Fe3O4 nanoparticles-mediated solar-driven enzymatic PET degradation with PET hydrolase

Abstract

Cost-effective and eco-friendly treatment or recycled use of poly (ethylene terephthalate) (PET) is highly desired. Enzymatic PET degradation is considered a promising approach, but currently available PET hydrolases (PETases) have low activity at ambient temperature. Thus, elevating the reaction system temperature in a cost-effective way becomes a key to the economical enzymatic PET degradation. Herein, we proposed solar-driven enzymatic PET degradation with DuraPETase, a stable mutant of PETase, by using Fe3O4 nanoparticles (NPs) as the solar-to-thermal agent. Simulated solar irradiation could elevate the suspension of Fe3O4 NPs from 25 °C to 46 °C for the effective PET degradation. The enzyme immobilized onto Fe3O4 NPs, DuraPETase@Fe3O4, had higher stability than free DuraPETase, but a 10-d PET degradation experiments under simulated solar irradiation revealed that free DuraPETase in the presence of Fe3O4 NPs was approximately three times more effective than the DuraPETase@Fe3O4 system because of the superiority of free DuraPETase in degrading PET. This implies that enzyme immobilization is unnecessary in such a single-use system. By contrast, the DuraPETase-only system showed only 15.5% efficiency of the Fe3O4-mediated solar-driven system with free DuraPETase. The research demonstrated the potential of the Fe3O4-mediated solar-driven enzymatic PET degradation strategy for further development in different practical scenarios