A fluorescent probe based on tryptophan-coated silver nanoclusters for copper (II) ions detection and bioimaging in cells

Silver nanoclusters (Ag NCs) have been widely used in sensing and bioimaging owing to their excellent photoluminescence properties and biocompatibility. Herein, we fabricated blue fluorescent tryptophan-coated silver nanoclusters (Trp-Ag NCs) by a facile one-step method for Cu2+ detection and multicolour bioimaging. Trp-Ag NCs displayed a strong blue luminescence with a high quantum yield of 35.6% and a long lifetime of 18.48 ns. In the presence of Cu2+, the fluorescence was quenched via static quenching and charge transfer. The developed fluorescence probe for Cu2+ detection showed a high selectivity and sensitivity with a low limit detection of 0.029 μM. Meanwhile, due to their excellent biocompatibility, the demonstration of bioimaging in cells was also provided.