A Dual-Hue Recognizable Lateral Flow Immunoassay Corresponding to Distinct Sensitivity Ranges for Timely and Quantitative Diagnosis of Prostate Cancer

Early cancer screening is pivotal for reducing mortality yet remains constrained by the trade-off between analytical accuracy and operational simplicity. Here, we present a dual-hue recognizable lateral flow immunoassay (DHLFIA) that enables rapid, quantitative, and user-friendly detection of prostate cancer biomarkers. The platform integrates dual-ratiometric fluorescence transitions, establishing two hue recognition pathways (green-to-red and blue-to-red) with distinct sensitivities for the precise quantification of total (t-PSA) and free (f-PSA) prostate-specific antigens. The differentiated color responsiveness of the two ratio system, governed by the inner filter effect, was elucidated both theoretically and experimentally. This dual-hue strategy enables semiquantitative visual discrimination of the clinically significant "gray zone" (t-PSA: 4-10 ng/mL) by the naked eyes, while smartphone-based tonal analysis of the f-PSA/t-PSA ratio (cutoff = 0.16) allows accurate risk stratification within this range. Validated with clinical serum samples, the DHLFIA achieved a diagnostic accuracy of 96.7%, comparable to chemiluminescent assays, yet offered markedly improved speed and ease of operation. By coupling a modular design with dual-ratiometric readout principles, this work establishes a generalizable framework for multiplexed, point-of-care diagnostics of noncommunicable diseases.