Induction of Low-Level Hydrogen Peroxide Generation by Unbleached Cotton Nonwovens as Potential Wound Dressing Materials

Ascorbic Acid as an Adjuvant to Unbleached Cotton Promotes Antimicrobial Activity in Spunlace Nonwovens

The development of affordable, effective, and environmentally friendly barrier fabrics is a current goal in antimicrobial textile development. The discovery of new routes to achieve non-toxic naturally occurring molecules with antimicrobial activity is of interest in the development of materials that promote wound healing, improve hygiene, and offer protection against nosocomial infection. Highly cleaned and sterile unbleached cotton has constituents that produce hydrogen peroxide at levels commensurate with those that favor cell signaling in wound healing. Here, we show the antimicrobial and antiviral properties of spunlaced griege cotton-containing nonwovens treated with ascorbic acid formulations. The mechanism of action occurs through the promotion of enhanced hydrogen peroxide activity. The levels of hydrogen peroxide activity afford antimicrobial activity against Gram-negative and Gram-positive bacteria and antiviral activity against MS2 bacteriophages. Spun-bond nonwoven unbleached cotton was treated with ascorbic acid using traditional pad-dry-cure methods. An assessment of antibacterial and antiviral activity against Staphylococcus aureus, Klebsiella pneumoniae, and MS2 bacteriophages with the AATCC 100 test method showed a 99.99% inhibitory activity. An approach to the covalent attachment of ascorbic to cellulose through citric acid crosslinking chemistry is also discussed. Thus, a simple, low-cost approach to antimicrobial and antiviral cotton-based nonwovens applicable to dressings, nosocomial barrier fabrics, and face masks can be adopted by combining ascorbic acid with spunlace greige cotton nonwoven fabrics.

Antimicrobial and Hemostatic Activities of Cotton-Based Dressings Designed to Address Prolonged Field Care Applications

INTRODUCTION

Developing affordable and effective hemostatic and antimicrobial wound dressings for prolonged field care (PFC) of open wounds is of interest to prevent infection, to prevent sepsis, and to conserve tissue viability. The need for an effective hemostatic dressing that is also antimicrobial is required of a hemostatic dressing that can be left in place for extended periods (days). This is particularly important in light of the existence of pathogens that have coagulopathy properties. Thus, dressings that provide effective hemostasis and reduction in the frequency of dressing changes, whereas exerting robust antimicrobial activity are of interest for PFC. Highly cleaned and sterile unbleached cotton has constituents not found in bleached cotton that are beneficial to the hemostatic and inflammatory stages of wound healing. Here, we demonstrate two approaches to cotton-based antimicrobial dressings that utilize the unique components of the cotton fiber with simple modification to confer a high degree of hemostatic and antimicrobial efficacy.

METHODS

Spun bond nonwoven unbleached cotton was treated using traditional pad dry cure methods to add ascorbic acid, zeolite (NaY) with pectin, calcium chloride, and sodium carbonate/calcium chloride. Similarly, nanosilver-embedded cotton fiber was blended with pristine cotton fibers at various weight ratios to produce hydroentangled nonwoven fabrics. The resulting treated fabrics were assessed for hemostasis using thromboelastographic clotting assays and antimicrobial activity utilizing American Association of Textile Chemists and Colorists 100.

RESULTS

Zeolite-containing dressings possessed significant hemostatic activity, whereas ascorbic acid- and silver-containing dressings reduced Gram-positive and Gram-negative organism numbers by several logs.

CONCLUSION

Based on this study, a multilayered hemostatic dressing with antimicrobial properties is envisioned. This dressing would be safe, would be economical, and have a stable shelf-life that would be conducive for using PFC.

