Blocking the Cu (II) Ions Mediated Catalytical Ability for Construction of Ratiometric Fluorescence Sensing Platform Based on Glutathione-Stabilized Copper Nanoclusters

It is of great importance to integrate two kinds of fluorescent probes in one system to construct ratiometric sensing platform. Inspired by the efficient overlapped spectrum of glutathione-stabilized copper nanoclusters (GSH-CuNCs) and 2, 3-diaminophenazine (DAP), a novel and label-free ratiometric fluorescent sensor has been developed for Cu ²⁺ and kojic acid (KA) detection on the basis of in situ converting o -phenylenediamine (OPD) into DAP by the catalytic oxidation ability of Cu ²⁺ . The Cu ²⁺ catalytically generated DAP was served as an energy acceptor to inhibit the fluorescence emission of GSH-CuNCs (energy donor). As a result, the sensitivity and accuracy of the strategy were greatly improved due to the dual-emission reverse change ratiometric profile. The sensing system showed high sensitivity toward Cu ²⁺ in a range of 0.1–50 μ M and with a limit of detection of 20 nM. Furthermore, based on the specific coordination interaction between Cu ²⁺ and KA, the ratiometric sensor displayed the range of detection of KA from 0.2 μ M to 300 μ M with a limit of detection of 50 nM. Thus, the ratiometric method paved a new way for the effective quantification of Cu ²⁺ and KA in real samples, which were closely concerned with human health.