Bioartificial biodegradable materials were prepared mixing chitosan (CHI) and poly(vinyl al-cohol) (PVA), then manufactured as films, and finally cross-linked with glutaraldehyde (GTA), both in the absence and in the presence of the edible hexa-alcohol sorbitol (SOR), as a plasticizer. The release of the components into water was tested by high performance liquid chromatography (HPLC); no release of CHI and scarce release of PVA were found. The water uptake was tested by measuring the swelling of the materials, after incubating them for 20 hours in an atmosphere saturated with water vapour at 37 °C. The swelling percentage in-creases with increasing CHI content in the blends, although it is the less hydrophilic polymer. This behaviour was attributed to the difficulty of water to diffuse through the crystalline PVA structure, which is partially altered in the blends. The addition of SOR enhances the water sorption, as expected. The biodegradability of the materials was tested using the specific en-zyme chitosanase, and was found to depend on the blend composition, as well as to be en-hanced by the addition of SOR. The initial degradation rates were calculated; the maximum rates were found when the CHI to PVA ratio was 80:20 for all systems. The results of the en-zymatic degradation generally agree with those of the swelling. The cross-linked blends were tested also as drug-delivery systems. The drugs chosen were the vitamin L-ascorbic acid (AsA) and the anti-cancer drug paclitaxel (PTX). The effective diffusion coefficients, Deff, were evaluated for the release of both drugs from each material. Those of AsA are greater, of many powers of ten, than those of PTX, owing mainly to the hydrophilic nature of the first drug and to that hydrophobic of the second one. In conclusion, these materials seem available for a biomedical use.
Biodegradable bioartificial materials made by chitosan and poly(vinyl alcohol). Part II: Enzymatic degradability and drug-releasing ability
Cristallini C;Guerra GD
2008
Abstract
Bioartificial biodegradable materials were prepared mixing chitosan (CHI) and poly(vinyl al-cohol) (PVA), then manufactured as films, and finally cross-linked with glutaraldehyde (GTA), both in the absence and in the presence of the edible hexa-alcohol sorbitol (SOR), as a plasticizer. The release of the components into water was tested by high performance liquid chromatography (HPLC); no release of CHI and scarce release of PVA were found. The water uptake was tested by measuring the swelling of the materials, after incubating them for 20 hours in an atmosphere saturated with water vapour at 37 °C. The swelling percentage in-creases with increasing CHI content in the blends, although it is the less hydrophilic polymer. This behaviour was attributed to the difficulty of water to diffuse through the crystalline PVA structure, which is partially altered in the blends. The addition of SOR enhances the water sorption, as expected. The biodegradability of the materials was tested using the specific en-zyme chitosanase, and was found to depend on the blend composition, as well as to be en-hanced by the addition of SOR. The initial degradation rates were calculated; the maximum rates were found when the CHI to PVA ratio was 80:20 for all systems. The results of the en-zymatic degradation generally agree with those of the swelling. The cross-linked blends were tested also as drug-delivery systems. The drugs chosen were the vitamin L-ascorbic acid (AsA) and the anti-cancer drug paclitaxel (PTX). The effective diffusion coefficients, Deff, were evaluated for the release of both drugs from each material. Those of AsA are greater, of many powers of ten, than those of PTX, owing mainly to the hydrophilic nature of the first drug and to that hydrophobic of the second one. In conclusion, these materials seem available for a biomedical use.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
