title: Photocatalytic inhibition of microbial adhesion by anodized titanium.
abstract: Biofouling is one of the concerns in the use of titanium for seawater cooled condensers of power plants. Earlier studies have shown that anodized titanium and its alloys with a thin film of anatase (TiO(2)) on its surface can inhibit attachment of Pseudomonas sp. when illuminated with near-UV light (350 - 380 nm). In the present study, a comparison of the photocatalytic inhibition of microbial attachment on titanium surfaces anodized at different voltages was carried out. Thin films of anatase of varying thickness were produced on titanium grade-2 by anodizing in dilute orthophosphoric acid solution at 30 V, 50 V and 100 V. The photocatalytic efficiency of these anodized surfaces was measured by the methylene blue degradation method. The anodised surfaces were exposed to liquid cultures of Gram-negative Pseudomonas sp., Gram-positive Micrococcus sp. and to a mixed algal culture. Photocatalytic inhibition of microbial attachment was maximum on the titanium surface anodized at 30 V, followed by the surface anodized at 50 V and then at 100 V. The photocatalytic inhibition of microbial attachment was also found to be dependent on the cell wall characteristics of the organism. The Gram-negative Pseudomonas sp. with a lipoproteinaceous outer membrane was the most susceptible to the photocatalytic effect, while the Gram-positive Micrococcus sp. with peptidoglycan cell wall showed moderate susceptibility and the algae with siliceous cell wall showed no susceptibility at all.
authors.affiliation: Corrosion Science and Technology Division, Materials Characterization Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102, India.
authors.forename: Judy
authors.initials: J
authors.lastname: Gopal
authors.forename: R P
authors.initials: RP
authors.lastname: George
authors.forename: P
authors.initials: P
authors.lastname: Muraleedharan
authors.forename: H S
authors.initials: HS
authors.lastname: Khatak
mesh_terms: D000900:Anti-Bacterial Agents / Q000737:chemistry / Q000494:pharmacology; D001422:Bacterial Adhesion / Q000187:drug effects*; D002384:Catalysis / Q000187:drug effects; D002448:Cell Adhesion / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D002734:Chlorophyll / Q000378:metabolism; D056890:Eukaryota / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D008837:Micrococcus / Q000166:cytology / Q000187:drug effects; D010100:Oxygen / Q000737:chemistry; D010777:Photochemistry; D011549:Pseudomonas / Q000166:cytology* / Q000187:drug effects*; D014025:Titanium / Q000737:chemistry* / Q000494:pharmacology*
chemical_list: D000900:Anti-Bacterial Agents; D002734:Chlorophyll; D014025:Titanium; D010100:Oxygen