Titanium alloys nanostructured surfaces - from laboratory to implants
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1
University of Chemistry and Technology, Department of Metals and Corrosion Engineering, Czechia
Introduction: Direct connection of the implant with bone could be long term and difficult process. Surface of the titanium and its alloys can be bioactivated by nanostructuring. The growth of nanotubes is result of two simultaneous processes. First of them is anodic oxidation of the surface and the second one is the local dissolution of the growing titanium dioxide by fluoride ions. Morphology of tubes can be influenced by appropriate electrolyte and anodic polarization parameters[1]. Nanostructured surfaces stimulate the deposition of osteoblast cells, which leads to easier integration of the implant into the bone[2]. Titanium beta alloy surfaces should be modified in the same way. This work was focused on the nanostructuing of the titanium alloys and on the studying of the nanostructures properties.
Materials and Methods: Ti-6Al-4V and titanium beta alloys based on Ti-Nb were studied. Nanostructures were created in electrolytes with phosphoric acid or ammonium sulphate in combination with fluoride ions. For characterization of samples and nanostructures, scanning electron microscope and X-ray photoelectron spectroscopy (XPS) were used. Electrochemical behaviour of the nanotubes was studied. Bioactivity was predicted by immersion test in the simulated body fluid with single frequency impedance monitoring. The adhesion of the nanotubes was tested by a pull-off method.
Results and Discussion: Nanotubular structures were created by anodic polarisation on all of the studied materials. The tubes inner diameter was in the range from 15 nm to 120 nm depending on the applied voltage. XPS analysis showed that the nanotubes were composed of titanium and alloying elements in the highest oxides state. Increased concentration of the alloying elements was detected in the case of beta alloys. Fluoride ions were detected in nanostructures at the level of atomic percent. The adhesion of nano-layers was sufficient for biomedical applications (over 30 MPa). The electrochemical tests indicated very good corrosion resistance higher than that of the natively formed passive layer. The immersion test in the simulated body fluid showed more distinct precipitation of the hydroxyapatite (HAP) like layer on the nanostructures with higher tubes diameter. The single frequency impedance allows for precise monitoring of the HAP precipitation. The preliminary tests with nanostructuring of the real Ti-6Al-4V implants were realised.
Conclusion: The conditions leading to the creation of organised nanotubes on commonly used Ti-6Al-4V alloy and new titanium beta alloys were determined. The preliminary bioactivity test showed higher ability for HAP-like compound precipitation on the nanostructured surface in comparison with non-treated surfaces. The nanostructuring seems to be a very promising surface modification for medical implants made from titanium alloys. This surface treatment was successfully realized on real implants.
The works were carried out as a part of the MZ 15-27726A project, which is financially supported by Ministry of Health, Czech Republic.
References:
[1] D. Regonini, C.R. Bowen, A. Jaroenworaluck, R. Stevens, "A review of growth mechanism, structure and crystallinity of anodized TiO2 nanotubes", Mat Sci Eng R. Vol. 74, 2013
[2] A.W. Tan, B. Pingguan-Murphy, R. Ahmad, S.A. Akbar, "Review of titania nanotubes: Fabrication and cellular response", Ceramics International. Vol. 38, 2012
Keywords:
corrosion,
Implant,
nanotube,
surface property
Conference:
10th World Biomaterials Congress, Montréal, Canada, 17 May - 22 May, 2016.
Presentation Type:
General Session Oral
Topic:
Nanotopography of biomaterials
Citation:
Fojt
J,
Joska
L,
Moravec
H and
Filip
V
(2016). Titanium alloys nanostructured surfaces - from laboratory to implants.
Front. Bioeng. Biotechnol.
Conference Abstract:
10th World Biomaterials Congress.
doi: 10.3389/conf.FBIOE.2016.01.01016
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Received:
27 Mar 2016;
Published Online:
30 Mar 2016.
*
Correspondence:
Dr. Jaroslav Fojt, University of Chemistry and Technology, Department of Metals and Corrosion Engineering, Prague, Czechia, Email1
Dr. Ludek Joska, University of Chemistry and Technology, Department of Metals and Corrosion Engineering, Prague, Czechia, joskal@vscht.cz
Dr. Hynek Moravec, University of Chemistry and Technology, Department of Metals and Corrosion Engineering, Prague, Czechia, moravech@vscht.cz
Dr. Vladimir Filip, University of Chemistry and Technology, Department of Metals and Corrosion Engineering, Prague, Czechia, vl.filip@tiscali.cz