| 1. |
- Brohede, Ulrika, et al.
(författare)
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A novel graded bioactive high adhesion implant coating
- 2009
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Ingår i: Applied Surface Science. - : Elsevier BV. - 0169-4332 .- 1873-5584. ; 255:17, s. 7723-7728
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Tidskriftsartikel (refereegranskat)abstract
- One method to increase the clinical success rate of metal implants is to increase their bone bonding properties, i.e. to develop a bone bioactive surface leading to reduced risks of interfacial problems. Much research has been devoted to modifying the surface of metals to make them become bioactive. Many of the proposed methods include depositing a coating on the implant. However, there is a risk of coating failure due to low substrate adhesion. This paper describes a method to obtain bioactivity combined with a high coating adhesion via a gradient structure of the coating. Gradient coatings were deposited on Ti (grade 5) using reactive magnetron sputtering with increasing oxygen content. To increase the grain size in the coating, all coatings were post annealed at 385 degrees C. The obtained coating exhibited a gradual transition over 70 nm from crystalline titanium oxide (anatase) at the surface to metallic Ti in the substrate, as shown using cross-section transmission electron microscopy and X-ray photoelectron spectroscopy depth pro. ling. Using scratch testing, it could be shown that the adhesion to the substrate was well above 1 GPa. The bioactivity of the coating was verified in vitro by the spontaneous formation of hydroxylapatite upon storage in phosphate buffer solution at 37 degrees C for one week. The described process can be applied to implants irrespective of bulk metal in the base and should introduce the possibility to create safer permanent implants like reconstructive devices, dental, or spinal implants.
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| 2. |
- Lindahl, Carl, et al.
(författare)
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Biomimetic calcium phosphate coating of additively manufactured porous CoCr implants
- 2015
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Ingår i: Applied Surface Science. - : Elsevier BV. - 0169-4332 .- 1873-5584. ; 353, s. 40-47
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this work was to study the feasibility to use a biomimetic method to prepare biomimetic hydroxyapatite (HA) coatings on CoCr substrates with short soaking times and to characterize the properties of such coatings. A second objective was to investigate if the coatings could be applied to porous CoCr implants manufactured by electron beam melting (EBM). The coating was prepared by immersing the pretreated CoCr substrates and EBM implants into the phosphate-buffered solution with Ca2+ in sealed plastic bottles, kept at 60 degrees C for 3 days. The formed coating was partially crystalline, slightly calcium deficient and composed of plate-like crystallites forming roundish flowers in the size range of 300-500 nm. Cross-section imaging showed a thickness of 300-500 nm. In addition, dissolution tests in Tris-HCl up to 28 days showed that a substantial amount of the coating had dissolved, however, undergoing only minor morphological changes. A uniform coating was formed within the porous network of the additive manufactured implants having similar thickness and morphology as for the flat samples. In conclusion, the present coating procedure allows coatings to be formed on CoCr and could be used for complex shaped, porous implants made by additive manufacturing.
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| 3. |
- Lindahl, Carl, et al.
(författare)
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Effect of strontium ions on the early formation of biomimetic apatite on single crystalline rutile
- 2013
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Ingår i: Applied Surface Science. - : Elsevier BV. - 0169-4332 .- 1873-5584. ; 266, s. 199-204
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Tidskriftsartikel (refereegranskat)abstract
- Single crystalline rutile is a good model to investigate the growth mechanism of hydroxyapatite on bioactive Ti surfaces. Previous studies have shown the difference on different crystalline rutile faces in the early stage and during the growth of HAp crystals from simulated body fluids. It is known that the biological apatite crystal is an ion-substituted apatite. Ion substitution will influence the HAp crystal growth and morphology. In the present study, the effect of strontium ions on the adsorption of Ca and phosphate ions on three different faces of single crystalline rutile substrates has been investigated. The ion adsorption is the crucial step in the nucleation of HAp crystals on specific surfaces. Single crystalline rutile surfaces ((1 1 0), (1 0 0) and (0 0 1)) were soaked in phosphate buffer solutions containing calcium and strontium ions for different time periods. The results showed that the adsorption of Sr, Ca and P is faster on the (1 1 0) surface than on the (1 0 0) and (0 0 1) surfaces. Almost same amount of Sr ion was adsorbed on the surfaces compared to the adsorption of Ca ion. Strontium ion influenced the biological apatite formation in the early stage in this study.
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| 4. |
- Unosson, Erik, 1983-, et al.
(författare)
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Stability and prospect of UV/H2O2 activated titania films for biomedical use
- 2013
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Ingår i: Applied Surface Science. - : Elsevier BV. - 0169-4332 .- 1873-5584. ; 285:Part B, s. 317-323
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Tidskriftsartikel (refereegranskat)abstract
- Biomedical implants and devices that penetrate soft tissue are highly susceptible to infection, but also accessible for UV induced decontamination through photocatalysis if coated with suitable surfaces. As an on-demand antibacterial strategy, photocatalytic surfaces should be able to maintain their antibacterial properties over repeated activation. This study evaluates the surface properties and photocatalytic performance of titania films obtained by H2O2-oxidation and heat treatment of Ti and Ti-6Al-4V substrates, as well as the prospect of assisting photocatalytic reactions with H2O2 for improved efficiency. H2O2-oxidation generated a nanoporous coating, and subsequent heat treatment above 500 °C resulted in anatase formation. Tests using photo-assisted degradation of rhodamine B showed that prior to heat treatment, an initially high photocatalytic activity (PCA) of H2O2-oxidized substrates decayed significantly with repeated testing. Heat treating the samples at 600 °C resulted in stable yet lower PCA. Addition of 3% H2O2 during the photo-assisted reaction led to a substantial increase in PCA due to synergetic effects at the surface and H2O2 photolysis, the effect being most notable for non-heat treated samples. Both heat treated and non-heat treated samples showed stable PCA through repeated tests with H2O2-assisted photocatalysis, indicating that the combination of H2O2-oxidized titania films, UV light and added H2O2 can improve efficiency of these photocatalytic surfaces.
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