Hydrothermally Assisted Fabrication of TiO 2 -Fe 3 O 4 Composite Materials and Their Antibacterial Activity.

The TiO ₂ -Fe ₃ O ₄ composite materials were fabricated via the hydrothermal-assisted technique. It was determined how the molar ratio of TiO ₂ to Fe ₃ O ₄ influences the crystalline structure and morphology of the synthesized composite materials. The effect of the molar ratio of components on the antibacterial activity was also analyzed. On the basis of XRD patterns for the obtained titanium(IV) oxide-iron(II, III) oxide composites, the two separate crystalline forms-anatase and magnetite -were observed. Transmission electron microscopy revealed particles of cubic and tetragonal shape for TiO ₂ and spherical for Fe ₃ O ₄ . The results of low-temperature nitrogen sorption analysis indicated that an increase in the iron(II, III) oxide content leads to a decrease in the BET surface area. Moreover, the superparamagnetic properties of titanium(IV) oxide-iron(II, III) oxide composites should be noted. An important aim of the work was to determine the antibacterial activity of selected TiO ₂ -Fe ₃ O ₄ materials. For this purpose, two representative strains of bacteria, the Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus , were used. The titanium(IV) oxide-iron(II, III) oxide composites demonstrated a large zone of growth inhibition for both Gram-positive and Gram-negative bacteria. Moreover, it was found that the analyzed materials can be reused as antibacterial agents in three consecutive cycles with good results.