Carboxymethyl chitosan: Properties and biomedical applications

Vitamin K (Menadione)-incorporated chitosan/alginate hydrogel as a novel product for periorbital hyperpigmentation

The possibility of controlling periorbital hyperpigmentation disorders is one of the most important research goals in cosmetic preparations. In the current investigation, 1% vitamin K (Vit K) was incorporated into a Chitosan/alginate hydrogel which aimed to increase the dermal delivery and anti-pigmentation effect. The Vit K-hydrogel was evaluated using several different tests, including volume expansion/contraction analysis, differential scanning calorimetry (DSC), scanning electron microscopy (SEM), ultraviolet (UV) absorbance spectroscopy, and attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy. Vit K hydrogel's drug release profile showed a steady increase over time. Furthermore, the modified Vit K hydrogel formulations showed no harmful effects in an in vitro cytotoxicity study. The Vit K hydrogel was tested for dermal irritation on Wistar rats, and the hydrogel was found to be non-irritating. Furthermore, Vit K-hydrogel inhibited melanin formation (31.76 ± 1.14%) and was remarkably higher than free Vit K. In addition, Vit K-hydrogel inhibited L-dopa auto-oxidation to a greater extent (94.80 ± 2.41%) in comparison with Vit K solution (73.95 ± 1.62%). Vit K-hydrogel enhanced percutaneous transport of Vit K, according to in vitro percutaneous absorption findings, suggesting that this innovative formulation may provide new therapeutic options for periorbital hyperpigmentation.

Effect of Soybean Oil on the Improvement of the Functionality of Edible Membrane-Type Food Packaging Films Based on Caseinate-Carboxymethyl Chitosan Compositions

Edible film biopolymers are gaining attention to tackle problems of plastic waste and food safety to alleviate environmental problems associated with plastic products in food packaging. In this study, caseinate-carboxymethyl chitosan (CA-CMCH) composite films were made with the incorporation of soybean oil (SO) using a casting technique. The influence of different soybean oil concentrations at 0, 0.5, and 1% (w/w) on physical, mechanical, barrier, and surface characteristics of films composed of caseinate-carboxymethyl chitosan (CA-CMCH) was evaluated. The brightest film (L* value of 95.95 ± 0.30) was obtained with the edible film made from the control group of samples with sodium caseinate (NaCA-100; 100% NaCA). The results also indicated that samples with 1% SO in NaCA-75 and CaCA-75 had lower water vapor permeability (WVP), while those with NaCA-50 and CaCA-50 showed higher values of WVP. For mechanical properties, this study found that incorporating soybean oil into the caseinate-carboxymethyl (CA-CMCH) composite films led to an enhancement of both tensile strength and elongation at break. The morphological structures, determined using SEM, of control and composite films showed compact and homogenous surfaces. Overall, the addition of soybean oil contributed to the improvement of the functional properties of the edible films, offering potential solutions to the environmental issues associated with plastic packaging and enhancing the safety and performance of food packaging.

Biological scaffold as potential platforms for stem cells: Current development and applications in wound healing

Wound repair is a complex challenge for both clinical practitioners and researchers. Conventional approaches for wound repair have several limitations. Stem cell-based therapy has emerged as a novel strategy to address this issue, exhibiting significant potential for enhancing wound healing rates, improving wound quality, and promoting skin regeneration. However, the use of stem cells in skin regeneration presents several challenges. Recently, stem cells and biomaterials have been identified as crucial components of the wound-healing process. Combination therapy involving the development of biocompatible scaffolds, accompanying cells, multiple biological factors, and structures resembling the natural extracellular matrix (ECM) has gained considerable attention. Biological scaffolds encompass a range of biomaterials that serve as platforms for seeding stem cells, providing them with an environment conducive to growth, similar to that of the ECM. These scaffolds facilitate the delivery and application of stem cells for tissue regeneration and wound healing. This article provides a comprehensive review of the current developments and applications of biological scaffolds for stem cells in wound healing, emphasizing their capacity to facilitate stem cell adhesion, proliferation, differentiation, and paracrine functions. Additionally, we identify the pivotal characteristics of the scaffolds that contribute to enhanced cellular activity.

A Holographic-Type Model in the Description of Polymer-Drug Delivery Processes

A unitary model of drug release dynamics is proposed, assuming that the polymer-drug system can be assimilated into a multifractal mathematical object. Then, we made a description of drug release dynamics that implies, via Scale Relativity Theory, the functionality of continuous and undifferentiable curves (fractal or multifractal curves), possibly leading to holographic-like behaviors. At such a conjuncture, the Schrödinger and Madelung multifractal scenarios become compatible: in the Schrödinger multifractal scenario, various modes of drug release can be "mimicked" (via period doubling, damped oscillations, modulated and "chaotic" regimes), while the Madelung multifractal scenario involves multifractal diffusion laws (Fickian and non-Fickian diffusions). In conclusion, we propose a unitary model for describing release dynamics in polymer-drug systems. In the model proposed, the polymer-drug dynamics can be described by employing the Scale Relativity Theory in the monofractal case or also in the multifractal one.

