Role of visible light-activated photocatalyst on the reduction of anthrax spore-induced mortality in mice

PLoS One. 2009;4(1):e4167. doi: 10.1371/journal.pone.0004167. Epub 2009 Jan 9.


Background: Photocatalysis of titanium dioxide (TiO(2)) substrates is primarily induced by ultraviolet light irradiation. Anion-doped TiO(2) substrates were shown to exhibit photocatalytic activities under visible-light illumination, relative environmentally-friendly materials. Their anti-spore activity against Bacillus anthracis, however, remains to be investigated. We evaluated these visible-light activated photocatalysts on the reduction of anthrax spore-induced pathogenesis.

Methodology/principal findings: Standard plating method was used to determine the inactivation of anthrax spore by visible light-induced photocatalysis. Mouse models were further employed to investigate the suppressive effects of the photocatalysis on anthrax toxin- and spore-mediated mortality. We found that anti-spore activities of visible light illuminated nitrogen- or carbon-doped titania thin films significantly reduced viability of anthrax spores. Even though the spore-killing efficiency is only approximately 25%, our data indicate that spores from photocatalyzed groups but not untreated groups have a less survival rate after macrophage clearance. In addition, the photocatalysis could directly inactivate lethal toxin, the major virulence factor of B. anthracis. In agreement with these results, we found that the photocatalyzed spores have tenfold less potency to induce mortality in mice. These data suggest that the photocatalysis might injury the spores through inactivating spore components.

Conclusion/significance: Photocatalysis induced injuries of the spores might be more important than direct killing of spores to reduce pathogenicity in the host.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Anti-Bacterial Agents / pharmacology
  • Antigens, Bacterial / metabolism
  • Bacillus anthracis / pathogenicity
  • Bacillus anthracis / radiation effects*
  • Bacillus subtilis / metabolism
  • Bacterial Toxins / antagonists & inhibitors*
  • Bacterial Toxins / metabolism
  • Light*
  • Mice
  • Mice, Inbred C57BL
  • Photosensitizing Agents / pharmacology*
  • Spores, Bacterial / pathogenicity
  • Spores, Bacterial / radiation effects
  • Titanium / pharmacology*


  • Anti-Bacterial Agents
  • Antigens, Bacterial
  • Bacterial Toxins
  • Photosensitizing Agents
  • anthrax toxin
  • titanium dioxide
  • Titanium