Synergistic Ag/Cu-TCPP MOFs-based plasmonic SERS platform for non-invasive and time-resolved monitoring of salivary uric acid.

Surface-enhanced Raman scattering (SERS) methods offer high sensitivity for uric acid (UA) detection, but efficient molecular enrichment and reliable analysis in complex biological matrices remain challenging. Here, we developed an Ag/Cu-TCPP SERS platform for noninvasive determination of UA in saliva. The platform combined the electromagnetic enhancement provided by Ag nanoparticles (Ag NPs) with the molecular enrichment capability of Cu-TCPP. Density functional theory calculations further indicated that UA can be enriched on Cu-TCPP through weak Cu···O quasi-coordination between the UA carbonyl oxygen and exposed Cu centers, accompanied by interfacial charge redistribution. Consequently, the platform achieved a low detection limit of 0.04 μM and a wide linear range of 0.1-1000 μM. Beyond conventional single-point determination, the platform enabled time-resolved assessment of salivary UA concentration, revealing temporal fluctuations under physiological and feeding-related conditions. These results highlight the potential of MOF-integrated SERS platforms for noninvasive monitoring of small-molecule biomarkers.