Graded composites for regenerative medicine
Barbara Szaraniec, Krzysztof Kotula, Jan Chłopek
Quarterly No. 3, 2009 pages 205-209
DOI:
keywords: graded composites, polymer composites, biomimetic materials, fibrous composites
abstract Composites are the most often investigated materials for tissue repair or replacement. Especially the biomimetic composites with graded structure are under special attention. The majority of natural tissues, among other bone tissue, represents the same structure and can be characterized by properties varying with directions. The Young modulus and porosity gradients, existing in bone, are the most important gradients from the point of view of biomedical applications. One of the most important expectations for present and future implants for regenerative medicine is their various microstructure (e.g. strengthening directions, porosity), and controllable biodegradation rate that match the rate of tissue growth. Concept of graded composite material allows manufacturing of biofunctional implants tailored to fit tissue structure and properties. In this work we present three types of graded composites differing in composition and arrangement of modifying phases. All these composites are biodegradable. They are containing polylactide-co-glycolide (PGLA) as a matrix and long fibers of carbon (C) and polyacrylonitryle (PAN) as reinforcement. Additionally resorbable powders of tricalcium phosphate (TCP) and sodium alginate (NaAlg) assure an obtainment of proper porosity and improvement of osteointegration with tissue. The samples (cubes 10x10 mm) were prepared by mould pressing of thin composite films. As a consequence of their graded nature they show controlled Young modulus, porosity and resorption time. Their behaviour was examined in artificial biological environment (8 weeks, distilled water, 37°C) by measuring the velocity of ultrasonic wave, conductivity, pH and mass changes, and microscopic observations (SEM). Before and after incubation mechanical properties of composites were compared using universal testing machine.