Sources of variability in SERS spectra of bacteria: comprehensive analysis of interactions between selected bacteria and plasmonic nanostructures

Abstract

The surface-enhanced Raman spectroscopy (SERS)-based analysis of bacteria suffers from the lack of a standard SERS detection protocol (type of substrates, excitation frequencies, and sampling methodologies) that could be employed throughout laboratories to produce repeatable and valuable spectral information. In this work, we have examined several factors influencing the spectrum and signal enhancement during SERS studies conducted on both Gram-negative and Gram-positive bacterial species: Escherichia coli and Bacillus subtilis , respectively. These factors can be grouped into those which are related to the structure and types of plasmonic systems used during SERS measurements and those that are associated with the culturing conditions, types of culture media, and method of biological sample preparation. Electronic supplementary material The online version of this article (10.1007/s00216-019-01609-4) contains supplementary material, which is available to authorized users.

In Search of Spectroscopic Signatures of Periodontitis: A SERS-Based Magnetomicrofluidic Sensor for Detection of Porphyromonas gingivalis and Aggregatibacter actinomycetemcomitans

“…gingivalis wild-type strains exhibit black pigmentation when grown on blood agar and pale white when cultured in a broth. The appearance of the black pigment is due to accumulation of heme on the cell surface. , This finding is crucial, as the presence of, e.g., artificial pigmentation of bacterial colonies due to the agar medium supplementation, usually affects the SERS spectra of bacteria …”

“…37,57 This finding is crucial, as the presence of, e.g., artificial pigmentation of bacterial colonies due to the agar medium supplementation, usually affects the SERS spectra of bacteria. 58 Comparison of SERS Spectra and PCA Results of P. gingivalis and Streptococcal Strains. Additionally, we compared the SERS spectra of strains belonging to P. gingivalis with those obtained for S. mitis 3705/04 and S. pseudopneumoniae 6178/12.…”

Electric Field Tunability of Photoluminescence from a Hybrid Peptide–Plasmonic Metal Microfabricated Chip

“…The detection of bacterial pathogens such as Pseudomonas fluorescens ( P. fluorescens ) is of significant interest both in life science and in environmental research, due to the fact that microbial contamination can result in significant health concern. 50 − 55 In this study, we have investigated the use of a microfabricated chip device in the detection of P. fluorescens and Pseudomonas putida ( P. putida ) strains ( Figure 4 c,d and Figures S20–S22 ). It can be clearly seen that using our microfabricated chip device with a voltage of 20 V results in an ∼11-fold increase ( P. fluorescens mCherry), 6-fold increase ( P. fluorescens wild type), and 10-fold increase ( P. putida GFP) in PEF intensity in comparison to 0 V. The ability of the template to improve PEF intensity from different types of bacteria in water offers potential as a tool for early-stage detection of bacteria in water.…”

Discrimination between Carbapenem-Resistant and Carbapenem-Sensitive Klebsiella pneumoniae Strains through Computational Analysis of Surface-Enhanced Raman Spectra: a Pilot Study

“…Currently, surface-enhanced Raman spectroscopy (SERS) has been extensively developed to overcome the weak Raman scattering effect, which uses metallic nanoparticles (gold, silver, and copper) to concentrate electromagnetic energy via surface plasmons ( 27 ), although the reproducibility and repeatability of SERS is also debatable ( 28 ). For example, Witkowska et al systematically compared the differences between RS and SERS in terms of bacterial detection, according to which SERS spectra had much better quality than the normal Raman spectra for both Escherichia coli and Bacillus subtilis ( 29 ). In addition, low reproducibility and repeatability are caused by several uncontrollable external factors during an experiment ( 30 ), which could be partially reduced through increased number of biological and technical repeats.…”