Researchers have developed a promising new material that can be used to repair severed nerves by combining chitosan, a compound found in the shells of crabs and shrimp, and polycaprolactone, a strong, flexible, biodegradable polyester commonly used in sutures. The hybrid fiber combines the biologically favorable qualities of the natural material with the mechanical strength of the synthetic polymer.

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.

[snip] 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 would also work well for wound dressings, heart grafts, tendons, ligament, cartilage, muscle repair and other biomedical applications, Zhang said.

The details of the study is available online in the journal Advanced Materials.

Image: The left panel shows a closeup of chitosan and polyester fibers woven at the nanometer scale. The middle panel shows a nerve cell growing on the resulting mesh, which has a texture similar to the body's fibrous connective tissue. The right panel shows a cross-section of the synthetic nerve guide. Arrows point to nerve cells that have attached to the inner and outer surfaces of the tube. Credit: University of Washington

Source