4-MPBA@CuNCs for imprint-free and highly specific fluorescence visual sensing of erythromycin

In this study, we facilely prepared a 4-mercaptophenylboronic acid (4-MPBA) modified copper nanocluster fluorescent probe (4-MPBA@CuNCs) with aggregation-induced emission (AIE) properties for the imprint-free visual sensing of erythromycin (ERY), and a novel sensing strategy for superb specific detection of ERY was established. The mechanism of specific recognition and response to ERY by the 4-MPBA@CuNCs fluorescent probe was clarified through a combination of experimental and theoretical calculations. The boric acid group on 4-MPBA@CuNCs served as a recognizer, undergoing ester cyclization with the cis-1,2-diol on ERY, which decreased the solubility of the resulting 4-MPBA@CuNCs-ERY complex and triggered the AIE of the nanoclusters. The developed method realized a fluorescence turn-on sensing of ERY with a detection linear range from 0.05 to 100 μM and a detection limit of 0.042 μM. Notably, even the concentration of ERY was as low as 0.05 μM, it still could be detected by naked eye. By combining with smartphones for online visual sensing data analysis, the fluorescent probe enabled precise and rapid differentiation of ERY with different concentrations. The fluorescent probe was also successfully applied to the detection of ERY in real medical wastewater, and effluent discharged from cleaning the ERY treated acne skin, and erythromycin dispersible tablets, demonstrating high accuracy and stability. This work provided an innovative approach for on-site, low-cost, and rapid ERY detection, offering new perspectives on the use of ligand-regulated metal nanoclusters for rapid antibiotic recognition and sensing.