Different fluorescence emitting copper nanoclusters protected by egg white and double-emission fluorescent probe for fast detection of ethanol.

Green emitting copper nanoclusters (G-Cu NCs), yellow emitting Cu NCs (Y-Cu NCs), orange emitting Cu NCs (O-Cu NCs) and red emitting Cu NCs (R-Cu NCs) were prepared using chicken egg white as the stabilizer by changing the reaction conditions. This is a green, facile and cheap method to explore different color emitting CuNCs by the same precursor and stabilizers. The G-Cu NCs were employed for the detection of ethanol due to their aggregation induced emission enhancement (AIEE) effect. The fluorescence emission of Cu NCs at 526 nm under the excitation of 444 nm can be effectively enhanced in the presence of ethanol due to AIEE effect, thus realizing the quantitative determination of ethanol content in the range 5-60%. In addition, a visual dual-emission fluorescence probe with the combination of G-Cu NCs and silicon nanoparticles (Si NPs/G-Cu NCs) was designed to evaluate ethanol content conveniently and rapidly. Desirable linear relationship is observed between ratio of fluorescence intensity (I525/I441) and ethanol content under the excitation of 383 nm. Visible color transformation of this probe is observed in the ethanol content range 2-20%. Moreover, the ethanol sensing platforms were applied to the detection and evaluation of the alcohol content of liquor, and the recoveries in liquor were in the range 99.7% to 113%, broadening the applications of Cu NCs and providing a sensitive detection method for ethanol.