A whole-course-repair system based on ROS/glucose stimuli-responsive EGCG release and tunable mechanical property for efficient treatment of chronic periodontitis in diabetic rats

Elevated glucose levels, multiple pro-inflammatory cytokines and the generation of excessive reactive oxygen species (ROS) are pivotal characteristics within the microenvironments of chronic periodontitis with diabetes mellitus (CPDM). Control of inflammation and modulation of immune system are required in the initial phase of CPDM treatment, while late severe periodontitis requires a suitable scaffold to promote osteogenesis, rebuild periodontal tissue and reduce alveolar bone resorption. Herein, a whole-course-repair system is introduced by an injectable hydrogel using phenylboronic acid functionalized oxidized sodium alginate (OSA-PBA) and carboxymethyl chitosan (CMC). Epigallocatechin-3-gallate (EGCG) was loaded to simultaneously adjust the mechanical property of the OSA-PBA/CMC + EGCG hydrogel (OPCE). This hydrogel has distinctive adaptability, injectability, and ROS/glucose-triggered release of EGCG, making it an ideal drug delivery carrier. As expected, OPCE hydrogel shows favourable antioxidant and anti-inflammatory properties, along with a regulatory influence on the phenotypic transition of macrophages, providing a favourable immune microenvironment. Apart from that, it provides a favourable mechanical support for osteoblast/osteoclast differentiation regulation at the late proliferation stage of periodontal regeneration. The practical therapeutic effects of OPCE hydrogels were also confirmed when applied for treating periodontitis in diabetic rats. In summary, OPCE hydrogel may be a promising whole-course-repair system for the treatment of CPDM.

Strongly Adhesive, Self-Healing, Hemostatic Hydrogel for the Repair of Traumatic Brain Injury

With wide clinical demands, therapies for traumatic brain injury (TBI) are a major problem in surgical procedures and after major trauma. Due to the difficulty in regeneration of neurons or axons after injury, as well as the inhibition of blood vessel growth by the formation of neural scars, existing treatment measures have limited effectiveness in repairing brain tissue. Herein, the biomultifunctional hydrogels are developed for TBI treatment based on the Schiff base reaction of calcium ion (Ca2+)-cross-linked oxidized sodium alginate (OSA) and carboxymethyl chitosan (CMCS). The obtained COCS hydrogel exhibits excellent adhesion to wet tissues, self-repair capability, and antimicrobial properties. What's particularly interesting is that the addition of Ca2+ increases the hydrogel's extensibility, enhancing its hemostatic capabilities. Biological assessments indicate that the COCS hydrogel demonstrates excellent biocompatibility, hemostatic properties, and the ability to promote arterial vessel repair. Importantly, the COCS hydrogel promotes the growth of cerebral microvessels by upregulating CD31, accelerates the proliferation of astrocytes, enhances the expression of GFAP, and stimulates the expression of neuron-specific markers such as NEUN and β-tubulin. All of these findings highlight that the strongly adhesive, self-healing, hemostatic hydrogel shows great potential for the repair of traumatic brain injury and other tissue repair therapy.

Preparation of Emamectin Benzoate·Hexaflumuron Granules Based on Response Surface Methodology

In order to obtain particles with an optimal loading rate and encapsulation efficiency and to explore the effects of sodium alginate, carboxymethyl chitosan, and bentonite on the particle loading rate and encapsulation rate, the preparation parameters of particles were optimized by the response surface method. A series of particles with constantly changing components were prepared, and the particle loading rate and encapsulation rate were determined. The release experiment of granules in different mass release media was implemented, and the optimal loading rate and encapsulation efficiency of particles were used to control the fall armyworm (FAW). The results showed that when the amount of sodium alginate was 1.83%, that of carboxymethyl chitosan was 0.41% and that of bentonite was 0.37%. The maximum theoretical value based on the response surface simulation was 92.63%, and the actual value at this ratio was 91.61%, which was 98.90% of the theoretical value. The release assay indicated that the mechanism of particle release in 2, 4, and 6 mL of the release medium was non-Fickian diffusion, and the controlled mechanism in 25 mL of the medium was Fickian diffusion. The beads were spread directly into maize leaf whorls in field production; at 14 days after application, the efficacy reached 91.28-98.82%. The combination of emamectin benzoate and hexaflumuron granules has a good control effect on the FAW.

A bioactive composite hydrogel dressing that promotes healing of both acute and chronic diabetic skin wounds

Mesenchymal stem cell derived exosomes (MSC-Exos) demonstrate beneficial effects on wound healing via anti-inflammatory and angiogenic properties. Chitosan (CS) exhibits excellent biocompatibility and accelerates cellular migration, adhesion, and proliferation. The ions released from bioactive glass (BG) and titanium dioxide (TiO2) nanoparticles exhibit sustained angiogenic and antibacterial potency. In this study, CMCS-CEBT hydrogel was synthesized from exosomes encapsulated carboxymethyl chitosan (CMCS), chitosan nanoparticles (CS-NPs), BG, and TiO2 nanoparticles for a preliminary evaluation of its impacts on the treatment of full-thickness skin defects, diabetic wounds, and burn skin injury due to burns. In vitro analysis indicated that the hydrogel exhibits excellent cell compatibility, stimulates endothelial cell adhesion and proliferation, and presents anti-inflammatory, angiogenic, and antibacterial activities. In vivo, the composite hydrogel dressing accelerated a wound healing acceleration effect, stimulated angiogenesis, and increased collagen deposition and the expression of anti-inflammatory factors. This innovative composite hydrogel dressing as a potential clinical therapy, utilizing bioactive materials, holds promise as a potential clinical therapy that aims to facilitate the regeneration of acute and chronically damaged skin tissue.

