Laccase-Mediated Wood Surface Functionalization

Laccase‐catalyzed grafting of functional molecules on wood surface presents an eco‐friendly opportunity to improve wood properties. In a novel stepwise approach, functional molecules were bound to an enzymatically modified wood surface containing anchor groups. As anchor groups, phenolic amines were coupled to lignin moieties of wood using the 62 kDa Trametes hirsuta laccase. The coupling reaction to lignin was mimicked using the lignin model compounds 4‐O‐methyl guaiacylglycerol β‐guaiacyl ether A, guaiacylglycerol β‐guaiacyl ether E, dehydrodivanillyl alcohol type dibenzodioxocin D and syringylglycerol β‐guaiacylether G. Using this approach it was possible to increase binding of the fungicides propiconazole and thiabendazole by 42 % and 58 %, respectively, when compared to coupling onto wood pieces which were oxidized by laccase only. Most impregnation processes for wood based materials involve adsorptive binding of functional materials resulting in a low fastness. It is shown that enzymes (i.e. laccases) can be used to covalently bind functional molecules onto the lignin moieties present on the wood surface which can in turn serve as versatile anchor groups for further modification.