Biodegradation of Lignin into Low-Molecular-Weight Oligomers by Multicopper Laccase-Mimicking Nanozymes of the Cu/GMP Complex at Room Temperature

Abstract

Laccase is a highly versatile multicopper oxidase for lignin biodegradation. Using nanomaterials to realize functional laccase simulations is attractive for applications and fundamental research. Herein, this study reports a facile strategy to fabricate a Cu metal–organic framework (MOF) by using copper as a metal center with guanosine 5′-monophosphate (GMP) as organic ligands (Cu/GMP). This obtained catalyst exhibits excellent chemoselectivity for lignin depolymerization into oligomers with low molecular weights at room temperature and atmospheric pressure. It was found that Cu/GMP shows superior laccase-like activity, which is beneficial for the C–O bond cleavage within lignin, thus affording oligomers in a high yield (81.7 wt %). Furthermore, the effects of the obtained lignin oligomers on the oxidative stability of canola oil biodiesel were evaluated. They were novel, renewable, and of low cost, which as biodiesel additives exhibited high potential in replacing expensive merchand biodiesel antioxidants commonly used to date.