Supramolecular hydrogels for creating gold and silver nanoparticles in situ

In situ fabrication of metal nanostructures such as metal nanoparticles (NPs) and nanoclusters (NCs) in supramolecular gels (particularly hydrogels) is important for the construction of novel and promising bio-/chemosensing platforms, and catalytic and antibacterial functional materials, because of their intriguing properties. Reported herein are our recent findings, in which we employed sodium salts of a series of structurally similar bile acid derivatives (BAs) to construct supramolecular hydrogels incorporating various metal ions including Ag+ and Au3+, and to investigate the feasibility of in situ fabrication of Ag NPs and Au NPs in these supramolecular hydrogel systems via a simple and environmentally friendly method of photoreduction, without adding any external reducing or stabilizing agents. These results demonstrated that the gelation ability of BAs induced by the coordination of Mn+ could also be tuned by a slight structural alteration of BAs, and forming Ag or Au NPs as effective nodes could facilitate increasing strength of the resulting supramolecular hydrogels. This is the first reported supramolecular hydrogel system capable of in situ formation of both Ag NPs and Au NPs, expected to open an entry for preparing novel functional gel materials incorporating metal nanostructures for numerous potential applications.