title: Characteristics andin vitroresponse of thin hydroxyapatite-titania films produced by plasma electrolytic oxidation of Ti alloys in electrolytes with particle additions.
abstract: The enhancement of the biological properties of Ti by surface doping with hydroxyapatite (HA) is of great significance, especially for orthodontic applications. This study addressed the effects of HA particle size in the electrolyte suspension on the characteristics and biological properties of thin titania-based coatings produced on Ti-6Al-4V alloy by plasma electrolytic oxidation (PEO). Detailed morphological investigation of the coatings formed by a single-stage PEO process with two-step control of the electrical parameters was performed using the Minkowski functionals approach. The surface chemistry was studied by glow discharge optical emission spectroscopy and Fourier transform infrared spectroscopy, whereas mechanical properties were evaluated using scratch tests. The biological assessment includedin vitroevaluation of the coating bioactivity in simulated body fluid (SBF) as well as studies of spreading, proliferation and osteoblastic differentiation of MC3T3-E1 cells. The results demonstrated that both HA micro- and nanoparticles were successfully incorporated in the coatings but had different effects on their surface morphology and elemental distributions. The micro-particles formed an irregular surface morphology featuring interpenetrated networks of fine pores and coating material, whereas the nanoparticles penetrated deeper into the coating matrix which retained major morphological features of the porous TiO2coating. All coatings suffered cohesive failure in scratch tests, but no adhesive failure was observed; moreover doping with HA increased the coating scratch resistance.In vitrotests in SBF revealed enhanced bioactivity of both HA-doped PEO coatings; furthermore, the cell proliferation/morphometric tests showed their good biocompatibility. Fluorescence microscopy revealed a well-organised actin cytoskeleton and focal adhesions in MC3T3-E1 cells cultivated on these substrates. The cell alkaline phosphatase activity in the presence of ascorbic acid and β-glycerophosphate was significantly increased, especially in HA nanoparticle-doped coatings.
authors.affiliation: University of Sheffield, Mappin Street, Sheffield, S1 3JD, UK. Email: A.Yerokhin@Sheffield.ac.uk ; ; Tel: +44 (0)1142 225970.
authors.forename: W K
authors.initials: WK
authors.lastname: Yeung
authors.affiliation: National University of Science and Technology 'MISiS', Leninsky prospect 4, Moscow 119049, Russia.
authors.forename: I V
authors.initials: IV
authors.lastname: Sukhorukova
authors.affiliation: National University of Science and Technology 'MISiS', Leninsky prospect 4, Moscow 119049, Russia.
authors.forename: D V
authors.initials: DV
authors.lastname: Shtansky
authors.affiliation: National University of Science and Technology 'MISiS', Leninsky prospect 4, Moscow 119049, Russia.
authors.forename: E A
authors.initials: EA
authors.lastname: Levashov
authors.affiliation: N.N. Blokhin Russian Cancer Research Centre, Kashirskoe shosse 24, Moscow 115478, Russia.
authors.forename: I Y
authors.initials: IY
authors.lastname: Zhitnyak
authors.affiliation: N.N. Blokhin Russian Cancer Research Centre, Kashirskoe shosse 24, Moscow 115478, Russia.
authors.forename: N A
authors.initials: NA
authors.lastname: Gloushankova
authors.affiliation: National University of Science and Technology 'MISiS', Leninsky prospect 4, Moscow 119049, Russia.
authors.forename: P V
authors.initials: PV
authors.lastname: Kiryukhantsev-Korneev
authors.affiliation: National University of Science and Technology 'MISiS', Leninsky prospect 4, Moscow 119049, Russia.
authors.forename: M I
authors.initials: MI
authors.lastname: Petrzhik
authors.affiliation: University of Sheffield, Mappin Street, Sheffield, S1 3JD, UK. Email: A.Yerokhin@Sheffield.ac.uk; ; Tel: +44 (0)1142 225970; University of Manchester, Oxford Road, Manchester, M13 9PL, UK.
authors.forename: A
authors.initials: A
authors.lastname: Matthews
authors.affiliation: University of Sheffield, Mappin Street, Sheffield, S1 3JD, UK. Email: A.Yerokhin@Sheffield.ac.uk; ; Tel: +44 (0)1142 225970; National University of Science and Technology 'MISiS', Leninsky prospect 4, Moscow 119049, Russia.
authors.forename: A
authors.initials: A
authors.lastname: Yerokhin