Biocompatible multicomponent coatings for load-bearing medical applications

The main goal of the project is to improve adhesive surface properties under conditions of contact with the living tissue and to increase the life-time of artificial implants in a human body by depositing protective coatings.

There is no simple monolithic material that fulfils the complex requirements as far as biomaterials for medicine are concerned. Instead, very complex material combinations are to be favoured. Advanced biomaterials to be used in load-bearing applications must possess high levels of hardness, excellent fatigue levels and tensile strength, superior corrosion and wear resistance, high antibacterial activity, good biocompatibility and non-toxicity. Unfortunately, the high loads required for many orthopaedic implants restrict the selection of biomaterials. Ti is a well-established material used in artificial implants; however, it is bio-inert and has a relatively poor resistance against wear. Ti-based alloys have been widely used for the biomedical applications due to their high mechanical properties, corrosion resistance and superior biocompatibility. It is well known that the interfacial bonding between the metallic surface and the surrounding bone is poor or does not exist at all. One approach to increase bioactivity of Ti and Ti-based alloys is the deposition of hydroxyapatite (HAP) coating onto the metallic implant surface. Unfortunately, HAP (Ca10(PO4)6(OH)2) cannot be used as a heavy-loaded implant due to its poor mechanical properties, such as strength and fracture toughness, when compared to the human bone. The combination of excellent mechanical properties with biocompatibility and non-toxicity makes Ti-Ca-C-O-N, Ti-Si-Zr-O-N and Ti-Zr-C-O-N coatings promising candidates as tribological coatings to be used for various tribological applications like total joint prostheses and dental implants [Shtansky et al., Surf. Coat. Technol., 182 (2004) 101]. These coatings have been developed at MSISA. Thus, it is expected that careful design of multi-component nano-structured coatings will further enhance their application in the biomedical field. In the present project, CaO-, TiO2-, ZrO2 or HAP-doped TiC0.5-based composite targets for PVD (Physical Vapour Deposition) will be manufactured by means of the self-propagating high-temperature synthesis (SHS) method. The synthesized targets will be subjected to magnetron sputtering (MS) or high-energy metal ion-assisted MS in an atmosphere of argon or reactively in a gaseous mixture of argon and nitrogen. The films will be characterised in terms of their structure, surface topography, hardness, elastic modulus, elastic recovery, surface charge (Zeta potential), friction coefficient and wear resistance. The best approach to evaluate the biocompatibility of new materials is to investigate cell attachment, spreading and proliferation. Therefore the films will be investigated in-vitro using cultured Rat-1 fibroblasts, IAR-2 epitheliocytes and MC3T3-E1 osteoblast cells. In-vivo studies will be completed by the subcutaneous implantation of Teflon plates coated with the tested films in mice, and analysis of the population of cells on the surfaces. In ISRAEL PIRAC - Powder Immersion Reaction Assisted Coating [A. Shenhar, I. Gotman, E.Y. Gutmanas and P. Ducheyne, Mater. Sci. Eng. A268, 40-46 (1999)] will be used for the processing of TiN based coatings on orthopedic and dental implants made from Ti alloys. PIRAC processing is based on reactive diffusion and coatings produced have excellent adhesion to the substrate. The coatings will be tested in-vitro employing hip wear simulator [E.Y. Gutmanas and I. Gotman, J.Mater.Sci.:Mater in Medicine 15, 327-330 (2004) as well as in-vivo on dogs and on rats. Part of the specimens from RUSSIA and the CZECH REPUBLIC will be also tested employing a hip wear simulator. In the CZECH REPUBLIC, a new coating system for biomedical application based on hydrocarbon coatings will be developed. This type of non-toxic coating excels in tribological, mechanical and chemical properties. The research will be concentrated on optimisation of the adhesion interlayer and coating from the point of view of biocompatibility. DLC (Diamond-like Carbon) coatings will be prepared by the PACVD method (Plasma Activated Chemical Vapour Deposition) and the reproducibility of the deposition process will be tested on an industrial scale. The equipment of both laboratories (HVM and CTU) will be utilised for testing developed coating characteristics and for comparison with the properties of specimens from RUSSIA and ISRAEL. Keywords: biocompatible films, coatings, PVD (Physical Vapour Deposition).
Project ID: 
3 412
Start date: 
Project Duration: 
Project costs: 
960 000.00€
Technological Area: 
Surface treatment (painting, galvano, polishing, CVD, PVD)
Market Area: 
Pacemakers and artificial organs

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