title: Preparation and bioactive properties of nanocrystalline hydroxyapatite thin films obtained by conversion of atomic layer deposited calcium carbonate.
abstract: Nanocrystalline hydroxyapatite thin films were fabricated on silicon and titanium by atomic layer deposition (ALD) of CaCO3 and its subsequent conversion to hydroxyapatite by diammonium hydrogen phosphate (DAP) solution. The effects of conversion process parameters to crystallinity and morphology of the films were examined. DAP concentration was found to be critical in controlling the crystal size and homogeneity of the films. The hydroxyapatite phase was identified by XRD. ToF-elastic recoil detection analysis studies revealed that the films are calcium deficient in relation to hydroxyapatite with a Ca/P ratio of 1.39 for films converted with 0.2 M DAP at 95 °C. The coatings prepared on titanium conformally follow the rough surface topography of the substrate, verifying that the good step coverage of the ALD method was maintained in the conversion process. The dissolution tests revealed that the coating was nondissolvable in the cell culture medium. Annealing the coated sample at 700 °C for 1 h seemed to enhance its bonding properties to the substrate. Also, the biocompatibility of the coatings was confirmed by human bone marrow derived cells in vitro. The developed method provides a new possibility to produce thin film coatings on titanium implants with bone-type hydroxyapatite that is biocompatible with human osteoblasts and osteoclasts.
authors.affiliation: Laboratory of Inorganic Chemistry, Department of Chemistry, University of Helsinki, P.O. Box 55, FI-00014 Helsinki, Finland.
authors.forename: Jani
authors.initials: J
authors.lastname: Holopainen
authors.affiliation: Department of Anatomy and Cell Biology, Institute of Biomedicine, University of Oulu, P.O. Box 5000, FI-90014 Oulu, Finland.
authors.forename: Kyösti
authors.initials: K
authors.lastname: Kauppinen
authors.affiliation: Division of Materials Physics, Department of Physics, University of Helsinki, P.O. Box 43, FI-00014 Helsinki, Finland.
authors.forename: Kenichiro
authors.initials: K
authors.lastname: Mizohata
authors.affiliation: Laboratory of Inorganic Chemistry, Department of Chemistry, University of Helsinki, P.O. Box 55, FI-00014 Helsinki, Finland.
authors.forename: Eero
authors.initials: E
authors.lastname: Santala
authors.affiliation: Laboratory of Inorganic Chemistry, Department of Chemistry, University of Helsinki, P.O. Box 55, FI-00014 Helsinki, Finland.
authors.forename: Esa
authors.initials: E
authors.lastname: Mikkola
authors.affiliation: Laboratory of Inorganic Chemistry, Department of Chemistry, University of Helsinki, P.O. Box 55, FI-00014 Helsinki, Finland.
authors.forename: Mikko
authors.initials: M
authors.lastname: Heikkilä
authors.affiliation: Department of Anatomy and Cell Biology, Institute of Biomedicine, University of Oulu, P.O. Box 5000, FI-90014 Oulu, Finland.
authors.forename: Hanna
authors.initials: H
authors.lastname: Kokkonen
authors.affiliation: Laboratory of Inorganic Chemistry, Department of Chemistry, University of Helsinki, P.O. Box 55, FI-00014 Helsinki, Finland.
authors.forename: Markku
authors.initials: M
authors.lastname: Leskelä
authors.affiliation: Department of Anatomy and Cell Biology, Institute of Biomedicine, University of Oulu, P.O. Box 5000, FI-90014 Oulu, Finland.
authors.forename: Petri
authors.initials: P
authors.lastname: Lehenkari
authors.affiliation: Department of Anatomy and Cell Biology, Institute of Biomedicine, University of Oulu, P.O. Box 5000, FI-90014 Oulu, Finland.
authors.forename: Juha
authors.initials: J
authors.lastname: Tuukkanen
authors.affiliation: Laboratory of Inorganic Chemistry, Department of Chemistry, University of Helsinki, P.O. Box 55, FI-00014 Helsinki, Finland.
authors.forename: Mikko
authors.initials: M
authors.lastname: Ritala
mesh_terms: D002119:Calcium Carbonate / Q000737:chemistry*; D017886:Durapatite / Q000737:chemistry*; D006801:Humans; D053758:Nanoparticles / Q000737:chemistry*; D010710:Phosphates / Q000737:chemistry; D012995:Solubility; D014961:X-Ray Diffraction
chemical_list: D010710:Phosphates; C024788:ammonium phosphate; D017886:Durapatite; D002119:Calcium Carbonate