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Formation of highly adherent nano-porous alumina on Ti-based substrates: a novel bone implant coating
Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Surface Biotechnology.
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2004 (English)In: Journal of materials science. Materials in medicine, ISSN 0957-4530, E-ISSN 1573-4838, Vol. 15, no 9, 1021-1029 p.Article in journal (Refereed) Published
Abstract [en]

Thin, nano-porous, highly adherent layers of anodised aluminium formed on the surface of titanium alloys are being developed as coatings for metallic surgical implants. The layers are formed by anodisation of a 1–5 m thick layer of aluminium which has been deposited on substrate material by electron beam evaporation. The surface ceramic layer so produced is alumina with 6–8 wt % phosphate ions and contains 5×108 cm–2 pores with a 160 nm average diameter, running perpendicular to the surface. Mechanical testing showed the coatings'' shear and tensile strength to be at least 20 and 10 MPa, respectively. Initial cell/material studies show promising cellular response to the nano-porous alumina. A normal osteoblastic growth pattern with cell number increasing from day 1 to 21 was shown, with slightly higher proliferative activity on the nano-porous alumina compared to the Thermanox control. Scanning electron microscopy (SEM) examination of the cells on the porous alumina membrane showed normal osteoblast morphology. Flattened cells with filopodia attaching to the pores and good coverage were also observed. In addition, the pore structure produced in these ceramic coatings is expected to be suitable for loading with bioactive material to enhance further their biological properties.

Place, publisher, year, edition, pages
2004. Vol. 15, no 9, 1021-1029 p.
National Category
Natural Sciences
URN: urn:nbn:se:uu:diva-91965DOI: 10.1023/B:JMSM.0000042688.33507.12ISI: 000224061500010PubMedID: 15448410OAI: oai:DiVA.org:uu-91965DiVA: diva2:164885
Available from: 2004-09-01 Created: 2004-09-01 Last updated: 2014-01-28Bibliographically approved
In thesis
1. Nano-porous Alumina, a Potential Bone Implant Coating
Open this publication in new window or tab >>Nano-porous Alumina, a Potential Bone Implant Coating
2004 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

This thesis describes a method of growing a highly adherent nano-porous alumina coating on titanium implant materials, a design which might be useful in hard tissue replacement. Alumina layers were formed by anodisation of aluminium, which had been deposited on titanium and titanium alloys by electron beam evaporation. Mechanical testing showed the coatings’ shear and tensile strength to be ~20MPa and ~10MPa respectively.

Human osteoblasts were cultured on purchased membranes, produced in the same way with similar characteristics as the coating mentioned above. Cell viability, proliferation and phenotype were assessed by measuring redox reactions, DNA, tritiated thymidine incorporation and alkaline phosphatase production. Results showed normal osteoblastic growth patterns with increasing cell numbers the first two weeks after which cell growth decreased and alkaline phosphatase production increased, indicating that osteoblastic phenotype was retained on the alumina. Flattened cell morphology with filipodia attached to the pores of the material was seen.

Implants frequently trigger inflammatory responses due to accumulation and activation of cells such as polymorphonuclear granulocytes (PMN), also called neutrophils. Activation and morphology of human PMN in response to nano-porous alumina with two pore sizes (20 and 200 nm) was investigated by luminol-amplified chemiluminescence, granule enzyme deposition measurement, optical and scanning electron microscopy. Activation was observed on both membrane types, however less pronounced on the 200 nm alumina. For both membranes a decrease in activation was seen after coating with fibrinogen, collagen I and serum (more pronounced for the two latter). On fibrinogen-coated alumina many flattened cells were observed, indicating frustrated phagocytosis. Finally when culturing osteoblasts on non-coated and collagen-coated membranes (after exposure to PMN) many more cells had established on the protein-coated surface after 24 h.

The overall results indicate that it might be possible to produce a novel bone implant coating by anodisation of aluminium deposited on titanium and that this material will support osteoblast adhesion and proliferation. Furthermore neutrophil activation can be suppressed when coating the alumina with collagen I, which is beneficial considering the fact that this protein also is essential for bone formation.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2004. 75 p.
Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1104-232X ; 997
Chemistry, Nano-porous aluminium oxide, Biomaterial, Hard tissue implant, Surface topography, Osteoblast, Biocompatibility, Neutrophil, Inflammation, Kemi
National Category
Chemical Sciences
urn:nbn:se:uu:diva-4452 (URN)91-554-6007-0 (ISBN)
Public defence
2004-09-29, B-42, BMC, Husargatan 3, Uppsala, 09:15
Available from: 2004-09-01 Created: 2004-09-01Bibliographically approved

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