Microcavity Array-Based Digital SERS Chip for Rapid and Accurate Label-free Quantitative Detection of Live Bacteria

Area of Science:

• Analytical Chemistry
• Biotechnology
• Materials Science

Background:

• Traditional bacterial detection methods can be time-consuming and lack precision.
• Surface-enhanced Raman spectroscopy (SERS) offers high sensitivity but faces challenges with signal fluctuations in analog detection.

Purpose of the Study:

• To develop a novel digital SERS chip for rapid, accurate, and label-free bacterial quantification.
• To leverage microcavity arrays and gold nanoparticle substrates for enhanced SERS detection.

Main Methods:

• Integration of an inverted pyramid microcavity array, microchannel cover plate, and multilayer gold nanoparticle (AuNP) SERS substrate.
• Digital discretization of bacterial suspensions within picoliter cavities for SERS analysis.
• Label-free, in situ SERS testing for precise identification and quantification using Poisson statistics.

Main Results:

• Accurate quantification of *Escherichia coli* (E. coli) BL21 within a 4-hour incubation period.
• Demonstrated improved detection efficiency and accuracy compared to analog SERS methods by reducing signal intensity fluctuations.
• Successful identification of live bacteria via in situ SERS testing.

Conclusions:

• The developed digital SERS chip enables efficient and accurate bacterial detection.
• This technology shows significant potential for applications in bacterial detection, antibiotic resistance analysis, and cellular dynamics monitoring.
• The digital SERS approach overcomes limitations of analog methods, paving the way for advanced biosensing.