A state-of-the-art review on plant-derived cellulose-based green hydrogels and their multifunctional role in advanced biomedical applications

The most prevalent carbohydrate on Earth is cellulose, a polysaccharide composed of glucose units that may be found in diverse sources, such as cell walls of wood and plants and some bacterial and algal species. The inherent availability of this versatile material provides a natural pathway for exploring and identifying novel uses. This study comprehensively analyzes cellulose and its derivatives, exploring their structural and biochemical features and assessing their wide-ranging applications in tissue fabrication, surgical dressings, and pharmaceutical delivery systems. The use of diverse cellulose particles as fundamental components gives rise to materials with distinct microstructures and characteristics, fulfilling the requirements of various biological applications. Although cellulose boasts substantial potential across various sectors, its exploration has predominantly unfolded within industrial realms, leaving the biomedical domain somewhat overlooked in its initial stages. This investigation, therefore, endeavors to shed light on the contemporary strides made in synthesizing cellulose and its derivatives. These innovative techniques give rise to distinctive attributes, presenting a treasure trove of advantages for their compelling integration into the intricate tapestry of biomedical applications.

Carboxymethyl chitosan-modified UiO-66 for the rapid detection of fenpropathrin in grains

Fenpropathrin residues in grain are potentially harmful to humans. Therefore, a fluorimetric lateral flow immunoassay using a zirconium-based organic skeleton (UiO-66) as a signal marker was developed for detecting fenpropathrin. Herein, carboxymethyl chitosan (CMCS) was used to modify UiO-66 and improve its water solubility to facilitate stable binding with sodium fluorescein (NaFL). This resulted in formation of a new fluorescent probe that is more suitable for lateral flow immunoassay (LFIA). The materials were characterized via electron microscopy, Fourier-transform infrared spectroscopy, and powder X-ray diffraction. CMCS and NaFL were successfully bound to UiO-66. Under optimized conditions, the constructed NaFL/UiO-66@CMCS-LFIA exhibited a good linear relationship within the range of 0.98-62.5 μg/L, with a detection limit of 3.91 μg/L. This probe was fourfold more sensitive than traditional colloidal gold nanoparticle-based LFIA. Finally, NaFL/UiO-66@CMCS-LFIA was successfully applied to detect fenpropathrin in wheat and maize samples. The detection limit was 1.56 μg/kg and recoveries ranged from 96.58 % to 118.56 %. This study provides a sensitive, stable, and convenient method for the rapid detection of pesticide residues.

Recombinant human collagen I/carboxymethyl chitosan hydrogel loaded with long-term released hUCMSCs derived exosomes promotes skin wound repair

BACKGROUND

Stem cell exosomes are beneficial in accelerating wound repair. However, the therapeutic function is limited due to its rapid clearance in vivo. To improve the functionality of exosomes in cutaneous wound healing, a novel hydrogel was designed and fabricated by recombinant human collagen I and carboxymethyl chitosan loaded with exosomes derived from human umbilical cord mesenchymal stem cells (hUCMSCs), named as the rhCol I/CMC-Exos hydrogel.

METHODS

Exosomes were extracted from hUCMSCs and were characterizated by TEM (Transmission Electron Microscopy), and biomarker detection. The rhCol I hydrogel, rhCol I/carboxymethyl chitosan (rhCol I/CMC) hydrogel and the rhCol I/CMC-Exos hydrogel composites were cross-linked by genipin. These materials were assessed and compared for their physical characteristics, including cross-sectional morphology, porosity, pore distribution, and hydrophilicity. Cell biocompatibility on biomaterials was investigated using scanning electron microscopy and CFDA staining, as well as assessed in vivo through histological examination of major organs in mice. Effects of the hydrogel composite on wound healing were further evaluated by using the full-thickness skin defect mice model.

RESULTS

Successful extraction of hUCMSCs-derived exosomes was confirmed by TEM，Western Blotting and flow cytometry. The synthesized rhCol I/CMC-Exos hydrogel composite exhibited cytocompatibility and promoted cell growth in vitro. The rhCol I/CMC-Exos hydrogel showed sustained release of exosomes. In the mice full skin-defects model, the rhCol I/CMC-Exos-treated group showed superior wound healing efficiency, with 15 % faster wound closure compared to controls. Histological examinations revealed thicker dermis formation and more balanced collagen deposition in wounds treated with rhCol I/CMC-Exos hydrogel. Mechanistically, the application of rhCol I/CMC-Exos hydrogel increased fibroblasts proliferation, alleviated inflammation responses as well as promoted angiogenesis, thereby was beneficial in promoting skin wound healing and regeneration.

CONCLUSION

Our study, for the first time, introduced recombinant human Collagen I in fabricating a novel hydrogel loaded with hUCMSCs-derived exosomes, which effectively promoted skin wound closure and regeneration, demonstrating a great potential in severe skin wound healing treatment.

