Self-assembly and phase transition of gold nanoclusters in natural deep eutectic solvent for visual detection of toxicants in water environment

Ecological damage derived from water pollution has increased greatly accompanying by the development of industries, which promotes the exploration of water environment monitoring platform. Structure-oriented synthesis of gold nanoclusters (NADES-Au NCs) based on novel natural deep eutectic solvent (NADES), has been successfully obtained without the use of any stabilizer or capping agents. With the pH stability and photobleaching resistance in the complex environment, spongy NADES-Au NCs showed superior optical properties than other forms. Moreover, this green sensing platform based on NADES-Au NCs displayed two well-separated emission peaks at 440 and 669 nm, respectively. There was a linear range of 0.5–200 µM with a detection limit of 0.25 µM for Hg 2+ and a linear range of 1–150 µM with a detection limit of 0.12 µM for nitroanilines. Such NADES-Au NCs demonstrated the satisfactory recoveries and reliabilities in water samples, which presented great potential of water pollution detection. Simultaneously, the application of NADES as a green solvent for the synthesis of metal nanoclusters may provide new avenues for sensing platform.