Development of a nonwoven hemostatic dressing based on unbleached cotton: a de novo design approach

Authors: Edwards, Judson - Vince; GRAVES, ELENA; Prevost, Nicolette; CONDON, BRIAN; YAGER, DORNE - VIRGINIA COMMONWEALTH UNIVERSITY; DACORTA, JOSEPH - H&H MEDICAL CORPORATION; BOPP, ALVIN - SOUTHERN UNIVERSITY

Submitted to: Pharmaceutics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/22/2020
Publication Date: 6/30/2020
Citation: Edwards, J.V., Graves, E.E., Prevost, N.T., Condon, B.D., Yager, D., Dacorta, J., Bopp, A. 2020. Development of a nonwoven hemostatic dressing based on unbleached cotton: a de novo design approach. Pharmaceutics. 12(7):1-19. https://doi.org/10.3390/pharmaceutics12070609.
DOI: https://doi.org/10.3390/pharmaceutics12070609

Interpretive Summary: Cotton has been a dressing staple to establish wound tamponade for centuries. With the exception of its use in historically high demand periods as in ancient times of battle and the American Civil War, greige, unbleached cotton has been relatively unexplored with regard to hemostatic dressing applications. Due to innovations in raw cotton fiber cleaning and nonwoven hydroentanglement processes, there is growing interest in the potential use of greige cotton in nonwoven dressings. Nonwoven unbleached cotton retains the cuticle lipids, which confer a hydrophobic character presented as a thin waxy layer across the fiber surface. The lipid-containing layer is loosened from the cellulosic primary cell wall during the hydroentanglement process and thus, exposes the cellulosic secondary cell wall. It is the hydrophilic cellulosic portion of the cotton fibers that confers wettability and absorbency. These same properties make greige cotton ideally suited as a hemostatic material for dressing development. This paper details utilization of the concepts of material induced blood clotting that were used to design, prepare and test the nonwoven cotton for use as a hemostatic dressing. The results of this study show how greige cotton when combined with other fibers of varying polarity can be applied to hemostatic dressing developemnt useful in trauma and surgical applications.

Technical Abstract: Minimally processed greige (unbleached) cotton fibers demonstrate enhanced clotting relative to highly processed USP type 7 bleached cotton gauze. This effect is thought to be due to the material surface polarity and tendency of the unbleached cotton fiber to swell. We hypothesized that a textile could be constructed conserving the hemostasis-accelerating properties of greige cotton, while maintaining structural integrity. Spun bond nonwovens of varying surface polarity were designed and prepared based on ratios of greige cotton/bleached cotton/polypropylene fibers. Thromboelastographic analysis was performed on fibrous samples in citrated blood to evaluate the rate and strength of fibrin and clot formation. Lee White clotting times were obtained to assess the material’s clotting activity in platelet fresh blood. Electrokinetic analysis of samples was performed to analyze for material surface polarity. Hemostatic properties varied with composition ratios, fiber density, and nonwoven entanglement hydrostatic process pressures. It was found that the correlation of increased percent greige cotton and decreased clotting time was based on 'plateau and delta Zeta swell values, and demonstrates that greige cotton may be utilized along with hydrophilic and hydrophobic fiber to improve initiation of fibrin formation and a decrease in clotting times in hemostatic dressings. Hydroentanglement is an efficient and effective process for imparting structural integrity to cotton-based textiles, while conserving enhanced hemostatic function.