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

Abstract

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.

Applications of liquid metals in nanotechnology

“…The in situ formation of LM nanodroplets was reported to directly initiate the polymerization of various monomers. 5,[133][134][135] As an example, the synthesis of EGaIn nanodroplets via sonication was shown to initiate free radical polymerization reaction of vinyl monomers in an aqueous solution (Fig. 4a).…”

Advancement of Gallium and Gallium-Based Compounds as Antimicrobial Agents

“…On the one hand, hydrogel, bioceramics, and other materials with good biocompatibility can be directly used as tissue engineering scaffolds for the repair of infectious defects. On the other hand, chemical processes, such as electrophoretic deposition, thermochemical treatment (Rodriguez-Contreras et al, 2020), solid-state method (Pajor et al, 2020), radio-frequency magnetron sputtering (Stan et al, 2020), and gel/sol can form antibacterial coatings (Pajor et al, 2020;Rodriguez-Contreras et al, 2020;Stan et al, 2020;Almohandes et al, 2021;Centurion et al, 2021) containing gallium on the surface of implants to prevent and treat iatrogenic infections. The controlled release of gallium by the above materials mainly benefits from their biodegradability, porous network structure, and adjustable porosity.…”

Gallium-Based Liquid Metal Materials for Antimicrobial Applications

“…In spite of its inherent bactericidal role, LM has been proven to work as a catalyst to accelerate chemical reactions. Franco et al, [ 119 ] facilitated the oxidative auto-polymerization of natural polyphenols with Ga-based LM as a catalyst, resulting in nanofilms with high kinetic reactivity. As is shown, the LM nanofilms exhibited excellent antioxidant and antibacterial properties under acidic conditions.…”