Investigation of immunosensor modification with reduced Graphene Oxide with Au Nanoparticles on glassy carbon electrode in Label-free for Escherichia coli detection

Escherichia coli is an indicator in the quality control of pharmaceutical and other samples. Reduced graphene oxide (rGO) as a kind of carbon compositions was immobilized on glassy carbon electrode (GCE). Chronoamperometric and reduction methods were used for Au NPs decoration and it completed with polyclonal E. coli antibody and 0.5 W/V% Bovine Serum Albumin solution. Morphology and structure of rGO and Au NPs were verified by SEM as well as the surface of bare glassy carbon electrode before and after modification. Square-Wave Voltammetry and Cyclic Voltammetry techniques were used for detection of E. coli in different samples which prepared in 0.1M PBS (pH 7.4) mixed with 0.5mM acetaminophen. In comparison with biosensor, classical method of detection performed with serial dilutions of E. coli ATCC 8739 (1×101–1×108 CFU/ml) which cultured on media. In spite of two methods of Au NPs immobilization, SEM pictures established that current deviation with Au was not applicable in GC/rGO/Au  NPs/Ab/BSA modification. Its modification had not significant change in currents and it wasnot a successful experiment for E. coli detection. In compare with plate method biosensor couldn’t use for detection.