Smartphone-Colorimetric Biosensor for Uric Acid through Morphological Transition of Silver Nanoplates

Elevated uric acid (UA) serves as a critical biomarker for hyperuricemia-related disorders, yet conventional detection faces cost and complexity limitations. Here, we developed an enzyme-free smartphone-colorimetric biosensor using silver triangular nanoplates (AgTNPs). These anisotropic nanostructures exhibit morphology-dependent surface plasmon resonance (SPR), enabling UA-selective etching that induces a blue-to-yellow color shift. Spectrophotometry revealed a linear response (40–110 μM, R 2 > 0.992) correlating with blue shifts. Smartphone-based green-channel analysis achieved comparable accuracy (R 2 = 0.98) in a 96-well plate. Transmission electron microscopy confirmed UA-driven morphological evolution from triangular to spherical nanoparticles via anisotropic etching. This dual-mode platform provides a cost-effective solution for point-of-care UA monitoring.