Composition-dependent antibacterial activity of porous multicomponent transition metal oxides

Multicomponent transition metal oxides (MTMOs) have attracted increasing interest as multifunctional materials; however, the relationships between their composition, structure, and antibacterial properties remain insufficiently understood. In this work, the structural, morphological, and antibacterial properties of three multicomponent transition metal oxide systems, MTMO_1 = (TiZrHfNbTa)O₁₁, MTMO_2 = (WTaVHfFe)₂O₂₁, and MTMO_3 = (WTaVHfTi)O₁₁, were investigated. The materials were synthesized by a coprecipitation route and characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and photoluminescence analysis. XRD revealed that all synthesized materials consist of multiphase crystalline oxide systems rather than single-phase high-entropy oxides, while SEM revealed homogeneous porous morphologies, and EDS mapping indicated a homogeneous surface distribution of the constituent elements within the analyzed regions. Photoluminescence measurements demonstrated the ability of all samples to generate hydroxyl radicals under irradiation, indicating the formation of reactive oxygen species. The antibacterial activity of the synthesized oxides was evaluated against Escherichia coli and Bacillus subtilis. All investigated materials inhibited bacterial growth, with stronger activity observed against B. subtilis. The MTMO_2 sample, a novel material among the multicomponent metal oxide systems, exhibited the strongest inhibition of bacterial proliferation. The enhanced antibacterial activity of MTMO_2 appears to be composition-dependent and may arise from the combined effects of its multiphase composition, surface chemistry, and surface redox properties. These findings demonstrate the potential of porous multicomponent transition metal oxides as promising candidates for antibacterial materials and provide insight into the relationship between composition, structure, surface properties, and antibacterial activity.