Mediator free highly sensitive polyaniline-gold hybrid nanocomposite based immunosensor for prostate-specific antigen (PSA) detection

Polyaniline nanowires (PANI) and gold nanoparticle (AuNPs) based hybrid nanocomposite film fabricated onto a Au substrate has been used to fabricate a mediator free immunosensor for the detection of PSA. Microscopic studies reveal uniform distribution of the AuNPs on the PANI backbone resulting in a nanoporous morphology that provides the desired microenvironment for antibody immobilization. The results of electrochemical studies suggest that AuNPs increase the electro-active surface area of PANI and result in high electron transport in a mediator free electrolyte. The AuNP-PANI hybrid nanocomposite also provides a very effective surface for the immobilization of anti-PSA revealing an increase in electron transport that results in improved sensing performance. The electrochemical response of the anti-PSA/AuNP-PANI/Au immunoelectrode as a function of PSA concentration exhibits a linear range of 1 pg mL(-1) to 100 ng mL(-1), a detection limit of 0.6 pg mL(-1) (lower than ELISA), a sensitivity of 1.4 mu A M-1 (higher than ELISA) along with a regression coefficient of 98.99%.