Laccase-loaded functionalized graphene oxide assemblies with improved biocatalytic properties and decolorization performance

Immobilization is a fascinating subject that helps in designing biocatalysts, their economic 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 immobilization 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 °C retaining over 40% of its relative activity, while the free enzyme kept only 5.2% under identical conditions. After immobilization, the K_m value of TvL was decreased, and a V_max 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 decolorizing potential of the FGO–TvL illustrate its potential as a green and eco-friendly nano-biocatalytic system for sustainable development bioremediation applications.