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International Journal of Photoenergy
Volume 2014, Article ID 785037, 17 pages
http://dx.doi.org/10.1155/2014/785037
Research Article

TiO2 and TiO2-Doped Films Able to Kill Bacteria by Contact: New Evidence for the Dynamics of Bacterial Inactivation in the Dark and under Light Irradiation

1Ecole Polytechnique Fédérale de Lausanne, EPFL-SB-ISIC-GPAO, Station 6, 1015 Lausanne, Switzerland
2Ecole Polytechnique Fédérale de Lausanne, EPFL-SB-IPMC-LNNME, Bat PH, Station 3, 1015 Lausanne, Switzerland

Received 17 January 2014; Accepted 18 March 2014; Published 5 May 2014

Academic Editor: Cathy McCullagh

Copyright © 2014 John Kiwi et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

This paper addresses recent developments in the design, evaluation, and characterization of flexible, uniform polyethylene-TiO2 (PE-TiO2), TiO2-In2O3, and TiO2-polyester able to inactivate bacteria under band gap irradiation and in the dark. The preparation of these bactericide films by sol-gel or by sputtering techniques is reported. The E. coli loss of viability kinetics under low intensity and actinic light is evaluated. Evidence for kinetics of the major steps leading to bacterial disinfection in the dark is presented by electron microscopy (TEM). The film surface properties were characterized by surface techniques like EM, DRS, XPS, ATR-IR, CA, AFM, XRD, and XRF. The surface characterization allows the correlation of the film surface morphology with the self-disinfection performance. The events taking place at the cell wall leading to bacterial inactivation when in contact with the TiO2 films are presented and the steps related to the bond stretching preceding bond scission identified by ATR-IR.