Luminescence enhancement of gold nanoclusters hydrogel through co-assembly strategy and its application for detection

Gold nanoclusters (AuNCs) with ultrasmall size have attracted enormous interest due to their unique luminescent properties. Especially, luminescent AuNCs-based hydrogel with three-dimensional (3D) structures is valuable. Herein, hydrogel with effective enhancement of emission (QY increased from 0.45% to 14.6%) is reported through the co-assembly of AuNCs stabilized by 4,6-diamino-2-pyrimidinethiol (DPT) with citric acid (CA) and Al 3+ . With the formation of hydrogel, the microstructures of DPT-AuNCs changed from nanofibers into microdisks. X-ray photoelectron spectroscopy (XPS), photoluminescence (PL) spectra and Fourier transform infrared (FT-IR) reveal that CA is crucial for the emission enhancement of NCs and Al 3+ is benefit for the gelation of NCs. Furthermore, the obtained luminescent hydrogel could be used as a selective sensor for Fe 3+ /ascorbic acid (AA) through the “switch off/on” of luminescence and may find an application in information security. This study offers a convenient strategy for building AuNCs-based luminescent hydrogel through co-assembly method, and presents potential applications as functional materials.