Ratiometric fluorescence method for malachite green detection based on dual-emission BSA-protected gold nanoclusters

The ratiometric fluorescence measurement has drawn great attention due to its selective and sensitive sensing property for numerous analyzes. In this sensing system, a ratiometric fluorescence method is described for the determination of malachite green (MG) based on bovine serum albumin-stabilized Au nanoclusters (BSA-AuNCs) with dual emission. The as-prepared BSA-AuNCs exhibit two emission peaks around 430 and 610 nm under a single excitation, which may be from the intrinsic structure of BSA and AuNCs, respectively. As MG was added, the fluorescence at 610 nm was obviously quenched, and the fluorescence intensity at 430 nm decreased slowly, which might be mainly ascribed to fluorescence resonance energy transfer and dynamic quenching. The fluorescence intensity ratio of F-430/F-610 shows good linearity for detecting MG in the 0.3-20 mu M range with a low detection limit of 0.19 mu M. In addition, the ratiometric sensing strategy is successfully applied to real water samples, which reveals its potential practicability for detecting MG in environmental water samples.