Immobilization of Ficin Enzyme onto Surface-Modified Iron Oxide Nanoparticles: Characterization and Catalytic Activity

Biocatalytic performance of immobilized ficin onto silica-coated iron oxide magnetic nanoparticles (MNPs) was examined. FTIR study indicated the successful immobilization of ficin onto silica-coated MNPs. The MNPs were synthesized by an ultrasonic-assisted sol-gel method, resulting in coarse silica-coated MNPs with an amorphous or nanocrystalline phase. Results showed that the affinity of ficin to the substrate decreased due to the immobilization. However, the immobilized ficin exhibited enhanced stability and catalytic activity, with a wider pH range and higher thermal stability compared to free ficin. The optimum pH for immobilized ficin activity was found to be shifted from 7.0 to 6.0, making it a suitable candidate for slight acidic conditions. After five days of storage, immobilized ficin retained its initial activity, while free ficin showed a 30% decrease in activity. The immobilized ficin also exhibited a substantially higher activity than its free form after multiple cycles of usage. These findings suggest that immobilized ficin onto silica-coated iron oxide MNPs is a promising candidate for biocatalysis and industrial processes in a wide range of temperature and solutions with high reusability and stability.