Blendas de PVA – polímeros naturais carregados com mel de manuka

Abstract

PVA blends with natural polymers loaded with Manuka honey were developed for the treatment of pressure ulcers/bed sores, since most bandages used for this treatment are hydrogels. Starch and sodium Carboxymethyl cellulose (NaCMC) and gelatin are non-toxic, biocompatible, biodegradable polymers that have low cost and they can alter the properties of PVA, when mixed to it. Manuka honey was used because it presents antibacterial activity and it accelerates the wound healing. The hydrogels were manufactured by the casting method and they were characterized by FTIR, DSC, swelling degree, honey release kinetics analysis, and microbiological analysis. The FTIR analysis showed that physical interaction occurred between the blends’ materials. The highest swelling rates were found in PVA/NaCMC and PVA/NaCMC/Honey samples and the lowest in PVA/Starch and PVA/Honey samples. The difference of the swelling degree can be related to the crystallites’ formation as well as to the presence of honey, both acting as barrier to fluid entrance. The PVA/Starch and PVA/Gel/Honey samples presented the highest values of gel fraction and the lowest values of weight loss. DSC analysis showed that in samples containing honey, the honey can not only interfere with the movement of amorphous chains, but also in the packaging of PVA chains. In honey release analysis, it was observed that there is a maximum release in 48 h. It was observed a diffusion exponent n<1 in the kinetic model, showing that physical cross-linking occurred, and the average relative deviation was between 2.5 % and 17.65 %. The gels showed no activity against S. aureus, but pure honey showed antibacterial activity and honey dilutions above 25 % presented bacteriostatic activity.