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Biomimetic composites consisting of polymer and mineral components, resembling bone in structure and composition, were produced using a rapid prototyping technique for bone tissue engineering applications. Solid freeform fabrication, known as rapid prototyping (RP) technology, allows scaffolds to be designed with pre-defined and controlled external and internal architecture. Using the indirect RP technique, a three-component scaffold with a woodpile structure, consisting of poly-L-lactic acid (PLLA), chitosan and hydroxyapatite (HA) microspheres, was produced that had a macroporosity of more than 50% together with micropores induced by lyophilization. X-ray diffraction analysis indicated that the preparation and construction of the composite scaffold did not affect the phase composition of the HA. The compressive strength and elastic modulus (E) for the PLLA composites are 0.42 and 1.46 MPa, respectively, which are much higher than those of chitosan/HA composites and resemble the properties of cellular structure. These scaffolds showed excellent biocompatibility and ability for three-dimensional tissue growth of MC3T3-E1 pre-osteoblastic cells. The pre-osteoblastic cells cultured on these scaffolds formed a network on the HA microspheres and proliferated not only in the macropore channels but also in the micropores, as seen from the histological analysis and electron microscopy. The proliferating cells formed an extracellular matrix network and also differentiated into mature osteoblasts, as indicated by alkaline phosphatase enzyme activity. The properties of these scaffolds indicate that they can be used for non-load-bearing applications., (Copyright 2009 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.)

A series of polymer/cholesteryl liquid crystal (LC) composite membranes were prepared. Polyurethane and polyvinyl chloride, as a substrate, were blended with cholesteryl tetraethylene glycol carbonate to form composite membranes in an electric field under normal conditions. The blood compatibility of composite materials was identified by the dynamic blood-clotting test, haemolysis ratio measurement, platelet adhesion and SEM observation. The results showed that the content of LC, the ordered extent of LC domains embedded in composite materials and the type of substrate have greater effects on the blood compatibility of polymer/LC composite materials. When the LC domains were properly oriented, polymer/LC composite membranes had an excellent haemocompatibility, fewer platelets were adhered and spread and showed little distortion on the surface of materials.

Objective: To prepare a scaffold material with good biocompatibility and biodegradability by compounding polylactic acid (PLA) and chitin., Methods: After preparation of PLA from lactic acid, the compounding of PLA and chitin was carried out by dissolving these 2 materials in one solution for reaction. The composite material was obtained and molded after the solvent was evaporized, and the safety tests of this resultant material were conducted in guinea pigs and New Zealand rabbits, respectively., Results: In allergic test, the guinea pigs responded to the digestion solution of the composite material in almost the same manner as to normal saline (the latter serving as negative control), and no obvious allergic reaction was observed in the animals except those in positive control group. Pyrogenic test by injecting the digestion solution of the composite material in 6 rabbits found a raise in the body temperature less than 0.2 degrees Celsius, with the total increase (adding up the individual temperature raise) less than 1.0 degrees Celsius, to meet the accepted criteria for the pyrogenic test. In subsequent toxicity test, the rabbits showed no signs of agitation or inanimate behavior after injection., Conclusions: PLA/chitin composite material conforms to the ISO10993-1, and can be used as a basic scaffold material in tissue engineering.