Development of a dual-emitting nanohybrids ratiometric fluorescent probe for highly sensitive detection of L-cysteine based on Cu-Ag alloy nanoclusters and carbon quantum dots

In this study, we successfully synthesized Cu-Ag alloy nanoclusters (CuAgCs) by introducing Ag, which exhibited superior stability compared to Cu nanoclusters (CuNCs). Additionally, carbon quantum dots (CQDs) with an impressive quantum yield of 26% were prepared. By combining short-wavelength CQDs with long-wavelength CuAgNCs, ratiometric fluorescent probes capable of dual emission with peaks at 468 nm (F 468 ) and 560 nm (F 560 ) were developed for detecting L-cysteine (L-Cys). The detection mechanism involves the aggregation-induced emission enhancement (AIEE) effect of CuAgNCs in the presence of L-Cys, resulting in an increase in F 560 while F 468 remains unchanged. The fluorescence intensity ratio F 560 /F 468 exhibits a linear relationship with L-Cys concentration in the range of 0–60 μM, with a low detection limit of 0.367 μM. Notably, the practical applicability of the fluorescent probe was validated through successful detection in real samples, achieving a high recovery rate of 98.7%-109%. These results demonstrate the promising potential of the developed fluorescent probe for practical applications.