Online SERS Quantification of Staphylococcus aureus and the Application to Diagnostics in Human Fluids

Abstract

Staphylococcus aureus is a common cause of serious infections. One of the main drawbacks in its treatment is the time required for a positive diagnosis, over 24 h, as most methods are still based in bacterial culture. Herein, a microfluidic optical device for the rapid and ultrasensitive quantification of S. aureus in real human fluids is designed. In this approach, the surface‐enhanced Raman scattering (SERS)‐encoded particles, functionalized with either an antibody or an aptamer, form a dense collection of electromagnetic hot spots on the surface of S. aureus. This allows for an exponentially increase of the SERS signal when particles accumulate on the microorganism as compared to their free condition in bulk solution. Quantification is achieved by passing the sample through a microfluidic device with a collection window where a laser interrogates and classifies each of the induced bacteria–nanoparticle aggregates in real time. Further, the advantages of using aptamers versus antibodies as biorecognition elements are extensively investigated.

Enhancing Disease Diagnosis: Biomedical Applications of Surface-Enhanced Raman Scattering

“…The objective of using SERS is to obtain unique "whole-organism" metabolic fingerprints to discern intrinsic biochemical content and dynamics of microbial cells. The differential characteristic SERS frequencies of chemical bonds are used to identify, discriminate and define phenotypes of infectious microbes at species and strain levels in just a few minutes, as demonstrated previously [18,113]. Of the successful applications of SERS for microbial diagnostics, the report by Jarvis and Goodacre was the first to study urinary tract infection (UTI) [72].…”

Sensitive and Reproducible Immunoassay of Multiple Mycotoxins Using Surface‐Enhanced Raman Scattering Mapping on 3D Plasmonic Nanopillar Arrays

“…In the case of 2D plasmonic substrate, the final Raman intensity value was determined by averaging randomly selected multiple detection points (10–20) but this is not enough for determining a final value. Recently, Raman imaging technique through the fast mapping of all pixel points was developed for the reliable quantification of specific target molecules on a plasmonic substrate . Average ensemble effects by averaging all randomly distributed hot spots on the substrate made this SERS mapping technique possible to realize a reliable quantification of target molecules …”

Surface‐Enhanced Raman Scattering for Rapid Detection and Characterization of Antibiotic‐Resistant Bacteria

“…Catala et al explicitly compared the SERS performance of antibody and aptamer labeled AgNPs for the detection of S. aureus in a microfluidic device . Both biorecognition elements effectively increased the detection sensitivity.…”

“…b) TEM images of S. aureus after incubation with the aptamer‐modified (top row) and antibody‐modified (bottom row) AgNPs showing the faster kinetic response of the aptamer‐modified AgNPs. Reproduced with permission . Copyright 2016, Wiley.…”