Optimization of enzyme immobilization on functionalized magnetic nanoparticles for laccase biocatalytic reactions

Magnetic materials can be easily separated from reaction media by application of an external magnetic field. On the other hand, nanomaterials are innovative platforms which present high surface-to-volume ratio allowing low mass transfer limitations. Magnetic nanoparticles (MNPs) can be considered as supports for catalysts immobilization since they greatly improve their reutilization avoiding the need of energy and time consuming centrifugation steps. Enzyme immobilization processes providing high biocatalysts stability are very desirable due to enzyme associated costs. Laccase (EC 1.10.3.2), an oxidative enzyme with numerous industrial applications, requires new technologies for its immobilization in order to improve its biocatalytic activity with reduced costs. In this study, the conditions of laccase immobilization on magnetic nanoparticles were optimised by box-Benhken experimental design. Laccase was successfully bound on functionalized MNPs according to FTIR spectroscopy. At the optimal conditions, the highest recovery activity of immobilized laccase reached 36.3 U/L. Compared to free laccase, thermal stability of immobilized laccase was improved. The immobilized laccase was able to retain above 75% of activity after 6 consecutive cycles of reaction. MNPs can be used for immobilization of important enzymes at industrial level, as these nanomaterials can improve both enzymatic application properties and easy and fast recovery for reutilization.