Zarei_2025_Colloids.Surf.B.Biointerfaces_260_115408

Poly (ethylene terephthalate) (PET) is a widely used synthetic polymer in textiles, but its hydrophobicity limits its applications despite excellent mechanical properties. Enzymatic hydrolysis provides a sustainable and environmentally friendly approach for PET surface modification, but its efficiency is restricted by the polymer's high crystallinity and limited enzyme accessibility. In this study, a synergistic plasma-enzyme treatment strategy was developed to enhance PET fiber surface hydrophilicity. Molecular dynamics (MD) simulations were employed to identify thermally unstable regions in leaf-branch compost cutinase (LCC), guiding the design of a thermostable variant, KI (T60K/N122I). The engineered KI exhibited a 10 degreesC improvement in thermal stability and a 1.33-fold increase in hydrolytic efficiency on amorphous PET compared to the native enzyme. PET fibers were subjected to ten sequential plasma-enzyme treatment cycles (90 min, 70 degreesC each), varying plasma exposure time (90 s and 180 s) and reactive gas type (O or O). Surface analyses revealed that pretreatment with O plasma significantly enhanced enzyme activity by promoting higher surface roughness and introducing more oxygen-containing functional groups. The combination of O plasma and KI resulted in 1.5-fold higher water absorption and 1.2-fold higher color strength relative to O plasma-treated samples. Gravimetric measurements confirmed greater mass loss for the O-KI system, attributable to enhanced thermal robustness and substrate affinity of the engineered enzyme. Overall, the cyclic plasma-enzyme process demonstrated superior performance compared to conventional modification methods, providing an efficient and sustainable route for functionalizing PET surfaces.