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Study on Electrochemical Immunoassay methodology for Protein A: A modified approach towards detection and quantification of Staphylococcus aureus in food samples

Author Affiliations

  • 1Department of Food Technology and Biochemical Engineering Jadavpur University, Kolkata-700032, INDIA

Res.J.chem.sci., Volume 2, Issue (8), Pages 62-68, August,18 (2012)


In the present work, an amperometric electrochemical detection and quantification of Staphylococcus aureus (S.aureus) present in food samples have been done. The method was based on sandwich enzyme immunoassay (EIA) technique where the enzyme label was used to catalyze the dephosphorylation of substrate NADP+ to NAD+. NAD+ so formed then catalytically activates an NAD+-specific redox cycle by incorporating an enzyme amplification step with ethanol, diaphorase and alcohol dehydrogenase. The NADH so formed further reduces the mediator, ferricyanide which induces a redox cycle at Platinum (Pt) electrode. The response obtained had a linear relationship to the increasing concentration of the protein antigen of S.aureus NCIM 2602 in pure culture as well as in artificially contaminated food samples. The study was also extended for naturally contaminated milk samples and S.aureus contamination for this case gave similar result as of the known strain. The detection limit was found to be 10 CFU/ml of S.aureus.


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