Plant-Derived Silver Nanoparticles from Sandoricum koetjape as a Platform for Rapid Electrochemical Prostate Cancer Biomarker Detection

The green synthesis of silver nanoparticles (AgNPs) offers an eco-friendly alternative to conventional chemical methods. In this study, santol ( Sandoricum koetjape ), including peels, leaves, and pulp were used as reducing and stabilizing agents for the synthesis of AgNPs (P-AgNPs, L-AgNPs, and Pu-AgNPs). The formation of AgNPs was confirmed by UV–Vis spectroscopy using surface plasmon resonance observed at 450 nm. Transmission electron microscopy (TEM) analysis showed that the AgNPs were spheroidal, and the particle size distribution was in the range of 65 nm (P-AgNPs), 50 nm (L-AgNPs), and 55 nm (Pu-AgNPs). X-ray diffraction (XRD) analysis indicated that the AgNPs had a face-centered cubic (FCC) structure. Furthermore, Fourier transform infrared spectroscopy (FTIR) analysis revealed the presence of functional groups associated with biomolecules involved in silver ion bioreduction. Electrochemical techniques, including cyclic voltammetry (CV) and differential pulse voltammetry (DPV), were used to evaluate the performance of the AgNP-based biosensor. The developed electrochemical biosensor demonstrated a high linear detection range for prostate-specific antigen (PSA) of up to 200 ng/mL, with a low detection limit of 10 ng/mL under optimized conditions. This study demonstrated that santol extracts can serve as effective bioreductants for AgNP synthesis. The resulting AgNP-based biosensor exhibited high sensitivity, simplicity, and cost-effectiveness, making it suitable for rapid PSA screening in biomedical applications.