A trinity sensing platform for uric acid detection in clinical samples using Fe-functionalized carbon quantum dot nanozymes

Designing and developing a simple and reliable method for detecting disease biomarkers is crucial for early disease prevention and diagnosis. Fe-functionalized carbon quantum dot (Fe-CQD), synthesized from natural dandelion biomass through a controlled process, were developed as nanozymes with outstanding peroxidase-like activity. Uricase decomposes uric acid to release hydrogen peroxide (H 2 O 2 ), which the Fe-CQD nanozymes catalyze to produce reactive oxygen species (ROS) such as singlet oxygen ( 1 O 2 ) and hydroxyl radicals (•OH). These ROS then oxidize the colorless substrate o -phenylenediamine (OPD) into yellow 2,3-diaminophenazine (DAP), enabling visual detection of uric acid. Building on this principle, we have developed, for the first time, a visual sensing platform using Fe-CQD nanozymes. This platform integrates absorption spectra, a microplate reader, and smartphone-assisted visible-light imaging to detect uric acid, achieving detection limits as low as 0.31, 0.36, and 0.83 μM, respectively. The platform demonstrated excellent accuracy in clinical blood sample analysis, yielding results highly consistent with standard hospital methods and the UA Assay Kit-based colorimetric method. It also exhibited robust anti-interference capabilities and practicality, making it a reliable tool for UA detection in real-world clinical settings. This innovative platform highlights the potential of nanozymes in biomarker detection and lays a theoretical foundation for integrating intelligent, portable sensing technologies into clinical diagnostics.