The second component, chitosan, is found in the shells of crustaceans. It's cheap, readily available, biodegradable and biocompatible, meaning that it won't trigger an immune response. Chitosan has a rough surface similar to the surfaces found inside the body that cells can attach to. The problem is chitosan swells in water, making it weak in wet environments.
Researchers combined the fibers at the nanometer scale by first using a technique called electrospinning to draw the materials into nanometer-scale fibers, and then weaving the fibers together. The resulting material has a texture similar to that of the nanosized fibers of the connective tissue that surrrounds human cells.
The two materials are different and are difficult to blend, but proper mixing is crucial because imperfectly blended fibers have weak points.
Zhang and colleagues built prototype nerve guides measuring 1.5 millimeters (0.06 inches) in diameter, and between five and 15 centimeters (two to six inches) long. They tested a guide made from the chitosan-polyester blend against another biomaterial under study, polylacticcoglycolic acid, and a commercially available collagen guide.
Of the three materials, the chitosan-polyester weave showed the most consistent performance for strength, flexibility and resistance to compression under both dry and wet conditions. Under wet conditions, which the researchers say best mimics those in the body, the chitosan-polyester blend required twice as much force to push the tube halfway shut as the other biomaterial, and eight times as much force as the collagen tube.
The new material showed promise for nerve guides but w
|Contact: Hannah Hickey|
University of Washington