Development of a Modified Graphene Oxide-Alginate Electrochemical Impedance Aptasensor for Rapid E. Coli Detection Publisher



Fatemi K ; Lau SY ; Fatemi R ; Sadeghi K ; Obayomi KS ; Coorey R ; Chung LY
Source: Microchemical Journal Published:2026

Abstract

The study presents a sensitive and rapid electrochemical impedance aptamer-based biosensor (aptasensor) was developed for detecting Escherichia coli (E. coli) ATCC 25922, a model that offers diagnostic tools using a modified graphene oxide (MGO)–alginate composite platform. Electrochemical aptasensors employ ssDNA aptamers as selective bioreceptors, offering a promising alternative to conventional bacterial detection methods. Because of the high surface area of MGO and alginate biocompatibility, the combination as a composite sensing platform improves immobilization stability and signal amplification, hence boosting biosensor performance. The MGO–alginate-based aptasensor exhibited a concentration-dependent decrease in charge-transfer resistance upon E. coli binding, as measured by electrochemical impedance spectroscopy (EIS). Under optimized conditions (50 nM aptamer, 2 mg/mL modified GO, 30 min incubation at 37 °C), the sensor detected E. coli over a wide range from 102 to 108 CFU/mL (p < 0.05, n = 3). MGO-alginate-based aptasensor has shown remarkable sensitivity in identifying E. coli, with charge transfer resistance dropping when bacteria attach to the immobilized aptamers. The biocompatible alginate enhances sensitivity and provides structural stability, making it suitable for real-world bacterial detection applications requiring strong stability, quick response, and high sensitivity. © 2026