Carbon dots and graphene oxide based FRET immunosensor for sensitive detection of Helicobacter pylori

We report a novel Fluorescence Resonance Energy Transfer (FRET) immunosensor for sensitive detection of whole cell H. pylori, a causative organism for gastric carcinoma. Highly fluorescent and well-dispersed functionalized carbon dots (FCDs) were synthesized and chemically conjugated with anti-H. pylori antibody to fabricate a fluorescent probe (FCDs-Ab). The fluorescence of FCDs-Ab gets quenched upon interaction with graphene oxide (GO), whereas in presence of H. pylori, the interaction between the FCD-Ab and GO gets interrupted and gradual restoration of fluorescence was observed due to the specific affinity and binding of Ab towards H. pylori. The immunosensor was characterized at each step of fabrication. The assay exhibits a linear detection range of 5-10⁷ cells mL^-1 with limit of detection (LOD) of 10 cells mL^-1 with high specificity and selectivity to target pathogen. The analytical performance of the developed immunosensor was evaluated with different spiked food samples and the substantial recovery validates its potential for risk assessment in food testing, thus ensuring general safety of public health.