Language use in universities: Internationalisation and protection of the own language

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Controllable and reproducible calcium phosphate deposition on rapid prototyped titanium scaffods by perfusion electrodeposition

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Calcium phosphate functionalisation of Ti6Al4V scaffolds by perfusion electrodeposition

Introduction: Functionalisation of titanium (Ti) implants with calcium phosphate (CaP) is a widely used approach in orthopaedic applications to obtain a mechanically strong system that is Osteoconductive . In order to deposit CaP in a controlled way on complex 3D Ti surfaces, like scaffolds, this study applied a perfusion electrodeposition (P-ELD) system. Materials and Methods: 3D Ti-scaffolds were fabricated by selective laser melting. A P-ELD system was developed to deposit CaP onto Ti-scaffolds (cathode) using a platinum ring as anode. A supersaturated calcium phosphate (SCP) solution was used as electrolyte. A full factorial (24) design was performed to analyse the effect of current density (I), temperature (T), deposition time (t) and flow rate (f) on the characteristics of the deposited CaP. The parameter I and t were optimised by performing P-ELD at: (a) varying I at constant t (12 hr) and (ii) varying t at constant I (3 mA/cm2). The coating morphology, distribution, thickness, crystalinity and Ca/P ratio were characterised by scanning electron microscopy (SEM), X-ray diffraction (XRD) and electron probe micro- analysis (EPMA). The biocompatibility of CaP-coated Ti-scaffolds was tested by live-dead staining and SEM-analysis of human periosteum derived cells (HPDCs) seeded scaffolds after 7 days of culture. Results and Discussion: CaP deposition increased with increasing t, T and f, whereas 20 & 40 mA/cm2 of I were too high and disrupted CaP deposition. In fact, the effect of t and the t-f interaction on the CaP deposition were statistically significant (p=0.001 & p=0.019). 50 oC and 10 ml/min were selected for subsequent experiments. SEM analysis showed that P-ELD for t > 6 hr with 2 – 10 mA/cm2 resulted in a full coating of the scaffolds, up to a thickness of 40μm and with a Ca/P ratio of 1.41. Interestingly, P-ELD at 5 mA/cm2 for 6 hr produced a cauli flower-like crystal structure of 28 μm thick with a Ca/P ratio of 1.45. XRD analysis indicated that the CaP coatings were carbonated synthetic hydroxyapatite. Live-dead staining of HPDCs cultured on coated Ti-scaffolds for 7 days showed high cell viability and biocompatibility. SEM imaging showed that the HPDCs had a fibroblastic phenotype and interacted with the CaP coating. Conclusion: Perfusion electrodeposition (P-ELD) can become a useful tool to functionalise complex Ti structures (e.g. scaffolds) with CaP, in which the physiochemical properties of the CaP coating could be controlled and optimised for effective bone formation.status: publishe

Peri-implant bone response to novel PM porous Ti coatings

Current orthopaedic implant technology focuses on fixation by osseointegration to maximise the implant longevity and reduce the need for burdensome and expensive revision surgery. In this respect, porous Ti coated implants, which enable bone ingrowth into the porous structure and the establishment of biological anchoring of the implant, are of interest. In previous work a new powder metallurgical processing route was reported for the application of porous Ti coatings on Ti alloy substrates by electrophoretic deposition (EPD) of TiH2 powder suspensions. To validate the function of these coatings for potential clinical applications, the early peri-implant bone response was evaluated in vivo in a rabbit model. The results clearly demonstrate bone ingrowth in porous coatings with pore channels down to 10 mm, as opposed to the minimum pore size of 50–100 mm commonly claimed in the literature. Moreover, the observed interconnectivity with surrounding cortical bone confirmed the envisaged mechanical interlocking of the implant.peerreview_statement: The publishing and review policy for this title is described in its Aims & Scope. aims_and_scope_url: http://www.tandfonline.com/action/journalInformation?show=aimsScope&journalCode=ypom20status: publishe

