Chitosan: Gels and Interfacial Properties

Abstract

Abstract:Chitosan is a unique biopolymer in the respect that it is abundant, cationic, low-toxic, non-immunogenic and biodegradable. The relative occurrence of the two monomeric building units (N-acetyl-glucosamine and D-glucosamine) is crucial to whether chitosan is predominantly an ampholyte or predominantly a polyelectrolyte at acidic pH-values. The chemical composition is not only crucial to its surface activity properties, but also to whether and why chitosan can undergo a sol-gel transition. This review gives an overview of chitosan hydrogels and their biomedical applications, e.g., in tissue engineering and drug delivery, as well as the chitosan's surface activity and its role in emulsion formation, stabilization and destabilization. Previously unpublished original data where chitosan acts as an emulsifier and flocculant are presented and discussed, showing that highly-acetylated chitosans can act both as an emulsifier and as a flocculant.

Effects of Genipin Concentration on Cross-Linked Chitosan Scaffolds for Bone Tissue Engineering: Structural Characterization and Evidence of Biocompatibility Features

“…Chitosan is a natural copolymer composed of -(1-4)-linked 2-acetamido-2-deoxy-D-glucopyranose and 2-amino-2-deoxy-D-glucopyranose units, derived from the alkaline deacetylation of chitin, the main constituent of the exoskeleton of crustaceans, such as shrimps, molluscs, and insects [16][17][18]. It is also the principal fibrillar polymer in the cell wall of certain fungi.…”

“…In fact, the presence of reactive amino side groups provides many possibilities of chemical bonds and crosslinking reactions; commonly, to stabilize CS hydrogels and to enhance their mechanical properties and biodegradability and/or to ameliorate cellular adhesion properties, chemical or ionic cross-linking methods (e.g., UV, ionic cross-linking) are employed [20]. For instance, chemical cross-linkers such as epoxy compounds [21], aldehydes (formaldehyde, glyceraldehyde, and glutaraldehyde) [22], and carbodiimides [23] or ionic cross-linkers such as sulfates, citrates, and phosphates [24,25] have been used to stabilize CS [17]. This paper is focused on the preparation and characterization of an innovative CS scaffold produced starting from chitosan hydrogel covalently cross-linked with genipin, a natural extract of Gardenia jasminoides Ellis [26].…”

The Effect of β-Glycerophosphate Crosslinking on Chitosan Cytotoxicity and Properties of Hydrogels for Vaginal Application

“…Recently, plenty of data has drawn attention to the use of CS hydrogels in controlled drug delivery intended for vaginal administration [15,16]. Despite several advantages offered by CS hydrogels, including ease of administration, lubricating properties or acidic pH close to vaginal pH value [17,18], hydrogels prepared with unmodified CS possess relatively low mechanical strength [19]. Modification of the CS structure by ion crosslinking enables the improvement of mechanical and rheological properties of its semisolid preparations [20].…”

pH-Sensitive Chitosan Hydrogel with Instant Gelation for Myocardial Regeneration

“…So, fluctuations caused by the addition of buffer and NaOH leading to hydrogen bonds and intermolecular ionic interactions between positive charge of chitosan and negatively charged ions of the buffer and sodium hydroxide, but no covalent bonds were observed in gel formation process that indicate hydrogels were formed through physical and ionic gelation [41]. As seen in Figure 1C, after combination of these components on the tip of designed unique co-current coaxial needle, hydrogel formed immediately via these favorable intermolecular interactions.…”

“…As shown in Figure 4A, the peaks of the MH sample in these ranges were intensified due to the presence of further carbohydrate and phosphate groups in DMEM used in this sample, compared with WH sample. It should be mentioned that the weakness of C-H peaks intensity with centrality ~2880 cm -1 is because of the high deacetylation degree of chitosan and this feature enhances the adhesion of cells due to the high amine groups on chitosan [41].…”