Composite biomaterials
Jan Chłopek
Quarterly No. 1, 2009 pages 3-18
DOI:
keywords: composites, biomimetics, nanocomposites, graded materials, biological reactions
abstract The presented article has a review character and it shows the possibilities of using the composite materials in medicine. Applying the biomimetic approach connected with mimicking the structure and properties of natural tissues, it presents the principles of designing synthetic composites fulfilling the biocompatibility and biofunctionality criteria. The analysis concerns both fibrous and particle composites and it shows how it is possible to achieve the synergetic effect leading additionally to supporting the regeneration process of damaged tissues using the composite materials with biologically active phases. Such an approach is possible thanks to the cooperation of mainly two disciplines: materials science and biology. The majority of presented problems is based on author's researches, taking into consideration the latest trends in biomaterials development. Particularly, it concerns bioactive composites, composites with carbon and organic fibers, mainly for fulfilling biomechanical function, nanocomposites, graded composites and phenomena on the border of composite material-biological environment (physiological fluids, cells, tissues). In the case of bioactive composites it has been shown how it is possible to obtain biologically active composite with enhanced mechanical properties and osteointegration ability by modification of the carbon-carbon composites manufacture process by hydroxyapatite particles addition. This effect was caused by the presence of two mechanisms: one connected with hydroxyapatite, the second one with TCP formed after hydroxyapatite decomposition. The investigations conducted on composites made of resorbable polymers, mainly by means of FTIR method, showed that the presence of modifying phases changes the resorption rate of polymer and influences bone tissue regeneration process. The modifiers (particles or fibers) can act as active scaffolds which stimulate the growth of bone tissue. The properties and the geometry of these phases can decide about cellular and tissue reactions. The presence of strongly developed interfaces in composite materials influences durability of the received implants. Creep tests at various stress levels carried out on polisulfone-carbon fiber composite revealed that life-time of such implants is shorter than for pure polymers. Graded materials with Young's modulus, porosity and resorption rate gradients can decide about the stress distribution, ability to overgrowth with bone tissue and blood vessels creation (vascularization). The analysis of properties of composite materials is a good base for designing and manufacturing multifunctional implants with controlled mechanical and biological behaviour.