Trimethyl and carboxymethyl chitosan carriers for bio-active polymer-inorganic nanocomposites

Assessment of the ability of Pseudomonas aeruginosa and Staphylococcus aureus to create biofilms during wound healing in a rat model treated with carboxymethyl cellulose/carboxymethyl chitosan hydrogel containing EDTA

The primary objective of this study was to develop a carboxymethyl cellulose (CMC) and carboxymethyl chitosan (CMCS) hydrogel containing ethylene diamine tetra acetic acid (EDTA) as the materials for wound healing. CMC and CMCS solutions were prepared with a concentration of 4% (w/v). These solutions were made using normal saline serum with a concentration of 0.5% (v/v). Additionally, EDTA with the concentrations of 0.01%, 0.05%, 0.1%, 0.5%, 1%, and 2% (w/v) was included in the prepared polymer solution. The analysis of the hydrogels revealed that they possess porous structures with interconnected pores, with average in size 88.71 ± 5.93 μm. The hydrogels exhibited a swelling capacity of up to 60% of their initial weight within 24 h, as indicated by the weight loss and swelling measurements. The antibacterial experiments showed that the formulated CMC/CMCS/EDTA 0.5% hydrogel inhibited the growth of Staphylococcus aureus and Pseudomonas aeruginosa. Moreover, the produced hydrogels were haemocompatible and biocompatible. At the last stage, the evaluation of wound healing in the animal model demonstrated that the use of the produced hydrogels significantly improved the process of wound healing. Finally, the findings substantiated the effectiveness of the formulated hydrogels as the materials for promoting wound healing and antibacterial agents.

Chitosan-based hemostatic sponges as new generation hemostatic materials for uncontrolled bleeding emergency: Modification, composition, and applications

The choice of hemostatic technique is a curial concern for surgery and as first-aid treatment in combat. To treat uncontrolled bleeding in complex wound environments, chitosan-based hemostatic sponges have attracted significant attention in recent years because of the excellent biocompatibility, degradability, hemostasis and antibacterial properties of chitosan and their unique sponge-like morphology for high fluid absorption rate and priority aggregation of blood cells/platelets to achieve rapid hemostasis. In this review, we provide a historical perspective on the use of chitosan hemostatic sponges as the new generation of hemostatic materials for uncontrolled bleeding emergencies in complex wounds. We summarize the modification of chitosan, review the current status of preparation protocols of chitosan sponges based on various composite systems, and highlight the recent achievements on the detailed breakdown of the existing chitosan sponges to present the relationship between their composition, physical properties, and hemostatic capacity. Finally, the future opportunities and challenges of chitosan hemostatic sponges are also proposed.

Advances in Chitosan-Based CRISPR/Cas9 Delivery Systems

Clustered regularly interspaced short palindromic repeat (CRISPR) and the associated Cas endonuclease (Cas9) is a cutting-edge genome-editing technology that specifically targets DNA sequences by using short RNA molecules, helping the endonuclease Cas9 in the repairing of genes responsible for genetic diseases. However, the main issue regarding the application of this technique is the development of an efficient CRISPR/Cas9 delivery system. The consensus relies on the use of non-viral delivery systems represented by nanoparticles (NPs). Chitosan is a safe biopolymer widely used in the generation of NPs for several biomedical applications, especially gene delivery. Indeed, it shows several advantages in the context of gene delivery systems, for instance, the presence of positively charged amino groups on its backbone can establish electrostatic interactions with the negatively charged nucleic acid forming stable nanocomplexes. However, its main limitations include poor solubility in physiological pH and limited buffering ability, which can be overcome by functionalising its chemical structure. This review offers a critical analysis of the different approaches for the generation of chitosan-based CRISPR/Cas9 delivery systems and suggestions for future developments.

