Facile Synthesis of TiO2 Nanoparticles of Different Crystalline Phases and Evaluation of Their Antibacterial Effect Under Dark Conditions Against E. coli

In this paper we report the antibacterial activity in the absence of UV–Vis irradiation of TiO 2 nanoparticles, in amorphous, anatase and rutile phases, obtained by the sol–gel process, on Escherichia coli strains. The synthesized TiO 2 powders were characterized using X-ray diffraction (XRD), IR spectroscopy and UV–Vis absorption, as well as scanning and transmission electron microscopies. The XRD results showed that the solids were amorphous up to a temperature of 350 °C and that when subjected to heat treatments of higher temperatures, anatase crystalline phases were obtained, at 450 °C, and rutile type at temperatures higher than 770 °C, with a sub-micron particle size (