Label-free amperometric biosensor for Escherichia coli O157:H7 detection

Foodborne pathogens pose a major threat of infectious life-threatening diseases all around the globe. Escherichia coli (E. coli) O157 is one such bacterial species that has caused several major outbreaks in the past. Advancement of a rapid sensing mechanism with high sensitivity is vital to avoid such epidemics by timely recognition of the infectious foodborne pathogens. The present work proposes the development of an amperometric biosensing platform for the detection of the pathogenic E. coli O157:H7. The developed biosensor works on the principle of antibody-antigen interactions, where the antibody is covalently bound to the surface of the nickel oxide thin film matrix prepared using sputtering technique. Accelerated charge transfer through NiO, an exceptional support provided to the antibody, and thus enhanced target capture efficiency leads to the direct detection of E. coli O157:H7 without the assistance of label. The electrochemical sensing results exhibit a wide linear range of 10(1) to 10(7) cells/mL and a low limit of detection of 10(0) i.e. 1 cell/mL along with high selectivity and specificity against other bacterial species.