Concepts for Developing Physical Gels of Chitosan and of Chitosan Derivatives

Abstract

Chitosan macro- and micro/nano-gels have gained increasing attention in recent years, especially in the biomedical field, given the well-documented low toxicity, degradability, and non-immunogenicity of this unique biopolymer. In this review we aim at recapitulating the recent gelling concepts for developing chitosan-based physical gels. Specifically, we describe how nowadays it is relatively simple to prepare networks endowed with different sizes and shapes simply by exploiting physical interactions, namely (i) hydrophobic effects and hydrogen bonds—mostly governed by chitosan chemical composition—and (ii) electrostatic interactions, mainly ensured by physical/chemical chitosan features, such as the degree of acetylation and molecular weight, and external parameters, such as pH and ionic strength. Particular emphasis is dedicated to potential applications of this set of materials, especially in tissue engineering and drug delivery sectors. Lastly, we report on chitosan derivatives and their ability to form gels. Additionally, we discuss the recent findings on a lactose-modified chitosan named Chitlac, which has proved to form attractive gels both at the macro- and at the nano-scale.

Staggered Herringbone Microfluid Device for the Manufacturing of Chitosan/TPP Nanoparticles: Systematic Optimization and Preliminary Biological Evaluation

“…As is already well-known, the synthesis of NPs is highly dependent on the ionic interactions involved between CS and TPP, in which their ratios can have a key role in the size of them. Moreover, CS in the presence of TPP undergoes a liquid-gel transition, increasing the compactness of the NPs modulating the drug release through the polymer matrix [38]. However, the synthesis of CS/TPP NPs by the microfluidic SHM-assisted ionic gelation method has not been systematically investigated yet.…”

The Innovation Comes from the Sea: Chitosan and Alginate Hybrid Gels and Films as Sustainable Materials for Wastewater Remediation

“…Considering that a major percentage of processed seafood consists of crustaceans and the wastes produced by their exoskeleton and cephalothoraxes represent 50%-70% of the weight of the raw material, the extraction of components contained in these scraps is a convenient way to produce valuable resources, applicable in different fields [13,14]. Chitosan has unique properties among biopolymers since it contains primary amino groups [14] and is considered a low-toxic, non-immunogenic and biodegradable polysaccharide [15]. Indeed, chitosan and its derivatives have been used in the cosmetic industry, for food packaging, agriculture, environmental remediation and biomedical applications such as drug-delivery systems and/or as antimicrobial agents [16][17][18][19].…”

“…Physical gels are networks held together by molecular entanglements and/or secondary forces including ionic and H-bonds or hydrophobic interactions. Conversely, in chemically crosslinked gels, covalent bonds are present between the different polymer chains forming the network (linked by addition or condensation reactions, by chemical reactions with aldehydes, or through high energy irradiation) [15,21,23]. In particular, gels made by mixing alginate and chitosan have been carefully studied as results of the cooperative electrostatic interaction between poly-cationic chains of chitosan and poly-anionic chains of alginate [24].…”

Glycosylated-Chitosan Derivatives: A Systematic Review

“…Chitosan is a polysaccharide that is commercially derived from chitin-the second most abundant polysaccharide on earth. Chitin is the main component of the exoskeleton of Arthropoda, although cell walls of fungi, such as zygomycetes, contain it in small amounts [1]. The term chitosan refers to a family of polysaccharides composed of β-1→4 linked D-glucosamine units (deacetylated units, D) interspersed by residual N-acetyl-D-Glucosamines (acetylated units, A).…”