Surface‐enhanced Raman spectroscopy using uncoated gold nanoparticles for bacteria discrimination

Abstract

In this work, surface‐enhanced Raman spectroscopy (SERS) method based on uncoated spherical gold nanoparticles as SERS substrate was applied for the detection and discrimination of three different bacterial strains: Gram‐positive Bacillus subtilis and Lactobacillus rhamnosus GG and Gram‐negative Escherichia coli. The exploitation of bacteria SERS spectra by multivariate data analysis (principal component analysis and partial least squares – discriminant analysis) proved the robustness of the developed method and its suitability to discriminate between the three different strains despite their relatively similar Raman signals. The SERS performance of the developed method was compared with that of the classical silver nanoparticles indicating a better bacteria signal enhancement, up to 15 times higher in case of E. coli, likely due to stronger interactions of gold nanoparticles with components such as purine molecules that show dominant bands in the bacterial SERS spectra.

The Golden Age: Shining the Light on Theragnostics

“…[ 13,14 ] As such, AuNP‐based SPR biosensors have been widely used to detect biomolecules for clinical diagnoses. [ 15,16 ] Provided we have the vibrational signatures of the Raman reporters, detailed spectroscopic information can be translated into imaging signals. Thus, Raman spectroscopy has recently emerged as a desirable modality for in vivo imaging (Raman imaging) with high sensitivity and molecular structure selectivity.…”

Raman Scattering Techniques for Defense and Security Applications

“…PCA is perhaps the most common chemometric technique used in chemical and biological hazard detection, with numerous studies having investigated its utility in threat agent identification, including chemical, , protein, ,, bacterial, ,,,− ,, and viral threats. , In their multiplex CARS study on CWAs, Brady et al subjected their CARS spectra of four common simulants to PCA. Plotting the first three principal components graphically revealed clear separation of the molecules, allowing easy identification of unknowns when compared to the results of a training set .…”

“…111−114 Though conventional RS is a very weak technique, it is possible to obtain whole-organism spectra from single spores or cells. 80,102,115,116 For applications where speed of acquisition may be required, the signal enhancement from SERS offers the possibility of reduced detection times and has also been shown to yield good signals for single cells and spores. 102,116 In addition to decreasing acquisition times, SERS offers other advantages over spontaneous RS for biological samples.…”

“…80,102,115,116 For applications where speed of acquisition may be required, the signal enhancement from SERS offers the possibility of reduced detection times and has also been shown to yield good signals for single cells and spores. 102,116 In addition to decreasing acquisition times, SERS offers other advantages over spontaneous RS for biological samples. First, it avoids the innate fluorescence associated with biological samples by offering a fluorescence-quenching pathway.…”

Metal Nanoparticle–Microbe Interactions: Synthesis and Antimicrobial Effects

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