Synthesis and preservative application of quaternized carboxymethyl chitosan containing guanidine groups

Dual-Cross-Linked Chitosan-Based Antibacterial Hydrogels with Tough and Adhesive Properties for Wound Dressing

Biocompatible chitosan-based hydrogels have attracted extensive attention in wound dressing due to their human skin-like tissue characteristics. However, it is a crucial challenge to fabricate chitosan-based hydrogels with versatile properties, including flexibility, stretchability, adhesivity, and antibacterial activity. In this work, a kind of chitosan-based hydrogels with integrated functionalities are facilely prepared by solution polymerization of acrylamide (AAm) and sodium p-styrene sulfonate (SS) in the presence of quaternized carboxymethyl chitosan (QCMCS). Due to the dual cross-linking between QCMCS and P(AAm-co-SS), the optimized QCMCS/P(AAm-co-SS) hydrogel exhibits tough mechanical properties (0.767 MPa tensile stress and 1100% fracture strain) and moderate tissue adhesion (11.4 kPa). Moreover, biological evaluation in vitro illustrated that as-prepared hydrogel possesses satisfactory biocompatibility, hemocompatibility, and excellent antibacterial ability (against S. aureus and E. coli are 98.8% and 97.3%, respectively). Then, the hydrogels are tested in a rat model for bacterial infection incision in vivo, and the results show that they can significantly accelerate epidermal regeneration and wound closure. This is due to their ability to reduce the inflammatory response, promote the formation of collagen deposition and granulation tissue. The proposed chitosan-based antibacterial hydrogels have the potential to be a highly effective wound dressing in clinical wound healing.

Strategies for the Preparation of Chitosan Derivatives for Antimicrobial, Drug Delivery, and Agricultural Applications: A Review

Chitosan has received much attention for its role in designing and developing novel derivatives as well as its applications across a broad spectrum of biological and physiological activities, owing to its desirable characteristics such as being biodegradable, being a biopolymer, and its overall eco-friendliness. The main objective of this review is to explore the recent chemical modifications of chitosan that have been achieved through various synthetic methods. These chitosan derivatives are categorized based on their synthetic pathways or the presence of common functional groups, which include alkylated, acylated, Schiff base, quaternary ammonia, guanidine, and heterocyclic rings. We have also described the recent applications of chitosan and its derivatives, along with nanomaterials, their mechanisms, and prospective challenges, especially in areas such as antimicrobial activities, targeted drug delivery for various diseases, and plant agricultural domains. The accumulation of these recent findings has the potential to offer insight not only into innovative approaches for the preparation of chitosan derivatives but also into their diverse applications. These insights may spark novel ideas for drug development or drug carriers, particularly in the antimicrobial, medicinal, and plant agricultural fields.

Polysaccharide-Based Supramolecular Hydrogel Coatings with Corrosion Barrier Zone for Protection of Patina Bronze

Protective coatings for bronze relics should adhere to the basic principles of cultural relic preservation, such as not altering the color and appearance of the artifacts, and being moderately combined with the artifacts to resist erosion due to external environments (such as water and gas). This paper presents the development of a physically crosslinked supramolecular hydrogel produced from guanidinium-based chitosan (GC). The hydrogel exhibits the excellent adsorption protection of bronze, and the addition of clay enhances the water barrier properties of the chitosan film. The supramolecular interaction between sodium polyacrylate/GC/clay confers corrosion buffering capability to the hydrogel coating in corrosive environments, and the gel coating can be self-healing at room temperature for 24 h. The fabricated nanocomposites were comprehensively characterized using various methods (Fourier transform infrared spectroscopy, X-ray diffraction, thermogravimetric analysis, X-ray photoelectron spectroscopy, scanning electron microscopy, etc.). The electrochemical properties of coated specimens were evaluated, and the impedance spectrum revealed a large impedance arc indicating high charge resistance, which has a corrosion resistance effect.

