Smartphone-assisted multicolor aptamer-lateral flow assay using trimetallic nanoprobes and enzyme-free signal...

Nanozyme-mediated lateral flow assay (LFA) remains limited by monochromatic signals, which hampers rapid visual recognition in field testing. Intelligent detection of antibiotic is essential for ensuring food safety. Here, we proposed a reliable multicolor LFA tool for detecting enrofloxacin (ENR) residues. The strategy employed aptamer-integrated catalytic hairpin assembly (CHA) to amplify molecular recognition signals. Besides, polyA-bridged DNA strands were coupled to lychee-like AuCuPt trimetallic plasmonic nanoparticles (ACPNLs) to construct cost-effective reporting probes. During result readout, the enzyme-like activity of ACPNLs regulated the etching of Au nanostars, generating structurally distinguishable multicolor changes. Combined with smartphone software, hue values as high-precision parameters were extracted from the color wheel (0-360°). The analysis revealed a robust linear relationship between ENR concentration (0.1-600 ng/mL) and colorimetric response, achieving a detection limit of 0.06 ng/mL. In contrast to single-color LFA, the multicolor platform offered an expanded hue range and enhanced visual discernibility. Overall, this method provides a new avenue for intuitive monitoring of antibiotic, showing great promise for point-of-care food safety testing.