Ultrahighly sensitive sandwich-type electrochemical immunosensor for selective detection of prostate specific antigen based on functionalized bimetallic Au-Ag nanoclusters as label for signal amplification

The present research aimed to construct an ultrahighly sensitive sandwich-style electrochemical immunosensor to quantitatively evaluate prostate-specific antigen (PSA) by amperometric (i-t) measurements. Initially, gold nanoparticles were placed on reduced graphene oxide (AuNPs/rGO), serving as a sensing platform for anchoring the primary antibodies (Ab1) and enhancing electron transfer on the pencil graphite electrode (PGE) surface. AuAg nanoclusters, featuring an extensive surface area and superior biocompatibility, were subsequently applied as labels for the secondary antibody (Ab2) targeting PSA. The exceptional electrocatalytic activity of Au-Ag nanoclusters in reducing hydrogen peroxide significantly enhances the sensitivity of the sensor. The morphological and structural characteristics of the Au-Ag bimetallic nanoclusters were assessed through a range of analytical methodologies comprising Transmission electron microscopy (TEM), energy dispersive X-ray analysis (EDX), Fourier transform infrared (FTIR), and Fluorescence spectroscopy. The fabricated immunosensor demonstrated a linear response to PSA concentrations within the range of 0.1 to 1.0 x 107 pg/mL, achieving an impressively low detection limit of 30.0 fg/mL and a limit of quantification of 100.0 fg/mL, while maintaining high stability. The proposed immunosensor enabled the precise and ultrasensitive detection of PSA concentrations in serum samples, demonstrating results that correspond closely to those obtained through the benchmark enzyme-linked immunosorbent assay (ELISA). In conclusion, these results underscore the potential utility of the developed immunosensor for prostate cancer screening in its preliminary phase.