Chitosan-modified nanocarriers as carriers for anticancer drug delivery: Promises and hurdles

With the advent of drug delivery, various polymeric materials are being explored to fabricate numerous nanocarriers. Each polymer is associated with a few characteristics attributes which further facilitate its usage in drug delivery. One such polymer is chitosan (CS), which is extensively employed to deliver a variety of drugs to various targets, especially to cancer cells. The desired properties like biological origin, bio-adhesive, biocompatibility, the scope of chemical modification, biodegradability and controlled drug release make it a highly rough after polymer in pharmaceutical nanotechnology. The present review attempts to compile various chemical modifications on CS and showcase the outcomes of the derived nanocarriers, especially in cancer chemotherapy and drug delivery.

Antimicrobial Properties of Chitosan and Chitosan Derivatives in the Treatment of Enteric Infections

Antibiotics played an important role in controlling the development of enteric infection. However, the emergence of antibiotic resistance and gut dysbiosis led to a growing interest in the use of natural antimicrobial agents as alternatives for therapy and disinfection. Chitosan is a nontoxic natural antimicrobial polymer and is approved by GRAS (Generally Recognized as Safe by the United States Food and Drug Administration). Chitosan and chitosan derivatives can kill microbes by neutralizing negative charges on the microbial surface. Besides, chemical modifications give chitosan derivatives better water solubility and antimicrobial property. This review gives an overview of the preparation of chitosan, its derivatives, and the conjugates with other polymers and nanoparticles with better antimicrobial properties, explains the direct and indirect mechanisms of action of chitosan, and summarizes current treatment for enteric infections as well as the role of chitosan and chitosan derivatives in the antimicrobial agents in enteric infections. Finally, we suggested future directions for further research to improve the treatment of enteric infections and to develop more useful chitosan derivatives and conjugates.

Preparation and Antimicrobial Activity of Chitosan and Its Derivatives: A Concise Review

Despite the advantages presented by synthetic polymers such as strength and durability, the lack of biodegradability associated with the persistence in the environment for a long time turned the attention of researchers to natural polymers. Being biodegradable, biopolymers proved to be extremely beneficial to the environment. At present, they represent an important class of materials with applications in all economic sectors, but also in medicine. They find applications as absorbers, cosmetics, controlled drug delivery, tissue engineering, etc. Chitosan is one of the natural polymers which raised a strong interest for researchers due to some exceptional properties such as biodegradability, biocompatibility, nontoxicity, non-antigenicity, low-cost and numerous pharmacological properties as antimicrobial, antitumor, antioxidant, antidiabetic, immunoenhancing. In addition to this, the free amino and hydroxyl groups make it susceptible to a series of structural modulations, obtaining some derivatives with different biomedical applications. This review approaches the physico-chemical and pharmacological properties of chitosan and its derivatives, focusing on the antimicrobial potential including mechanism of action, factors that influence the antimicrobial activity and the activity against resistant strains, topics of great interest in the context of the concern raised by the available therapeutic options for infections, especially with resistant strains.

Biomedical and Pharmacological Uses of Fluorescein Isothiocyanate Chitosan-Based Nanocarriers

Chitosan-based nanocarriers (ChNCs) are considered suitable drug carriers due to their ability to encapsulate a variety of drugs and cross biological barriers to deliver the cargo to their target site. Fluorescein isothiocyanate-labeled chitosan-based NCs (FITC@ChNCs) are used extensively in biomedical and pharmacological applications. The main advantage of using FITC@ChNCs consists of the ability to track their fate both intra and extracellularly. This journey is strictly dependent on the physico-chemical properties of the carrier and the cell types under investigation. Other applications make use of fluorescent ChNCs in cell labeling for the detection of disorders in vivo and controlling of living cells in situ. This review describes the use of FITC@ChNCs in the various applications with a focus on understanding their usefulness in labeled drug-delivery systems.

