Synthesis of C-coordinated O-carboxymethyl chitosan metal complexes and evaluation of their antifungal activity

Exploring the potent hydrolytic activity of chitosan-cerium complex microspheres resin for organophosphorus pesticide degradation

Chitosan is a biocompatible, non-toxic and renewable natural basic polysaccharide that can be cross-linked and reacted with Ce(IV) to form a physiologically active chitosan-Ce(IV) complex. To investigate this novel complex and its potential to hydrolyze phosphate ester bonds, chitosan-cerium complex microspheres resin (CS-CCMR) was prepared from chitosan and ceric ammonium nitrate by reversed-phase suspension cross-linking polymerization. CS-CCMR was characterized, its ability to hydrolyze disodium p-nitrobenzene phosphate (PNPP2Na) and organophosphorus pesticides was investigated, and the hydrolytic mechanism was explored. CS-CCMR was composed of dark yellow microspheres with smooth surfaces and dense pores. It was found that CS-CCMR contained 4.507 mg/g Ce(IV), indicating that coordination polymerization between Ce(IV) and chitosan was successful. The presence of Ce(IV) in CS-CCMR was confirmed by multiple analytical methods and it was found that coordination of Ce(IV) by chitosan was mediated by the nitrogen atom of the amino group and the oxygen atom of the hydroxyl group of chitosan. It was shown that CS-CCMR efficiently hydrolyzed the phosphate ester bonds of PNPP2Na and five organophosphorus pesticides. Hydrolysis of PNPP2Na is potentially accomplished by charge neutralization and nucleophilic substitution. The mechanism of parathion degradation by CS-CCMR involves modification of the nitro group to give aminoparathion, followed by cleavage of the P-O bond to generate diazinphos. Consequently, the novel chitosan-Ce(IV) complex exhibits great efficiency for hydrolysis of phosphate ester bonds and CS-CCMR is expected to be developed as an agent to reduce the possibility of contamination of fruit and vegetable drinks by organophosphorus pesticides.

Chitosan-based Schiff bases: Promising materials for biomedical and industrial applications

There is plenty of scope for modifying chitosan, an only polycationic natural polysaccharide, owing to its reactive functional groups, namely hydroxyl and amino groups. Although innumerable numbers of chitosan derivatives have been synthesized by modifying these groups and reported elsewhere, in this review article, an attempt has been exclusively made to demonstrate the syntheses of various chitosan-based Schiff bases (CSBs) simply by allowing the reactions of reactive amino groups of chitosan with different aldehydes/ketones of interest. Due to their very peculiar and unique characteristics, such as biodegradability, biocompatibility, metal-binding capability, etc., they are found to be very useful for diversified applications. Thus, we have also attempted to showcase their very specific biomedical fields, including tissue engineering, drug delivery, and wound healing, to name a few. In addition, we have also discussed the utilization of CSBs for industrial applications such as wastewater treatment, catalysis, corrosion inhibition, sensors, etc.

Recent advances in carboxymethyl chitosan-based materials for biomedical applications

Chitosan (CS) and its derivatives have been applied extensively in the biomedical field owing to advantageous characteristics including biodegradability, biocompatibility, antibacterial activity and adhesive properties. The low solubility of CS at physiological pH limits its use in systems requiring higher dissolving ability and a suitable drug release rate. Besides, CS can result in fast drug release because of its high swelling degree and rapid water absorption in aqueous media. As a water-soluble derivative of CS, carboxymethyl chitosan (CMC) has certain improved properties, rendering it a more suitable candidate for wound healing, drug delivery and tissue engineering applications. This review will focus on the antibacterial, anticancer and antitumor, antioxidant and antifungal bioactivities of CMC and the most recently described applications of CMC in wound healing, drug delivery, tissue engineering, bioimaging and cosmetics.

