Films and hydrogels base don Xylans complexes with chitosan

P. MOCCHIUTTI; M.V. GALVÁN; M. C. INALBON; C.N. SCHNELL; F. FABBRONI; M.A. ZANUTTINI

Montevideo

Workshop; Workshop on Insights and Strategies Towards a Bio-based Economy (I&S).; 2016

Facultad de Química. Universidad de la República. Uruguay

Lignocellulose biomass represents a renewable raw material for the production of polymeric material. Hemicellulose has potential uses as biopolymers. Xylans are the most abundant hemicellulose in nature. Glucuronoxylans are present in hardwood and non-wood raw materials. Regrettably, the use of them faces a limitation because, being alone, they have a strong tendency to shrink and they crack when drying. They do not form films. This behavior is assigned to their strong tendency to crystallize. The addition of a plasticizer compound allows to obtain a film and reduces rigidity but the breaking stress is notably affected. A possible alternative to this drawback is the combination with another polyelectrolyte of opposite charge, such as chitosan, to form polyelectrolyte complexes (PECs). The ionic cross-links established in the complexes can restrict freedom of xylan chains to crystallize. We have shown that the gradual addition of a glucuronoxilan solution on a chitosan solution in a slightly acid medium leads to a stable suspension of colloidal complexes. These complexes can be characterized by their size and colloidal charge. The proportion of xylan in this PECs can be as high as 70 %. From this suspension, homogenous films can be obtained by casting/evaporation method. Films are strong and have excellent barrier properties against oxygen and moisture. Therefore, they has potential application in packaging. Due to the presence of chitosan, films have antibacterial properties that can be useful in many applications. These films withstand water immersion resulting in a hydrogel with relatively highly water uptake. Their free cationic amine groups allow reinforcement treatment. Cross-links can be established using nontoxic agents such as sodium citrate. We have verified the increase in strength of the film and the hydrogel and the increase in water uptake that thistreatment produces. These natural hydrogels (ecological, biocompatible and biodegradable) can find many medical and industrial applications. One of them is use hydrogels as a matrix for controlled drug release in transdermal therapy. Our test of in vitro drug delivery, shows that these hydrogels can be useful for this application. Clear effects of the preparation variables on the performance of absorption and release ofdrugs have been found.