4-Mercaptobenzoic acid coated self-assembled aggregative luminescent copper nanoclusters for the detection of ethyl vanillin

Ethyl vanillin (EVA) is a food additive with strict requirements, and the addition of more than the standard will affect the human body, so the design of a fast and sensitive detection method for EVA has aroused people's interest. Here, we developed a fluorescence assay method for the sensitive detection of EVA by 4-mercaptobenzoic acid (4-MBA) coated self-assembled copper nanoclusters (4-MBA-CuNCs). Under alkaline conditions, 4-MBA-CuNCs self-assembled aggregation induces strong blue fluorescence, and its quantum yield is 5.51 %. Under very simple conditions, the fluorescence intensity of 4-MBA-CuNCs at 421 nm was reduced by EVA through static quenching and internal filtration effect. The detection method showed a good linear relationship between 0.1 and 5.1 μM, and its detection limit was 30 nM. Moreover, the preparation of 4-MBA-CuNCs could provide a simple and quick method for the detection of EVA in real samples.