Rapid, Label-Free Detection of PSA Using Graphene-Based Resistive Sensor

Prostate Cancer (PCa) is the second leading malignancy in men worldwide. Early diagnosis of PCa is crucial for preventing metastasis and enabling timely treatment, significantly improving the survival rate. Prostate-specific antigen (PSA) is the most commonly used biomarker for diagnosing PCa, but assessing free PSA (fPSA) in conjunction with total PSA (tPSA) is expected to significantly enhance diagnostic accuracy. In this study, a simple, easy-to-operate, and cost-effective resistive biosensor based on graphene/gold nanoparticles (AuNPs)/monoclonal antibodies (mAb) has been developed for fPSA detection. The binding of mAbs to graphene/AuNPs was confirmed by Raman spectroscopy. Electron microscopies further validated the morphologies of graphene, graphene/AuNPs, graphene/AuNPs/mAb, and graphene/AuNPs/mAb/fPSA devices. The sensor demonstrated an impressive sensitivity toward PSA with its response ranging from 1.4 to 24.7% for 0.1–100 ng/mL fPSA. Notably, the graphene/AuNPs/mAb sensor exhibited high selectivity for fPSA when tested with CA125, SPINK-1, and fetal bovine serum (FBS). The developed sensors were evaluated with real-life serum samples, and the observations were cross validated with enzyme linked immunosorbent assay (ELISA) readings. Our findings suggest that this novel biosensor holds promise for early and accurate PCa diagnosis, potentially improving patient outcomes.