Technological and Physical-Chemical Evaluation of Cotton Gauzes Impregnated with Semisolid Preparations for Wound Healing

Abstract

Chronic wounds are marked by an extended healing period during which damaged tissues fail to undergo orderly and timely repair. Examples of chronic wounds encompass venous ulcers, pressure ulcers, and diabetic foot ulcers. The process of wound healing is complex and dynamic, relying on the interplay and response among various cells and mediators. In this study, four marketed wound dressing products based on cotton gauzes impregnated with different semisolid products (namely Betadine^® 10%, Connettivina^® Bio Plus Fitostimoline^® Plus, and Non-Ad^® gauzes) have been characterized for their physicochemical properties and ex vivo behaviors. More in detail, the pH and rheological features of semisolid formulations impregnating the gauzes were analyzed along with their ability to adhere to the gauzes. The most promising ones were selected and compared in ex vivo experiments on fresh pig skin. The pH measurements showed an acidic environment for all the tested solutions, albeit with variations in mean values, ranging from 2.66 to 4.50. The outcomes of rheological studies demonstrated that all the semisolid preparations impregnating the gauzes exhibited a pseudoplastic behavior, with significant differences in the pseudoplasticity index across the preparations, which is likely to influence their ability to adhere to the gauze. A rheological study in oscillatory mode revealed rheological behavior typical of a viscous solution only for the cream impregnating non-paraffin gauzes. The other products exhibited rheological behavior typical of a weak gel, which is expected to be advantageous as regards the capability of the semisolid preparation to create and maintain the space within the wound and to provide protection to the injured tissue. Results of ex vivo experiments demonstrated that Fitostimoline^® Plus was more effective than Connettivina^® Bio Plus in promoting both skin hydration and energy.

Keywords: corneometry; rheology; skin energy; wound dressing; wound healing.

Figure 1

Flow curves at 25 °C and 37 °C of the cream taken from Betadine^® 10% gauze (A); Fitostimoline^® Plus gauze (B); Connettivina^® Bio Plus gauze (C); Non-Ad^® gauze (D). The results were expressed as mean values of triplicate tests ± SD. Triangles and circles represent experimental data. Solid lines are curves obtained by data fitting.

Figure 2

Viscoelastic moduli (G’ and G”) as a function of oscillation frequency, at 25 °C and 37 °C, of the of the cream taken from Betadine^® 10% gauze (A); Fitostimoline^® Plus gauze (B); Connettivina^® Bio Plus gauze (C); Non-Ad^® gauze (D). The values of the constant shear strain within the linear viscoelasticity regime (LVER) were 0.02 for (A,B,D) and 0.07 for (C). The results were expressed as mean values of triplicate tests ± SD.

Figure 3

Corneometry-based assessment of ex vivo skin hydration under various treatment conditions. Data points correspond to the rate of change of corneometer measurements per hour, with error bars showing the 95% confidence interval. For the ambient condition without treatment (control), asterisks denote rates of change significantly different from zero; for all other conditions, they denote rates of change that are significantly different from the control (*: p < 0.05; ***: p < 0.001).

Figure 4

Heat loss-based assessment of ex vivo skin energy under various treatment conditions. Data points correspond to the rate of change of local energy balance measurements per hour, with error bars showing the 95% confidence interval. For the ambient condition without treatment (control), asterisks denote rates of change significantly different from zero; for all other conditions, they denote rates of change that are significantly different from the control; ***: p < 0.001).