The pivotal issue of skin regeneration research is the development of effective biomaterials that exhibit biological activities as fungicide and bactericide, combining simple and low cost manufacturing technologies. In this context, nanocomposite scaffolds based on chitosan (Ch)/Laponite (Lap) were produced by using different concentrations of Lap via freeze‐drying process for potential application in skin regeneration. The influence of Lap concentration on the scaffold properties was evaluated. The prepared scaffolds were characterized by x‐ray diffraction (XRD), scanning electron microscopy (SEM), porosity, swelling capacity, and mechanical analyses. The results revealed that the scaffolds exhibited a porous architecture, besides the increase in the clay content, leads to an increase in the porosity, an improvement of mechanical strength, and a decrease of swelling capacity. In vitro tests were also carried out to evaluate the biocompatibility of the materials, such as bioadhesion, antibacterial activity, viability, and cell adhesion. Viability and cell adhesion demonstrated that all scaffolds were not cytotoxic and the fibroblast cells readily attached on the surface of the scaffolds. Thereby, the results suggested that the nanocomposite scaffolds are biomaterials potentially useful as wound dressings.

Polyacrylic acid (PAA)/clay mineral (SWy-1) nanocomposites were prepared by intercalation in solution and their photostability was evaluated. For the nanocomposite films containing 5, 10 and 20 wt % in SWy-1 mass occurred intercalation along with some clay exfoliation, while for PAA/30%SWy-1, the intercalation of PAA chains into the clay interlayers was observed. Scanning Electron Microscopy (SEM) images of the films suggested that nanocomposite films are homogeneous, indicating efficient dispersion of the polymer matrix into the SWy-1 clay. The thermal degradation temperatures of depolymerisation for the nanocomposite films were higher (362-370 °C) than pure PAA (361 °C), which means that the presence of SWy-1 clay promotes thermal stabilization.The photooxidative degradation of pure PAA and nanocomposite films was followed using Size Exclusion Chromatography (SEC). The degradation rate constant for pure PAA was higher than nanocomposite films; therefore, the increase of SWy-1concentration detained the degradation of PAA. The presence of SWy-1 clay contributes for the photostabilization of the material. SWy-1 has ability to disperse the incident light as well as also to absorb part of the UV light instead of PAA, hence minimizing the degradation rate.

momentos de descontração, pelas conversas e pelo companheirismo. Aos Técnicos, André, Luiz Antônio e Márcio pelo auxílio na realização das análises. À querida colega Daniele Soares e seu orientador Prof. Dr. Roy Edwards Bruns, pela ajuda nos resultados de quimiometria. Aos meus colegas de pós-graduação, Amanda, Emmanuela, Leandro, Kariny, Suzy, Anderson e Peter, pela ajuda direta ou indireta na realização deste trabalho e pelos momentos alegres.

Skin lesions represent a great challenge for health professionals, since the most modern wound dressings available today are imported and expensive. Thus, there is a need to achieve more accessible resources for the population. The main challenge of skin regeneration research is the development of effective biomaterials that present biological activities as fungicide and bactericide, combining simple and low cost manufacturing technologies. In this context, this work presents the development of porous membrane based on chitosan/laponite nanocomposite for potential application in skin regeneration. Firstly, the commercial chitosan was purified and characterized in relation to the average degree of acetylation and the average viscosity molar mass. The freeze-drying process was used to produce porous membranes with different content of clay. The influence of laponite concentration on the membrane properties was also evaluated. X-Ray Diffraction (XRD) was used to determine the structure of the nanocomposite. Porous membranes were characterized by Scanning Electron Microscopy (SEM), thickness measurements, swelling capacity, thermogravimetric and mechanical analyses. The results revealed the increase in the porosity and in the thermal stability in addition to the decrease of the swelling capacity with the increase of clay content. In vitro tests were also carried out to evaluate the biocompatibility of the materials, such as: bioadhesion, antibacterial activity, viability and cell adhesion. Thereby, the results indicated that the porous membranes are biomaterials potentially useful as wound dressings.