Smartphone-Powered Pdot Biosensors for Quantitative Phenylketonuria Screening at the Point of Care.

Current clinical management of hyperphenylalaninemia and phenylketonuria (PKU) lacks accessible, real-time diagnostic tools. To address this gap, a portable biosensing system integrating semiconducting polymer dot (Pdot) technology with miniaturized optics for rapid phenylalanine quantification is developed. The biosensor leverages phenylalanine dehydrogenase to enzymatically convert phenylalanine into NADH, enabling ratiometric fluorescence detection through electron transfer-mediated quenching of Pdots by NADH. This mechanism achieves exceptional sensitivity in human plasma, with a limit of detection (0.29 µm) surpassing conventional methods, alongside robust photostability. To ensure clinical practicality, the platform incorporates a 3D-printed, light-isolated housing and a compact optical module, enhancing field-deployable durability. A dedicated smartphone application facilitates real-time image capture and chromatic analysis, translating fluorescence signals into quantitative phenylalanine levels via a calibrated B/R ratio algorithm. Validation studies demonstrated linear correlation across the pathophysiological range (0-2400 µm), outperforming existing assays in accuracy and inter-device consistency. By merging biochemical specificity with engineered hardware, this innovation bridges laboratory-grade precision with point-of-care usability, providing a scalable solution for early diagnosis and personalized management of PKU and related metabolic disorders.