Sandwich-like heterostructured nanomaterials immobilized laccase for the degradation of phenolic pollutants and boosted enzyme stability

Abstract

A novel magnetic 2D/2D heterogeneous structure MXene@NiFe-LDH@Fe₃O₄ was prepared for immobilization of laccase. In this work, two-dimensional MXene nanosheets with abundant surface functional groups were heterogeneously assembled with layered double hydroxide (LDH) by in situ co-precipitation method, and magnetic nanoparticle Fe₃O₄ with excellent biocompatibility and rapid separation of materials and substrates was introduced subsequently, and then silane coupling agent was coated on the surface of MXene@NiFe-LDH@Fe₃O₄. The functionalized MXene@NiFe-LDH@Fe₃O₄ was employed as a carrier to immobilize laccase from Trametes-Versicolor. The enzyme loading of the nanocomposite material is as high as 167.9 mg/g. Compared with free enzymes, the immobilized laccase showed a notable improvement in stability in a wider range of pHs (2.0–8.0), temperatures (25–60 °C), and organic solvent concentration (1–5 M). The reusability study suggested that after 7 cycles of repeated catalysis, the degradation efficiency could reach 55.5% for 2,4-dichlorophenol, 92.1% for bisphenol A and70.9% for pyrocatechol. The results provide a new carrier preparation strategy for the efficient immobilization of laccase.