Chitosan-based hydrogels: From preparation to applications, a review

Chitosan, derived from the deacetylation of chitin, is an abundant natural biopolymer on earth. Chitosan and its derivatives have become promising biological materials because of their unique molecular structure and excellent biological activities. The reactive functional groups of chitosan such as the amino and hydroxyl groups play a crucial role in facilitating the synthesis of three-dimensional hydrogel. Chitosan-based hydrogels have been widely used in medical, pharmaceutical, and environmental fields for years. Nowadays, chitosan-based hydrogels have been found in a wide range of applications in the food industry such as food sensors, dye adsorbents and nutrient carriers. In this review, recently developed methods for the preparation of chitosan-based hydrogels were given, and the biological activities of chitosan-based hydrogels were systematically introduced. Additionally, the recent progress in food sensors, packaging, dye adsorbents, and nutrient carriers was discussed. Finally, the challenges and prospects for the future development of chitosan-based hydrogels were discussed.

Effect of chitosan and CMCS on dentin after Er:YAG laser irradiation: shear bond strength and surface morphology analysis

OBJECTIVES

The aim of the present study was to evaluate the effect of chitosan and carboxymethyl chitosan (CMCS) on dentin surface morphology and bonding strength after irradiation of Er:YAG laser.

METHODS

Eighty-four laser-irradiated dentin samples were randomly distributed into three groups (n = 28/group) according to different surface conditioning process: deionized water for 60s; 1wt% chitosan for 60s; or 1wt% CMCS for 60s. Two specimens from each group were subjected to TEM analysis to confirm the presence of extrafibrillar demineralization on dentin fibrils. Two specimens from each group were subjected to morphological analysis by SEM. Seventy-two specimens (n = 24/group) were prepared, with a composite resin cone adhered to the dentin surface, and were then randomly assigned to one of two aging processes: storage in deionized water for 24 h or a thermocycling stimulation. The shear bond strength of laser-irradiated dentin to the resin composite was determined by a universal testing machine. Data acquired in the shear bond strength test was analyzed by one-way ANOVA with the Tukey honestly significant difference post hoc test and Independent Samples t-test (α = 0.05).

RESULTS

CMCS group presented demineralized zone and a relatively smooth dentin surface morphology. CMCS group had significantly higher SBS value (6.08 ± 2.12) without aging (p < 0.05). After thermal cycling, both chitosan (5.26 ± 2.30) and CMCS group (5.82 ± 1.90) presented higher bonding strength compared to control group (3.19 ± 1.32) (p < 0.05). Chitosan and CMCS group preserved the bonding strength after aging process (p > 0.05).

CONCLUSIONS

CMCS has the potential to be applied in conjunction with Er:YAG laser in cavity preparation and resin restoration.

Hydrogel Loaded with Peptide-Containing Nanocomplexes: Symphonic Cooperation of Photothermal Antimicrobial Nanoparticles and Prohealing Peptides for the Treatment of Infected Wounds

Current treatment for chronic infectious wounds is limited due to severe drug resistance in certain bacteria. Therefore, the development of new composite hydrogels with nonantibiotic antibacterial and pro-wound repair is important. Here, we present a photothermal antibacterial composite hydrogel fabricated with a coating of Fe2+ cross-linked carboxymethyl chitosan (FeCMCS) following the incorporation of melanin nanoparticles (MNPs) and the CyRL-QN15 peptide. Various physical and photothermal properties of the hydrogel were characterized. Cell proliferation, migration, cycle, and free-radical scavenging activity were assessed, and the antimicrobial properties of the hydrogel were probed by photothermal therapy. The effects of the hydrogel were validated in a model of methicillin-resistant Staphylococcus aureus (MRSA) infection with full-thickness injury. This effect was further confirmed by changes in cytokines associated with inflammation, re-epithelialization, and angiogenesis on the seventh day after wound formation. The MNPs demonstrated robust photothermal conversion capabilities. The composite hydrogel (MNPs/CyRL-QN15/FeCMCS) promoted keratinocyte and fibroblast proliferation and migration while exhibiting high antibacterial efficacy, effectively killing more than 95% of Gram-positive and Gram-negative bacteria. In vivo study using an MRSA-infected full-thickness injury model demonstrated good therapeutic efficacy of the hydrogel in promoting regeneration and remodeling of chronically infected wounds by alleviating inflammatory response and accelerating re-epithelialization and collagen deposition. The MNPs/CyRL-QN15/FeCMCS hydrogel showed excellent antibacterial and prohealing effects on infected wounds, indicating potential as a promising candidate for wound healing promotion.

A Novel Zn(II) Coordination Polymer: Fluorescence Performances, Molecular Docking and Loaded with Bleomycin-Hydrogels on Hemangiomas

In this study, we successfully synthesized an innovative 1D-Zn(II) coordination polymer, denoted as [Zn(L)(H2O)2]n, employing the Schiff base {4-[(2-hydroxy-3-methoxy-benzylidene)-amino]-benzoic acid} (H2L). The Schiff base was obtained through the reaction of 4-aminobenzoic acid and o-vanillin under slow volatilization conditions. The resulting compound exhibits remarkable green fluorescence emission properties, indicating its potential as a novel fluorescent and sensing material. Hydrogels based on hyaluronic acid (HA) and carboxymethyl chitosan (CMCS), denoted as HA/CMCS hydrogels, were synthesized using a chemical method. Additionally, we utilized bleomycin as a model drug to synthesize a novel bleomycin metal gel and assessed its anti-hemangioma activity. Molecular docking simulations revealed that the Zn complex can form stable bonds with the key target, involving the methoxy and carboxyl groups on the Zn complex.