In Vitro Anti-tumoral and Anti-bacterial Activity of an Octamolybdate Cluster-Based Hybrid Solid Incorporated with a Copper Picolinate Complex

Inorganic drugs, especially polyoxometalate-based hybrids, are expected to be developed as promising future metallodrugs. Herein, an organic-inorganic hybrid solid based on pyridine-2-carboxylic acid or picolinic acid (pic), [(Cu(pic)₂)₂(Mo₈O₂₆)]·8H₂O (1), was synthesized. A single-crystal structure of a solid possesses a discrete β-type octamolybdate cluster that supramolecularly aggregates with a {Cu₂(pic)₄}^4- complex and eight lattice water molecules. The study indicates that the solid is stable in aqueous medium and less toxic toward normal cell lines. The in vitro anti-bacterial and anti-tumor properties of the solid 1 were investigated. The results of the anti-tumor action against various human cancer cell lines, namely, lung (A549), breast (MCF-7), and liver (HepG2) cancer cells suggest that this β-octamolybdate-based solid yielded the lowest IC₅₀ value reported so far among octamolybdate anion-based hybrid solids, i.e., 24.24 μM for MCF-7, 21.56 μM for HepG2, and 25 μM for A549, indicating significant anti-cancer activity. The cell cycle analysis further reveals the observed anti-tumor effect to be governed by the arrest of breast cancer cells in the G2/M phase while that of lung and liver cancer cells in the S phase of the cell cycle. A fluorescence quenching study suggests the binding interaction between solid and ctDNA, which in turn induces apoptosis and necrosis pathways leading to cancer cell death. This is also the first study of {Mo₈O₂₆}^4- cluster-based solids as an anti-bacterial agent against Escherichia coli, and it was found to be very effective with a minimal inhibitory concentration value of ∼135 μg/mL, which is the lowest so far reported for any octamolybdate-based solid.

Polyoxometalates as Potential Next-Generation Metallodrugs in the Combat Against Cancer

Polyoxometalates (POMs) are an emerging class of inorganic metal oxides, which over the last decades demonstrated promising biological activities by the virtue of their great diversity in structures and properties. They possess high potential for the inhibition of various tumor types; however, their unspecific interactions with biomolecules and toxicity impede their clinical usage. The current focus of the field of biologically active POMs lies on organically functionalized and POM-based nanocomposite structures as these hybrids show enhanced anticancer activity and significantly reduced toxicity towards normal cells in comparison to unmodified POMs. Although the antitumor activity of POMs is well documented, their mechanisms of action are still not well understood. In this Review, an overview is given of the cytotoxic effects of POMs with a special focus on POM-based hybrid and nanocomposite structures. Furthermore, we aim to provide proposed mode of actions and to identify molecular targets. POMs are expected to develop into the next generation of anticancer drugs that selectively target cancer cells while sparing healthy cells.

GABAB receptor ligand-directed trimethyl chitosan/tripolyphosphate nanoparticles and their pMDI formulation for survivin siRNA pulmonary delivery

The effect of gene silencing by survivin siRNA (siSurvivin) on the proliferation and apoptosis of lung tumor has been attracted more interest. GABA_B receptor ligand-directed nanoparticles consisting of baclofen functionalized trimethyl chitosan (Bac-TMC) as polymeric carriers, tripolyphosphate (TPP) as ionic crosslinker, and siSurvivin as therapeutic genes, were designed to enhance the survivin gene silencing. GABA_B receptor agonist baclofen (Bac) was initially introduced into TMC as a novel ligand. This Bac-TMC/TPP nanoparticles increased the uptake of survivin siRNA through the interaction with GABA_B receptor, further resulted in efficient cell apoptosis and gene silencing. For siRNA-loaded nanoparticles pulmonary delivery, mannitol was utilized for it delivery into pressurized metered dose inhalers (pMDI). The fine particle fractions of this formulation was (45.39±2.99)% indicating the appropriate deep lung deposition. These results revealed that this pMDI formulation containing Bac-TMC/TPP nanoparticles would be a promising siRNA delivery system for lung cancer treatment.

