Starch-Based Lactoperoxidase Immobilization on Metal Oxide Nanofılm: A Novel Approach for the Synthesis,...

This study aims to develop a novel method for immobilizing lactoperoxidase (LPO) on starch-based metal oxide bionanofilms and evaluate its structural and antibacterial properties. LPO is an enzyme with broad-spectrum antimicrobial activity, and its stabilization is crucial for industrial applications. In this research, LPO was successfully immobilized onto starch and starch-based metal oxide films (starch@magnesium oxide (MgO), zinc oxide (ZnO), and copper oxide (CuO)) via surface adsorption and entrapment techniques. The immobilization was confirmed by Fourier transform infrared spectroscopy (FT-IR), x-ray diffraction (XRD), and field emission scanning electron microscopy (FE-SEM). The optimal pH for both free and immobilized LPO was determined to be 6. Although the free enzyme exhibited maximum activity at 40°C, the immobilized enzyme demonstrated increased thermal stability, maintaining optimal activity at 60°C. Furthermore, the initial activity of the immobilized LPO was 16.5%-19% after 60 min at 60°C, whereas the free enzyme completely lost activity within 5 min. Storage stability tests revealed that immobilized LPO maintained 27.7%-39.6% of its initial activity for 21 days at 4°C and 25°C, whereas 95% of the free LPO was lost under the same conditions. The antibacterial properties of the prepared bionanofilms' were evaluated against gram-positive and gram-negative bacteria. The starch@ZnO/LPO film exhibited significant antibacterial activity among the tested films. These findings indicate that the immobilization of LPO onto starch-based metal oxide bionanofilms enhances its stability and antibacterial efficiency, making it a promising candidate for biomedical and industrial applications.