Rapid detection of single E. coli bacteria using a graphene-based field-effect transistor device.

Area of Science:

• Materials Science
• Biosensors
• Environmental Science

Background:

• Escherichia coli (E. coli) contamination in water causes widespread water-borne diseases.
• Current pathogen detection methods face challenges in speed, cost, and practicality for real-time monitoring.
• There is a critical need for sensitive and efficient tools to detect E. coli in water sources.

Purpose of the Study:

• To develop a highly sensitive and rapid biosensor for real-time E. coli detection.
• To fabricate a field-effect transistor (FET) based on thermally reduced graphene oxide (rGO) for pathogen sensing.
• To demonstrate the sensor's efficacy in detecting E. coli in environmental water samples.

Main Methods:

• Fabrication of a thermally reduced graphene oxide (rGO) field-effect transistor (FET).
• Passivation of the rGO FET with an ultrathin aluminum oxide (Al2O3) layer.
• Immobilization of E. coli specific antibodies on gold nanoparticles for selective capture.
• Real-time monitoring of E. coli concentration via charge carrier modulation in the rGO monolayer.

Main Results:

• The rGO FET sensor detected single E. coli cells within 50 seconds in a 1 µL sample.
• Achieved a low detection limit of single cell with a linear range of 1-100 CFU/µL (10^3 to 10^5 CFU/mL).
• Demonstrated successful E. coli sensing in river water with good selectivity and rapid detection.

Conclusions:

• The developed rGO FET biosensor offers a low-cost, label-free, and mass-producible platform for pathogen detection.
• This technology enables rapid and sensitive real-time monitoring of E. coli in water.
• The sensor shows potential for detecting a broad spectrum of pathogens in various liquid media.