Rational synthesis and characterization of temperature switching ZnFe2O4/ZnO nanocomposites used for anti-bacterial, anti-oxidant and seed germination properties

Abstract

Iron oxide and zinc oxide nanoparticles are particularly interesting because of their potent antibacterial and antioxidant properties. Here, we have created ZnFe₂O₄/ZnO nanocomposites using the co-precipitation process, calcined them at various temperatures (300–750 °C), and explored their various properties. With a rise in calcination temperature, the average crystal size grows and crystallinity increases while the dislocation density and microstrain are reduced. XRD patterns and SEM pictures confirm the formation of the existing desired composites. The distinct purity of the composites was demonstrated through EDAX spectra. At a concentration of 300 μg mL⁻¹, the nanocomposite calcined at 600 °C displays the highest anti-microbial action against Gram-positive bacterial strains like Bacillus subtilis and Bacillus megaterium and Gram-negative strains like Shigella flexneri, Salmonella typhimurium and Escherichia coli. Escherichia coli showed the highest susceptibility to IZ 3 with a mean zone of inhibition of 22.333 ± 0.577 mm. The overall findings of the synthesized nanocomposites, especially the low-temperature product, showed improved antioxidant activity against a wide range of free radicals and these nanocomposites showed the least activity against nitric oxide (higher IC 50 value) radicals and the highest activity against the ABTS⁺ (lower IC 50 value) radical. IZ 1 was also found to be effective in the enhancement of wheat seed germination and seedling growth, confirming its role in promoting plant growth (increase in carbohydrate, protein and chlorophyll content by 29.65%, 36.16% and 26.66%, respectively, over the control).