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SURFACE COATINGS FOR BIOMATERIALS.

Ziel

-To prepare and evaluate new coatings, biomaterials, providing a) increased corrosion resistance; b) improved surface wear; c) biocompatibility.
-To investigate the technology of the process required to optimise mechanical, physical and biological properties.
-To evaluate coatings by SEM, XRD, XPS, SIMS, Auger electrochemical corrosion methods and fatigue studies.
-To investigate biocompatibility by in vitro and in vivo methods.
-To examine the effect of the material on lymphoid cell functions and the influence of lymphoid cell derived molecules on the processes studied, particularly corrosion.
-To produce a specific implant for commercialisation.
The overall aim of the project was to develop the key factors in materials preparation and in coating production that would lead to the determination of the characteristics required in a coating of hydroxyapatite (HA) bioactive ceramic applied to a metallic substrate and intended for use as a surgical implant. Thw work concentrated on 3 metallic substrates, stainless steel, 350 chromium cobalt alloy and titanium aluminium vanadium alloy, and HA coatings of varying thicknesses and crystallinity were applied to them by a thermal spray process. Process parameters were examined for efect on coating substrate bond strength.

The results emphasised the need for a definitive test that would give a reliable value for substrate coating bond strength. The structural changes in HA revealed by Raman spectroscopy are of note. Work showed the influence of metal ions on the dissolution behaviour of HA and this was further investigated to show the progressive uptake of titanium ions by HA powders exposed to solutions of varying concentrations of titanium. The interfaces were also studied on cross sectioned samples.

From immunology studies, there seemed to be an individual variation among the donors in the way that their activated T-cells responded to the metallic discs both coated and uncoated, in spite of the group pattern of each metal. There 2 groups of responders, low and normal, in accordance with activation of alpha CD3 antibody.

A more crystalline coating is more stable during time but as a result of a less uniform degradation, can lead to bulky particles being produced. Thickness of the coating, together with crystallinity influences in a linear manner the overall resorption of the coating. A standardised implant has been studied and quantitative histology assessment was developed.
o prepare and evaluate new coatings, biomaterials, providing increased corrosion resistance, improved surface wear and biocompatibility;
to investigate the technology of the process required to optimise mechanical, physical and biological properties;
to evaluate coatings by scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), secondary ion mass spectroscopy (SIMS), Auger electrochemical corrosion methods and fatigue studies;
to investigate biocompatibility by in vitro and in vivo methods;
to examine the effect of the material on lymphoid cell functions and the influence of lymphoid cell derived molecules on the processes studied, particularly corrosion;
to produce a specific implant for commercialisation.

The first 6 months have seen good progress. Coatings of hydroxyapatite ceramic have been applied by thermal spray methods to substrates of titanium and stainless steel. Dissolution studies of coatings immersed in sodium chloride solution to which metal ions have been added show that cation release from substrates may be inhibited by the coating. Physical methods used to examine coatings have been set up and early results show effects of pretreatment on substrate (eg aluminium enrichment of titanium). A modular prototype implant is to be coated and tested.

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Koordinator

QUEEN MARY AND WESTFIELD COLLEGE - UNIVERSITY OF LONDON
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Adresse
Mile End Road
E1 4NS LONDON
Vereinigtes Königreich

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Letzte Aktualisierung: 21 November 1990

Mein Booklet

Permalink: https://cordis.europa.eu/project/id/BREU0172/de

European Union, 2024