Carboxymethylated and Sulfated Furcellaran from Furcellaria lumbricalis and Its Immobilization on PLA Scaffolds

This study involved the creation of highly porous PLA scaffolds through the porogen/leaching method, utilizing polyethylene glycol as a porogen with a 75% mass ratio. The outcome achieved a highly interconnected porous structure with a thickness of 25 μm. To activate the scaffold's surface and improve its hydrophilicity, radiofrequency (RF) air plasma treatment was employed. Subsequently, furcellaran subjected to sulfation or carboxymethylation was deposited onto the RF plasma treated surfaces with the intention of improving bioactivity. Surface roughness and water wettability experienced enhancement following the surface modification. The incorporation of sulfate/carboxymethyl group (DS = 0.8; 0.3, respectively) is confirmed by elemental analysis and FT-IR. Successful functionalization of PLA scaffolds was validated by SEM and XPS analysis, showing changes in topography and increases in characteristic elements (N, S, Na) for sulfated (SF) and carboxymethylated (CMF). Cytocompatibility was evaluated by using mouse embryonic fibroblast cells (NIH/3T3).

Bifunctional lignocellulose nanofiber hydrogel possessing intriguing pH-responsiveness and self-healing capability towards wound healing applications

Lignocellulose nanofibers (LCNF) obtained from agricultural waste are potential candidates for enhancing composite materials because of their excellent mechanical properties, abundant groups and high biocompatibility. However, the application of LCNF has received limited attention to date from researchers in the healthcare field. Herein, based on the bifunctional group (carboxyl and aldehyde groups) modified LCNF (DCLCNF) and chitosan (CS), we developed a multifunctional bio-based hydrogel (CS-DCLCNF). The addition of lignin-containing DCLCNF strengthened the internal crosslinking and the intermolecular interaction of hydrogels, and the presence of lignin and carboxyl groups increased the mechanical strength of the hydrogel and the adsorption of aromatic drugs. Results revealed that the hydrogels exhibited self-healing, injectable, and high swelling rates. The hydrogels had favorable mechanical strength (G'max of ~16.60 kPa), and the maximum compressive stress was 24 kPa. Moreover, the entire tetracycline hydrochloride (TH) release process was slow and pH-responsive, because of the rich noncovalent and π-π interactions between DCLCNF and TH. The hydrogels also exhibited excellent biocompatibility and antibacterial properties. Notably, the wound healing experiment showed that the hydrogels were beneficial in accelerating wounds healing, which could heal completely in 13 days. Therefore, CS-DCLCNF hydrogels may have promising applications in drug delivery for wound healing.

Carboxymethyl chitosan-N-alkylimine derivatives: Synthesis, characterization and use for preservation of symbiotic biofertilizer bacteria on chickpea seeds

A series of carboxymethyl chitosan-N-alkylimine derivatives with side chain length of 4 to 10 carbons (CMCS-n, n = 4, 6, 8, 10) was prepared in a one-step solvent-free synthesis using Schiff base chemistry. The modified polysaccharides were characterized by their spectral, thermal and physical properties. The prepared polymers demonstrated an ability to spontaneous self-assembly with a clear correlation between critical aggregation concentration and the chain length of the alkyl substituent. N-alkylimine-CMCS derivatives were found to deliver hydrophobic (curcumin) and hydrophilic (ascorbic acid) active agents in unfavorable environments of water and oil, respectively. Then, N-alkylimine-CMCS derivatives were used as a platform for the delivery of symbiotic gram-positive bacteria Bacillus subtilis CJ onto chickpea seeds. These bacteria demonstrated a significantly higher survival rate (106 CFU/mL) in dried CMCS-6 derivative film than in other films tested. The seeds treated with N-alkylimine-CMCS coatings that contained B. subtilis CJ demonstrated up to 100-fold increase of this bacterial population on the seedlings in comparison to the pristine CMCS.

Chitosan-based thermosensitive hydrogel with long-term release of murine nerve growth factor for neurotrophic keratopathy

Neurotrophic keratopathy is a persistent defect of the corneal epithelium, with or without stromal ulceration, due to corneal nerve deficiency caused by a variety of etiologies. The treatment options for neurotrophic keratopathy are limited. In this study, an ophthalmic solution was constructed from a chitosan-based thermosensitive hydrogel with long-term release of murine nerve growth factor (CTH-mNGF). Its effectiveness was evaluated in corneal denervation (CD) mice and patients with neurotrophic keratopathy. In the preclinical setting, CTH-mNGF was assessed in a murine corneal denervation model. CTH-mNGF was transparent, thermosensitive, and ensured sustained release of mNGF for over 20 hours on the ocular surface, maintaining the local mNGF concentration around 1300 pg/mL in vivo. Corneal denervation mice treated with CTH-mNGF for 10 days showed a significant increase in corneal nerve area and total corneal nerve length compared with non-treated and CTH treated mice. A subsequent clinical trial of CTH-mNGF was conducted in patients with stage 2 or 3 neurotrophic keratopathy. Patients received topical CTH-mNGF twice daily for 8 weeks. Fluorescein sodium images, Schirmer's test, intraocular pressure, Cochet-Bonnet corneal perception test, and best corrected visual acuity were evaluated. In total, six patients (total of seven eyes) diagnosed with neurotrophic keratopathy were enrolled. After 8 weeks of CTH-mNGF treatment, all participants showed a decreased area of corneal epithelial defect, as stained by fluorescence. Overall, six out of seven eyes had fluorescence staining scores < 5. Moreover, best corrected visual acuity, intraocular pressure, Schirmer's test and Cochet-Bonnet corneal perception test results showed no significant improvement. An increase in corneal nerve density was observed by in vivo confocal microscopy after 8 weeks of CTH-mNGF treatment in three out of seven eyes. This study demonstrates that CTH-mNGF is transparent, thermosensitive, and has sustained-release properties. Its effectiveness in healing corneal epithelial defects in all eyes with neurotrophic keratopathy suggests CTH-mNGF has promising application prospects in the treatment of neurotrophic keratopathy, being convenient and cost effective.

