Direct binding and characterization of laccase onto iron oxide nanoparticles

Iron oxide nanoparticles (IONPs) exhibit unique magnetic properties and possess a high surface-to-volume ratio, making them ideal candidates for the conjugation of substances, including enzymes. Laccase (EC 1.10.3.2), an oxidative enzyme with diverse applications, presents an opportunity for enhancing stability and reusability through innovative immobilization techniques, thus reducing overall process costs. In this study, we employed a direct binding procedure via carbodiimide activation to conjugate laccase onto IONPs synthesized using thermal chemical coprecipitation. Stabilization of the nanoparticles was achieved using thioglycerol and polyvinyl alcohol (PVA) as capping agents. Characterization of the synthesized nanoparticles was conducted using UV-spectroscopy, Fourier transform infrared spectroscopy (FTIR), x-ray diffraction, scanning electron microscopy, and energy dispersive x-ray spectroscopy. FTIR spectroscopy analysis confirmed successful laccase binding to magnetic nanoparticles, with binding efficiencies of 90.65% and 73.02% observed for thioglycerol and PVA capped IONPs, respectively. Furthermore, the conjugated enzyme exhibited remarkable stability, retaining nearly 50% of its initial activity after 20 reuse cycles. This research demonstrates that immobilizing laccase onto IONPs enhances its activity, stability, and reusability, with the potential for significant cost savings and expanded applications in various fields.