Surface-Initiated Synergistic Disassembly of Metal-Phenolic Networks by Redox and Hydrolytic Reactions

Metal-phenolic networks (MPNs) provide a versatile and biocompatible platform for engineering various interfaces with stimuli-responsive coatings. However, while pH, competitive chelation, and redox reactions have been explored as stimuli for MPN disassembly, it has been challenging to trigger disassembly in physiologically relevant pH, which is important for a variety of biomedical and biotechnological applications. Here, we expand the library of molecules capable of disassembling MPNs and introduce a synergistic MPN disassembly strategy using both hydrolysis and redox reactions. This synergistic disassembly strategy is effective in various environmental conditions and exhibits outstanding disassembly efficiency across wide pH and ionic strength ranges. Despite the permeability of MPNs, this disassembly strategy exhibits a surface-initiated nature, allowing rapid but controllable disassembly kinetics. We also demonstrate that the oxidation of the phenols and hydrolysis of the phenolic ligand, tannic acid, the reduction of the metal ion, Fe 3+, and the production of hydroxyl radicals all contribute to the rapid disassembly of MPNs. Moreover, the in situ disassembly of MPNs on cell surfaces highlights the cytocompatibility and buffer independence of this disassembly method. We envision that this versatile disassembly mechanism will find application for stimuli-responsive MPN films needed in sophisticated ambient and physiological conditions.