A novel SERS method for detecting E. coli based on an aptamer-functionalized Au-Ag@Si triangular pyramid substrate.

Area of Science:

• Analytical Chemistry
• Biosensing
• Nanotechnology

Background:

• Escherichia coli (E. coli) contamination poses a significant risk in food and pharmaceuticals, necessitating stringent regulatory control.
• Current methods for E. coli detection often lack the required speed and sensitivity for effective monitoring.
• Developing rapid and sensitive detection techniques is crucial for ensuring public health and product safety.

Purpose of the Study:

• To develop a novel aptamer-based surface-enhanced Raman spectroscopy (SERS) sandwich method for the rapid and sensitive detection of E. coli.
• To utilize aptamer-functionalized gold-silver@silicon triangular pyramid (Au-Ag@Si TP) substrates for enhanced E. coli detection.
• To validate the method's efficacy in detecting E. coli in complex matrices like pharmaceutical preparations.

Main Methods:

• Fabrication of an aptamer-functionalized Au-Ag@Si TP substrate serving as both capture probe and SERS tag.
• Integration of a Raman reporter (6-carboxy-X-rhodamine) for signal amplification.
• Development of a sandwich assay format for selective E. coli capture and detection.

Main Results:

• The aptamer-functionalized Au-Ag@Si TP substrate was fabricated rapidly (20.5 hours).
• The developed method achieved selective and rapid E. coli detection with a limit of detection of 2.8 CFU/mL within approximately 3 hours.
• Successful application to Xinhuang tablets demonstrated high recovery rates (90.19%–104.17%), indicating robustness.

Conclusions:

• The aptamer-based SERS sandwich method offers a simple, rapid, and sensitive approach for E. coli detection.
• This technique shows significant potential as an alternative for on-site E. coli monitoring in pharmaceutical and food industries.
• The use of functionalized Au-Ag@Si TP substrates enhances detection capabilities for bacterial contaminants.