An electrochemical immunosensor for the prostate specific antigen based on the use of reduced graphene oxide decorated with gold nanoparticles

The authors describe an immunosensor for the prostate specific antigen (PSA). It was obtained by modifying a glassy carbon electrode (GCE) first modified with gold nanoparticles and then with reduced graphene oxide that was decorated with gold nanoparticles. The AuNPs on reduced graphene oxide provide a suitable surface for attachment of antibodies. On binding of the antigen, the square wave voltammetric signal (measured by using hexacyanoferrate as a probe) reduced. This method has two logarithmically linear analytical ranges that extend from 25 to 55 fg.mL(-1) and from 1 to 36 ng.mL(-1), respectively. The lowest detection limit is 2 pg.mL(-1). Electrochemical impedance spectroscopy was also carried out for PSA determination. EIS works in the 0.0018 to 41 ng.mL(-1) concentration range and has an LOD of 60 pg.mL(-1). This method was applied to the determination of PSA in (spiked) human serum samples. In order to survey the selectivity of immunosensor, determination of PSA was performed in human serum samples, and finally sensitivity and reproducibility were examined.