<p> A highly sensitive immunochromatographic test strip has been developed based on upconversion nanoparticles (UCNPs) for the quantitative detection of prostate-specific antigen (PSA). UCNPs exhibit distinctive anti-Stokes luminescence properties, enabling near-infrared excitation with visible light emission, which significantly reduces background autoluminescence and enhances signal clarity. The fabricated test strip demonstrated excellent sensitivity, specificity, and reproducibility in PSA detection, offering a promising platform for rapid, point-of-care testing. This approach holds potential for improving prostate cancer screening and real-time disease management in clinical and resource-limited settings.</p> Graphical Abstract <p></p>