Carboxymethyl chitosan and octadecylamine-coated liposome-containing WPTS: design, optimization, and evaluation

Liposomes (LPs) are a delivery system for stabilizing pharmaceuticals with limited use due to their propensity to congregate and fuse. A proposed method of addressing these problems is polymer coating. In this study, the potential of octadecylamine (ODA)-coated liposomes and carboxymethyl chitosan (CMCS/ODA-LPs) for enhancing Wacao pentacyclic triterpene saponin (WPTS) transport capacity was investigated. CMCS/ODA-LPs were produced by electrostatic adsorption and thin-film hydration. Response surface methodology (RSM) was employed to enhance the process and encapsulation efficiency (EE) for optimum drug encapsulation efficiency. The synthesized WPTS-CMCS/ODA-LPs were uniformly dispersed in a circular shape, and during 14 days of storage at 4 °C, the particle size and morphology did not significantly change. Vesicle size, zeta potential, polydispersity index (PDI), and entrapment efficiency (%) were 179.1 ± 7.31 nm, -29.6 ± 1.35 mV, 0.188 ± 0.052, and 75.62 ± 0.43, respectively. The hemolysis test revealed that WPTS-CMCS/ODA-LPs were sufficiently biocompatible. Compared to WPTS-LPs, WPTS-CMCS/ODA-LPs consistently showed a much more significant cytotoxic effect on cancer cells. Early and WPTS-CMCS/ODA-LPs-induced apoptosis resulted in almost seven times more cell death than the control. Compared to physiological pH 7.3, the pH-sensitive CMCS coupled LPs increased drug release at acidic pH 6.5. These findings suggest the efficacy of pH-sensitive CMCS/ODA-LPs as a medication delivery method for WPTS.

Recent Advances of Chitosan-Based Hydrogels for Skin-Wound Dressings

The management of wound healing represents a significant clinical challenge due to the complicated processes involved. Chitosan has remarkable properties that effectively prevent certain microorganisms from entering the body and positively influence both red blood cell aggregation and platelet adhesion and aggregation in the bloodstream, resulting in a favorable hemostatic outcome. In recent years, chitosan-based hydrogels have been widely used as wound dressings due to their biodegradability, biocompatibility, safety, non-toxicity, bioadhesiveness, and soft texture resembling the extracellular matrix. This article first summarizes an overview of the main chemical modifications of chitosan for wound dressings and then reviews the desired properties of chitosan-based hydrogel dressings. The applications of chitosan-based hydrogels in wound healing, including burn wounds, surgical wounds, infected wounds, and diabetic wounds are then discussed. Finally, future prospects for chitosan-based hydrogels as wound dressings are discussed. It is anticipated that this review will form a basis for the development of a range of chitosan-based hydrogel dressings for clinical treatment.

Harnessing the Potential of Chitosan and Its Derivatives for Enhanced Functionalities in Food Applications

As one of the most abundant natural polysaccharides that possess good biological activity, chitosan is extracted from chitin. Its application in the food field is being increasingly valued. However, chitosan extraction is difficult, and its poor solubility limits its application. At present, the extraction methods include the acid-base method, new chemical methods, and biological methods. The extraction rates of chitin/chitosan are 4-55%, 13-14%, and 15-28%, respectively. Different chemical modifications have different effects on chitosan, making it applicable in different fields. This article reviews and compares the extraction and chemical modification methods of chitosan, emphasizing the importance of green extraction methods. Finally, the application prospects of chitosan in the food industry are discussed. This will promote the understanding of the advantages and disadvantages of different extraction methods for chitosan as well as the relationship between modification and application, providing valuable insights for the future development of chitosan.

A review of chitosan in gene therapy: Developments and challenges

Gene therapy, as a revolutionary treatment, has been gaining more and more attention. The key to gene therapy is the selection of suitable vectors for protection of exogenous nucleic acid molecules and enabling their specific release in target cells. While viral vectors have been widely used in researches, non-viral vectors are receiving more attention due to its advantages. Chitosan (CS) has been widely used as non-viral organic gene carrier because of its good biocompatibility and its ability to load large amounts of nucleic acids. This paper summarizes and evaluates the potential of chitosan and its derivatives as gene delivery vector materials, along with factors influencing transfection efficiency, performance evaluation, ways to optimize infectious efficiency, and the current main research development directions. Additionally, it provides an outlook on its future prospects.

