Mixing chitosan, found in the shells of crabs and shrimp, with industrial polyester creates a new material for the tiny tubes that support repair of a severed nerve, and for other medical uses.
The research was done at the University of Washington.
The researchers say that the hybrid fiber combines the biologically favorable qualities of the natural material with the mechanical strength of the synthetic polymer.
"A nerve guide requires very strict conditions. It needs to be biocompatible, stable in solution, resistant to collapse and also pliable, so that surgeons can suture it to the nerve. This turns out to be very difficult," said Miqin Zhang, a UW professor of material science and engineering and lead author of a paper now available online in the journal Advanced Materials.
The researchers combined polycaprolactone, a strong, flexible, biodegradable polyester commonly used in sutures-with chitosan at the nanometre scale by first using a technique called electrospinning, and then weaved the fibres together.
Zhang and colleagues reveal that the resulting material had a texture similar to that of the nano-sized fibres of the connective tissue that surrounds human cells.
They highlight the fact that the two materials are different and are difficult to blend, but proper mixing is crucial because imperfectly blended fibres have weak points.
The team 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.
According to the researchers, under wet conditions, similar to those inside 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.
Zhang said that the new material, though showed promise for nerve guides, might also work well for wound dressings, heart grafts, tendons, ligament, cartilage, muscle repair, and other biomedical applications.