Zeolite/chitosan/gelatin films: preparation, supercritical CO2 processing, characterization and bioactivity

Abstract

Chitosan/gelatin and chitosan/gelatin/zeolite films prepared by solvent casting method were impregnated with a mixture of thymol and carvacrol using a green solvent, supercritical carbon dioxide at 35 °C and 30 MPa, during 18 h. Proposed method enabled preparation of biocompatible and biodegradable blends with strong antioxidant and antibacterial activity, whereby amounts of loaded thymol/carvacrol mixture were in the range from 3.3-6%. After initial burst release, both types of films exhibited gradual release of bioactive compounds, with around 72 and 96% of impregnated thymol/carvacrol mixture released in water and PBS (pH 7.4) during tested period of 10 days, respectively. Results of water vapor transmission rate (> 76 gm-2 day-1) confirmed that prepared composites are suitable for wound dressing application. Thermal analysis showed superior properties of prepared thymol/carvacrol loaded films compared to control samples. In addition, mechanical and structural properties, as well as solubility and swelling behavior of the obtained films were investigated in detail.