Synthesis of Switch-off Fluorescent Water-Stable Copper Nanoclusters Hg2+ Sensors in Simple One-Pot Approach by In-Situ Metal Reduction Strategy in the Presence of Thiolated Polymer Ligand Template
The fabrication of stable fluorescent copper nanoclusters (CuNCs) in aqueous media is still challenging despite their low price and potential biomedical applications. Herein, we report a facile and efficient strategy to assemble CuNCs using multifunctional thiolated copolymers with pH and thermoresponsive features. The new nanohybrids are formed in a simple one-pot approach by reduction of the copper salt with hydrazine in the presence of the multithiolated polymer, which provides a template during nanocluster assembly and further efficient protection against oxidation and aggregation. Furthermore, the thermo- and pH-response properties of pristine copolymers endow the nanohybrids with these stimuli-response features. The thiol content as well as the macromolecular size of the polymer ligand exert strong influence on the final photophysical properties of these new hybrid luminescent nanoclusters. The stable bright greenish-yellow emission in water over long periods of time, high photostability under UV irradiation and strong oxidation resistance toward hydrogen peroxide of the hybrid CuNCs show great promise toward nanomedicine, bioassays and nanosensors. Futhermore, the polymeric CuNCs obtained have been successfully tested as optical switch-off sensors for the sensitive and highly selective detection of Hg2+ against other metal ions, as liquid and solid-state sensors. Finally, we demonstrate the practical applicability of the new hybrid for Hg2+ detection in human urine.