AND logic-gate-based Au@MnO2 sensing platform for tetracyclines with fluorescent and colorimetric dual-signal readouts

Tetracyclines (TCs) are the most common antibiotic drugs in the world. However, due to the overuse and difficulty of degradation, TCs pollution is becoming a global threat to aquatic and terrestrial biodiversity. Current methods for detecting TCs mainly rely on fluorescent probes or nanomaterials with enzyme-mimicking catalytic activities , which only provide a single signaling mode and are vulnerable to experimental factors. Herein, this study reports the development of an AND logic-gate-based sensing platform for TCs with fluorescent and colorimetric dual-signal readouts using Au@MnO 2 nanoparticles that could be mutually verified for the selective sensing of TCs. It was found that Au@MnO 2 nanoparticles could oxidize TC into its oxidation state (oxTC), resulting in significant green fluorescence emission . Meanwhile, the MnO 2 shell was etched away, and the released Au core nanoparticles gradually aggregated, with a color change from brown to light blue. As such, we established the fluorescence “turn-on” and colorimetric quantitative relationships towards TC with detection limits of 21.9 and 83.3 nM, respectively. Furthermore, Au@MnO 2 -based analytical paper devices were prepared and demonstrated successfully for the fluorescent and colorimetric dual-signal readout detection of TC in real samples. This paper sheds light on the on-site detection of tetracycline using paper-based analytical devices and smartphones.