Chitosan is a sugar compound derived from the exoskeletons of shrimp, crab, and other shellfish. It is used extensively in medicine, including in dressings, because of its well known hemostatic properties. These properties work at the nanoscale, so delivering tiny bits of chitosan to the site of a wound can help improve how it works compared with larger pieces. However, chitosan tends to clump, so simply delivering it as a powder doesn’t work.

Researchers at Texas A&M and Assiut University in Egypt have now managed to encapsulate chitosan nanofibers within a hydrogel, which can be placed inside a wound and left to slowly dissolve. The hydrogel is sugar-based and biocompatible. Because the chitosan within it consists of nanoscale fibers, a huge surface area is exposed to the body, facilitating rapid hemostasis. The dressing doesn’t have to be removed from the wound, so there’s no chance of it pulling on the wound and causing bleeding to start again.

“Bioabsorbable wound dressings that can be applied and left in the injury site are desirable for a variety of blood loss scenarios — for example, to control bleeding in traumatic injuries and to save lives on both civilian and military fronts,” said Eric Leonhardt, the first author of the study appearing in Nature Communications. “The composite materials we’ve developed are malleable and could be easily administered to wound sites. They have also performed significantly better in terms of reducing the amount of blood loss and the time required to achieve hemostasis against commercially available bioabsorbable wound dressing in several animal models.”

The technology was made possible by placing chitosan within special nano-scaffolds that keep it from clumping and expose a great deal of it to blood passing by the hydrogel. The scaffolds were placed within hydrogels made of cyclodextrin, a saccharide, that has special spots that bind with chitosan particles. Freeze drying this hydrogel and washing it with a special solution allowed the researchers to remove the scaffolds, leaving only chitosan nanofibers behind.

The team tested their bioabsorbable dressings on rats, pigs, and rabbits with liver injuries, demonstrating that their new material can stop blood loss at an unprecedented rate. Moreover, after about a week no signs of the dressings were left within the livers of the animals.

Study in Nature Communications: Absorbable hemostatic hydrogels comprising composites of sacrificial templates and honeycomb-like nanofibrous mats of chitosan

Via: Texas A&M



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