A newly designed label-free immunosensor with reduced Graphene Oxide & Au Nanoparticles on glassy carbon electrode for Escherichia coli detection in real samples

BACKGROUND AND OBJECTIVESEscherichia coli is an indicator in the quality control of pharmaceutical and other samples.Current methods for E. coli detection are time consuming and expensive. Biosensr is one of instruments for bacterial rapid detection.MATERIALS AND METHODSIn this study, reduced graphene oxide (rGO) as carbon composition was immobilized on glassy carbon electrode (GCE). Chronoamperometric and reduction methods were used to decorate Au NPs and modification was completed with polyclonal E. coli antibody and ۰.۵ W/V% Bovine Serum Albumin solution. SEM was used to verify morphology and structure of rGO and Au NPs as well as the surface of bare glassy carbon electrode before and after modification. E. coli in different samples which prepared in ۰.۱M PBS (pH ۷.۴) and mixed with ۰.۵mM acetaminophen was investigated with Square-Wave Voltammetry and Cyclic Voltammetry techniques. In comparison with biosensor, classical detection method was performed with serial dilutions of E. coli ATCC ۸۷۳۹ (۱×۱۰۱–۱×۱۰۸ CFU/ml).RESULTS AND DISCUSSIONAlthough, two methods of Au NPs immobilization were used, SEM pictures established that current deviation with Au was not applicable in GC/rGO/Au NPs/Ab/BSA modification. Currents didn’t increase during electrode modification and it wasn’t a successful design for E. coli detection.CONCLUSIONIn 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 so it couldn’t compare with classic method.

کلیدواژه ها:

Reduced graphene oxide ، Biosensor ، E. coli ، Au NPs ، Immobilization