Thin-film Composite Biocatalytic Nanofibrous Membrane System for Pharmaceuticals’ Degradation: Performance, stability, and Continuity

Recently, biocatalytic nanofibrous membranes have drawn attention in various fields such as biosensing and wastewater treatment because of their high specificity, prolonged reusability and low-cost efficiency. This study investigates a facile laccase-assisted nanofibrous filtration membrane system for transformation of pharmaceuticals. Laccases are successfully covalently immobilized on functionalized electrospun polyacrylonitile/β-cyclodextrin nanofibers. β-Cyclodextrin (β-CD), a cone-shape cyclic hepta-α-1,4-glucosyl compound, whose apolar cavity can encapsulate a variety of hydrophobic guest molecules. Intrestingly, β-CD offer a functional and spatial scaffold for enzyme immobilization. The catalytic kinetics parameters of both free and immobilized laccases are investigated. The immobilized enzyme shows a weaker affinity to the substrate but vastly improved stability compared to the free form, indicating that the immobilization elicits a considerable descrease in the rate of irreversible activation of the enzyme. The biocatalytic membrane can be reused and retains up to 90% of the initial activity after five cycles. Inspired by the improved stability, the enzymatic membranes combined with thin-film composite membrane are furthered investigated in a cross-flow filtration system to achieve a continuous and efficient removal of mefenamic acid. The removal of mefenamic acid could be maintained at 90%. Our findings demonstrate that laccase-assisted electrospun materials have the potential for application in environmental protection processes.