Development of PEI-GA modified antibody based sensor for the detection of S. aureus in food samples

In this article, an amperometric immunosensor based on antibody immobilization onto the platinum (Pt) electrode surface by cross-linkage via glutaraldehyde (GA) pre-coated with polyethyleneimine (PEI) layer for the detection of Staphylococcus aureus (S. aureus) in food samples has been developed. Immobilization of antibodies on the sensor surfaces lead to a change in response for control (absence of test bacteria) and samples (presence of test bacteria). The changes were quantified by the increase in amperometric response. Response of the sensors to increasing concentrations (101–108 CFU/ml) of pure culture of S. aureus NCIM 2602 as well as S. aureus inoculated food samples (milk, cheese and meat) was studied and for all the samples similar response pattern was observed. The amperometric response obtained between the increasing concentrations of test bacteria and current output showed good linearity, achieving detection limit down to 10 CFU/ml. Further Scanning Electron Microscopy studies justified the response obtained for amperometric measurements.