Functionalized multilayer structures for burns treatment

Wound healing is a multiphase and multifactorial physiological process. The complexity of this phenomenon makes the healing process very difficult and painful due to several abnormalities. Apart from cellular and biochemical components, a number of external pathways also become active during repair and help the tissue to heal. Wound dressing is one of the main external effectors during the healing process of wounds. Wound is the disruption of the integrity of anatomical tissues caused by exposure to any factor [1-2]. The following characteristics are required for ideal modern wound dressings: bio-adhesiveness to the wound surface, ease of applications, easily sterilised inhibition of bacterial invasion, biodegradability, oxygen permeability, nontoxic, etc [3]. The balance between contraction and wound closure depends on the depth and location of the wound and the presence of complications, such as infection which could impair healing [4]. As a response to this problematic issue, as primary or secondary dressing, complex composites matrix for hemostasis and connective tissue regeneration were developed. The three-layered structure consists of outer layer I which plays the role of carrier, insulator and protector of the underlying layers, being elastic, resistant and submicro-porous (to block the physical access of microorganisms to the lesion), layer II – has the purpose of managing the liquid compositions in the lesion area, macroporous and compressible, with open pores and high tortuosity and layer III - impermeable substrate - non-adherent, biologically inert and microporous. The statistical indicators of the defining variables for each variant of textile structures (intended for layers I and III) are calculated, the histograms, the box plot graphs and the interactive spatial graphs, in the form of band type graphs are drawn. The obtaining of the substrate (II) based on hydrogel included an experimental plan with correlated factors, of the laticeal simplex type A {q, m}, with three factors (q=3) and four discretization intervals on the axes of the major simplex (m=4). The experimental matrix of the plan (dosed mass fractions) was designed, as well as the components of the mixtures. The plan was tested for optimality in D and A criteria. The measured experimental response was the apparent density of the hydrogel. The evaluation of the antimicrobial activity of the textile structures was performed using standardized strains: Staphylococcus aureus ATCC 6538, Escherichia coli ATCC 8739 and Candida albicans ATCC 10231. The biocompatibility assessment of textile supports for layers I and III was performed by MTT viability test and the LDH cell integrity test. The in vitro study for testing the biocompatibility of the functionalized multilayer matrix showed that they are biocompatible because the phenomenon of cell adhesion was present, regardless of the cell line used. In vivo testing according to ISO 10993-6 used the model of thermal burn injury on white rats (Wistar albino). The treated rats showed a rate of rapid healing and at 7 days of treatment the closure of the wound was observed between 40% - 60%, with areas of tissue regeneration. Inhibition of the invasion of exogenous microorganisms has been noted.