title: Pre-conditioning and dual constant composition dissolution kinetics of pulsed laser deposited hydroxyapatite thin films on silicon substrates.
abstract: The kinetics of dissolution of pulsed laser deposited crystalline and amorphous thin films of hydroxyapatite on silicon substrates were measured at 37 degrees C and a pH value of 6.5 using the dual constant composition method. Solutions in which the pulsed laser deposited films were pre-conditioned (0.15 M NaCl) remained undersaturated or slightly supersaturated with respect to hydroxyapatite after equilibrium was reached, indicating only a very small coating release and the absence of re-precipitation on the surfaces. The amorphous films released more calcium and phosphate during pre-conditioning than the more crystalline films. Dual constant composition dissolution rates decreased as film crystallinity increased. The film with the lowest dissolution rate (approximately one sixth that of a crystalline film deposited using a hydroxyapatite powder target) was fabricated using a human tooth as the laser target. During pre-conditioning of plasma-sprayed coatings, more calcium and phosphate were released than for pulsed laser deposited films, and dual constant composition dissolution rates were much higher.
authors.affiliation: Department of Chemistry, SUNY at Buffalo 14260, USA.
authors.forename: B E
authors.initials: BE
authors.lastname: Tucker
authors.forename: C M
authors.initials: CM
authors.lastname: Cottell
authors.forename: R C
authors.initials: RC
authors.lastname: Auyeung
authors.forename: M
authors.initials: M
authors.lastname: Spector
authors.forename: G H
authors.initials: GH
authors.lastname: Nancollas
mesh_terms: D002130:Calcium Phosphates / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D006882:Hydroxyapatites / Q000737:chemistry / Q000378:metabolism*; D007834:Lasers; D012825:Silicon / Q000737:chemistry*; D012995:Solubility; D013696:Temperature; D014961:X-Ray Diffraction
chemical_list: D002130:Calcium Phosphates; D006882:Hydroxyapatites; C485828:alpha-tricalcium phosphate; C485830:tetracalcium phosphate; C485838:calcium phosphate, monobasic, anhydrous; C020243:calcium phosphate; C485829:calcium phosphate, dibasic, anhydrous; D012825:Silicon