Surface-enhanced Raman scattering-based label-free microarray readout for the detection of microorganisms

Area of Science:

• Biotechnology
• Analytical Chemistry
• Microbiology

Background:

• Label-free detection methods are crucial for sensitive and specific biological analyses.
• Surface-enhanced Raman scattering (SERS) offers high sensitivity for molecular detection.
• Current SERS techniques for microorganisms often require sample dehydration, limiting in situ analysis.

Purpose of the Study:

• To develop an optimized SERS substrate for label-free microarray readout.
• To enable in situ, label-free detection and quantification of microorganisms using Raman microscopy.
• To facilitate the chemical characterization of microorganisms through their unique SERS spectra.

Main Methods:

• Development and optimization of chemically synthesized nanoparticles for SERS substrates.
• Application of SERS in an immunoassay for label-free detection of single microorganisms.
• Utilizing Raman mapping for quantitative analysis of immobilized bacteria.
• Performing in situ analysis of microorganisms in an aqueous environment.

Main Results:

• Species-specific, reproducible, and strong SERS spectra were obtained from various bacteria.
• Successful label-free detection and quantification of microorganisms in situ.
• Demonstrated nondestructive analysis of living bacterial cells.
• Established the potential of "whole-organism fingerprint" SERS spectra for chemical characterization.

Conclusions:

• The developed SERS technique provides a powerful tool for label-free, in situ analysis of microorganisms.
• This method overcomes the limitations of dehydration requirements in conventional SERS bacterial detection.
• The approach enables sensitive detection, quantification, and chemical profiling of living bacteria.