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www.meddelcoat.eu1
Multi-functional bioresorbable coatings
with biofilm inhibitionand optimal implant fixation
Project n NMP3-CT-2006-026501
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www.meddelcoat.eu2
LEMI
The MEDDELCOAT consortium
Project coordinatorIndustry (SME)
Research
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Outline
1. Objectives
2. State-of-the-art
3. Innovative substrate materials
4. Innovative coating techniques
5. Advanced characterisation
6. Contact
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1. Objectives
Combinatorial approach:
Design and engineer the structure of the implant surface to optimiseimplant fixation by osteointegration,
Promote osteointegration by the application of a bioactive top
coating,
Incorporate a biofilm formation inhibiting function into the coating.
Implant material
(Ti or Ti6Al4V)
Porous coating
(Ti + bioactive coating)
Metal
Bioactive and/or
biofilm inhibiting coating
Open porosity
Development of innovative,multi-functional bioactive and
anti-inflammatory coatingson Ti6Al4V
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The project focused on acetabular cups, glenoids and humeralbodies ofinverse shoulder implants and dental implants providedby LIMA and HeliPro.
1. Objectives
Glenoid
Humeral
body
Targeted coating:
Bioactive
Biofilm inhibiting
Targeted coating:
Porous
Bioactive
Biofilm inhibiting
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State-of-the-art vacuum plasma sprayed coatings were used as areference throughout the project. This technique is commerciallyapplied by Alhenia, a leading provider of medical instruments andimplants.
2. State-of-the-art
500 m500 m
State-of-the-art Ti vacuum plasma sprayed cup (left),
cross-sectional view (middle) and top view (right)
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An increased surface roughness improves the implant stability, butalso increases the risk of biofilm formation. Viable cells (green)tend to spread throughout the porous coating.
2. State-of-the-art
SEM top view (left) and CSLM cross-sectional (right) imageof staphylococcal biofilm formation on a VPS Ti surface
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A new biomedical grade titanium alloy was developed withadvantageous microstructure, excellent biocompatibility, andwithout aluminium or vanadium!
3. Innovative substrate materials
Nanostructured TNZ(X)
Negative control TNZ(X)
CSLM top view of human osteogenic cells ona TNZ(X) surface showing enhanced in vitro
cell adhesion and proliferation
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Electrophoretic deposition (EPD)
EPD of particle stabilised emulsions and/or suspensions followed byclassical vacuum sintering or vacuum microwave sintering creates aporous Ti mask with an average porosity of 50% and pores ranging
from 10-60 m, improving mechanical interlocking, i.e. biologicalimplant fixation.
4. Innovative coating techniques
Porous Ti coating on dental screw and Ti6Al4V cup
100 m 100 m
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Electrophoretic deposition (EPD)
EPD of particle stabilised emulsions and/or suspensions followed byclassical vacuum sintering or vacuum microwave sintering creates aporous Ti mask with an average porosity of 50% and pores rangingfrom 10-60 m, improving mechanical interlocking, i.e. biologicalimplant fixation.
4. Innovative coating techniques
SEM image and EDX compositional analysis of the bone
ingrowth in a porous Ti coating
100 m
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Electrophoretic deposition (EPD)
Additional application of bioactive glass enhances the bioactivefixation of the implant
4. Innovative coating techniques
Bioactive glass coating on a Ti6Al4V humeral
body (left) and Ti dental implant (middle)
Hybrid microwave furnace
for vacuum sintering
(10-6mbar) of Ti alloys
100 m
100 m
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Hydrothermal treatment
Provides a bioactive TiO2 layer, which promotes HAp formation,
exhibits a photocatalytic effect enabling sterilisation by UV-light andprevents leaching of metal ions into the body.
4. Innovative coating techniques
Hydrothermally treated dental Ti implant
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Micro-arc oxidation(MAO)
Creates a titania-based amorphous coating with incorporated calciumphosphates, which acts as a biocompatible top coating for implantswith a porous Ti layer for cementless fixation. The highly hydrophylicnature of the coating reduces biofilm formation.
4. Innovative coating techniques
MAO coated cups
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Sol-gel synthesis
Sol-gel synthesis of bioactive glass enables coating the internalsurface of a porous Ti coating without filling the voids completely(left). As an alternative, the porous structure can be infiltrated withbioactive glass prepared by the particulate sol-gel method (right).
4. Innovative coating techniques
100 m20 m
SEM images of VPS Ti surfaces impregnated with bioactive glass
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Spraying of anti-microbial coatings
An active anti-microbial coating, which releases an antibiotic drugduring more than 2 weeks, was sprayed on top to avoid infection andbiofilm formation.
4. Innovative coating techniques
Submicron CT images of a VPS Ti surface without (left)
and with an additional anti-microbial coating (right)
revealing no difference in bone ingrowth
SEM image of a VPS Ti surface
with anti-microbial coating
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Microbial interaction
Microbial interaction results in biofilm formation and thus difficult totreat biomaterial-related infections. The influence of various substrate-coating systems on biofilm formation was studied. The importance ofthe composition and physico-chemical properties of the coating likeroughness, porosity, interconnective pore channel size andhydrophobicity were analysed.
5. Advanced characterisation
1m5 m
SEM pictures ofStaphylococcus epidermidis cells
adhering on a Ti coating and formation of biofilm
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Mechanical characterisation of coating-substratesConstant Depth scratch procedure to measure the shear adhesionstress along thick substrate-coating interfaces (> 30 m). For thincoatings (< 5 m), AFM was successfully incorporated and combinedwith a mathematical model correlating the force deformation
components.
5. Advanced characterisation
Platform
head
Diaphragm
load cell
Specimen
Scratch head
withintegrated
load cell
Scratch test setup (left) and micrograph
of a scratched specimen (right)
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In vitro and in vivo evaluation
In vitro evaluation to investigate the biocompatibility and cell/materialinteractions of powders and various substrate-coating systems toevaluate the osteogenic potential. A short and long term in vivo study
was performed, to evaluate the bone response of porous Ti coatingscombined with different bioactive and anti-microbial coatings.
5. Advanced characterisation
Collagen type I expression
1 3 9 15 27 days
Gene expression and cytoskeleton and focal
adhesion study of human osteogenic cells on a
porous Ti coating
Light microscopic image of a stained histological
section after 4 weeks of implantation and nano-CT
scan of a VPS-Ti coated implant after 12 weeks of
implantation showing bone ingrowth
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For further information:
Visit www.meddelcoat.eu
Project coordinator
Prof. Dr. Ir. Jef VleugelsKatholieke Universiteit Leuven
Department of Metallurgy and Materials Engineering (MTM)Kasteelpark Arenberg 44, B-3001 Heverlee (Belgium)
Phone: +32 16 32 12 44
Fax: +32 16 32 19 92E-mail: [email protected]
6. Contact