Immobilization of lactoperoxidase on Fe3O4 magnetic nanoparticles with improved stability.

OBJECTIVE: The study aimed to develop a facile and effectual method to increase the stability of lactoperoxidase (LPO) by using its immobilization on Fe3O4 magnetic nanoparticles (Fe3O4 MNPs). RESULTS: The successful immobilization of LPO on Fe3O4 MNPs was confirmed by using Fourier transform infrared spectroscopy (FT-IR) and field emission scanning electron microscopy (FE-SEM). The Km values of free LPO and LPO immobilized on Fe3O4 were 53.19, 72.46 mM and their Vmax values were 0.629, 0.576 µmol/mL min respectively. The overall results indicated that the stability of the immobilized LPO was significantly improved compared to free LPO. The LPO immobilized on Fe3O4 (LPO- Fe3O4) retained 28% of the initial activity within 30 days at 25 °C whereas the free enzyme lost its activity after 7 days at the same temperature. Moreover, evaluation of the thermal stability of LPO at 75 °C determined the conservation of 19% of the initial activity of LPO in the LPO- Fe3O4 sample after 60 min whereas the free enzyme lost its activity after 5 min. CONCLUSIONS: According to the present results, Fe3O4 magnetic nanoparticles are suitable for the immobilization of LPO.