All-Natural Injectable Antibacterial Hydrogel Enabled by Chitosan and Borneol

Hydrogels with intrinsic antimicrobial capabilities based on natural strategies have been studied as a hot topic in biomedicine. Nevertheless, it is highly challenging to thoroughly develop a bacteriostatic natural hydrogel. Borneol as a traditional Chinese medicine possesses a unique broad-spectrum antibacterial activity under a membrane-breaking mechanism. In this study, a range of fully natural antibacterial hydrogels are designed and synthesized via the Schiff base cross-linking of carboxymethyl chitosan and dialdehyde dextran grafted natural borneol. The borneol with three configurations is hydrophilically modified onto dextran to boost its antibacterial activity. Also, the synergism of hydrophilic-modified borneol groups and positively charged ammonium ions of carboxymethyl chitosan make the hydrogels totally constrict the E. coli and S. aureus growth during 24 h. Furthermore, the hydrogels exhibit good in vitro cytocompatibility through cytotoxicity, protein adhesion, and hemolytic tests. In view of the injectability, the hydrogels can be delivered to the target site through a minimally invasive route. In short, this work offers a potential tactic to develop antibacterial hydrogels for the treatment of topical wound infections.

Inhalation of Carboxymethyl Chitosan Alleviates Posttraumatic Tracheal Fibrosis

OBJECTIVES

The present study was performed to determine whether the inhalation of carboxymethyl (CM)-chitosan can alleviate tracheal fibrosis in a rabbit model.

METHODS

We designed a rabbit model of tracheal stenosis involving electrocoagulation with a spherical electrode. Twenty New Zealand white rabbits were randomly divided into experimental and control groups (10 animals each). Tracheal damage was successfully established by electrocoagulation in all animals. The experimental group was given CM-chitosan (inhalation for 28 days), while the control group inhaled saline. The effects of CM-chitosan inhalation on tracheal fibrosis were analyzed. Laryngoscopy was performed to evaluate and grade tracheal granulation, while tracheal fibrosis was evaluated by histological examination. The effects of CM-chitosan inhalation on the tracheal mucosa were examined by scanning electron microscopy (SEM), and hydroxyproline content in tracheal scar tissue was determined by enzyme-linked immunosorbent assay (ELISA).

RESULTS

Laryngoscopy showed that the tracheal cross-sectional area was smaller in the experimental than control group. The amounts of loose connective tissue and damaged cartilage, as well as the severity of collagen and fibrosis, decreased following inhalation of CM-chitosan. According to the ELISA, the experimental group had low levels of hydroxyproline in the tracheal scar tissue.

CONCLUSION

The findings presented here showed that inhalation of CM-chitosan mitigated posttraumatic tracheal fibrosis in a rabbit model, thus suggesting a potential new treatment for tracheal stenosis.

Chlorogenic acid-chitosan copolymers: Synthesis, characterization and application in O/W emulsions for enhanced β-carotene stability

In this study, chlorogenic acid-chitosan (CA-CS) copolymers were prepared with varying Chitosan (CS): chlorogenic acid (CA)ratios and characterized for their water solubility, antioxidant capacity, and emulsions stability. Results showed that CA-CS samples exhibited up to 90.5 % increase in DPPH scavenging efficiency and 20 % increase in hydroxyl radical scavenging efficiency compared to CS alone. CA-CS copolymers used to stabilize oil in water (O/W) emulsions, which were evaluated for their potential in encapsulating and protecting β-carotene. Microscopic observations revealed homogeneous spherical droplets in stable emulsions, suggesting effective interfacial structures. The selected CA-CS-stabilized O/W emulsions demonstrated encapsulation efficiencies of 74.8 % and 75.26 % for β-carotene. The CA-CS stabilized O/W emulsions provided the most effective protection against β-carotene degradation under UV exposure, retaining over 80 % of β-carotene content after 12 h of testing. These findings indicate that CA-CS-based O/W emulsions show promise as carriers and protectors for bioactive compounds, due to their improved antioxidant capacity, emulsions stability, and protection against degradation.

Pharmacotherapy of urethral stricture

Urethral stricture is characterized by the chronic formation of fibrous tissue, leading to the narrowing of the urethral lumen. Despite the availability of various endoscopic treatments, the recurrence of urethral strictures remains a common challenge. Postsurgery pharmacotherapy targeting tissue fibrosis is a promising option for reducing recurrence rates. Although drugs cannot replace surgery, they can be used as adjuvant therapies to improve outcomes. In this regard, many drugs have been proposed based on the mechanisms underlying the pathophysiology of urethral stricture. Ongoing studies have obtained substantial progress in treating urethral strictures, highlighting the potential for improved drug effectiveness through appropriate clinical delivery methods. Therefore, this review summarizes the latest researches on the mechanisms related to the pathophysiology of urethral stricture and the drugs to provide a theoretical basis and new insights for the effective use and future advancements in drug therapy for urethral stricture.

