Label-free impedance-based aptasensor for Escherichia coli detection in real matrices

The development of a new, low-cost, and portable electrochemical biosensor for rapid and point-of-care detection of bacteria represents a significant advancement over conventional methodologies, offering a rapid diagnostic tool for managing infectious diseases. This innovation is particularly crucial in the study and application of novel bioreceptors like aptamers on electrode surfaces, a key step towards enhancing biosensor efficiency. Our research introduces the development of a label-free impedance-based electrochemical biosensor utilizing a new aptamer, to detect Escherichia coli (E. coli) in various matrices. The aptamer (P12-55) proved to effectively work as a biorecognition element, and the biosensor demonstrated the ability to detect various strains of E. coli with a limit of detection of 1.4 CFU/mL, with a linear range of detection between 100 and 104 CFU/mL in various matrices, within 20 min of sample exposure. Crucially, it demonstrates minimal to no cross-reactivity with other bacteria like Pseudomonas aeruginosa and Staphylococcus aureus, often present in the tested matrices. Additionally, successful testing was performed using real samples, including urine and tap water, showcasing its potential for broad application in public health and safety. Future research could implement the use of other aptamer variants and explore the detection of other bacterial strains and validate the biosensor’s performance in more complex matrices, such as blood or food samples.