Analyte mediated transformation of metasurface: A dual-mode plasmonic sensing platform for uric acid

The concentration range of uric acid (UA) varies significantly across different biological fluids, and therefore, highly sensitive and wide-range detection of UA is of great importance for the early diagnosis of UA-related diseases. Surface-enhanced Raman spectroscopy (SERS) offers high sensitivity and molecular fingerprint specificity; however, challenges remain regarding its signal uniformity and detection range. In this work, a uniform and stable two-dimensional metasurface is constructed via liquid–liquid interface (LLI) self-assembly of silver nanoparticles (NPs) functionalized with bis (p-sulfonatophenyl) phenylphosphine di-potassium salt (BSPP). UA is catalytically oxidized by uricase, which in turn oxidizes the BSPP ligands on the NP surface, inducing microstructural changes in the metasurface, which led to a decrease in the BSPP signal in the SERS mode at low UA concentrations and a reduction in reflectance in the reflectance mode at high UA concentrations. Using this dual-mode strategy, a detection limit (LOD) of 3.22 ± 0.10 nM for UA and a dynamic range of 0.100–1500 μM are achieved. The strategy enables rapid NPs assembly and complementary linear ranges, offering a versatile approach with potential for extension to diverse analytes and portable point-of-care applications, highlighting its potential significance for the early diagnosis of UA–related diseases.