Peri-implant bone response to novel PM porous Ti coatings

The current orthopaedic implant technology focuses on an optimized fixation by osseointegration to maximize the implant longevity and reduce the need for a burdening and expensive revision surgery. In this respect, porous Ti coated implants, enabling bone ingrowth into the porous structure and establishing a biological anchorage of the implant, are of interest. Recently, we reported on a new powder metallurgical processing route for the application of porous Ti coatings on Ti alloy substrates by electrophoretic deposition (EPD) of TiH₂ powder suspensions. To functionally validate these coatings for potential clinical applications, the early peri-implant bone response was evaluated in vivo in a rabbit model. The results clearly demonstrate bone ingrowth in porous coatings with pore channels down to 10 μm, as opposed to the minimum pore size of 50-100 μm commonly claimed in literature. Moreover, the observed interconnectivity with the surrounding cortical bone confirms the envisaged mechanical interlocking of the implant.CD-Romstatus: publishe

Peri- and intra-implant bone response to microporous Ti coatings with surface modification

Bone growth on and into implants exhibiting substantial surface porosity is a promising strategy in order to improve the long-term stable fixation of bone implants. However, the reliability in clinical applications remains a point of discussion. Most attention has been dedicated to the role of macroporosity, leading to the general consensus of a minimal pore size of 50–100 μm in order to allow bone ingrowth. In this in vivo study, we assessed the feasibility of early bone ingrowth into a predominantly microporous Ti coating with an average thickness of 150 μm and the hypothesis of improving the bone response through surface modification of the porous coating. Implants were placed in the cortical bone of rabbit tibiae for periods of 2 and 4 weeks and evaluated histologically and histomorphometrically using light microscopy and scanning electron microscopy. Bone with osteocytes encased in the mineralized matrix was found throughout the porous Ti coating up to the coating/substrate interface, highlighting that osseointegration of microporosities (<10 μm) was achievable. The bone trabeculae interweaved with the pore struts, establishing a large contact area which might enable an improved load transfer and stronger implant/bone interface. Furthermore, there was a clear interconnection with the surrounding cortical bone, suggesting that mechanical interlocking of the coating in the host bone in the long term is possible. When surface modifications inside the porous structure further reduced the interconnective pore size to the submicrometer level, bone ingrowth was impaired. On the other hand, application of a sol–gel-derived bioactive glass–ceramic coating without altering the pore characteristics was found to significantly improve bone regeneration around the coating, while still supporting bone ingrowth.publisher: Elsevier articletitle: Peri- and intra-implant bone response to microporous Ti coatings with surface modification journaltitle: Acta Biomaterialia articlelink: http://dx.doi.org/10.1016/j.actbio.2013.10.017 content_type: article copyright: Copyright © 2013 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.status: publishe

Bioactive glass-ceramic coatings on Ti-6Al-4V scaffolds by electrophoretic deposition

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Nanofocus X-ray computed tomography based analysis of the in vivo bone response of functionalised porous Ti coatings

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Porous titanium coatings through electrophoretic deposition of TiH2 suspensions

In the biomedical field, modification of titanium surfaces to improve the osteoinductive and antibacterial behavior is widely investigated. This functionalization can be further ameliorated by providing a porous coating with high loading capacity for bioactive materials and drug delivery carriers at the implant surface. In this work, a new powder metallurgical processing route used to deposit such porous pure titanium coatings on Ti based substrates is presented. The coatings were prepared by electrophoretic deposition (EPD) of TiH2 powder suspensions followed by dehydrogenation and sintering in vacuum. The use of hydrides allowed to lower the sintering temperature below that of the alpha-beta transition of the Ti6Al4V substrate. Measurement of the tensile bond strength confirmed a strong adhesion of the porous coating. Deposition of powders with different grain sizes resulted in porous titanium coatings with varying thickness, pore morphology, and surface roughness. The possibility to extend this coating technique to complex shaped implants is highlighted.status: publishe

Sol-gel based bioactive coatings inside open porous titanium structures

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