The healing process of a wound injury follows the steps of hemostasis, inflammation, cell proliferation, and regeneration until complete healing of the damaged tissue. In chronic wounds, the progress of these steps is disturbed, leaving the wounds inflamed for a long time. In an aging society with bad health habits (poor diet, little exercise), the number of chronic wounds is going to increase. Therefore, the research on materials that improve wound healing is important. The publications presented below are devoted to research about chitosan-based materials for the treatment of chronic wounds.
Effect of Different Crosslinking Strategies on Physical Properties and Biocompatibility of Freestanding Multilayer Films Made of Alginate and Chitosan
G. Apte, A. Repanas, C. Willems, A. Mujtaba, C. E. H. Schmelzer, A. Raichur, F. Syrowatka, T. Groth. Macromolecular Bioscience. 2019
The authors produced multilayer films of chitosan and alginate using layer-by-layer technique that could be applied as wound dressing material. The swelling behavior of alginate could provide optimal moisturization of the wound while chitosan stimulates platelets aggregation. Chitosan 85/500 (degree of deacetylation [%] / viscosity [mPas]) of Heppe Medical Chitosan GmbH was used for this study. The study investigated the cross-linking strategy for chitosan and alginate, which improves the mechanical properties of the film without adversely affecting biocompatibility. Three different networking agents were examined:
- Calcium ions for cross-linking alginate
- 1-ethyl-3- (3-imethylaminopropyl) carboiimide (EDC) in combination with N-hydroxysuccinimide to crosslink alginate with chitosan
- Genipin for cross-linking chitosan
To characterize the resulting films, surface morphology, wettability, swelling, roughness and mechanical properties were determined.
- Film characteristics after crosslinking:
- thinner films
- rougher surfaces
- Lower water absorption
- Increased mechanical strength (especially for EDC-crosslinked films)
- Wettability was slightly changed, depending on the crosslinking method
The calcium ion-crosslinked alginate-chitosan films were the thickest, softest and most hydrophilic in comparison to the other crosslinking strategies.
Biocompatibility was investigated with human dermal fibroblast cells.
- No cytotoxicity of chitosan-alginate films after 7 days, no effect of the cross-linking method
- No growth of fibroblast cells directly on the films (low adhesion)
Summary: The combination of alginate and chitosan is a promising material for wound dressings. In the next step, the release of wound healing growth factors through the slides could be researched.
Vancomycin-loaded chitosan aerogel particles for chronic wound applications
López-Iglesias C., Barros J., Ardao I., Monteiro F. J., Alvarez-Lorenzo C., Gómez-Amoza J. L., García-González C. A. Carbohydrate Polymers 204: 223-231, 2019, doi: 10.1016/j.carbpol.2018.10.012
In the second study, chitosan-based aerogel particles loaded with the antibiotic vancomycin were tested for the treatment of infected wounds. Aerogels are highly porous and sponge-like with pore sizes in the nanometer range and a large inner surface.
The chitosan particles were prepared by sol-gel method using chitosan 90/1000 (degree of deacetylation [%] / viscosity [mPas]) by HMC. The morphological and structural characteristics of the chitosan aerogel particles were investigated by N2 adsorption-desorption analysis and scanning electron microscopy.
- Chitosan aerogel particles have high porosity (> 96%) and surface area (> 200 m2 / g)
- High water sorption and air permeability
- Rapid release of vancomycin by the chitosan particles within the first hour, slow release for up to 24 hours
- No inhibition of collagenase activity, thus no disruption of wound healing
- No cytotoxicity for fibroblasts
- Antimicrobial effect against Staphylococcus aureus of vancomycin-loaded aerogel particles was demonstrated
Summary: The chitosan-based vancomycin-loaded aerogel particles could be a formulation to apply antibiotics locally to the wound site to achieve optimal wound care. The next step would be the development of an aerosol formulation in powder form, which can be applied directly to the wound and studied in animal models.