A Whole-cell Extended Gate Field Effect Transistor-Based Immunosensor for Rapid and Sensitive Detection of E. coli

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Abstract
A whole bacterial cell immunosensing method based on extended-gate field-effect transistor (EGFET) is presented for the first time in this report. Herein, a commercial n-type MOSFET is modified into an EGFET by extending the gate to the biosensing layer via a simple signal line. As a biosensing layer, a gold electrode functionalized with antibodies is fabricated to confer specificity to Escherichia coli (E. coli). The transistor’s transfer and output characteristics I-V curves were acquired with a commercial parameter analyzer, and the sensor response is characterized by observing how the channel current counters to different concentrations of bacteria bound to the biosensing layer. The EGFET immunosensor demonstrates the detection limit of ≤1.5 CFU mL-1, linearity (R² > 0.98) within the range of concentrations from 1.5×101 to 1.5×10⁸ CFU mL-1. The specificity is confirmed with two non-target bacteria species (Klebsiella aerogenes and Bacillus subtilis). The developed whole-cell, label-free immunosensor has the potential to be adapted as a point-of-care diagnostic device as a practical, low-cost alternative to conventional laboratory-bound methods.
Funding Information
  • Antares horizon 2020 (739570)
  • MSCA Rise Horizon 2020 (872662)
  • Horizon Europe Know4Nano (101159710)
  • Technological Development, and Innovations of the Republic of Serbia (451-03-33/2026-03/200358)
  • National Council for Scientific and Technological Development ? CNPq (446943/2024-0)

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