A novel chitosan gels: Supercritical CO2 drying and impregnation with thymol

Abstract

Supercritical carbon dioxide (scCO2) technology was used for preparation of functional pH sensitive chitosan-based aerogels characterized with micron size pores and their impregnation with thymol as a natural bioactive substance. Hydrogels based on chitosan, itaconic and methacrylic acids were transformed to alcogels and dried in the air or with scCO2 to obtain xero- and aerogels, respectively. Applying 10 min of static and 120 min of dynamic scCO2 drying at 11 MPa and 45°C followed with the decompression at a rate of 1 MPa/min yielded an advantageous aerogel with favorable swelling kinetics and elasticity, compared to the xerogel and aerogels obtained at other decompression rates and drying times. This aerogel was successfully loaded with thymol (up to 4.6 wt.%) using supercritical scCO2 at 10 MPa and 35°C. In vitro studies of swelling in PBS at 37°C indicated a great potential of the obtained stimuli-responsive chitosan gels for topical administration of thymol known for antimicrobial, antioxidant and anti-inflammatory activities. POLYM. ENG. SCI., 58:2192–2199, 2018. © 2018 Society of Plastics Engineers.