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J Photochem Photobiol B. 2015 Jan;142:178-85. doi: 10.1016/j.jphotobiol.2014.12.010. Epub 2014 Dec 17.

Photocatalytic antibacterial activity of nano-TiO2 (anatase)-based thin films: effects on Escherichia coli cells and fatty acids.

Author information

1
Institute of Physics, University of Tartu, Ravila 14c, 50411 Tartu, Estonia; Estonian Nanotechnology Competence Center, Ravila 14c, 50411 Tartu, Estonia. Electronic address: urmas.joost@ut.ee.
2
Laboratory of Environmental Toxicology, National Institute of Chemical Physics and Biophysics, Akadeemia tee 23, 12618 Tallinn, Estonia; Department of Chemistry, Tallinn University of Technology, Akadeemia tee 15, 12618 Tallinn, Estonia.
3
Institute of Physics, University of Tartu, Ravila 14c, 50411 Tartu, Estonia; Laboratory of Environmental Toxicology, National Institute of Chemical Physics and Biophysics, Akadeemia tee 23, 12618 Tallinn, Estonia.
4
Laboratory of Environmental Toxicology, National Institute of Chemical Physics and Biophysics, Akadeemia tee 23, 12618 Tallinn, Estonia.
5
Institute of Physics, University of Tartu, Ravila 14c, 50411 Tartu, Estonia.
6
Institute of Physics, University of Tartu, Ravila 14c, 50411 Tartu, Estonia; Estonian Nanotechnology Competence Center, Ravila 14c, 50411 Tartu, Estonia.
7
Laboratory of Environmental Toxicology, National Institute of Chemical Physics and Biophysics, Akadeemia tee 23, 12618 Tallinn, Estonia. Electronic address: angela.ivask@kbfi.ee.

Abstract

Titanium dioxide is a photocatalyst with well-known ability to oxidise a wide range of organic contaminants as well as to destroy microbial cells. In the present work TiO2 nanoparticles with high specific surface area (150m(2)/g) were used to prepare nanostructured films. The TiO2 nanoparticle-based film in combination with UV-A illumination with intensity (22W/m(2)) comparable to that of the sunlight in the UV-A region was used to demonstrate light-induced antibacterial effects. Fast and effective inactivation of Escherichia coli cells on the prepared thin films was observed. Visualization of bacterial cells under scanning electron microscopy (SEM) showed enlargement of the cells, distortion of cellular membrane and possible leakage of cytoplasm after 10min of exposure to photoactivated TiO2. According to the plate counts there were no viable cells as early as after 20min of exposure to UV-A activated TiO2. In parallel to effects on bacterial cell viability and morphology, changes in saturated and unsaturated fatty acids - important components of bacterial cell membrane-were studied. Fast decomposition of saturated fatty acids and changes in chemical structure of unsaturated fatty acids were detected. Thus, we suggest that peroxidation and decomposition of membrane fatty acids could be one of the factors contributing to the morphological changes of bacteria observed under SEM, and ultimately, cell death.

[Indexed for MEDLINE]

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