A promising gold nanocluster fluorescent sensor for the highly sensitive and selective detection of S2−

Bright red-emissive gold nanoclusters (AuNCs) were synthesized by a facile one-pot approach in aqueous solution using bovine serum albumin (BSA) as a protecting agent. A new BSA-AuNC fluorescent sensor for the detection of S2− has been designed based on the sharp fluorescence quenching of BSA-AuNCs, which results from the degradation of its structure due to the formation of Au2S by the reaction between Au and S2−. The proposed highly sensitive (the detection limit [LD] was 0.029 μM) and selective sensor was applied to the detection of S2− in the presence of high concentrations of different anions in aqueous solution, and the results were in good agreement with those determined by electrochemical methods. The sensor is shown to be environmentally friendly, simple, responsive and practical. Meanwhile, the morphological changes of BSA-AuNCs and BSA-AuNCs-S2− were characterized by high-resolution transmission electron microscopy (HRTEM). Furthermore, the sensing mechanism for the detection of S2− is discussed.