Hybrid biocomposites based on titania nanotubes and a hydroxyapatite coating deposited by RF-magnetron sputtering

Surface topography, structure, and mechanical properties

Roman V. Chernozem, Maria A. Surmeneva, Bärbel Krause, Tilo Baumbach, Viktor P. Ignatov, Alexander I. Tyurin, Kateryna Loza, Matthias Epple, Roman A. Surmenev

Research output: Contribution to journalArticle

9 Citations (Scopus)

Abstract

In this study, biocomposites based on porous titanium oxide structures and a calcium phosphate (CaP) or hydroxyapatite (HA) coating are described and prepared. Nanotubes (NTs) with different pore dimensions were processed using anodic oxidation of Ti substrates in a NH4F-containing electrolyte solution at anodization voltages of 30 and 60 V with a DC power supply. The external diameters of the nanotubes prepared at 30 V and 60 V were 53 ± 10 and 98 ± 16 nm, respectively. RF-magnetron sputtering of the HA target in a single deposition run was performed to prepare a coating on the surface of TiO2 NTs prepared at 30 and 60 V. The thickness of the CaP coating deposited on the mirror-polished Si substrate in the same deposition run with TiO2 NTs was determined by optical ellipsometry (SE) 95 ± 5 nm. Uncoated and CaP-coated NTs were annealed at 500 °C in air. Afterwards, the presence of TiO2 (anatase) was observed. The scanning electron microscopy (SEM), X-ray diffraction (XRD), photoelectron spectroscopy (XPS) and nanoindentation results revealed the influence that the NT dimensions had on the CaP coating deposition process. The tubular surfaces of the NTs were completely coated with the HA coating when prepared at 30 V, and no homogeneous CaP coating was observed when prepared at 60 V. The XRD patterns show peaks assigned to crystalline HA only for the coated TiO2 NTs prepared at 30 V. High-resolution XPS spectra show binding energies (BE) of Ca 2p, P 2p and O 1s core-levels corresponding to HA and amorphous calcium phosphate on TiO2 NTs prepared at 30 V and 60 V, respectively. Fabrication of TiO2 NTs results in a significant decrease to the elastic modulus and nanohardness compared to the Ti substrate. The porous structure of the NTs causes an increase in the elastic strain to failure of the coating (H/E) and the parameter used to describe the resistance of the material to plastic deformation (H3/E2) at the nanoscale level compared to the Ti substrate. Furthermore, only the HA coating on the NTs exhibits a significantly increased H/E ratio and H3/E2 factor compared to the NTs and Ti substrate. Increases in resistance to penetration for the indenter were also observed for HA-coated TiO2 NTs prepared at 30 V compared to uncoated and CaP-coated NTs prepared at 60 V.

Original languageEnglish
Pages (from-to)229-237
Number of pages9
JournalApplied Surface Science
Volume426
DOIs
Publication statusPublished - 31 Dec 2017

Fingerprint

Surface topography
Durapatite
Hydroxyapatite
Magnetron sputtering
Nanotubes
Titanium
Coatings
Mechanical properties
Calcium phosphate
Phosphate coatings
Substrates
titanium dioxide
Photoelectron spectroscopy
Nanohardness
X ray diffraction
Core levels
Titanium oxides
Ellipsometry
Anodic oxidation
Nanoindentation

Keywords

  • Amorphous calcium phosphate
  • Bone tissue engineering
  • Hydroxyapatite
  • Magnetron sputtering
  • Nanohardness
  • Titanium oxide nanotubes
  • Young's modulus

ASJC Scopus subject areas

  • Surfaces, Coatings and Films

Cite this

Hybrid biocomposites based on titania nanotubes and a hydroxyapatite coating deposited by RF-magnetron sputtering : Surface topography, structure, and mechanical properties. / Chernozem, Roman V.; Surmeneva, Maria A.; Krause, Bärbel; Baumbach, Tilo; Ignatov, Viktor P.; Tyurin, Alexander I.; Loza, Kateryna; Epple, Matthias; Surmenev, Roman A.

In: Applied Surface Science, Vol. 426, 31.12.2017, p. 229-237.

Research output: Contribution to journalArticle

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AU - Krause, Bärbel

AU - Baumbach, Tilo

AU - Ignatov, Viktor P.

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