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

Abstract

Supercritical carbon dioxide (scCO 2 ) 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 scCO 2 to obtain xero-and aerogels, respectively. Applying 10 min of static and 120 min of dynamic scCO 2 drying at 11 MPa and 458C 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 scCO 2 at 10 MPa and 358C. In vitro studies of swelling in PBS at 378C 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., 00:000-000,

Antimicrobial Cellulose Nanofibril Porous Materials Obtained by Supercritical Impregnation of Thymol

“…Thymol and other essential oil molecules have been impregnated into various matrices using scCO 2 . 30,31 The solubility of thymol was investigated by Milovanovic et al at different pressures and temperatures. Consequently, they performed the impregnation on cotton gauzes at 35°C and 155 bars which conferred antimicrobial properties to the material.…”

Chemistry of Chitosan Aerogels: Three‐Dimensional Pore Control for Tailored Applications

“…[216] Ag nanoparticles also act as antibacterial additives. [217] Chitosan-biopolymer composites are proposed for biomedical scaffolds,e ither as wet cryogels or as freeze-dried gels: [218] Gelatin-agarose,a lginate,c ollagen, caprolactone, carrageenan, chondroitin sulfate,h yaluronic acid, cellulose, cyclodextrin, polylactide and poly(lactic-co-glycolic acid), polyglutamic acid, pectin, silk fibroin, starch, and chitin are typical biopolymers for this purpose,s ometimes combined with HAp and TCP to modify mechanical properties.Scaffold functionalization with polymers and macromolecules is also am ajor topic, for example,w ith DNA, [219] peptides, [220] nucleoside diphosphates, [221] and enzymes [222] for delivery and sensing applications,w ith polypyrrole [223] and polyaniline [224] for electrical conductivity,a nd with polyacrylamides, [225] polyethylene glycol, [226] polyvinyl alcohol, [227] polymethyl methacrylate, [228] and polyethylenimine [229] for improving mechanical properties and other functions.Carbon-based materials,s uch as graphene oxide, [230] carbon nanotubes, [231] and carbon black, [232] are also suitable components for electrical conduction and sensing applications.…”

Supercritical Fluid Applications in the Design of Novel Antimicrobial Materials

“…Terzić et al [58] applied scCO 2 technology to the preparation of functional pH-sensitive chitosan-itaconic acid-methacrylic acid (Ch/IA/MAA) aerogels characterized with micron-size pores and their impregnation with thymol. Ch/IA/MAA hydrogels were obtained first, transferred to alcogels, and then dried in air to obtain xerogel or in scCO 2 to obtain aerogels.…”

“…The scCO 2 drying consisting of 10 min of static and 120 min of dynamic drying at 11 MPa and 45 • C followed by the decompression at a rate of 1 MPa/min resulted in an advantageous aerogel with favorable swelling kinetics and elasticity, compared to the xerogel and aerogels obtained at other decompression rates and drying times. The aerogel was subsequently loaded with thymol (up to 4.6 wt.%) in a batch SSI process at 10 MPa and 35 • C with the impregnation time of up 5 h. In vitro studies of swelling in phosphate buffered saline (PBS) at 37 • C indicated a considerable potential of the obtained stimuli-responsive gel for topical administration of thymol [58].…”