In-situ fabrication of functionalized starch magnetic nanoparticles for immobilization of laccase

Abstract

Surface chemistry of magnetic nanoparticles (MNP) is crucial to provide a strong protein-support interaction for the immobilization process. The stability and biocompatibility of the MNP can be structurally enhanced by integrating with organic materials. In this study, MNP from KI/FeCl3 has successfully synthesized that showed a stronger magnetic strength (72.5 emu/g) compared to common standard precursors, FeCl2/FeSO4 (< 60 emu/g). The synthesized MNP was then incorporated via in-situ with functionalized starch; dialdehyde (DAS-MNP), thiol (TS-MNP), and carboxymethyl (CMS-MNP) for Laccase (Lac) immobilization. From docking analysis, CMS-MNP portrayed the highest binding affinity and interacted with highest number of Lac amino acids residues compared to DAS-and TS-MNP. Aligned with this result, immobilized Lac using CMS-MNP achieved the highest recovery activity (80.3%), highly stable at 75 °C for 4 h, and retained more than 50% of its initial activity after 10 cycles. The CMS-MNP-Lac also showed about the same catalytic efficiency with free Lac (1.19 and 1.58 mM-1s-1, respectively). It is demonstrated that the functional group of the starch-MNP plays a crucial role in attaining a stable immobilized Lac. Therefore, yield a promising biocatalyst to be applied in various fields.