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The effect of heat- or ultra violet ozone-treatment of titanium on complement deposition from human blood plasma
Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
Gothenburg University.
Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
University of Turku.
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2010 (English)In: BIOMATERIALS, ISSN 0142-9612, Vol. 31, no 18, 4795-4801 p.Article in journal (Refereed) Published
Abstract [en]

Titanium (Ti) is a well known metallic biomaterial extensively used in dental, orthopaedic-, and occasionally also in blood contacting applications. It integrates well to bone and soft tissues, and is shown upon blood plasma contact to activate the intrinsic pathway of coagulation and bind complement factor 3b. The material properties depend largely on those of the nm-thick dense layer of TiO2 that becomes rapidly formed upon contact with air and water. The spontaneously formed amorphous Ti-oxide has a pzc similar to 5-6 and its water solubility is at the order of 1-2 micromolar. It is often subjected to chemical- and heat treatments in order to increase the anatase- and ruble crystallinity, to modify the surface topography and to decrease the water solubility. In this work, we prepared sol gel derived titanium and smooth PVD titanium surfaces, and analysed their oxide and protein deposition properties in human blood plasma before and after annealing at 100-500 degrees C or upon UVO-treatment for up to 96 hours. The blood plasma results show that complement deposition vanished irreversibly after heat treatment at 250-300 degrees C for 30 minutes or after UVO exposure for 24 hours or longer. XPS and infrared spectroscopy indicated change of surface water/hydroxyl binding upon the heat- and UVO treatments, and increased Ti oxidation. XRD analysis confirmed an increased crystallinity and both control (untreated) and annealed smooth titanium displayed low XRD-signals indicating some nanocrystallinity, with predominantly anatase phase. The current results show that the behaviour of titanium dioxide in blood contact can be controlled through relatively simple means, such as mild heating and illumination in UV-light, which both likely irreversibly change the stoichiometry and structure of the outmost layers of titanium dioxide and its OH/H2O binding characteristics.

Place, publisher, year, edition, pages
Elsevier Science B.V., Amsterdam. , 2010. Vol. 31, no 18, 4795-4801 p.
Keyword [en]
Titanium, Titanium oxide, Sol-gel, Blood plasma, Protein adsorption, Complement
National Category
Engineering and Technology
URN: urn:nbn:se:liu:diva-56807DOI: 10.1016/j.biomaterials.2010.02.060ISI: 000277783100002OAI: diva2:322254
Available from: 2010-06-04 Created: 2010-06-04 Last updated: 2011-10-10
In thesis
1. Improved titanium and steel implants: Studies on bisphosphonate, strontium and surface treatments
Open this publication in new window or tab >>Improved titanium and steel implants: Studies on bisphosphonate, strontium and surface treatments
2011 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Purpose: The general aim of this thesis was to increase the understanding of biomaterial surface modifications and local delivery of osteoporosis drugs for bone integration. We therefore (i) characterised and investigated model surface coatings for controlled drug delivery in a rat tibia screw model (ii) elucidated the effect of surface treatment for activation of complement system in vitro.

Materials and methods: Bisphosphonate was immobilised directly to implant surfaces by two methods. In the first method, bisphosphonate was bound via a crosslinked fibrinogen layer to titanium surfaces. In the second method, stainless steel screws were first dip coated in a TiO2 solgel, and thereafter incubated in simulated body fluid (SBF). The so prepared thin calcium phosphate layer on titania bound then bisphosphonate directly with high affinity. The drug release kinetics was determined in vitro by 14C marked alendronate that was quantified with scintillation techniques. The screws were inserted in the metaphysis of rat tibia and the mechanical fixation monitored by screw pullout measurements after 2 or 4 weeks of implantation. In order to compare two different osteoporosis drugs, bisphosphonate and strontium ranelate, stainless steel and PMMA screws were inserted in the tibial metaphysis of rat for 4 and 8 weeks. Bisphosphonate was then delivered subcutaneously and strontium ranelate orally during the whole implantation period. The mechanical fixation was analysed by pullout force measurements, and bone architecture studied by micro-computed tomography (μCT). The immune complement activation on sol-gel- and smooth titanium surfaces was analysed in human blood plasma before and after annealing of titanium at 100-500ºC or upon UVO-treatment for up to 96 hours.

Results: Bisphosphonate coated screws enhanced the screw pull out force after 2 weeks of implantation by more than 30% (fibrinogen coating) and by 93% after 4 weeks (sol-gel derived TiO2 coating). Systemically administered bisphosphonate enhanced the mechanical screw fixation after 4 weeks by more than 96% and after 8 weeks by more than 55% as compared to strontium ranelate treated animals (p = 0.00). Strontium ranelate treatment did not show significant improvement of screw pullout force after 4 and 8 weeks, compared to control. The immune complement surface deposition from blood plasma vanished irreversibly after Ti heat treatment at 250-300 ºC during 30 minutes or after UVO exposure for 24 hours or longer. Tentatively, changes in surface water/hydroxyl binding upon heat- and UVO treatments were observed by XPS and infrared spectroscopy.

Conclusions: The results show that fixation at short implantation time (weeks) of orthopaedic implant can be enhanced by immobilised bisphosphonate on stainless steel or titanium implants. Systemic delivery of strontium ranelate showed no significant effect on implant fixation in rat tibia, and we hypothesise therefore that strontium ranelate will not become a power tool to increase the early implant fixation, but may be beneficial at longer times. Heat annealing or UVO-treatment of titanium surfaces change the surface hydroxylation, leading to decreased immune complement deposition from blood plasma.

Place, publisher, year, edition, pages
Linköping: Linköping University Electronic Press, 2011. 75 p.
Linköping Studies in Science and Technology. Dissertations, ISSN 0345-7524 ; 1391
National Category
Natural Sciences
urn:nbn:se:liu:diva-71289 (URN)978-91-7393-085-7 (ISBN)
Public defence
2011-10-07, Planck, Fysikhuset, Campus Valla, Linköpings universitet, Linköping, 10:15 (Swedish)
Available from: 2011-10-10 Created: 2011-10-10 Last updated: 2011-10-10Bibliographically approved

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Linderbäck, PaulaAskendal, Agneta
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