Enzymatic polymerization of plant-derived phenols for material-independent and multifunctional coating

Versatile binding features of ortho-dihydroxyphenyl groups ubiquitously found in mussel adhesive proteins are inducible with polyphenolic moieties that are widespread in the plant kingdom, strongly supporting the idea that previously reported mussel-related material-independent adhesion is reproducible with plant-derived phenolics. Here, we directly demonstrate that material-independent coating action can be achieved by in vitro laccase-catalyzed polymerization of plant phenols. Deposition rates of polymeric products onto solid surfaces are superior to that of polydopamine, the known mussel-derived coating agent. The coated surfaces are robust against strong acid and salt. In addition, FTIR-ATR and analyses of bactericidal action, phenol content, charge-dependent sorption behavior, and free radical scavenging activity strongly indicate that the coating agents are structurally multiple hydroxyphenyl group-bearing polyaromatics. We finally demonstrate that hydroxyphenyl group bearing polymers act as either conjugation sites for proteins or chelating/reduction sites for metal ions, and also that co-deposition of functional organics during the enzymatic polymerization of plant phenols is feasible. Both immobilization results strongly suggest that coated layers by our products can lead to further surface functionalization.