Aptamer-based SERS biosensor for whole cell analytical detection of E. coli O157:H7

Area of Science:

• Food Safety
• Biosensors
• Nanotechnology

Background:

• Foodborne pathogens like E. coli O157:H7 pose significant global food safety risks.
• Existing biosensor platforms often fail to transition from lab to market.
• Aptamers offer a promising alternative to antibodies for pathogen detection due to their stability and specificity.

Purpose of the Study:

• To develop and validate an aptamer-based Surface-Enhanced Raman Spectroscopy (SERS) biosensor for detecting E. coli O157:H7.
• To assess the sensitivity, specificity, and speed of the developed SERS method.
• To evaluate the feasibility of using aptamers conjugated to gold nanoparticles for pathogen detection in complex samples.

Main Methods:

• Conjugation of aptameric DNA sequences to 4-aminothiophenol-gold nanoparticle complexes.
• Detection of E. coli O157:H7 using Surface-Enhanced Raman Spectroscopy (SERS).
• Quantification and specificity testing in pure cultures and ground beef samples against various interfering microorganisms.

Main Results:

• Sensitive detection and quantification of low E. coli O157:H7 concentrations (down to ~10^1 CFU/mL in culture, ~10^2 CFU/mL in beef) within 20 minutes.
• A strong negative linear correlation (r^2 = 0.995) was observed between SERS intensity and E. coli O157:H7 concentration.
• High specificity was demonstrated against related bacteria species and serotypes, with no significant signal interference.

Conclusions:

• Aptamer-DNA-gold nanoparticle conjugates enable sensitive and specific detection of E. coli O157:H7 via SERS.
• The developed method shows potential for rapid, low-cost, and high-throughput food safety monitoring.
• This approach can be extended for multiplexed detection of various foodborne pathogens.