Phyllis S. Howley

Development of a Continuous Finishing Chemistry Process for Manufacture of a Phosphorylated Cotton Chronic Wound Dressing

A phosphorylated form of cotton gauze for treatment of chronic wounds was designed to improve the wound dressings 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 batch-type 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 dressings 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 (DAP) : urea formulation generally gave a more effective dressing as an active protease sequestrant, and phosphorylation with sodium hexametaphosphate (SMP) : urea gave a higher whiteness index. Finishing formulations combining the two phosphorylating reagents, DAP and SMP: urea, were assessed to improve both whiteness and efficacy. However, sterilization of DAP treated cotton with ethylene oxide eradicated activity through apparent masking of the cellulose phosphate hydroxyls. Side reactions that may occur during ethylene oxide treatment were 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 SMP : 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.

Specific and direct measurement of theβ-1,3-glucan in developing cotton fiber

The reaction of N,N-diethylaziridinium chloride with raw cotton (Gossypium hirsutum L.) seed fibers to introduce N,N-diethylaminoethyl (DEAE) substituents at a low degree of substitution was used for demonstrating the presence of O(4)H, characteristic of a β-1,3-glucan. The derivatized 1,3-glucan/cellulose was hydrolyzed to DEAE-glucoses that were analyzed by gas-liquid chromatography. Capillary columns proved effective for measuring the small amounts of 4-O-DEAE-glucose in the presence of major amounts of 2-O- and 6-O-DEAE-glucoses. Analyses of raw cotton fibers were carried out through fiber development (20, 27, 34, 41 and 48 d post anthesis, DPA) and field exposure (62, 83 and 104 DPA) periods. The yields of 4-O- and other individual DEAE-glucoses and the yield of 4-O-DEAE-glucose in relation to 2-O-DEAE-glucose were particularly informative concenring the role of the β-1,3-glucan in cellulose. The results confirmed the early production and almost immediate decrease of the β-1,3-glucan and demonstrated continued production of accessible cellulose followed by a sharp decrease in accessibility after boll opening. The β-1,3-glucan content of the raw cotton fiber, estimated from the yield of 4-O-DEAE-glucose (representing 1,3-glucan) and the yield of 2-O-DEAE-glucose (approximating 1,3-glucan plus cellulose) was 10%, 4%, 1% and 0.6% at, in the order given, 20, 27, 48, and 104 DPA. These results are in general agreement with other conventional analyses.

Influence of the location of substituents in substituted celluloses on solution hydrolysis of the d-glucosidic linkages

Abstract Sensitivity of the d -glucosidic linkages in cellulose to hydrolysis in homogeneous acidic media was found to be directly related to the location of a substituent in the d -glucoyranosyl unit. The 2-diethylaminoethyl (DEAE) substituent caused sensitivity toward hydrolysis to decrease in the order d -glucose > 3-O >6-O- 2-O-DEAE- d -glucopyranosyl-unit in hydrolyses beginning in 72% sulfuric acid and in 100% trifluoroacetic acid (TFA). Differences in the substituent effects were larger in TFA than in sulfuric acid. The effects reported for acid-catalyzed hydrolyses in homogeneous media are discussed relative to enzymic hydrolysis of a water-soluble, O-substituted cellulose.