Gallol-Tethered Injectable AuNP Hydrogel with Desirable Self-Healing and Catalytic Properties

Injectable self-healing hydrogels have drawn growing attention for their extensive applications in biomedical fields. Hydrogels containing nanoparticles also exhibit promising potentials in catalysis, wastewater treatment, and organic synthesis. Inspired by the multifunction of gallol presented herein, a simple one-pot method to produce a gallol-tethered gelatin hydrogel via Schiff base under oxidizing conditions using various oxidants is presented. The hydrogels prepared by NaIO4-induced cross-linking present a high self-healing rate (up to 84.5%), injectable ability, tunable mechanical property, flexible viscoelasticity, and macroporous structure owing to the combination of covalent cross-linking and supramolecular interactions. HAuCl4 contributes to the 3D structure formation of the gelatin hydrogel via oxidation cross-linking. It is reduced by the gallol groups to produce nanogold (AuNP)-decorated hydrogel (Au-gel). This Au-gel is fully characterized by UV-vis, XRD, TEM, SEM, EDX, and ICP-MS and exhibits a high-catalytic activity for the reduction of 4-nitrophenol. The solid Au-gel catalyst is robust, easily recyclable, and reused at least eight times.