Advances in chitooligosaccharides chemical modifications

Abstract

Chitooligosaccharides (COS) differ from chitosan by their molar mass: those of COS are defined to be lower than 20 kg mol−1. Their functionalization is widely described in the literature and leads to the introduction of new properties that broaden their application fields. Like chitosan, COS modification sites are mainly primary amine and hydroxyl groups. Among their chemical modification, one can find amidation or esterification, epoxy‐amine/hydroxyl coupling, Schiff base formation, and Michael addition. When depolymerized through nitrous deamination, COS bear an aldehyde at the chain end that can open the way to other chemical reactions and lead to the synthesis of new interesting amphiphilic structures. This article details the recent developments in COS functionalization, primarily focusing on amine and hydroxyl groups and aldehyde‐chain end reactions, as well as paying considerable attention to other types of modification. We also describe and compare the different functionalization protocols found in the literature while highlighting potential mistakes made in the chemical structures accompanied with suggestions. Such chemical modification can lead to new materials that are generally nontoxic, biobased, biodegradable, and usable in various applications.

Customized chitooligosaccharide production—controlling their length via engineering of rhizobial chitin synthases and the choice of expression system

“…While the production of tetramers only was not achieved, strains synthesizing either mainly pentamers ( E. coli NodC_GRH2 or the NodC_S19L muteins with both expression systems) or nearly pure hexamers ( C. glutamicum NodC_R346S) were successfully generated. Especially the practically pure hexamer is interesting for several applications: Firstly, purification is simpler if the synthesized COS are uniform, and A6 is still water-soluble, making it industrially manageable and applicable ( Bonin et al, 2020 ; Chapelle et al, 2021 ). Secondly, A6 is promising for several biological applications, e.g., plant strengthening ( Gubaeva et al, 2018 ; Shi et al, 2019 ) or biomedical and pharmaceutical applications ( Panda et al, 2012 ; Zhu et al, 2020 ).…”

Chitosan and chito-oligosaccharide: a versatile biopolymer with endless grafting possibilities for multifarious applications

“…However, COS dissolve in a wide variety of solvents, including water/alcohol solutions, DMSO, and DMF, depending on their size. Hence, researchers are focusing on ways to tailor these oligomers to make them useful in more contexts (Chapelle et al, 2021). GRFT-CH, a biocompatible and biodegradable polymer derived from CI, has attracted significant FIGURE 5 XRD spectra of glycerol monostearate (GMS), amphotericin (AmB), paromomycin, chitosan (Cs), and grafted chitosan-functionalized solid lipid nanoparticles (SLN) of drug (Cs-SLN).…”

Phospho-Chitooligosaccharides below 1 kDa Inhibit HIV-1 Entry In Vitro

“…COSs have also been subjected to carboxylation [19], sulfation [20], and phosphorylation [21]. Compared to unmodified COSs, these derivations improved COS bioactivity in some cases, adding new bioactivities which COS itself did not possess [22].…”