Aptasensor based on rGO-AuNPs Field-effect Transistor for selective detection of Escherichia coli in river water

Water and food-borne diseases are public health problems. It is estimated that only water-borne diseases cause 2.2 million deaths annually. E. coli is one of the most important bacteria in water monitoring and is on the WHO's list of priority pathogens for diagnosis and treatment. Conventional methods for detecting E. coli are not effective due to their time-consuming nature, the need for expensive equipment, and low sensitivity. Therefore, a rapid diagnostic method is essential for accurate detection of E. coli. Here, a Field-effect Transistor (FET) was used to detect E. coli based on rGO, AuNPs, and ssDNA-aptamer. After characterizing the rGO-AuNPs-Apt FET, the current of the nanobiosensor was measured with each modification. The nanobiosensor's linear range was (3-3 × 10⁶ CFU/ml), and LOD reached 3 CFU/ml in the PBS buffer. The nanobiosensor's response was completely selective and stable for up to 4 weeks. The rGO-AuNPs-Apt FET specifically detected E. coli in the river water down to 10 CFU/ml, even in a mixture of other bacteria at higher concentrations. The small sample size, ease of use, and accuracy of detection are the advantages of rGO-AuNPs-Apt FET, which can be used as a sensor for water monitoring in 15 min.