Copper nanocluster-based fluorescent sensors for sensitive and selective detection of kojic acid in food stuff

We utilized bovine serum albumin-capped copper nanoclusters (CuNCs) to develop a new fluorometric method for the identification and determination of kojic acid (KA) with good sensitivity and selectivity. The fluorescence of CuNCs was quenched effectively by KA, but not by the possible coexisting substances. Based on multiple spectroscopic studies, we propose that selective binding of KA to copper ions of CuNCs promotes the formation of copper kojate on the surface of CuNCs, which statically quenches CuNCs fluorescence. The as-proposed biosensor allows selective determination of KA in the range from 0.2 μM to 50 μM, with a detection limit of 0.07 μM at a signal-to-noise ratio of 3. The CuNC-based fluorescent sensor provides a simple, rapid, cost-effective, and label-free platform for KA detection. Furthermore, we demonstrated this fluorescent sensor can be used for KA detection in food samples.