Ultrasensitive aptamer-based electrochemical nanobiosensor in diagnosis of prostate cancer using 2D:2D reduced graphene oxide/graphitic carbon nitride decorated with Au nanoparticles

Prostate-specific antigen (PSA) remains the cornerstone for prostate cancer diagnosis. This study presents a highly sensitive aptamer-based electrochemical biosensor for PSA detection utilizing a novel two-dimensional (2D):2D reduced graphene oxide (rGO)/graphitic carbon nitride (g-C3N4) composite decorated with gold nanoparticles (Au NPs). The aptamer chains were immobilized on a glassy carbon electrode (GCE) modified with the rGO/g-C3N4/Au NPs composite. The successful synthesis of the nanomaterial and electrode modification were confirmed using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and transmission electron microscopy (TEM). The electrochemical properties and selectivity of the modified GCE were characterized by cyclic voltammetry (CV), square wave voltammetry (SQW), and electrochemical impedance spectroscopy (EIS). The biosensor exhibited high selectivity towards PSA compared to potential interferents like carbohydrate antigen 15-3 (CA 15-3), bovine serum albumin (BSA), fetal bovine serum (FBS), and glucose (C6H12O6). Under optimized conditions, the biosensor achieved a rapid detection time of 30 min for PSA and a remarkable limit of detection (LOD) of 0.44 fM (femtomolar) using methylene blue (MB) as the redox mediator. The limit of quantification (LOQ) was also exceptionally low at 2.5 fM. The applicability of the developed biosensor was further validated by analyzing real serum samples, demonstrating its potential for clinical use.