Trypsin encapsulated gold-silver bimetallic nanoclusters for recognition of quinalphos via fluorescence quenching and of Zn2+ and Cd2+ ions via fluorescence enhancement

In this work, gold-silver bimetallic nanoclusters (Au-Ag NCs) were produced via a simple synthetic approach by using trypsin as a ligand. The synthesized bimetallic nanoclusters have high intensity and shown red fluorescence. The trypsin-encapsulated Au-Ag bimetallic NCs exhibit emission peak at 418 nm and 665 nm at excitation of 350 nm. The trypsin-decorated Au-Ag NCs were successfully applied as probes for fluorescence turn-off for quinalphos and turn-on for Cd2+ and Zn2+ ions. Under optimal conditions, multiple analytes i.e., quinalphos, Cd2+ and Zn2+ ions were detected and exhibited linear range from 1.0 to 100 mu M, achieved detection limits at nanomolar concentration. Attractively, the present study provides a new analytical strategy for multiple pollutants assay of quinalphos via fluorescence turn-off and of Cd2+ and Zn2+ ions via fluorescence turn-on mechanisms. The practicability of the method is validated by quantifying quinalphos, Cu2+ and Zn2+ ions from food and environmental samples. (C) 2020 Elsevier B.V. All rights reserved.

Automated summary

In this study, gold-silver bimetallic nanoclusters were synthesized using trypsin as a ligand, showing high fluorescence intensity and potential applications in detecting multiple pollutants. The trypsin-decorated Au-Ag NCs were successfully used as probes for fluorescence turn-off for quinalphos and turn-on for Cd2+ and Zn2+ ions, with detection limits at nanomolar concentration. This work provides a new analytical strategy for detecting pollutants and has been validated in food and environmental samples.