Enzymes Immobilized Nanocarriers for the Selective Degradation of Synthetic Polymers

It is no secret that industrial plastics have become inevitable in nearly every facet of modern life and lifestyle due to their various properties for instance cost-effective production in large volumes. The development of finding new sustainable and reusable strategies for the degradation of omnipresent industrial plastics play a critical role in the future of our planet. (Bio)catalysts such as enzymes offer new pathways for the selective degradation of polymer materials. By the immobilization of such enzymes on nanocarriers enables unique opportunities for selective depolymerization and catalyst recovery. In this study, enzymes (lipase and cutinase) were covalently immobilized on carrier nanoparticles consisting of spherical SiO₂ and ellipsoidal Fe₃O₄@SiO₂ through 3-(aminopropyl)trimethoxysilane and glutaraldehyde linkers forming a stable bond to enzyme molecules. The successful linkage of the enzymes to the surface of the nanocarriers was confirmed by zeta potential and XPS measurements. In terms of degradation activity, high stability (&gt; 144 h) of as-prepared particles in conjunction with their repeatable use shows the promising potential of the controlled decomposition of polymers at room temperature as demonstrated by the conversion of 4-nitrophenyl acetate to 4-nitrophenol.<br/>For the investigation of the enzymatic decomposition (hydrolysis/oxidation), carbon nanofibers of polycaprolactone were electrospun and tested with the enzyme immobilized nanocarriers. The decomposition process of the fibers was verified through morphological (SEM) and weight loss studies, which showed a change in the fiber morphology due to enzymatic degradation and accordingly a weight loss.<br/>The immobilization of the enzymes improves their stability and simplifies their handling such as magnetic-field assisted recovery, which can be achieved by using magnetic carrier particles. Finally, the environmental impact of this approach is given by the stability of immobilized enzymes without compromise of their activity that makes them available for multiple and selective uses.