A highly sensitive detection platform based on surface-enhanced Raman scattering for Escherichia coli enumeration

Area of Science:

• Nanotechnology
• Analytical Chemistry
• Biotechnology

Background:

• Pathogen detection is crucial for public health and environmental monitoring.
• Existing methods for bacterial detection can be time-consuming or lack sensitivity.
• Development of rapid, sensitive, and specific diagnostic tools is essential.

Purpose of the Study:

• To develop a highly sensitive and specific heterogeneous immunoassay for detecting bacteria.
• To utilize surface-enhanced Raman scattering (SERS) with gold nanoparticles for pathogen detection.
• To evaluate the performance of different gold nanoparticle types for Escherichia coli detection.

Main Methods:

• Fabrication of Raman labels using gold nanospheres and gold nanorods coated with DTNB and a molecular recognizer.
• Application of a sandwich immunoassay format for bacterial detection.
• Analysis of SERS signal intensity for quantification of E. coli concentration.

Main Results:

• A linear calibration curve was obtained for E. coli concentrations ranging from 10(1) to 10(5) CFU/mL.
• Gold nanorod-based Raman labels exhibited over three times higher sensitivity than spherical gold nanoparticles.
• The immunoassay demonstrated high selectivity, with no significant response to other bacterial species.
• Successful detection of E. coli in real water samples was achieved.

Conclusions:

• The developed SERS-based immunoassay is a sensitive, specific, and rapid method for E. coli detection.
• Gold nanorods offer enhanced sensitivity compared to gold nanospheres for this application.
• The assay shows potential for practical application in water quality monitoring and food safety.