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 Ideonella sakaiensis 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 PETaseWT and its variant (PETaseFAST) 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 (PETaseWT and PETaseFAST) 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.