Biomedical Exploitation of Chitin and Chitosan via Mechano-Chemical Disassembly, Electrospinning, Dissolution in Imidazolium Ionic Liquids, and Supercritical Drying

Abstract

Recently developed technology permits to optimize simultaneously surface area, porosity, density, rigidity and surface morphology of chitin-derived materials of biomedical interest. Safe and ecofriendly disassembly of chitin has superseded the dangerous acid hydrolysis and provides higher yields and scaling-up possibilities: the chitosan nanofibrils are finding applications in reinforced bone scaffolds and composite dressings for dermal wounds. Electrospun chitosan nanofibers, in the form of biocompatible thin mats and non-wovens, are being actively studied: composites of gelatin + chitosan + polyurethane have been proposed for cardiac valves and for nerve conduits; fibers are also manufactured from electrospun particles that self-assemble during subsequent freeze-drying. Ionic liquids (salts of alkylated imidazolium) are suitable as non-aqueous solvents that permit desirable reactions to occur for drug delivery purposes. Gel drying with supercritical CO2 leads to structures most similar to the extracellular matrix, even when the chitosan is crosslinked, or in combination with metal oxides of interest in orthopedics.

Gecko-inspired chitosan adhesive for tissue repair

“…19 Of relevance is the fact that the nanoscale modification of the flat chitosan adhesive did not alter its chemical composition and thus its excellent biocompatibility and biodegradability. 38 In this respect, a recent study has highlighted that the degradation of the flat chitosan adhesives can be modulated if a physiological amount of lysozyme is added during the fabrication process of the adhesive. The lysozyme loaded adhesive degraded 20% after 4 weeks implantation into biocompatible monomers and oligomers of glucosamine and N-acetyl-glucosamine.…”

Encapsulation of Mentha Oil in Chitosan Polymer Matrix Alleviates Skin Irritation

“…Therefore, X2 and X3 are the limiting factors as small variation in their concentrations would alter the %EE to a considerable extent. The entrapment of MVO in chitosan might be due to extensive active amine and hydroxyl groups which allow subsequent modification intended for the attachment of drug (29).…”

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“…Intramolecular hydrogen bonds between C 3 -OH hydroxyl and C 5 -O ring oxygen across each β(1→4)-glycosidic linkage limit chitin units to the low-energy chair conformation, which results in a strong, rigid and linear polymer structure. This prevents the polymer from dissolving completely in common organic solvents (DMSO, DMF, DCM, and NMP) and aqueous solvents 9 .…”