Selective degradation of synthetic polymers through enzymes immobilized on nanocarriers

In order to develop new sustainable and reusable concepts for the degradation of omnipresent industrial plastics, immobilization of (bio)catalysts on nanocarriers offers unique opportunities for selective depolymerization and catalyst recovery. In this study, enzymes (lipase and cutinase) were covalently immobilized on carrier nanoparticles (SiO2and Fe3O4@SiO2) through 3-(aminopropyl)trimethoxysilane and glutaraldehyde linkers forming a stable bond to enzyme molecules. The presence of enzymes on the surface was confirmed by zeta potential and XPS measurements, while their degradation activity and long-term stability of up to 144 h was demonstrated by the conversion of 4-nitrophenyl acetate to 4-nitrophenol. Furthermore, enzymatic decomposition (hydrolysis/oxidation) of electrospun polycaprolactone fiber mats was verified through morphological (SEM) and weight loss studies, which evidently showed a change in the fiber morphology due to enzymatic degradation and accordingly a weight loss. Graphic abstract