Construction of multicolor fluorescence hydrogels based on the dual-emission CDs@SiO2/AuNCs for alternative visual recognition of copper ions and glutathione

[Display omitted] •The dual-emission CDs@SiO2/AuNCs fluorescent probe was prepared for the detection of Cu2+ and GSH.•The ratiometric fluorescence method can be used to detect Cu2+ and GSH in food samples.•Alternative visual recognition was realized by the multicolor fluorescent gel of the probe. Hydrogels, as an extremely hydrophilic polymer with a network-like cross-linked structure, are considered as a promising material in the field of sensing and detection. In this work, a new ratiometric fluorescence sensor on the basis of the dual-emission of gold nanoclusters (AuNCs) and carbon dots (CDs) was developed to recognize copper ions (Cu2+) and glutathione (GSH). AuNCs with excellent photostability and biocompatibility could electrostatically interact with aminated-CDs@SiO2. After adding Cu2+, the fluorescence of AuNCs gradually weakened, while the fluorescence of CDs in silicon spheres was basically not affected, thus a fluorescence ratio signal was generated to realize the recognition of Cu2+. Subsequently, the strong combination of GSH with Cu2+ could recover the fluorescence of AuNCs, and a new fluorescence ratio signal was generated to further recognize GSH. The developed ratiometric fluorescence sensor could detect Cu2+ over a range from 0.5 to 16 μM with a detection limit of 0.25 μM and GSH over a range from 0.05 to 48 μM with a detection limit of 0.035 μM. Such dual-emission CDs@SiO2/AuNCs fluorescent probe was located in the visible region, thus a multi-color fluorescent platform for the alternative visual recognition of Cu2+ and GSH was realized by implanting CDs@SiO2/AuNCs in agar gel. The construction of multicolor fluorescent hydrogels can be not only applied to fast and visual on-site sensing, but also used in the bioimaging, information encoding, and other fields.