Biomedical Applications of Quaternized Chitosan

The natural polymer chitosan is the second most abundant biopolymer on earth after chitin and has been extensively explored for preparation of versatile drug delivery systems. The presence of two distinct reactive functional groups (an amino group at C2, and a primary and secondary hydroxyl group at C3 and C6) of chitosan are involved in the transformation of expedient derivatives such as acylated, alkylated, carboxylated, quaternized and esterified chitosan. Amongst these, quaternized chitosan is preferred in pharmaceutical industries owing to its prominent features including superior water solubility, augmented antimicrobial actions, modified wound healing, pH-sensitive targeting, biocompatibility, and biodegradability. It has been explored in a large realm of pharmaceuticals, cosmeceuticals, and the biomedical arena. Immense classy drug delivery systems containing quaternized chitosan have been intended for tissue engineering, wound healing, gene, and vaccine delivery. This review article outlines synthetic techniques, basic characteristics, inherent properties, biomedical applications, and ubiquitous challenges associated to quaternized chitosan.

An Overview of Current Knowledge on the Properties, Synthesis and Applications of Quaternary Chitosan Derivatives

Chitosan, a chitin-derivative polysaccharide, known for its non-toxicity, biocompatibility and biodegradability, presents limited applications due to its low solubility in neutral or basic pH medium. Quaternization stands out as an alternative to modify this natural polymer, aiming to improve its solubility over a wide pH range and, consequently, expand its range of applications. Quaternization occurs by introducing a quaternary ammonium moiety onto or outside the chitosan backbone, via chemical reactions with primary amino and hydroxyl groups, under vast experimental conditions. The oldest and most common forms of quaternized chitosan involve N,N,N-trimethyl chitosan (TMC) and N-[(2-hydroxy-3-trimethyl ammonium) propyl] chitosan (HTCC) and, more recently, quaternized chitosan by insertion of pyridinium or phosphonium salts. By modifying chitosan through the insertion of a quaternary moiety, permanent cationic charges on the polysaccharide backbone are achieved and properties such as water solubility, antimicrobial activity, mucoadhesiveness and permeability are significantly improved, enabling the application mainly in the biomedical and pharmaceutical areas. In this review, the main quaternized chitosan compounds are addressed in terms of their structure, properties, synthesis routes and applications. In addition, other less explored compounds are also presented, involving the main findings and future prospects regarding the field of quaternized chitosans.

Novel quaternarized N-halamine chitosan and polyvinyl alcohol nanofibrous membranes as hemostatic materials with excellent antibacterial properties

The aim of this study was to develop novel nanofibrous membranes based on the quaternary ammonium N-halamine chitosan (CSENDMH) and polyvinyl alcohol (PVA) for antibacterial and hemostasis wound dressing. To improve the antimicrobial properties of nanofibrous membranes, a new chitosan-quaternary ammonium N-halamine derivative was successfully synthesized, and the structure was analyzed by 1H NMR and 13C NMR, fourier transform infrared (FTIR) spectroscopy, and elemental analysis. The morphological and water absorption ability studies showed that the membrane had a uniform bead-free network and high porosity structure like natural extracellular matrix as well as high hydrophilicity. For in vitro evaluation of the hemostatic effect, the membranes showed excellent blood clotting capacity, especially the PVA/CSENDMH membranes. The antimicrobial assay demonstrated excellent antibacterial activity of nanofibrous membranes against both gram-negative and gram-positive bacteria. Furthermore, the cytocompatibility assay results indicated that human fibroblasts could adhere and proliferate on the membranes, thus corroborating their biocompatibility.

Bio-Based Polymers with Antimicrobial Properties towards Sustainable Development

This article concisely reviews the most recent contributions to the development of sustainable bio-based polymers with antimicrobial properties. This is because some of the main problems that humanity faces, nowadays and in the future, are climate change and bacterial multi-resistance. Therefore, scientists are trying to provide solutions to these problems. In an attempt to organize these antimicrobial sustainable materials, we have classified them into the main families; i.e., polysaccharides, proteins/polypeptides, polyesters, and polyurethanes. The review then summarizes the most recent antimicrobial aspects of these sustainable materials with antimicrobial performance considering their main potential applications in the biomedical field and in the food industry. Furthermore, their use in other fields, such as water purification and coating technology, is also described. Finally, some concluding remarks will point out the promise of this theme.

