Smartphone-Integrated Molecularly Imprinted Ratiometric Fluorescent Sensor for Selective and Visual Detection of Doxycycline in Lake Water and Foodstuff
Yan Li, Yiqun Wu, Yifei Wang, Yichuan Cao, Yan Liu, Guozhen Fang, Shuo Wang
Abstract
Doxycycline (DOX) is extensively utilized as a broad-spectrum antibiotic in animals and aquaculture. However, excessive residues of DOX can endanger human health and ecosystems, adversely affecting sustainable development. A novel ratiometric fluorescent probe was designed for specific monitoring of DOX based on boron- and nitrogen-codoped carbon quantum dots encapsulated in metal–organic frameworks coupled with molecularly imprinted polymers (B,N-CQDs/ZIF-8@MIP). In the existence of DOX, the blue fluorescence was quenched owing to the inner filter effect, while the yellow-green fluorescence was enhanced due to the combination of DOX and Zn 2+ . Benefiting from the dual-signal strategy and the molecularly imprinted layer, the probe exhibited a wide linearity range (0.05–20 mg L –1 ), a favorable detection limit (LOD) of 14.21 ng mL –1, a fast response time (5 min), and exceptional selectivity. The validity of the probe was verified by detecting DOX in lake water and milk with desirable recoveries (90.16–97.18%). Moreover, a portable sensing device based on a smartphone-integrated B,N-CQDs/ZIF-8@MIP was utilized to achieve DOX visual sensing with a clear color change and an LOD of 44.98 ng mL –1 . Therefore, the sensor with the advantages of portability, easy operation, and sensitivity showed tremendous application prospects for on-site detection in food and environmental safety.