Synthesis, Characterization, and Bioactivities of Polysaccharide Metal Complexes: A Review

Natural polysaccharides are critical to a wide range of fields (e.g., medicine, food production, and cosmetics) for their various remarkable physical properties and biological activities. However, the bioactivities of naturally acquired polysaccharides may be unsatisfactory and limit their further applications. It is generally known that the chemical structure exhibited by polysaccharides lays the material basis for their biological activities. Accordingly, possible structural modifications should be conducted on polysaccharides for their enhancement. Recently, polysaccharides complexed with metal ions (e.g., Fe, Zn, Mg, Cr, and Pt) have been reported to be possibly used to improve their bioactivities. Moreover, since the properties exhibited by metal ions are normally conserved, polysaccharides may be endowed with new applications. In this review, the synthesis methods, characterization methods, and bioactivities of polysaccharide metal complexes are summarized specifically. Then, the application prospects and limitations of these complexes are analyzed and discussed.

Design of Chitosan Sterilization Agents by a Structure Combination Strategy and Their Potential Application in Crop Protection

Chitosan is the only cationic polysaccharide in nature. It is a type of renewable resource and is abundant. It has good biocompatibility, biodegradability and biological activity. The amino and hydroxyl groups in its molecules can be modified, which enables chitosan to contain a variety of functional groups, giving it a variety of properties. In recent years, researchers have used different strategies to synthesize a variety of chitosan derivatives with novel structure and unique activity. Structure combination is one of the main strategies. Therefore, we will evaluate the synthesis and agricultural antimicrobial applications of the active chitosan derivatives structure combinations, which have not been well-summarized. In addition, the advantages, challenges and developmental prospects of agricultural antimicrobial chitosan derivatives will be discussed.

Synthesis of carboxymethyl chitosan-strontium complex and its therapeutic effects on relieving osteoarthritis

Osteoarthritis (OA) is an age-related joint disorder and one of the leading causes of physical disability. In this study, we designed and synthesized a new polysaccharide complex, carboxymethyl chitosan strontium (CMCS-Sr), which is believed to have positive effects on relieving OA. The synthesized CMCS-Sr was structurally verified by SEM, EDS, FTIR, etc. The therapeutic effects of CMCS-Sr were evaluated using various biological experiments. The cell viability and apoptosis results reveal that CMCS-Sr can significantly promote the proliferation and suppress OA chondrocytes apoptosis in vitro. The immunofluorescence staining results suggest that CMCS-Sr facilitates the promotion of the secretion of Type II collagen (Col-II). The transcriptomic results support the observed positive effects of CMCS-Sr on inhibiting chondrocytes apoptosis and alleviating inflammatory reactions. Moreover, animal study demonstrates that CMCS-Sr effectively reduced articular cartilage damage and subchondral bone degradation. Therefore, we propose the use of CMCS-Sr as a promising candidate for relieving OA.

Versatile Use of Chitosan and Hyaluronan in Medicine

Chitosan is industrially acquired by the alkaline N-deacetylation of chitin. Chitin belongs to the β-N-acetyl-glucosamine polymers, providing structure, contrary to α-polymers, which provide food and energy. Another β-polymer providing structure is hyaluronan. A lot of studies have been performed on chitosan to explore its industrial use. Since chitosan is biodegradable, non-toxic, bacteriostatic, and fungistatic, it has numerous applications in medicine. Hyaluronan, one of the major structural components of the extracellular matrix in vertebrate tissues, is broadly exploited in medicine as well. This review summarizes the main areas where these two biopolymers have an impact. The reviewed areas mostly cover most medical applications, along with non-medical applications, such as cosmetics.

Effect of chitosan on adult longevity when fed, in no-choice experiments, to Musca domestica L., Tabanus nigrovittatus Macquart, and Phormia regina (Meigen) adults and its consumption in adult Musca domestica L

BACKGROUND

The literature reports that more research needs to be done on using chitosan as an environmentally friendly bioinsecticide, especially against dipterans. Thus, we examined the effect of chitosan when fed, in no-choice experiments, to adult Musca domestica, Tabanus nigrovittatus, and Phormia regina.

RESULTS

A 2% chitosan solution was fed, in no-choice experiments, to adults of Musca domestica, Tabanus nigrovittatus, and Phormia regina to study the effects on survivorship. In all species, the uptake of chitosan caused a significant decrease in survivorship. Examination of the digestive tract of house flies showed a thick material within the midgut, plus a shriveling of the midgut only in chitosan-treated flies. A survivorship curve of adult house flies fed a 10% sucrose and 2% w/v ascorbic acid-only solution showed that the effect of the chitosan solution was due to the chitosan and not the ascorbic acid. Intake experiments revealed that by day 2, chitosan treated house flies consumed significantly less of the diet compared to controls.