Therapeutic Potential of Reactive Oxygen Species: State of the Art and Recent Advances

In the last decade, several studies have proven that when at low concentration reactive oxygen species (ROS) show an adaptive beneficial effect and posited the idea that they can be utilized as inexpensive and convenient inducers of tissue regeneration. On the other hand, the recent discovery that cancer cells are more sensitive to oxidative damage paved the way for their use in the selective killing of tumor cells, and sensors to monitor ROS production during cancer treatment are under extensive investigation. Nevertheless, although ROS-activated signaling pathways are well established, less is known about the mechanisms underlying the switch from an anabolic to a cytotoxic response. Furthermore, a high variability in biological response is observed between different modalities of administration, cell types, donor ages, eventual concomitant diseases, and external microenvironment. On the other hand, available preclinical studies are scarce, whereas the quest for the most suitable systems for in vivo delivery is still elusive. Furthermore, new strategies to control the temporal pattern of ROS release need to be developed, if considering their tumorigenic potential. This review initially discusses ROS mechanisms of action and their potential application in stem cell biology, tissue engineering, and cancer therapy. It then outlines the state of art of ROS-based drugs and identifies challenges faced in translating ROS research into clinical practice.

Use of a new pneumatic system to support capillary microperfusion in surgical wound healing: an animal model

OBJECTIVE

To test the efficacy of the a developed medical device, based on the principle of mechanical support of capillary microperfusion.

METHOD

In this pilot study involving experimental animals, each pig had two standardised surgical wounds. A cuff that delivered pneumatic three-second micropulses was applied to the wound designated as the 'experimental wound'. The pressure inside the cuff was kept at a level <10mmHg so that during the pulse, the pressure would decrease by one third of the established value. The second wound, designated as the 'control wound', was covered with a standard dressing. Over the course of five days, the pressure inside the cuff was monitored. After the five days, the experimental animal was euthanised and two specimens were collected for histological analysis (one sample from each wound site). Wound healing parameters for the experimental and control wounds were examined by a pathologist. The level of statistical significance was set at 0.05.

RESULTS

In this study, 10 experimental animals were used. The average pressure in the cuffs was 8.46mmHg (standard deviation: 3.86). No disparities in wound healing were observed in cases of different average pressures in the experimental wound. With respect to wound healing parameters, a statistically significant difference (p<0.05) was found in favour of the experimental wound. The occurrence of histological signs of poor healing was identical in both study wounds.

CONCLUSION

The study shows that a device for the support of capillary microperfusion of the surgical wound had a positive effect. It was confirmed that the mechanical support system of capillary microperfusion was safe and reliable.

Hydrogen Peroxide Generation of Copper/Ascorbate Formulations on Cotton: Effect on Antibacterial and Fibroblast Activity for Wound Healing Application

Greige cotton (unbleached cotton) is an intact plant fiber that retains much of the outer cotton fiber layers. These layers contain pectin, peroxidases, and trace metals that are associated with hydrogen peroxide (H₂O₂) generation during cotton fiber development. When greige cotton is subjected to a nonwoven hydroentanglement process, components of the outer cotton fiber layers are retained. When hydrated, this fabric can generate H₂O₂ (5⁻50 micromolar). This range has been characterized as inducing accelerated wound healing associated with enhanced cell signaling and the proliferation of cells vital to wound restoration. On the other hand, H₂O₂ levels above 50 micromolar have been associated with bacteriostatic activity. Here, we report the preparation and hydrogen peroxide activity of copper/ascorbate formulations, both as adsorbed and in situ synthesized analogs on cotton. The cooper/ascorbate-cotton formulations were designed with the goal of modulating hydrogen peroxide levels within functional ranges beneficial to wound healing. The cotton/copper formulation analogs were prepared on nonwoven unbleached cotton and characterized with cotton impregnation titers of 3⁻14 mg copper per gram of cotton. The copper/ascorbate cotton analog formulations were characterized spectroscopically, and the copper titer was quantified with ICP analysis and probed for peroxide production through assessment with Amplex Red. All analogs demonstrated antibacterial activity. Notably, the treatment of unbleached cotton with low levels of ascorbate (~2 mg/g cotton) resulted in a 99 percent reduction in Klebsiella pneumoniae and Staphylococcus aureus. In situ synthesized copper/ascorbate nanoparticles retained activity and did not leach out upon prolonged suspension in an aqueous environment. An assessment of H₂O₂ effects on fibroblast proliferation are discussed in light of the copper/cotton analogs and wound healing.