Nebulized anionic guanidinylated O-carboxymethyl chitosan/N-2-hydroxypropyltimehyl ammonium chloride chitosan nanoparticles for siRNA pulmonary delivery: preparation, characterization and in vitro evaluation

This study developed a pH-sensitive anionic system composed of guanidinylated O-carboxymethyl chitosan (GOCMCS) and N-2-hydroxypropyltimehyl ammonium chloride chitosan (N-2-HACC) for efficient siRNA delivery to the lungs following nebulization. About 16.8% of guanidine groups were incorporated into O-carboxymethyl chitosan (OCMCS) with the aid of O-methylisourea. Gel electrophoresis images demonstrated that siRNA was successfully encapsulated in nanoparticles ranging from 150 to 180 nm with zeta potential of about -17 mV. The nanoparticles containing GOCMCS existed superior transfection performance compared with their amino-based analogs. The evaluation in vitro revealed that nanoparticles were internalized into A549 cells by energy-dependent endocytosis, then achieved endosomal escape by direct transmembrane penetration of guanidine moieties as well as swelling behavior of nanoparticles due to the pH sensitivity of GOCMCS. The mRNA level of survivin gene was down-regulated to 6.9% using GOCMCS/N-2-HACC/siSurvivin NPs. The survivin siRNA mediated by nanoparticles caused 30% of cell growth inhibition and induced 19.45% of cell apoptosis, which was comparable to Lipofectamin2000. After nebulization of siRNA-loaded nanoparticles, the stability of siRNA was maintained and fine particle fractions were detected by two-stage impinger that accounted for more than 60%. These results suggested that GOCMCS/N-2-HACC nanoparticles possessed potential as safe and efficient carrier for siRNA pulmonary delivery.

Protein Interactions With Quaternized Chitosan/Heparin Multilayers

Understanding the behavior of single proteins at the polyelectrolyte multilayer film/solution interface is of prime importance for the designing of bio-functionalized surface coatings. In the present paper, we study the adsorption of the model proteins, albumin and lysozyme, as well as basic fibroblast growth factor (FGF-2) on a polysaccharide multilayer film composed of quaternized chitosan and heparin. Several analytical methods were used to describe the formation of the polysaccharide film and its interactions with the proteins. Both albumin and lysozyme adsorbed on quaternized chitosan/heparin films, however this process strongly depended on the terminating polysaccharide. Protein adsorption was driven mainly by electrostatic interactions between protein and the terminal layer of the film. The effective binding of FGF-2 by the heparin-terminated film suggested that other interactions could also contribute to the adsorption process. We believe that this FGF-2-presenting polysaccharide film may serve as a biofunctional surface coating for biologically-related applications.

Self-patterning porous films of giant vesicles of {Mo72Fe30}(DODMA)3 complexes as frameworks

This work describes the preparation and properties of self-patterning porous films consisting of giant vesicles formed by a 2.5-nm-diameter, polyoxometalate (POM) cluster {Mo72Fe30} macroanion, and a double-tailed cationic surfactant dimethyldistearylammonium bromide (DODMABr) in CHCl3-CH3OH mixture solvent (VCHCl3: VCH3OH=3:1). These inverse vesicles with the diameter in the range of 0.45~1.3μm in organic solution and the porous films consisting of the giant vesicles of the {Mo72Fe30}(DODMA)3 complexes were characterized by SEM, TEM, XPS and AFM observations. Self-patterning of these giant vesicles into porous films that are highly ordered honeycomb films on solid surfaces can survive drying as the frameworks are firstly studied in detail. Water contact angle measurements proved that the porous films of {Mo72Fe30}(DODMA)3 vesicles were endowed hydrophobic property from the hydrophilic surface. This porous film materials consisting of giant vesicles may be promising new options in many fields like photoelectrochemistry, sterilization, template, catalysis, in-situ synthesis.

