Development and characterization of a functionalized graphene oxide-based fluorescent aptasensor for point of care detection of foodborne E. coli

Herein, we report the development of a novel fluorometric aptasensor based on modified graphene oxide (MGO) conjugated with aptamer P12–31 via non-covalent π–π stacking for sensitive detection of E. coli ATCC 25922™ using Förster resonance energy transfer (FRET). MGO was created using a modified Hummers' technique and carboxylation. To verify successful functionalization, it was then thoroughly characterized using FTIR, TEM, SEM, Raman spectroscopy, and Thermogravimetric Analysis (TGA). When bacteria bind to the fluorescently labelled ssDNA aptamer, the aptasensor uses MGO's quenching capacity to recover the fluorescence. The assay showed a linear detection range of 10 5 –10 7 CFU/mL with acceptable sensitivity ( p < 0.05, n = 3) under ideal circumstances (aptamer 50 nM, MGO 2 mg/mL, and 30 min incubation at 37 °C). With potential uses in food safety monitoring, this platform provides quick and affordable real-time foodborne pathogen detection. Validation in intricate food matrices and enhancing selectivity against microbial contamination will be the main goals of future research.