Immobilization of lactoperoxidase on Fe₃O₄ magnetic nanoparticles with improved stability

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).

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 K_m values of free LPO and LPO immobilized on Fe₃O₄ were 53.19, 72.46 mM and their V_max 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.

According to the present results, Fe₃O₄ magnetic nanoparticles are suitable for the immobilization of LPO.