Discriminating Between Living and Dead Bacteria With a Field-Effect Transistor Based on Nano-Channels

Low-cost and easy-to-operate biosensors allow for bacteria detection for on-site and real-time applications. However, current biosensors cannot distinguish between living and dead bacteria, critical in determining the persistence of bacterial contamination. The Meta-Nano-Channel field-effect transistor (MNC FET) is employed. Its design allows the formation of numerous conducting nano-channels each coupled to the sensing area binding events with a different efficiency addressing the challenge of molecular localized gating. The MNC FET is biofunctionalized with a recognition layer composed of E. coli antibodies. Sensing is performed in 0.5 µL drops of Lysogeny Broth (ionic strength of 197 mM, protein-rich background of 200 mg/L), providing a complex food environment, and without either sample pre-processing or pre-measurement washing. Specific, label-free, quantitative, and real-time sensing is demonstrated with a limit-of-detection of a single-bacterium and with excellent linearity and sensitivity. Furthermore, the platform's capacity to distinguish living from dead bacteria is validated by comparing the MNC FET response to living E. coli against populations subjected to thermal denaturation, antibiotic treatment, or metabolic inhibition. The MNC FET distinguishes between living and dead E. coli bacteria with a limit-of-detection of a single-bacterium. This method paves the way for biosensors for the discrimination of bacterial viability.