Structure design of polysaccharides – Chemoselective sulfoethylation of chitosan

Insight into divergent chemical modifications of chitosan biopolymer: Review

Chitosan is used in many applications due to its biodegradability, biocompatibility, nontoxicity, nonadhesiveness, and film-forming capabilities. Chitosan has antibacterial and antifungal activities, which are two of its other desirable attributes. However, chitosan can only dissolve in acidic liquids (1-3 % acetic acid), limiting its practical application. The hydroxyl and amino functional groups in the chitosan backbone are essential for chemical modification, which is a viable alternative for overcoming this obstacle. So, N- or O-, and N, O-substituted chitosan may yield derivatives with increased water solubility, biocompatibility, biodegradability, and bio-evaluation. In the same manner, the physicochemical properties of chitosan, including its mechanical and thermal properties, can be improved by cross-linking reactions. This review provides an overview of chitosan, including its origins and their solubility. Also, the review extend and discuss in details most of all chemical reactions that happened on the amino group, hydroxyl group, or both amino group and hydroxyl group to create modified chitosan-based organic materials. Finally, the problems that still need to be solved and probable future areas for study are discussed.

Recent Applications of Chitosan and Its Derivatives in Antibacterial, Anticancer, Wound Healing, and Tissue Engineering Fields

Chitosan, a versatile biopolymer derived from chitin, has garnered significant attention in various biomedical applications due to its unique properties, such as biocompatibility, biodegradability, and mucoadhesiveness. This review provides an overview of the diverse applications of chitosan and its derivatives in the antibacterial, anticancer, wound healing, and tissue engineering fields. In antibacterial applications, chitosan exhibits potent antimicrobial properties by disrupting microbial membranes and DNA, making it a promising natural preservative and agent against bacterial infections. Its role in cancer therapy involves the development of chitosan-based nanocarriers for targeted drug delivery, enhancing therapeutic efficacy while minimising side effects. Chitosan also plays a crucial role in wound healing by promoting cell proliferation, angiogenesis, and regulating inflammatory responses. Additionally, chitosan serves as a multifunctional scaffold in tissue engineering, facilitating the regeneration of diverse tissues such as cartilage, bone, and neural tissue by promoting cell adhesion and proliferation. The extensive range of applications for chitosan in pharmaceutical and biomedical sciences is not only highlighted by the comprehensive scope of this review, but it also establishes it as a fundamental component for forthcoming research in biomedicine.

Structural and conformational changes on chitosan after green heterogeneous synthesis of phenyl derivatives

Four aromatic acid compounds: benzoic acid (Bz), 4-hydroxyphenylpropionic acid (HPPA), gallic acid (GA) and 4-aminobenzoic acid (PABA) were covalently bonded to chitosan in order to improve water solubility at neutral pH. The synthesis was performed via a radical redox reaction in heterogeneous phase by employing ascorbic acid and hydrogen peroxide (AA/H₂O₂) as radical initiators in ethanol. The analysis of chemical structure and conformational changes on acetylated chitosan was also the focus of this research. Grafted samples exhibited as high as 0.46 M degree of substitution (MS) and excellent solubility in water at neutral pH. Results showed a correlation between the disruption of C3-C5 (O3…O5) hydrogen bonds with increasing solubility in grafted samples. Spectroscopic techniques such as FT-IR and ¹H and ¹³C NMR showed modifications in both glucosamine and N-Acetyl-glucosamine units by ester and amide linkage at C2, C3 and C6 position, respectively. Finally, loss of crystalline structure of 2-helical conformation of chitosan after grafting was observed by XRD and correlated with ¹³C CP-MAS-NMR analyses.

Evaluating the Role of Hydrophobic and Cationic Appendages on the Laundry Performance of Modified Hydroxyethyl Celluloses

Soil-release polymers (SRPs) are essential additives of laundry detergents whose function is to enable soil release from fabric and to prevent soil redeposition during the washing cycle. The currently used SRPs are petrochemical-based; however, SRPs based on biorenewable polymers would be preferred from an environmental and regulatory perspective. To explore this possibility, we have synthesized SRPs based on hydroxyethyl cellulose (amphiphilic HEC) appended with controlled compositions of hydrophobic and cationic appendages and assessed their cleaning abilities. The results demonstrate that the introduction of hydrophobic lauryl appendages onto the HEC backbone is essential to deliver anti-redeposition and soil-release performance. Conversely, further introduction of cationic groups onto hydrophobic modified HECs had no clear impact on soil-release performance but caused significant disadvantages on anti-redeposition performance. We speculate that this poor performance arises on account of coacervation formation between the cationic HEC polymer and the anionic surfactant in the detergent, negatively impacting soil suspension and suggests that the inclusion of cationic appendages on HECs can ultimately lead to detrimental effects on performance. Interestingly, in contrast to conventional SPRs that exhibit good soil-release performance exclusively on synthetic fabrics, amphiphilic HEC displayed encouraging results on both synthetic and cotton-based textiles, possibly as a result of a good chemical affinity with natural fabrics. This work highlights that the nature and hydrophobic content of HEC ethers are key variables that govern HEC applicability as SRPs, thus paving the way for the design and synthesis of new SRPs.

Efficient N-sulfopropylation of chitosan with 1,3-propane sultone in aqueous solutions: neutral pH as the key condition

Conjugation of strong anionic sulfonate groups to chitosan (CS) is typically used for converting the weak cationic CS to its polyampholyte derivatives, which are of interest to different areas benefiting from both cationic and anionic groups.