Immobilization of PETase on Magnetic Nanoparticles Enhances Their Stability and Activity for Efficient Degradation of Polyethylene Terephthalate

Polyethylene terephthalate (PET) is a widely used thermoplastic, but its environmental persistence has become a growing concern. Compared with conventional PET recycling methods, enzymatic degradation of PET waste provides an eco-friendly alternative. Among various PET-degrading enzymes, PETase from <i>Ideonella sakaiensis</i> has attracted significant attention for its high selectivity for PET degradation. However, the practical deployment of PETase remains limited by low operational stability, poor tolerance to harsh conditions, and a lack of reusability. It is still challenging to degrade PET on a large scale. To address these challenges, we developed a nanointerface biocatalytic platform by covalently modifying PETase^WT and its variant (PETase^FAST) onto silica-coated magnetic nanoparticles (Fe₃O₄@SiO₂ MNP) to degrade PET waste. This platform preserves the enzymatic activity of PETases while improving their tolerance to temperature, pH, and organic solvents. Immobilized PETases (PETase^WT and PETase^FAST) exhibited higher PET degradation efficiency than their free counterparts and retained over 50% activity after seven reuse cycles. The degradation of postconsumer plastic bottles confirmed the system's robustness and real-world applicability. This work addresses key challenges in enzyme stability and reuse in enzymatic PET depolymerization, providing insights that could inform future scalable circular strategies.