Label-free impedimetric immunosensing of pathogenic <i>E. coli O157:H7</i> using amine functionalized carbon

Pathogenic <i>E. coli O157:H7</i> remains a major global concern due to its role in foodborne illnesses, highlighting the need for more efficient detection methods. Conventional approaches to detecting bacteria samples are time-intensive and laborious. To address these issues, here we propose an impedimetric immunosensor for rapid and early detection of <i>E. coli O157:H7</i> using an amino-functionalised graphite powder synthesised through a simple wet chemical functionalisation process. The synthesised amino-functionalised carbon was analytically characterized using various characterization techniques to confirm the surface functionalisation and its morphology. The developed biosensor demonstrated a theoretical detection limit (LOD) of 1.36 ± 0.16 CFU/mL across a concentration range of 1.5 CFU/mL to 1.5 × 10⁶ CFU/mL. Notably, the biosensor exhibited excellent selectivity toward <i>E. coli O157:H7</i> in the presence of interfering species and has a sensitivity of 4.43 ± 0.52 ((Δ<i>Ω</i>/<i>Ω</i>)/(CFU/mL))/cm². This developed sensor offers an effective pathway for the early diagnosis of <i>E. coli</i> to prevent foodborne outbreaks.