Polymers with shungit for artificial bones
Shungit Filled Polymers for Artificial Bone Articulations
Tech Area / Field
- CHE-POL/Polymer Chemistry/Chemistry
3 Approved without Funding
Russian Academy of Sciences / Semenov Institute of Chemical Physics, Russia, Moscow
- NIIIT (Pulse Techniques), Russia, Moscow\nKarpov Institute of Physical Chemistry, Russia, Moscow\nInstitute of the Problems of Laser and Information Technologies RAS, Russia, Moscow reg., Troitsk
- Potsdam University / Interdisciplinary Center for Dynamics of Complex Systems, Germany, Potsdam\nKyoto University / Graduate School of Engineering, Japan, Kyoto\nNanoCarbon Research Institute Ltd., Japan, Chiba\nUniversity of Nottingham / School of Chemistry, UK, Nottingham
Project summaryShungit containing polymers for implants
Design of biomaterials for prosthetic appliances is rapidly developed at last decades. USA and Europe yearly produce about 4 millions of artificial bones starting from 90-th years. Metals, alloys, ceramics, polymers and composites are used as materials for implants. Metallic prosthetic appliances are technologically convenient, sufficiently cheep and chemically passive. However, they are characterized by an important defect – subjection to corrosion, - which lowers mechanical strength of artificial limbs and causes poisoning of organism by metal ions.
Ceramic materials are prepared mainly on the basis of SiO2 mixed with oxides of certain metals. Ceramic materials do not subject to corrosion, are chemically passive, strong and reveal good dynamic endurance. However, brittleness is a common defect of ceramic prosthetic appliances. It is hard to produce and treat ceramic appliances of complex shape.
Polytetrafluoroethylene, polyethylene, polypropylene, silicones, metylmetacrylates are used for a design of polymeric prosthetic appliances. Composite polymer materials are convenient due to their lightness, initial non-toxicity, technology reasons. However, their main negative feature is a subjection to aging processes, which proceed in human organism because of action of ferments, free radicals, etc., and cause worsening of mechanical properties. Beside that polymer destruction is accompanied by a break of a chain, which leads to isolation into organism of toxic monomer or oligomer fragments. Presently active investigations are caring out in the field of possibility of application of biodegradable polymers (polylactides, polyglycolides, polycaprolactones), which are able to resolve gradually in organism without of formation of toxic substances and to replace by natural tissue under certain conditions. However, implants on the basis of biodegradable polymers have not sufficient strength, necessary for exploitation of artificial limb at early stage after operation before its complete replacement by the bone tissue.
So, every mentioned type of material (metals, ceramics, polymers) is characterized by certain restrictions in application for implants production.
Development of multifunctional polymer composite materials for implants with application of pounded natural carbon-mineral component – shungit – is the goal of the Project proposed. Quasicrystalline carbon and silicon dioxide are main compounds of shungit. Their content verify in wide limits (from 2.5 to 98 wt.%). Main distinguish features of shungit filler (SF) is impossibility to separate carbon and silicate parts at pounding (homogeneity up to nano level is observed by X-ray tomography) and compatibility with both polar and non-polar polymers due to hydrophobic and hydrophilic features of shungit surface. Shungit applying can lower polymer destruction in organism and upgrade mechanical properties of materials, because of using carbon usually for improving mechanical properties. Also carbon is biocompatibility material. Dioxide silicon can decrease composite destruction and play main role in organism bone tissue regeneration.
The treatment of SF in conditions of super critical extraction, electrical and thermal treatments is also planned. It will provide possibility of the control of the content of solvable organic substance in SF and promote an increase in surface area. Presence of nano-size carbon particles in the texture of modified SF will provide additional strength for shungit filled composites and will allow verifying the level of mechanical parameters necessary for the design of various implants.
Recently found biologically active fullerene fragments in shungit, which are known to reveal properties of anti-oxidants is likely the fact of the special interest for the world community. That will promote hasten accommodation of implant and suppress the tearing reaction.
Shungit filled composites with complex of required physical and mechanical properties, characterizing by biocompatibility, bioactivity and bactericidal feature will be elaborated as a result of the Project performance.
Polyolefin matrices, super high molecular weight polyethylene (SHMPE), first of all, will be used. SHMPE is characterized by high strength and dynamic endurance, by the endurance with respect to chemical destruction and by biocompatibility. However, SHMPE is not frequently used for artificial limbs because of a bad miscibility with commonly used mineral compound. Therefore, filling by it will provide uniformity of particles distribution in matrix, which will promote high quality of artificial limbs. Biodegradable polymers – polylactides, polyglycolides and natural polymer chitosans with its own bactericidal feature – will be also used as matrices. The use of biodegradable polymers in complex with biocompatible filler will promote the replacement of artificial limb by natural bond after a time.
Investigation of the possibility of application of the of selective laser agglomeration (method elaborated by the team) for composite production in addition to traditional one – mixing in the melt and pressing – will be the important part of the Project. Applying SH with different carbon containing will alloy to produce composites with needed physical and mechanical properties suitable for joints.
On the basis of the experience of participants of the Project the special equipment for the express analysis of physical and mechanical properties (uniformity of shungit distribution, uniformity of properties in various space directions, strength, tear and vibration steadiness, chemical stability, etc.) of materials produced will be constructed. It will greatly assist to standardize the testing treatment of materials produced under controlling conditions.
Development of the theoretical model, which reveals the effect of filler size and shape, the level of its adhesion with polymer, polymer crystallinity, etc. on polymer composites is the subject of the special interest of the world community.
Mechanical and working properties of implants essentially depend on the uniformity of filler distribution in matrix. Isotropy of shungit filler, having properties of semi-conductor, makes possible to elaborate the new way of the control of shungit composites uniformity: analysis of frequency dependence of electrical properties – conductivity and permittivity (dielectric spectroscopy).
The Project is meant for three years.
At the first stage is supposed to do:
- to get composite systems on the basis of polypropylene with shungit filler (SF) of various type (containing 2.5, 30 and 98wt.% of carbon) by mixing in the melt.;
- to characterize shungit filled composites by the complex of mechanical and special properties;
- to treat SF with SAS of various chemical nature, extraction at super critical conditions, electrical and thermal treatment.
At the second stage it is supposed to do:
- to ellaborate theoretical model describing mechanical characteristics of composites in dependence on shungit content and properties (size and shape of particles, porosity, adhesion with polymer matrix), which will make possible further to get composites of desired properties;
- to develop compositions for the design of implants on the basis of SH and polyolefin, also biodegradable;
- to get modeling samples of composites based on all polymer matrices by mixing in melt, pressing and selective laser agglomeration for further mechanical testing.
At the third, final stage it is supposed:
- to formulate recipes on the basis of optimal SF and natural polysaccharids (chitozans);
- to produce triple composite on the base of SHMPE, hydrooxyapatite and SF by mixing in melt and selective laser agglomeration;
- to test methods of express analysis of main physical and mechanical characteristics of materials produced;
- to conduct comparable testing of every composite produced for the design of implants accounting physical, mechanical characteristics and biocompatibility;
- to formulate recommendations for the design of shungit filled implants.
In the process of the Project performance participants plan information exchange with foreign collaborators, joint discussion of the results obtained at every stage of the project and comparison of the results getting by collaborators and by the world science. performance of the project will give possibility to RF scientists and specialists previously participated in the nuclear weapon tests and in the design of rocket materials and technologies to reorient their experience and abilities onto peaceful activity, will encourage integration of RF scientists into world scientific community, will support fundamental and applied investigations in peace areas and will assist in solutions of national and international bio technological problems, which correspond to aims and directions of ISTC activity.