(217cd) Evaluation of the Characteristics of Chitosan-Xanthan Films in Comparison to Those of Other Chitosan-Polymer Complexes Focusing the Application As Wound Dressings

Chitosan, a biocompatible and biodegradable polysaccharide, can be combined with different types of synthetic and natural polymers to prepare particles, films and sponges among other types of devices applicable as biomaterials. Despite xanthan gum is one of the few anionic polysaccharides which can be produced in large scale by fermentation instead of processed from natural sources as animals and plants, its use in the constitution of biomaterials is not yet widespread.

In this work, the properties of chitosan-xanthan membranes are compared to the characteristics of complexes formed by chitosan and alginate, pectin, guar gum or Arabic gum aiming at the application of these devices as wound dressings.

The polymers were mixed in solution under controlled flow rate, temperature and agitation rate. Afterwards, the films were dried, neutralized, ion-reticulated or washed as needed. All samples were sterilized by ethylene oxide exposure prior to the characterization.

Since the desirable characteristics of biomaterials developed for the mentioned purpose are low thickness, adequate transparency, mechanical strength, water vapor permeation, absorption and stability in the presence of body fluids, low toxicity to human cells and low permeability to microorganisms, among others, those were the properties analyzed.

The results attained showed that it is possible to produce stable membranes with xanthan gum, alginate, guar gum and pectin. The combination of chitosan with Arabic gum arabic did not result in stable membranes, which disrupted readily when in contact with water. All stable membranes showed lamellar structures, except for the chitosan-guar gum formulation, that presented dense structure. The formulations containing xanthan gum, alginate and guar gum were the most transparent, but the membranes composed of chitosan and alginate were the thickest. All stable membranes showed adequate tensile strength, but low elongation at break. Higher water absorption values were obtained for xanthan and pectin-containing formulations as well as higher water vapor transmission rates. However, the xanthan-gum and the guar gum-containing formulations were the most stable in the presence of water for seven days at 37°C. The membranes having xanthan, pectin and alginate were able to effectively prevent Pseudomonas aeruginosa permeation, but not as successfully the transport of Staphylococcus aureus. In conclusion, formulations consisting of chitosan combined to xanthan seem to be quite promising in the field of wound dressings, and strategies to improve their properties will be discussed along with preliminary in vivo results.

The authors thank the Foundation for Science and Technology from Portugal and the São Paulo Research Foundation (FAPESP), the Coordination of Enhancement of Higher Education Personnel (CAPES) and the National Council for Scientific and Technological Development (CNPq) from Brazil for the support.