Retraction Note to: Immobilization of lactoperoxidase on ZnO nanoparticles with improved stability.

The Editors have retracted this article [1] because significant parts of the text were duplicated from previously published articles by Ziyae et al. 2019 [2], Movahedi et al. 2019 [3] and Ziyae et al. 2018 [4]. The authors have not responded to any correspondence regarding this retraction.

Immobilization of lactoperoxidase on ZnO nanoparticles with improved stability.

OBJECTIVES: The study aimed to develop a facile and effectual method to enhance the stability of lactoperoxidase (LPO) by immobilizing it on ZnO Nanoparticles (ZnO NPs). RESULTS: The successful immobilization of LPO on ZnO NPs 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 ZnO were 53.19, 89.28 mM and their Vmax values were 0.629, 0.46 µmol/mL min, respectively. The overall results showed that the stability of the immobilized LPO was significantly improved compared to free LPO. The LPO immobilized on ZnO (LPO-ZnO) retained 18% 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 12% of the initial activity of LPO in the LPO-ZnO sample after 60 min whereas the free enzyme lost its activity after 5 min. CONCLUSIONS: According to the present results, ZnO nanoparticles are suitable for the immobilization of LPO.

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.