Antibacterial activity of TiO2, CuO, and CuO/TiO2 nanomaterials and their potential application on construction surfaces

Abstract

In the construction sector, diverse microorganisms have the ability to form biofilms on constructed surfaces affecting the health of the inhabitants. In this sense, diverse nanomaterials of titanium oxide (TiO₂), copper oxide (CuO), and CuO/TiO₂ were synthesized by the sol–gel method, Pechini method, and a mechanical synthesismethod. The influence of the thermal treatment (425–575 °C) on the formation of crystalline phases in the compounds, as well as their antibacterial activity on Escherichia coli and Staphylococcus aureus was investigated. X-ray diffraction technique(XRD) results displayed the formation of anatase, rutile, and tenorite phases on the as-synthesized samples. The Rietveld refinement analysis estimated the composition of phases, as well as the crystal size for each crystalline phase in the specimens (from ~ 16 up to ~ 165 nm). The Fourier Transform Infrared (FTIR) spectroscopy showed the characteristic M–O vibrations of the TiO₂ and CuO compounds. No relevant signals of the precursors were detected. RAMAN spectroscopy confirmed the formation of anatase and rutile phases in the TiO₂ nanomaterials. Scanning electron microscopy (SEM) micrographs revealed the morphology of the compounds and dynamic light scattering (DLS) and electrophoretic light scattering (ELS) analysis showed the particle sizes (from ~ 225 to ~ 750 nm) with Z-potentials between − 11 mV and − 21 mV. Nitrogen adsorption/desorption isotherms results revealed pore sizes between ~ 0.2 and ~ 12.4 nm as well as surface area values up to ~ 158 m²/g. Finally, the minimum inhibitory concentration (MIC) evaluation revealed that the compounds that CuO-based compounds exhibit good antibacterial activity, with MIC values starting at 0.625 mg/mL, and the CuO/TiO₂ sample at 475 °C showed the highest efficacy at 0.312 mg/mL. These results suggest that the as-synthesized compounds could be used as disinfection agents on construction surfaces and in sick buildings, as well as they could to reduce the health risks associated with exposure to bacteria.