Red-emitting BSA-stabilized copper nanoclusters acted as a sensitive probe for fluorescence sensing and visual imaging detection of rutin.

In this article, red-emitting copper nanoclusters (Cu NCs) were prepared in the matrix of bovine serum albumin (BSA) through using N2H4·H2O as a reducing agent and BSA as a stabilizer. In the aqueous suspension of BSA-Cu NCs, the addition of rutin enabled the combination of rutin with BSA around Cu NCs via hydrogen bond and electrostatic interactions between functional groups of BSA and rutin. The approaching of rutin to Cu NCs induced that the fluorescence (FL) of Cu NCs was quenched by rutin due to the electron transfer from Cu NCs to rutin. Under the optimal conditions, the FL of Cu NCs was linearly decreased with the increase of rutin concentration from 0.1 to100 μM, together with a low detection limit of ca. 0.02μM. The FL quenching responses of Cu NCs were highly selective and sensitive towards rutin, over potential interferents in real human serum samples. Based on BSA-Cu NCs, this as-proposed FL probe exhibited a superior capability of rutin detection in real human serum samples. Significantly, this probe of rutin could realize the FL sensing of rutin and the naked-eye visual FL imaging detection of rutin in aqueous solution and on filter paper.