Bactericidal Activity of Copper-Deposited TiO2 Thin Film under Weak UV Light Illumination

The bactericidal activity of copper-deposited titanium dioxide thin film (Cu/TiO2) was investigated under very weak ultraviolet (UV) light illumination. To elucidate the roles of the film photocatalyst and the deposited copper in the bactericidal activity, cells from a copper-resistant Escherichia c...

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Bibliographic Details
Published in:Environmental science & technology 2003-10, Vol.37 (20), p.4785-4789
Main Authors: Sunada, Kayano, Watanabe, Toshiya, Hashimoto, Kazuhito
Format: Article
Language:English
Subjects:
Applied sciences
Bacteria
Biological and physicochemical phenomena
Coloring Agents - pharmacology
Copper
Copper - chemistry
Drinking water and swimming-pool water. Desalination
Escherichia coli
Exact sciences and technology
Membranes, Artificial
Natural water pollution
Oxidation
Photocatalysis
Photochemistry
Pollution
Survival Analysis
Thin films
Titanium - pharmacology
Ultraviolet radiation
Ultraviolet Rays
Water Purification - methods
Water treatment and pollution
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Summary:The bactericidal activity of copper-deposited titanium dioxide thin film (Cu/TiO2) was investigated under very weak ultraviolet (UV) light illumination. To elucidate the roles of the film photocatalyst and the deposited copper in the bactericidal activity, cells from a copper-resistant Escherichia coli (E. coli) strain were utilized. A decrease in survival rate was not observed with the copper-resistant cells under dark conditions, but when illuminated with a very weak UV intensity of 1 μW/cm2, the survival rate decreased, suggesting photocatalytic bactericidal activity. The decay curve of survival on the Cu/TiO2 film under very weak UV light illumination consisted of two steps, similar to the survival change of normal E. coli on TiO2 films under rather strong UV illumination. The first step is due to the partial decomposition of the outer membrane in the cell envelope by a photocatalytic process, followed by permeation of the copper ions into the cytoplasmic membrane. The second step is due to a disorder of the cytoplasmic membrane caused by the copper ions, which results in a loss of the cell's integrity. These processes explain why the Cu/TiO2 film system shows an effective bactericidal activity even under very weak UV light illumination.
ISSN:0013-936X
1520-5851
DOI:10.1021/es034106g