Encapsulation and stabilization of polyoxometalates in self-assembled supramolecular hydrogels

We have encapsulated the polyoxoanions [P2W18O62](6-) and [P2W15V3O62](9-) in a self-assembled carboxy-methyl-chitosan (CMC) hydrogel, exhibiting a regular superstructure in water at physiological pH. We performed stability studies as a function of temperature and polyoxometalate (POM) loading, and observed exceptional Tgel properties. This work is a step forward towards developing biologically active polyoxometalate-based materials.

Cytotoxicity and enzyme inhibition studies of polyoxometalates and their chitosan nanoassemblies

Polyoxometalates (POMs) have become very significant in biomedical research for their structural diversity which renders them highly active against bacterial, viral and cancer diseases. In this study three different POMs were synthesized and nanoassemblies were made with chitosan (CTS), a natural biodegradable polymer with excellent drug carrier properties. The compounds were tested on two isoenzymes of alkaline phosphatases including tissue specific calf intestine alkaline phosphatase (CIAP) and tissue non-specific alkaline phosphatase (TNAP). Compound [TeW₆O₂₄]⁶⁻ (TeW₆) showed the highest activity (45.4 ± 11.3 nM) among tested compounds against TNAP. Similarly, chitosan-[TeW₆O₂₄]⁶⁻ (CTS-TeW₆) was proved to be a potent inhibitor of CIAP with K_i value of 22 ± 7 nM. A comparative study was made to evaluate their cytotoxic potential against HeLa cells. Among all tested compounds, Chitosan-[NaP₅W₃₀O₁₁₀]¹⁴⁻ (CTS-P₅W₃₀) has showed higher percent cytotoxicity (88 ± 10%) at 10 μM when compared with the standard anticancer drug vincristine (72 ± 7%). The study revealed that selected POMs proved excellent anticancer potential and were equally effective against alkaline phosphatase enzyme, an increased level of which may indicate cancer metastasis.

Ti7-containing, tetrahedral 36-tungsto-4-arsenate(iii) [Ti6(TiO6)(AsW9O33)4]20−

Ti₇-containing [Ti₆(TiO₆)(AsW₉O₃₃)₄]²⁰⁻ (1) comprises a central, octahedrally coordinated Ti⁴⁺ ion bridged to six square-pyramidally coordinated Ti⁴⁺ ions, and this titanium-oxo core is surrounded by four {AsW₉O₃₃} capping units, resulting in an overall tetrahedral assembly.

Artemether combined with shRNA interference of vascular cell adhesion molecule-1 significantly inhibited the malignant biological behavior of human glioma cells

Artemether is the derivative extracted from Chinese traditional herb and originally used for malaria. Artemether also has potential therapeutic effects against tumors. Vascular cell adhesion molecule-1 (VCAM-1) is an important cell surface adhesion molecule associated with malignancy of gliomas. In this work, we investigated the role and mechanism of artemether combined with shRNA interference of VCAM-1 (shRNA-VCAM-1) on the migration, invasion and apoptosis of glioma cells. U87 human glioma cells were treated with artemether at various concentrations and shRNA interfering technology was employed to silence the expression of VCAM-1. Cell viability, migration, invasiveness and apoptosis were assessed with MTT, wound healing, Transwell and Annexin V-FITC/PI staining. The expression of matrix metalloproteinase-2 (MMP-2), matrix metalloproteinase-9 (MMP-9) and phosphorylated Akt (p-Akt) was checked by Western blot assay. Results showed that artemether and shRNA-VCAM-1 not only significantly inhibited the migration, invasiveness and expression of MMP-2/9 and p-Akt, but also promoted the apoptosis of U87 cells. Combined treatment of both displayed the maximum inhibitory effects on the malignant biological behavior of glioma cells. Our work revealed the potential therapeutic effects of artemether and antiVCAM-1 in the treatments of gliomas.