Encapsulation strategy based on aggregation-induced emission effect for the dual-emission ratiometric fluorescence...

Metal-organic frameworks (MOFs) materials are highly porous and easily modified, and can have great potential for application in rapid fluorescence analysis of pollutants in materials with aggregation-induced emission (AIE) properties. Herein, a dual-emission ratiometric fluorescence nanosensor was constructed based on the copper nanoclusters encapsulated in zeolite imidazole framework-8 (CuNCs@ZIF-8) for visual detection of tetracycline (TC). Obviously, the fluorescence properties of CuNCs@ZIF-8 were highly enhanced by AIE effect under restriction of ZIF-8. After further TC molecule entered the ZIF-8 pores, its own green fluorescence was significantly enhanced through AIE, while the CuNCs in the original aggregated state were continuously dispersed, resulting in diminished red fluorescence of CuNCs@ZIF-8. Based on the sensing principle and benefiting from the efficient dual-emission inverse response, the CuNCs@ZIF-8 nanosensor exhibited excellent linearity in the range of 0.1-50 μM with a low detection limit down to 0.034 μM. Moreover, the distinct color transformation (red to green) made it ideal for high sensitivity visual detection of TC. Simultaneously, the CuNCs@ZIF-8 nanosensor was highly selective and has exhibited reliable quantitative TC analysis with satisfactory recoveries in real sample assays. Importantly, a visual sensing platform was designed by integrating CuNCs@ZIF-8 with smartphone assistance, and the visual sensing of TC was achieved by capturing and digitizing fluorescence images. Therefore, this work provides the possibility of meeting the requirements for convenient, sensitive and reliable rapid analysis of antibiotics, which has potential applications for pollutant detection in environmental and food safety.