Laccase-loaded Functionalized Graphene Oxide Assemblies with Improved Biocatalytic Properties and Decolorization Performance

Immobilization is a fascinating subject that helps in designing biocatalysts, their eco-nomic reuse, and the development of biocatalysis-based bioprocesses. The unique properties of graphene oxide, such as hydrophobicity, surface area, high mechanical strength, conductivity, and ease in tunability, render this material as a robust support matrix for enzyme immobilization. This work covalently immobilized laccase from Trametes versicolor (TvL) onto functionalization graphene oxide (FGO) to synthesize FGO-TvL nanoassemblies. Scanning electron microscopy and Fourier transform infrared spectroscopy techniques confirmed the morphological properties and adequate immobi-lization of laccase onto FGO. At an optimal laccase concentration of 5 mg/mL, the utmost relative activity of FGO-TvL and immobilization amount of laccase was 96.87% and 30.0 mg/g, respectively. The pH optimum of FGO-TvL was slightly displaced towards the neutral region. In contrast to the free enzyme, the FGO-TvL nanoassemblies presented improved thermal stability at 70 degrees C retaining over 40% of its relative activity, while the free enzyme kept only 5.2% under identical conditions. After immobilization, the Km value of TvL was decreased, and a Vmax value was increased. Immobilized FGO- TvL efficiently decolorizes different textile industry effluents in the range of 71.25 to 88.65%. Considering the noteworthy biocatalytic, thermal stability, and effluent decol-orizing potential of the FGO-TvL illustrate its potential as a green and eco-friendly nano-biocatalytic system for sustainable development bioremediation applications. (c) 2021 Elsevier B.V. All rights reserved.