Exploring Cu-substituted Zn nanoferrites: synthesis, structural, magnetic, morphological, and antibacterial properties

Abstract

The distinctiveness and variability of the ionic radius and oxidation states of the incorporated transition metals within the nanoferrite structure enable their integration into various technologies, including biomedical applications. This study aims to improve the influence of copper substitution on the structural, magnetic, morphological, and antimicrobial properties of zinc nanoferrites. Copper-substituted zinc nanoferrites were synthesized using the sol-gel auto-combustion method and thermal calcination at 425 °C. X-ray diffraction patterns detected the cubic phase of Zn_1−xCu_xFe₂O₄ (where x = 0.2, 0.4, and 0.6) powders. The obtained crystallite sizes are found to range from 23.883 to 24.718 nm. The pictures taken with a field emission scanning electron microscope show that the particle size grows from about 28.762 nm (x = 0.2) to about 39.025 nm (x = 0.6) with a copper substitution. FTIR of the studied samples shows two strong absorption bands around 600 and 400 cm⁻¹. This proves that a single-phase cubic spinel structure has formed. The magnetization investigations indicate increased saturation magnetization from 20.5482 to 58.7671 emu/g with increasing copper concentration. An elevation in mean Zeta potential values was noted with an augmentation in cu²⁺ substitution. It was also found that the hydrodynamic diameter size of the prepared nanoferrites increased from 243.2 to 314.2 nm with increasing copper substitution. Zn_1−xCu_xFe₂O₄ nanoferrites show promising inhibitory effects against four harmful bacteria: Streptococcus aureus, Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa. All copper treatments exhibited appropriate antibacterial properties. Nonetheless, the therapy with x = 0.2 proved the most efficacious. For E. coli (34.12 ± 0.28 mm), a Gram-negative bacterium, the optimal treatment was x = 0.2. In contrast, the most effective treatment for Staphylococcus aureus (34.11 ± 0.38 mm), a Gram-positive isolate, was x = 0.2 with 2 µg/mL. Our discovery paves the road for integrating copper-substituted zinc nanoferrites in biomedical applications, particularly against human pathogenic bacteria.

Graphical Abstract