title: Electrochemically assisted deposition of hydroxyapatite on Ti6Al4V substrates covered by CVD diamond films - Coating characterization and first cell biological results.
abstract: Although titanium and its alloys are widely used as implant material for orthopedic and dental applications they show only limited corrosion stability and osseointegration in different cases. The aim of the presented research was to develop and characterize a novel surface modification system from a thin diamond base layer and a hydroxyapatite (HAp) top coating deposited on the alloy Ti6Al4V widely used for implants in contact with bone. This coating system is expected to improve both the long-term corrosion behavior and the biocompatibility and bioactivity of respective surfaces. The diamond base films were obtained by Microwave Plasma Assisted Chemical Vapor Deposition (MW-PACVD); the HAp coatings were formed in aqueous solutions by electrochemically assisted deposition (ECAD) at varying polarization parameters. Scanning electron microscopy (SEM), Raman microscopy, and electrical conductivity measurements were applied to characterize the generated surface states; the calcium phosphate coatings were additionally chemically analyzed for their composition. The biological properties of the coating system were assessed using hMSC cells analyzing for cell adhesion, proliferation, and osteogenic differentiation. Varying MW-PACVD process conditions resulted in composite coatings containing microcrystalline diamond (MCD/Ti-C), nanocrystalline diamond (NCD), and boron-doped nanocrystalline diamond (B-NCD) with the NCD coatings being dense and homogeneous and the B-NCD coatings showing increased electrical conductivity. The ECAD process resulted in calcium phosphate coatings from stoichiometric and non-stoichiometric HAp. The deposition of HAp on the B-NCD films run at lower cathodic potentials and resulted both in the highest coating mass and the most homogenous appearance. Initial cell biological investigations showed an improved cell adhesion in the order B-NCD>HAp/B-NCD>uncoated substrate. Cell proliferation was improved for both investigated coatings whereas ALP expression was highest for the uncoated substrate.
authors.affiliation: Gdańsk University of Technology, Mechanical Engineering Faculty, Poland; Gdańsk University of Technology, Faculty of Electronics, Telecommunications, and Informatics, Poland.
authors.forename: Paulina
authors.initials: P
authors.lastname: Strąkowska
authors.affiliation: Max Bergmann Center, Technische Universität Dresden, Germany.
authors.forename: René
authors.initials: R
authors.lastname: Beutner
authors.affiliation: Gdańsk University of Technology, Faculty of Electronics, Telecommunications, and Informatics, Poland.
authors.forename: Marcin
authors.initials: M
authors.lastname: Gnyba
authors.affiliation: Gdańsk University of Technology, Mechanical Engineering Faculty, Poland.
authors.forename: Andrzej
authors.initials: A
authors.lastname: Zielinski
authors.affiliation: Max Bergmann Center, Technische Universität Dresden, Germany. Electronic address: Dieter.Scharnweber@tu-dresden.de.
authors.forename: Dieter
authors.initials: D
authors.lastname: Scharnweber
mesh_terms: D000328:Adult; D000497:Alloys; D049109:Cell Proliferation / Q000187:drug effects; D002478:Cells, Cultured; D020099:Coated Materials, Biocompatible / Q000737:chemistry* / Q000494:pharmacology; D018130:Diamond / Q000737:chemistry*; D017886:Durapatite / Q000737:chemistry*; D055664:Electrochemical Techniques / Q000379:methods*; D006801:Humans; D008297:Male; D059630:Mesenchymal Stem Cells; D014025:Titanium / Q000737:chemistry*; D055815:Young Adult
chemical_list: D000497:Alloys; D020099:Coated Materials, Biocompatible; C031462:titanium alloy (TiAl6V4); D018130:Diamond; D017886:Durapatite; D014025:Titanium
keywords: Biological activity; CVD deposition; Diamond films; ECAD deposition; Hydroxyapatite coatings; Ti alloys