Escherichia coli Enumeration in a Capillary-Driven Microfluidic Chip with SERS

Area of Science:

• Biosensing and Nanotechnology
• Food Safety and Microbiology
• Analytical Chemistry

Background:

• Pathogen detection in food is critical for public health.
• Traditional methods like plate counting are time-consuming (24-48 h).
• Low pathogen concentrations or limited sample volumes necessitate preconcentration steps.

Purpose of the Study:

• To develop a rapid and sensitive biosensor for pathogen detection in food matrices.
• To integrate immunomagnetic separation, preconcentration, and SERS detection.
• To establish an alternative to conventional pathogen detection methods.

Main Methods:

• Construction of a capillary-driven microfluidic chip with microchambers.
• Utilizing antibody-modified magnetic nanoparticles (MNPs) for capturing Escherichia coli (E. coli).
• Employing 4-aminothiophenol (4-ATP)-labelled gold nanorods (Au NRs) for SERS signal generation in a sandwich immunoassay format.

Main Results:

• The developed SERS-based biosensor detected E. coli in milk within 60 minutes.
• Achieved a detection range of 10^1-10^7 colony-forming units/mL for E. coli.
• Demonstrated high selectivity, with minimal signal interference from Salmonella enteritidis and Staphylococcus aureus.

Conclusions:

• The capillary-driven microfluidic SERS biosensor offers a rapid, sensitive, and selective method for E. coli detection in complex matrices like milk.
• This integrated approach overcomes limitations of traditional methods, enabling faster food safety assessments.
• The system shows promise for real-time pathogen monitoring in food products.