Plastic pollution caused by poly(ethylene terephthalate) (PET) highlights the urgent need for efficient biodegradation strategies. However, PET hydrolases such as DuraPETase typically exhibit limited substrate affinity for PET and insufficient operational stability. Although conventional immobilization improves enzyme stability, it often compromises catalytic activity. Here, we design a PET-targeting, orientation-controlled immobilization strategy that overcomes this traditional trade-off and enables efficient PET biodegradation. Guided by rational structural analysis, three Cys variants (R53C, R59C, R224C) were engineered for site-specific covalent attachment to a PDA@SiO2support with inherent PET-binding capability. The resulting conjugates (DuraR53C-PDA@SiO2, DuraR59C-PDA@SiO2, and DuraR224C-PDA@SiO2) displayed distinct catalytic and stability profiles. Among them, DuraR59C-PDA@SiO2achieved the optimal balance between activity and stability, retaining kinetic properties comparable to the free enzyme and maintaining 87.6% residual activity after 2 h at 80 °C. Water contact angle measurements confirmed its PET-targeting behavior, as evidenced by the reduction in the PET contact angle from 85° to 45°. In 10-day degradation assays at 50 °C, DuraR59C-PDA@SiO2released a total of 4865.32 μM degradation products, representing a 2.37-fold increase relative to free DuraPETase. These findings demonstrate an effective strategy for industrial enzymatic PET degradation and recycling.
Zixuan Li,Kun Chen,Linling Yu,Qinghong Shi,Yan Sun
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 Fe 3 O 4 nanoparticles (NPs) as the solar-to-thermal agent. Simulated solar irradiation could elevate the suspension of Fe 3 O 4 NPs from 25 °C to 46 °C for the effective PET degradation. The enzyme immobilized onto Fe 3 O 4 NPs, [email protected] 3 O 4 , 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 Fe 3 O 4 NPs was approximately three times more effective than the [email protected] 3 O 4 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 Fe 3 O 4 -mediated solar-driven system with free DuraPETase. The research demonstrated the potential of the Fe 3 O 4 -mediated solar-driven enzymatic PET degradation strategy for further development in different practical scenarios
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