Synthesis of Protein-Directed Orange/Red-Emitting Copper Nanoclusters via Hydroxylamine Hydrochloride Reduction Approach and Their Applications on Hg2+ Sensing

Abstract

Herein, we report a facile one-pot method for the synthesis of orange/red-emitting fluorescent copper nanoclusters (Cu NCs), in which bovine serum albumin (BSA) served as the capping scaffold (Cu NCs@BSA) and hydroxylamine hydrochloride (NH2OH[Formula: see text][Formula: see text][Formula: see text]HCl) as the reducing agent. To the best of our knowledge, this is the first time to adopt this mild reductant to synthesize fluorescent Cu NCs. The as-prepared Cu NCs@BSA exhibits strong orange or red fluorescence at room temperature depending on the synthesis process, and the maximum excitation and emission peaks were at 355[Formula: see text]nm and 615[Formula: see text]nm, 395[Formula: see text]nm and 645[Formula: see text]nm, respectively. Synthesis conditions including the amounts of NH2OH[Formula: see text][Formula: see text][Formula: see text]HCl, the selection of reducing agent, the molar ratio of BSA/Cu(NO3)2, the pH value, the reaction temperature, the reaction time, and various kinds of Cu sources have been systematically studied. Importantly, these Cu NCs exhibit excellent stability for at least 2 months when stored at 4[Formula: see text]C in the dark, and they also show strong oxidation resistance toward H2O2. Moreover, the prepared Cu NCs have been successfully applied to sensitively and selectively sensing Hg[Formula: see text] without suffering any interference from other metal ions and anions.