samples. Keywords Ultra-sensitive . Plasmon-coupled microcavities . SERS . Pathogens . Dual-mode . Fluorescence
Introduction Septicemia and bacteremia resulted from bacterial infection in the bloodstream are complicated clinical diseases, which can give rise to endocarditis, meningitis, vascular leakage, and so on, especially septicemia, even can be life-threatening [1–3]. Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) are two common pathogenic bacteria that can result in septicemia and bacteremia. Both of them are able to enter and grow in the blood and the infection can develop from a serious site to another bringing about systemic inflammatory
* Chunxiang Xu [email protected] 1
State Key Laboratory of Bioelectronics, School of Biological Science and Medical Engineering, Southeast University, Nanjing 210096, Jiangsu, China
reaction [4]. In addition, there are many other severe infectious diseases which are caused by S. aureus and E. coli, such as diarrhea, pneumonia, pericarditis, urinary tract infections, and other diseases, and are closely related with global mortal
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