Sponge-Like Dressings Based on the Association of Chitosan and Sericin for the Treatment of Chronic Skin Ulcers. I. Design of Experiments-Assisted Development.

The aim of the present work was the development of sponge-like dressings based on chitosan glutamate (high molecular weight) and sericin for the treatment of chronic skin ulcers. Dressings were prepared by freeze-drying and glycine was added as cryoprotectant agent. Dressing development was assisted by design of experiments, using a simplex centroid design. Mechanical resistance, hydration propensity, viscous, and viscoelasticity properties of dressings were considered as response variables. The superimposition of the contour plots, calculated by the best fit model for each response variable, permitted to individuate a region of the factor space where the dressing of optimized quantitative composition was chosen. Such a dressing was able to absorb high amount of phosphate-buffered saline forming a gel characterized by rheological properties enabling both a lubricant and a protective effect. The optimized formulation was characterized by optimal mechanical properties and by cell proliferation and antioxidant activity on human fibroblast cell line.