CONCLUSION

Chitosan, a biopesticide, when fed in no-choice experiments to three species of adult flies produced severe mortality within 4-6 days of ingestion. A working hypothesis suggests that by day 2 of the chitosan diet there appears to be a malfunction of the digestive tract and possibly the midgut microbiome. © 2020 Society of Chemical Industry.

Evidences of Biomimetic and Nonantibiotic Characteristics of the Zinc-Carboxymethyl Chitosan-Genipin Organometallic Complex and Its Biocompatibility Aspects

Bioinspired nonantibiotics can prove to be a better and an efficient tool to fight against antimicrobial resistance. In our study, biomaterial composed of zinc-carboxymethyl chitosan (CMC)-genipin was investigated for this purpose. Briefly, CMC was synthesized and transformed to porous scaffolds using the freeze drying method. The scaffolds were cross-linked and stabilized with genipin and zinc (2 M zinc acetate), respectively. FTIR spectroscopic data testified Zn complex formation and pointed out the absence of water molecule like that of zinc motif containing proteins. Hence, the complex may be termed as biomimetic. Genipin (0.5%) cross-linking appeared to contribute additively to the wet compressive strength of the zinc-CMC scaffolds. Biodegradation data revealed better stability of CMC-genipin-zinc scaffolds in enzymatic and nonenzymatic conditions than their redundant controls. The scaffolds seem to support adhesion and proliferation of human dental pulp stem cells and were hemocompatible to human red blood corpuscles, as revealed by scanning electron microscopy. The scaffolds were found to be antibacterial and mildly antibiofilm when tested against biofilm-forming bacteria, that is, Staphylococcus aureus (ATCC 9144), making it a potential nonantibiotic-like biomaterial. To conclude, this organometallic complex-based biomaterial may potentially serve as a weapon against antimicrobial resistance. Furthermore, the biomaterial potentially finds its application in dental, maxillofacial, and orthopedic tissue engineering applications.

Synthesis, Characterisation and In Vitro Permeation, Dissolution and Cytotoxic Evaluation of Ruthenium(II)-Liganded Sulpiride and Amino Alcohol

Sulpiride (SPR) is a selective antagonist of central dopamine receptors but has limited clinical use due to its poor pharmacokinetics. The aim of this study was to investigate how metal ligation to SPR may improve its solubility, intestinal permeability and prolong its half-life. The synthesis and characterisation of ternary metal complexes [Ru(p -cymene)(L)(SPR)]PF6 (L1 = (R)-(+)-2-amino-3-phenyl-1-propanol, L2 = ethanolamine, L3 = (S)-(+)-2-amino-1-propanol, L4 = 3-amino-1-propanol, L5 = (S)-(+)-2-pyrrolidinemethanol) are described in this work. The stability constant of the [Ru(p -cymene)(SPR)] complex was determined using Job's method. The obtained value revealed higher stability of the metal complex in the physiological pH than in an acidic environment such as the stomach. The ternary metal complexes were characterised by elemental analysis, Fourier transform infrared spectroscopy (FT-IR), 1H and 13C nuclear magnetic resonance (NMR), differential scanning calorimetry (DSC), thermal analyses, Ultraviolet-Visible (UV-Vis). Solubility studies showed higher aqueous solubility for complexed SPR than the free drug. Dissolution profiles of SPR from the metal complexes exhibited slower dissolution rate of the drug. Permeation studies through the pig's intestine revealed enhanced membrane permeation of the complexed drug. In vitro methyl thiazolyl tetrazolium (MTT) assay showed no noticeable toxic effects of the ternary metal complexes on Caco-2 cell line.

Zinc(ii) centered biologically active novel N,N,O donor tridentate water-soluble hydrazide-based O-carboxymethyl chitosan Schiff base metal complexes: synthesis and characterisation

In this study, novel eco-friendly and water-soluble chitosan Schiff base derivatives have been designed for potential use in antimicrobial applications.