A Portable QCM-Based Biosensor-Incorporated Graphene Oxide for Point-of-Care Prostate Cancer Marker Detection

Prostate cancer remains one of the most prevalent malignancies among men worldwide, with late-stage diagnosis contributing significantly to mortality rates. In this study, we report the development of a graphene oxide (GO)-based QCM biosensor for the early and sensitive detection of Prostate Cancer Antigen 3 (PCA3), a biomarker with higher specificity than conventional PSA tests. The sensor interface was fabricated via a layer-by-layer approach of L-cysteine, GO, and a capture probe onto a gold electrode, resulting in enhanced surface area and biomolecular recognition capacity. Structural and morphological characterizations using XRD, FE-SEM, AFM, and FT-IR confirmed the successful and uniform integration of GO and functional layers. Optimization of fabrication parameters, including EDC-NHS activation time, capture probe concentration, and target incubation time, was performed to achieve maximum sensitivity and binding efficiency. The biosensor demonstrated a distinct, concentration-dependent frequency shift upon hybridization with PCA3 targets over a range of 1.00 fM to 1.00 μM, with a calculated limit of detection (LOD) of 0.268 nM and a rapid response time of 20 min. These results underscore the potential of GO-modified QCM platforms for highly sensitive, rapid, and portable diagnostics, not only for prostate cancer screening but also for broader clinical applications involving biomarkers.