# Efficient Conversion of 5-Hydroxymethylfurfural to 2,5-Furandicarboxylic Acid by the Magnetic Laccase Nanoflowers-2,2,6,6-Tetramethylpiperidin-1-Oxyl System

## TL;DR

Scientists created a magnetic enzyme system that efficiently converts a biomass compound into a valuable chemical, with high stability and reusability.

## Contribution

A novel magnetic laccase nanoflower system is developed for efficient and reusable conversion of HMF to FDCA.

## Key findings

- MLac-NFs achieved 63.4 U mg−1 catalytic activity with high stability over 30 days.
- The system converted HMF to FDCA completely within 24 hours using 30 mM TEMPO.
- MLac-NFs retained 53.26% FDCA yield after six reuse cycles due to magnetic recovery.

## Abstract

Aiming to address the key challenges of poor enzyme stability, difficult recovery, and difficult synergistic optimization of catalytic efficiency in high-value conversion of biomass, this study utilizes mineralization self-assembly technology to combine laccase with Fe3O4@SiO2-PMIDA-Cu2+ composite, constructing magnetic laccase nanoflower (MLac-NFs) materials with a porous structure and superparamagnetism. This synthetic material can efficiently catalyze the selective oxidation of 5-hydroxymethylfurfural (HMF) to 2,5-furandicarboxylic acid (FDCA). The characterization results indicated that MLac-NFs exhibit optimal catalytic activity (63.4 U mg−1) under conditions of pH 6.0 and 40 °C, with significantly enhanced storage stability (retaining 94.26% of activity after 30 days of storage at 4 °C). Apparent kinetic analysis reveals that the substrate affinity and maximum reaction rate of MLac-NFs were increased by 38.3% and 439.6%, respectively. In the laccase–mediator system (LMS), MLac-NFs mediated by 30 mM TEMPO could achieve complete conversion of HMF to FDCA within 24 h. Moreover, due to the introduction of magnetic nanoparticles, the MLac-NFs could be recovered and reused via an external magnetic field, maintaining 53.26% of the initial FDCA yield after six cycles.