title: The effects of hydroxyl groups on Ca adsorption on rutile surfaces: a first-principles study.
abstract: Hydroxyl groups on titanium surfaces have been believed to play an important role in absorbing Ca in solution, which is crucial in the formation of bioactive calcium phosphates both in vitro and in vivo. CASTEP, a first-principles density functional theory (DFT) code, was employed to investigate Ca adsorption on various rutile (110) surfaces in order to clarify how hydroxyl groups effect Ca adsorption. The surfaces modeled in the present study include a bare rutile (110) surface, a hydroxylated rutile (110) surface, an oxidized rutile (110) surface, and a rutile (110) surface bonded with mixed OH groups and water. The results reveal that not all OH groups favors to attract Ca adsorption and loosely bonded OH and water on a rutile surface actually combine with Ca during adsorption. An oxidized rutile surface has the highest ability to attract Ca atoms, which partially explains that alkali-treated Ti surfaces could induce hydroxyapatite formation in alkaline environments.
authors.affiliation: Department of Mechanical Engineering, Hong Kong University of Science and Technology, Kowloon, Hong Kong, China. luxiong_2004@163.com
authors.forename: Xiong
authors.initials: X
authors.lastname: Lu
authors.forename: Hong-ping
authors.initials: HP
authors.lastname: Zhang
authors.forename: Yang
authors.initials: Y
authors.lastname: Leng
authors.forename: Liming
authors.initials: L
authors.lastname: Fang
authors.forename: Shuxin
authors.initials: S
authors.lastname: Qu
authors.forename: Bo
authors.initials: B
authors.lastname: Feng
authors.forename: Jie
authors.initials: J
authors.lastname: Weng
authors.forename: Nan
authors.initials: N
authors.lastname: Huang
mesh_terms: D000327:Adsorption / Q000187:drug effects; D002118:Calcium / Q000737:chemistry / Q000493:pharmacokinetics*; D019295:Computational Biology; D006882:Hydroxyapatites / Q000378:metabolism; D017665:Hydroxyl Radical / Q000494:pharmacology*; D008422:Materials Testing; D008954:Models, Biological; D008958:Models, Molecular; D008962:Models, Theoretical; D010084:Oxidation-Reduction; D013499:Surface Properties / Q000187:drug effects; D014025:Titanium / Q000737:chemistry / Q000378:metabolism*; D014867:Water / Q000494:pharmacology
chemical_list: D006882:Hydroxyapatites; D014867:Water; C009495:titanium dioxide; D017665:Hydroxyl Radical; D014025:Titanium; D002118:Calcium