title: Bacterial and osteoblast behavior on titanium, cobalt-chromium alloy and stainless steel treated with alkali and heat: a comparative study for potential orthopedic applications.
abstract: OBJECTIVE
  Anatase-modified titanium (Ti) substrates have been found to possess antibacterial properties in the absence of ultraviolet irradiation, but the mechanism is not known. We hypothesize that this is due to the bactericidal effects of reactive oxygen species (ROS) generated by the surface anatase.
  
  
  METHODS
  Alkali and heat treatment was used to form anatase on Ti surface. The generation of ROS, and the behavior of bacteria and osteoblasts on the anatase-modified Ti were investigated. Cobalt-chrome (Co-Cr) alloys and stainless steel (SS) were similarly treated with alkali and heat, and their surface properties and effects on bacteria and osteoblasts were compared with the results obtained with Ti.
  
  
  RESULTS
  The anatase-functionalized Ti substrates demonstrated significant bactericidal effects and promoted apoptosis in osteoblasts, likely a result of ROS generated by the anatase. The alkali and heat-treated Co-Cr and SS substrates also reduced bacterial adhesion but were not bactericidal. This effect is likely due to an increase in hydrophilicity of the surfaces, and no significant ROS were generated by the alkali and heat-treated Co-Cr and SS substrates. The treated Co-Cr and SS substrates did not induce significant apoptosis in osteoblasts, and thus with these properties, they may be promising for orthopedic applications.
authors.affiliation: Department of Chemical and Biomolecular Engineering, National University of Singapore, Kent Ridge 117576, Singapore. Electronic address: huxuefeng@nus.edu.sg.
authors.forename: Xuefeng
authors.initials: X
authors.lastname: Hu
authors.affiliation: Department of Chemical and Biomolecular Engineering, National University of Singapore, Kent Ridge 117576, Singapore; NUS Graduate School for Integrative Sciences and Engineering, National University of Singapore, Kent Ridge 117576, Singapore. Electronic address: chenkg@nus.edu.sg.
authors.forename: Koon Gee
authors.initials: KG
authors.lastname: Neoh
authors.affiliation: NUS Graduate School for Integrative Sciences and Engineering, National University of Singapore, Kent Ridge 117576, Singapore. Electronic address: a0068200@nus.edu.sg.
authors.forename: Jieyu
authors.initials: J
authors.lastname: Zhang
authors.affiliation: Department of Chemical and Biomolecular Engineering, National University of Singapore, Kent Ridge 117576, Singapore; NUS Graduate School for Integrative Sciences and Engineering, National University of Singapore, Kent Ridge 117576, Singapore. Electronic address: cheket@nus.edu.sg.
authors.forename: En-Tang
authors.initials: ET
authors.lastname: Kang
mesh_terms: D000468:Alkalies / Q000737:chemistry; D000900:Anti-Bacterial Agents / Q000737:chemistry* / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects; D001422:Bacterial Adhesion / Q000187:drug effects; D001672:Biocompatible Materials / Q000737:chemistry* / Q000494:pharmacology; D002858:Chromium Alloys / Q000737:chemistry* / Q000494:pharmacology; D004926:Escherichia coli / Q000187:drug effects / Q000254:growth & development; D006358:Hot Temperature; D006801:Humans; D010006:Osteoblasts / Q000166:cytology / Q000187:drug effects; D017382:Reactive Oxygen Species / Q000737:chemistry; D013193:Stainless Steel / Q000737:chemistry* / Q000494:pharmacology; D013211:Staphylococcus aureus / Q000187:drug effects / Q000254:growth & development; D013499:Surface Properties; D014025:Titanium / Q000737:chemistry* / Q000633:toxicity
chemical_list: D000468:Alkalies; D000900:Anti-Bacterial Agents; D001672:Biocompatible Materials; D002858:Chromium Alloys; D017382:Reactive Oxygen Species; D013193:Stainless Steel; C009495:titanium dioxide; D014025:Titanium
keywords: Alkali; Anatase; Apoptosis; Bacterial adhesion; Bactericidal effects; Heat treatment; Reactive oxygen species