2, Centro de Investigación en Alimentación y Desarrollo, Hermosillo, Sonora, Mexico
3, Centro de Investigación en Alimentación y Desarrollo, Guaymas, Sonora, Mexico
Polysaccharide-based smart cryogels respresent a promising platform for biotechnological and biomedical applications such as immobilization of bioactive molecules and cells, drug delivery, tissue engineering, among others . Polymeric cryogel is a three-dimensional cross-linked system formed via the cryogenic treatment of solutions or colloidal dispersions of the appropriate precursors . Recently, dual temperature and pH sensitiveness systems based on chitosan derivatives have been studied . In this work, novel thermoresponsive chitosan-g-poly(N-vinylcaprolactam) cryogels were prepared from polymeric solutions using glutaraldehyde as crosslinking agent at -20 °C. The morphology of the cryogel beads were characterized by SEM and confocal microscopy. The resultant materials showed interconnected regular macroporous structure. The pore size of the cryogels is around of 10 µm. The study of equilibrium swelling shows an abrupt decrement in water absorption ability around of 34 °C. The reversible thermal responsiveness for cryogel beads was analyzed by variation of swelling in pure water (pH 6) to stepwise periodic changes in temperature between 5 and 45 °C. Below transition temperature, copolymer chains in the cryogel are hydrated, while as temperature increases to 45 °C, the macromolecular chains are slightly contracted, and water is ejected from the cryogel beads. The capacity of drug delivery carrier of the system was evaluated using citral (3,7-dimethyl-2,6-octadienal) as a model molecule, varying pH and temperature of the medium. These chitosan derivatives cryogels exhibited loading ability, and the release of citral was pH- and temperature-dependent.
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