Cecilia Zorzi Bueno

Chitosan-alginate membranes accelerate wound healing.

The purpose of this study was to evaluate the efficacy of chitosan-alginate membrane to accelerate wound healing in experimental cutaneous wounds. Two wounds were performed in Wistar rats by punching (1.5 cm diameter), treated with membranes moistened with saline solution (CAM group) or with saline only (SL group). After 2, 7, 14, and 21 days of surgery, five rats of each group were euthanized and reepithelialization was evaluated. The wounds/scars were harvested for histological, flow cytometry, neutrophil infiltrate, and hydroxyproline analysis. CAM group presented higher inflammatory cells recruitment as compared to SL group on 2(nd) day. On the 7(th) day, CAM group showed higher CD11b(+) level and lower of neutrophils than SL group. The CAM group presented higher CD4(+) cells influx than SL group on 2(nd) day, but it decreased during the follow up and became lower on 14(th) and 21(st) days. Higher fibroplasia was noticed on days 7 and 14 as well as higher collagenesis on 21(st) in the CAM group in comparison to SL group. CAM group showed faster reepithelialization on 7(th) day than SL group, although similar in other days. In conclusion, chitosan-alginate membrane modulated the inflammatory phase, stimulated fibroplasia and collagenesis, accelerating wound healing process in rats.

Control of the properties of porous chitosan–alginate membranes through the addition of different proportions of Pluronic F68

This work addresses the development and characterization of porous chitosan-alginate based polyelectrolyte complexes, obtained by using two different proportions of the biocompatible surfactant Pluronic F68. These biomaterials are proposed for applications as biodegradable and biocompatible wound dressing and/or scaffolds. The results indicate that thickness, roughness, porosity and liquid uptake of the membranes increase with the amount of surfactant used, while their mechanical properties and stability in aqueous media decrease. Other important properties such as color and surface hydrophilicity (water contact angle) are not significantly altered or did not present a clear tendency of variation with the increase of the amount of surfactant added to the polyelectrolyte complexes, such as real density, average pore diameter, total pore volume and surface area. The prepared biomaterials were not cytotoxic to L929 cells. In conclusion, it is possible to tune the physicochemical properties of chitosan-alginate polyelectrolyte complexes, through the variation of the proportion of surfactant (Pluronic F68) added to the mixture, so as to enable the desired application of these biomaterials.

Docosahexaenoic acid ethyl esther (DHAEE) microcapsule production by spray-drying: optimization by experimental design

O acido docoso-hexaenoico e um acido graxo poli-insaturado essencial que desempenha importantes acoes metabolicas. Entretanto, por possuir duplas ligacoes conjugadas torna-se suscetivel a decomposicao. Uma das formas de minimizar esta possivel decomposicao e o emprego da tecnica de atomizacao para microencapsulacao. Porem, esta tecnica envolve uma serie de parâmetros de processo, que podem vir a alterar a qualidade do produto final. Assim, o objetivo deste trabalho foi microencapsular oleo de peixe enriquecido no ester etilico do acido docoso-hexaenoico (DHAEE-85%), variando condicoes operacionais e avaliar o rendimento pela analise por cromatografia gasosa, apos extracao das microcapsulas. Para tanto, foi utilizado o processo de microencapsulacao por atomizacao e o agente encapsulante foi a goma arabica. A avaliacao cromatografica de varios experimentos delineados pelo software Statistica, mostrou que os pontos otimos para obtencao das microcapsulas de DHAEE foram: temperatura de entrada 188 °C, porcentagem de recheio 30%, vazao de nitrogenio 55 mm N2 e vazao da bomba de 12,5 mL/minuto. Estas condicoes de processo foram testadas experimentalmente, resultando no teor de 66% m/m de DHAEE no oleo extraido, valor correspondente a 19,8% m/m de DHAEE encapsulado, valor considerado satisfatorio uma vez que 30% das microcapsulas correspondiam teoricamente ao material de parede.

Influence of the incorporation of the antimicrobial agent polyhexamethylene biguanide on the properties of dense and porous chitosan-alginate membranes

This work is a continuation of a previous study which described the development of dense and porous chitosan-alginate polyelectrolyte complexes through the addition of different amounts of Pluronic F68 to the polymeric mixture. The present study consisted in the incorporation of an antimicrobial agent, polyhexamethylene biguanide (PHMB), to the previously developed system. PHMB was incorporated at 1 and 10% (w/w) with high incorporation efficiencies, varying from 72 to 86%. Release profiles in phosphate buffered saline were evaluated using the Korsmeyer-Peppas equation, which suggested a quasi-Fickian diffusion mechanism for all obtained formulations. The maximum release percentage was approximately 15% as a result from the high affinity between PHMB and the polysaccharides. The obtained polyelectrolyte complexes were able to prevent the growth of both Staphylococcus aureus and Pseudomonas aeruginosa on their surfaces, being considered potentially effective wound dressings.