Synthesis, characterization, and antifungal evaluation of diethoxyphosphoryl polyaminoethyl chitosan derivatives

Botrytis cinerea, Phytophthora capsici Leonian, and Fusarium solani are important plant pathogenic fungi which can cause great crop losses worldwide, but their control methods are limited. It is necessary to develop efficient and green fungicides from abundant marine resources. Chitosan is a non-toxic, biodegradable, biocompatible marine polysaccharide which has prospective applications in agriculture. In this paper, to increase the antifungal activity of chitosan for application, novel water-soluble functional chitosan derivatives were synthesized by grafting polyaminoethyl and diethoxyphosphoryl groups in accordance with a strategy of improving protonation potential. The derivatives were characterized by FTIR, NMR, XRD, SEM, Gaussian 09 and elemental analysis. The antifungal activities against the three fungi and the cytotoxicity were estimated in vitro. The results showed that the derivatives had better antifungal activities and water solubility than chitosan, and had good biocompatibility. They confirmed that these chitosan derivatives can be developed as antifungal agents for plant protection purposes.

Microwave Assisted Preparation of Antimicrobial Chitosan with Guanidine Oligomers and Its Application in Hygiene Paper Products

Guanidinylated chitosan (GCS) was prepared by grafting guanidine oligomers onto chitosan under microwave irradiation. The structure of GCS characterized by FT-IR and ¹H NMR verified the covalent bonding between the guanidine oligomers and chitosan; the effects of molar ratio, reaction temperature, and time were investigated and the degree of substitution of GCS reached a maximum of 25.5% under optimized conditions in this work. The resulting GCS showed significantly enhanced antimicrobial activities. The results obtained from the dynamic UV absorption of Escherichia coli (E. coli) and atomic force microscopy (AFM) revealed that the deactivation of E. coli by GCS was due to the destructing of the cell membrane and the prompt release of cytoplasm from the bacterial cells. The adsorption of GCS onto cellulose fibers and the antimicrobial efficiency of the hygiene papers with GCS were also investigated. Microwave irradiation as a green assisted method was applied to promote this reaction. This facile approach allowed chitosan to be guanidinylated without tedious preparation procedures and thus broadened its application as a biocompatible antimicrobial agent.

Novel recyclable adsorbent for the removal of copper(II) and lead(II) from aqueous solution

Adsorbents synthesized with biopolymer have been widely used in the removal of toxic metal ions. Novel high-efficiency, recyclable, and low-cost adsorbents have received more and more attention. Chitosan and cellulose are the most abundant biopolymers in nature. Composite modified adsorbent (CSTEC) was synthesized as novel fibrous materials for the adsorption of Cu²⁺ and Pb²⁺ ions from water in this study. The functional fiber was characterized to investigate the surface appearance, functional groups, crystallinity, and thermal stability. The kinetics study revealed that adsorption processes of Cu²⁺ and Pb²⁺ ions on the CSTEC followed the second-order kinetics model. CSTEC showed better performance (Cu²⁺, 95.24; Pb²⁺, 144.93mgg^-1) than most of other adsorbents. The co-existing ions (K⁺, Na⁺, Mg²⁺) had no significant influence on the removal of target ions by the CSTEC. The excellent reusability indicated that CSTEC had the promising application in the treatment of toxic metal pollution.

Microwave-assisted synthesis of chitosan biguanidine hydrochloride and its regulation on InsR and GLUT2 in insulin resistant HepG2 cells

CSGH increased glucose consumption of HepG2 cells by accelerating the expression of InsR and inhibiting the high-insulin-induced over-expression of GLUT2.