Fluazinam direct detection based on the inner filter effect using a copper nanocluster fluorescent probe

Abstract

In this study, a label-free fluorescent probe based on L-cysteine modified copper nanoclusters (L-cys–Cu NCs) is applied to directly detect fluazinam via the inner filter effect. L-Cys–Cu NCs are synthesized through a simple method and show green fluorescence. The as-prepared L-cys–Cu NCs have an optimal emission wavelength of 497 nm under excitation of 365 nm. In the presence of fluazinam, the fluorescence of the Cu NCs is significantly quenched due to the abundant Cu NC affinitive sites recognizing fluazinam through molecular interactions. In addition, the absorption of fluazinam obviously overlaps with the excitation of the Cu NCs. Thus, an effective inner filter effect occurs. Under optimal conditions, the fluorescent probe shows a reliable linear relationship ranging from 0.05 to 25 μM with a correlation coefficient of 0.9953. And the detection limit of this probe is 1.4 nM (S/N = 3). The proposed fluorescent probe is applied to real samples with satisfactory results, indicating promising applications in environmental monitoring.