Surface-enhanced Raman spectroscopy for bacterial discrimination utilizing a scanning electron microscope with a...

Area of Science:

• Microbiology
• Spectroscopy
• Nanotechnology

Background:

• Surface-enhanced Raman scattering (SERS) with colloidal silver offers rapid bacterial identification.
• A key challenge in SERS analysis of bacteria is locating the substrate and biomass simultaneously for spectral acquisition.
• Existing methods struggle with targeted spectral collection from complex microbiological samples.

Purpose of the Study:

• To develop and demonstrate a Raman interface for scanning electron microscopy (SEM).
• To enable reproducible and targeted collection of bacterial SERS spectra.
• To overcome limitations in SERS analysis for microbiological samples.

Main Methods:

• Integration of a Raman spectroscopy system with a scanning electron microscope (SEM).
• Utilizing SEM secondary electron imaging to identify regions containing both silver nanoparticles and bacterial biomass.
• Acquisition of SERS spectra from targeted sample areas identified via SEM.

Main Results:

• The SEM-Raman interface successfully located regions with both SERS substrate (silver nanoparticles) and bacterial biomass.
• Targeted SERS spectra from bacteria exhibited rich vibrational bands, unlike non-targeted areas showing strong fluorescence.
• Replicate SERS spectra from two bacterial strains demonstrated high reproducibility, confirmed by principal components analysis.

Conclusions:

• The developed SEM-Raman interface facilitates precise and reproducible SERS spectral acquisition from bacteria.
• This technology enhances the reliability of SERS for bacterial identification and discrimination.
• The approach addresses a critical bottleneck in applying SERS to microbiological analysis.