RESUMO
Poly (vinyl alcohol) hydrogels containing different concentrations of chitosan with molecular weight of 471 and 101 kDa were crosslinked by gamma irradiation at a dose of 25 kGy. The swelling behavior, gel content and morphological structure of the blend were investigated. The antibacterial effect, as a function of chitosan content and molecular weight in the hydrogel, was investigated against Escherichia coli and Bacillus subtilis. With increasing chitosan content the equilibrium degree of swelling of the blend increased and the gel fraction decreased. Results of antibacterial activity of chitosan revealed that chitosan was more effective in inhibiting growth of gram positive bacteria than that of gram negative ones. It was observed that, the chitosan content as well as its molecular weight has a direct influence on bacteria growth inhibition. The higher the chitosan content in the blend and the higher its initial molecular weight, the larger was the inhibition zone diameter. The bacteria growth inhibition was attributed to the diffusion of entrapped chitosan from the hydrogel blend to the culture medium.
Assuntos
Antibacterianos/farmacologia , Quitosana/farmacologia , Raios gama , Hidrogéis/química , Álcool de Polivinil/farmacologia , Antibacterianos/química , Bacillus subtilis/efeitos dos fármacos , Materiais Biocompatíveis , Quitosana/química , Escherichia coli/efeitos dos fármacos , Teste de Materiais , Microscopia Eletrônica de Varredura , Álcool de Polivinil/química , Propriedades de SuperfícieRESUMO
Hydrogel based on poly(vinyl alcohol) containing 0.25% of chitosan was synthesized by gamma irradiation and evaluated as wound dressing material in a burn rat model. Histological analyses, Primary Irritation Index (P.I.I.) and Ocular Irritation Index (O.I.I.) were investigated. The comparative study showed that the wounds treated with PVA/chitosan hydrogel healed on the 9th day, while those treated with paraffin gauze dressing and cotton gauze healed on the 16th day. Histological analysis showed that new granulation tissue and epithelialization progressed better in wound treated with hydrogel PVA/chitosan. The determined values of P.I.I. and O.I.I. of the PVA/chitosan hydrogel were, respectively 0.5 and zero. These values indicate that the PVA/chitosan hydrogel can be considered as non-irritating to the skin.