A smartphone platform developed with AI assistance for ultrasensitive dual-mode detection of tetracycline using Au@ZnO/Pt nanozymes

Tetracycline (TC), a broad-spectrum antibiotic widely used in both human and veterinary medicine, has raised serious environmental and public health concerns due to its widespread misuse. Consequently, there is an urgent need to develop rapid and user-friendly methods for TC detection. In this study, we developed a dual-mode sensing platform based on Au@ZnO/Pt nanoparticles with oxidase-like activity. These nanoparticles catalyzed the oxidation of 3,3′,5,5′-tetramethylbenzidine (TMB) to a blue-colored product, which was visibly inhibited in the presence of TC, enabling sensitive colorimetric detection of TC with a limit of detection (LOD) as low as 0.34 nM. Simultaneously, the Zn²⁺ ions in the nanoparticles formed stable chelates with TC, resulting in a significant turn-on green fluorescence response, achieving a fluorescent detection method with an LOD of 0.48 nM. By integrating these two mechanisms, we established a dual-mode sensing strategy combining colorimetric and fluorescence outputs for the rapid (≤5 min), sensitive, and reliable detection of TC in real water samples. Furthermore, with the assistance of AI, we developed a smartphone application and integrated it with test strips embedded with Au@ZnO/Pt nanoparticles, providing a portable and practical solution for on-site TC monitoring.