Prostate cancer is the most common cancer among men except for skin cancer, and the detection at early stages is crucial. In the present work, nanofabricated memristive biosensors are subjected to surface bio-modification targeting at prostate-specific antigen (PSA) IgM detection. The electrical response of the nanofabricated devices examined before and after the bio-modification achieves a label-free detection for three biomarker concentrations. The presence of biomolecules linked to the surface of the nanostructures is detected by a voltage gap appearing in the memristive electrical characteristics. Enzyme-linked immunosorbent assay methodology is further applied to verify the efficiency of the application of diverse biomarker concentrations on the surface. Scanning electron microscopy shows details on the morphology of the nanofabricated structures before and after the bio-modification, and confocal microscopy is implemented to obtain a 3D fluorescent signal distribution of the biomolecules. The system shows the potential for applications in molecular diagnostics and for implementation targeting at the early detection of the prostate cancer disease.