Laccases for wood treatment: From composites manufacturing to surface modification

In nature, laccases are involved in lignin synthesis but also in its degradation. This versatility, its relative unspecificity and potential to act on lignin, allow these oxidases to be applied in several industrial sectors. Among them, wood industry shows several scopes where laccases could be included in order to obtain new products, or conventional ones by greener manufacturing processes. The manufacturing of wood composites is based in the use of different types of wood particles that are joined together by means of several adhesive formulations. Adhesives are mainly composed of chemicals from the petrochemical industry that are polymerized in contact with wood particles in order to form the composite. Laccases may help on this process by activating lignin and improving the adhesion process, resulting in the reduction of the conventional adhesive formulation, or even its absence. Laccases are also able to mediate in the grafting of several monomers onto wood and, therefore, could be used as a sustainable tool to treat wood in order to provide different properties to this natural material. This enzymatic grafting is based on the initial formation of radical compounds from the laccase substrates, which are subsequently linked onto the wood by radical polymerization. By using this method stable bonds between enzymatic substrates and wood are formed and, consequently, leaching of the grafted compounds is avoided. The use of substrates with specific characteristics could be used to confer such features to the wood. Thus, some interesting properties such as hydrophobicity, durability, biofouling resistance, etc. could be stably provided by this kind of treatments.