Liquid Metal-Triggered Assembly of Phenolic Nanocoatings with Antioxidant and Antibacterial Properties

Liquid metal (LM) catalysts have been demonstrated to accelerate chemical reactions, providing an intriguing route to fine chemical synthesis with immense technological implications. Herein, we explore gallium-based LMs as catalysts to promote the oxidative self-polymerization of natural polyphenols, an emerging class of natural building blocks for surface functionalization with diverse biochemical properties. The oxidative polymerization of polyphenols, triggered by eutectic alloy of gallium and indium, results in nanocoatings with remarkably high reaction kinetics. The oxidative polymerization occurs in a wide pH range including an acidic environment—a condition previously unexplored for the deposition of phenolic coatings. The LM triggers the generation of highly active radical species from the oxidant causing the rapid oxidation of the polyphenols and their subsequent deposition on a range of different substrates. We further show that the LM-based catalytic system addresses several other limitations of existing coating methods including a narrow pH range, substrate specificity (precursor–dependent), and low coating uniformity. Finally, we demonstrate that the phenolic nanocoatings obtained from the acidic pH environment have excellent antioxidant and antibacterial properties without requiring any post-functionalization step. This process for creating phenolic nanocoatings may find applications in a wide range of industries, food science, and biomedicine.