Title: Development of a continuous finishing chemistry process for manufacture of a phosphorylated cotton chronic wound dressing Authors
Submitted to: Journal of Industrial Textiles
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 18, 2009
Publication Date: July 1, 2009
Citation: Edwards, J.V., Howley, P.S., Yachmenev, V., Condon, B.D. 2009. Development of a continuous finishing chemistry process for manufacture of a phosphorylated cotton chronic wound dressing. Journal of Industrial Textiles. 39(1):27:43. Interpretive Summary: Chronic wounds are a major worldwide health problem. This research is directed at strengthening the role of cotton-based textiles in the growing market of high tech wound dressings. This paper demonstrates an important technology for development of value-added cotton-based wound dressings. An improvement on cotton gauze to accelerate healing in patients with bedsores and ulcers is the ultimate goal of this work. The paper shows how cotton gauze can be modified to reduce the activity of a destructive enzyme found to keep chronic wounds from healing. The destructive enzyme is human neutrophil elastase. High levels of elastase in the non-healing wound break down the recruitment of new tissue necessary for healing to take place. This work outlines the steps necessary to take a finished cotton dressing phosphorylated with cellulose from the laboratory to the industrial plant. The addition of intelligent cotton-based wound dressings to the market would boost cottons share in the rapidly growing field of high tech wound care, and aid both the consumer and the cotton farmer by providing an economic value-added product.
Technical Abstract: A phosphorylated form of cotton gauze for treatment of chronic wounds was designed to improve the wound dressing’s capacity to remove harmful proteases from the wound and facilitate healing. Development of the fabric finishing chemistry of the wound dressing with a process suitable for textile mill production required adapting the stationary finishing chemistry of the cotton phosphorylation from a pad-dry-cure finishing treatment to a continuous pilot scale finishing process. Issues in optimizing the cotton finishing process took into consideration dressing sterilization, the effect of city water versus de-ionized water, retention of the fabric whiteness index, and protease sequestration capacity of the dressing, which is the index of the dressing’s efficacy. Three types of sterilization approaches were assessed including gamma ray, ethylene oxide, and steam sterilization to determine the effect of sterilization on the phosphorylated cotton dressing and the subsequent efficacy of the sterilized dressing to remove proteases from the wound. Two phosphorylation reagents were compared for their ability to phosphorylate cotton in a urea-based formulation and yield an active, effective dressing, with a high whiteness index. Phosphorylation with a diammonium phosphate: urea formulation generally gave a more effective dressing as an active protease sequestrant and phosphorylation with sodium hexametaphosphate: urea gave a higher whiteness index. Finishing formulations combining the two phosphorylating reagents, diammonium phosphate and sodium hexametaphosphate: urea, were assessed to improve both whiteness and efficacy. However, sterilization of diammonium phosphate-treated cotton with ethylene oxide eradicated activity through apparent masking of the cellulose phosphate hydroxyls. Side reactions that may occur during ethylene oxide treatment are discussed as the possible origin of the phosphate hydroxyl masking. On the other hand sterilization with gamma irradiation produced significant yellowing of the dressing. A sodium hexametaphosphate: urea (16:30) formulation was employed in the continuous process finishing treatment, and found to be most optimal for whiteness, efficacy, and ease of sterilization when adapted to industrial scale production of the cotton chronic wound dressing.