Electrochemical sensor based on MWCNTs/ZnONPs for detection of prostate specific antigen.

An electrochemical immunosensor based on multiwalled carbon nanotube/zinc oxide nanoparticle (MWCNTs/ZnONPs) composites was fabricated for the sensitive and selective detection of prostate-specific antigen (PSA), an established biomarker for early prostate cancer diagnosis. The MWCNTs/ZnONPs-modified screen-printed carbon electrode (SPCE) provided an enlarged electroactive surface area and enhanced electron transfer kinetics, thereby improving the overall analytical performance. Monoclonal anti-PSA antibodies were covalently immobilized on the composite surface and PSA quantification was conducted using cyclic voltammetry (CV) and differential pulse voltammetry (DPV). Under optimized experimental conditions, the biosensor exhibited a linear response toward PSA concentrations ranging from 5 to 200 ng mL⁻¹, with a detection limit of 5 ng mL⁻¹ (R² = 0.979). The proposed platform demonstrated good sensitivity, specificity, and operational stability, whereas negligible interference was observed for potential coexisting species, such as glucose, bovine serum albumin (BSA), and ascorbic acid. Glucose showed minimal current variation because of its weak electroactivity under the selected conditions, while BSA produced only a slight signal increase, likely due to limited protein adsorption onto the electrode surface. In contrast, ascorbic acid generated a relatively higher current response owing to its intrinsic electrochemical activity; however, its electrochemical profile remained distinguishable from the PSA signal. The good anti-interference performance was attributed to the combined effect of the conductive MWCNTs/ZnONPs platform and the BSA blocking layer, which reduced non-specific adsorption while preserving efficient electron transfer. Because of its easy fabrication, cost-effectiveness, and reliable analytical performance, the MWCNT/ZnONP/SPCE immunosensor is promising as a portable point-of-care device for prostate cancer screening.