Synthesis of oxidized carboxymethyl cellulose-chitosan and its composite films with SiC and SiC@SiO2 nanoparticles for methylene blue dye adsorption

The cationic methylene blue (MB) dye sequestration was studied by using oxidized carboxymethyl cellulose-chitosan (OCMC-CS) and its composite films with silicon carbide (OCMC-CS-SiC), and silica-coated SiC nanoparticles (OCMC-CS-SiC@SiO2). The resulting composite films were characterized through various analytical techniques, including Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Thermogravimetric analysis (TGA), Field emission scanning electron microscopy (FESEM), and energy-dispersive X-ray spectroscopy (EDS). The dye adsorption properties of the synthesized composite films were comprehensively investigated in batch experiments and the effect of parameters such as contact time, initial dye concentration, catalyst dosages, temperature, and pH were systematically evaluated. The results indicated that the film's adsorption efficiency was increased by increasing the contact time, catalyst amount, and temperature, and with a decreased initial concentration of dye solution. The adsorption efficiency was highest at neutral pH. The experimental results demonstrated that OCMC-CS films have high dye adsorption capabilities as compared to OCMC-CS-SiC, and OCMC-CS-SiC@SiO2. Additionally, the desorption investigation suggested that the adsorbents are successfully regenerated. Overall, this study contributes to the development of sustainable and effective adsorbent materials for dye removal applications. These films present a promising and environmentally friendly approach to mitigate dye pollution from aqueous systems.

Surface modification of polyvinyl chloride with sodium alginate/carboxymethyl chitosan and heparin for realizing the anticoagulation

Thrombosis of extracorporeal circuits causes significant morbidity and mortality worldwide. In this study, plasma treatment technology and chemical grafting method were used to construct heparinized surfaces on the PVC substrate, which could not only reduce thrombosis but also decrease the side effects of the direct injection of anticoagulants. The PVC substrate was modified by plasma treatment technology firstly to obtain the active surface with the hydroxyl groups used for grafting. Then, heparin was grafted onto the modified PVC surface using different grafting strategies to prepare different heparinized surfaces. The experimental results indicated that the sodium alginate (SA) and carboxymethyl chitosan (CCS) used as interlayers could significantly increase the graft density of heparin to improve the anticoagulant effects and hemocompatibility of heparinized surfaces. In addition, the modification of heparin can further improve the anticoagulant effects. The CCS/low-molecular-weight heparin (LWMH) surface has the best anticoagulant properties, which can prolong the activated partial thromboplastin time (APTT) values of human plasma for about 35 s, reduce the hemolysis rates to <0.3 %, and perform well in the in-vitro blood circulation test. The heparinized surfaces prepared in this work have great application potential in anticoagulant treatment for medical devices.

Construction of carboxymethyl chitosan/PVA/chitin nanowhiskers multicomponent film activated with Cotylelobium lanceolatum phenolics and in situ SeNP for enhanced packaging application

This work focused on the construction of bioactive packaging films based on carboxymethyl chitosan and poly(vinyl alcohol) (CMP) as polymeric matrix and fortified with chitin nanowhiskers, Cotylelobium lanceolatum phenolic extract (CL) and in situ synthesized nano selenium. Extensive morphological, microstructural, physical and mechanical analysis revealed that the nanofillers were well-dispersed and integrated into CMP matrix. Incorporation of the extract and nano selenium produced excellent UV blocking properties without seriously compromising the transparency of the composite (CMP/CNW/CLNS1) film. Moreover, blending of CMP with the filler materials significantly elevated (p < 0.05) the surface hydrophobicity (WCA by 35.4°), water barrier (by 53.86 %), tensile strength (from 29.35 to 33.09 MPa), elongation at break (from 64.28 to 96.48 %), and thermal properties of the resultant CMP/CNW/CLNS1 film, with concomitant reduction in water solubility and swellability. Furthermore, the CMP/CNW/CLNS films exhibited remarkable improvement in antioxidant properties. When used for packaging of peeled fresh garlic cloves, the CMP/CNW/CLNS1 film pouch, not the plain CMP or CMP/CNW film pouches, inhibited weight loss, oxidative browning, and the emergence of black mold on the packaged cloves. The developed CMP/CNW/CLNS1 film demonstrated enhanced capacity to safeguard the quality of packaged food and improved shelf life. Therefore, the present study suggests that incorporation of CNW/CLNS into carboxymethyl chitosan/PVA films is a suitable and facile strategy for the fabrication of films with improved mechanical, physico-chemical and functional properties with great potential for application as a sustainable active packaging material in the food industry.

N-lauric-O-carboxymethyl chitosan: Synthesis, characterization and application as a pH-responsive carrier for curcumin particles

A pH-responsive amphiphilic chitosan derivative, N-lauric-O-carboxymethyl chitosan (LA-CMCh), is synthesized. Its molecular structures are characterized by FTIR, 1H NMR, and XRD methods. The influencing factors are investigated, including the amount of lauric acid (LA), carboxymethyl chitosan (CMCh), N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide hydrochloride (EDC), and N-hydroxysuccinimide (NHS), and their molar ratio, reaction time, and reaction temperature on the substitution. The degrees of substitution (DS) of the lauric groups on the -NH2 groups are calculated based on the integrated data of 1H NMR spectra. The optimum reaction condition is obtained as a reaction time of 6 h, a reaction temperature of 80 °C, and a molar ratio of lauric acid to O-carboxymethyl chitosan to N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide hydrochloride to N-hydroxysuccinimide of 1:3:4.5:4.5, respectively. The crystallinity and initial decomposition temperature of LA-CMCh decrease, but the maximum decomposition temperature increases. The crystallinity is reduced due to the introduction of LA and the degree of hydrogen bonding among LA-CMCh molecules. LA-CMCh could self-aggregate into particles, which size and critical aggregation concentration depend on the degree of substitution and medium pH. LA-CMCh aggregates could load curcumin up to 21.70 %, and continuously release curcumin for >200 min. LA-CMCh shows nontoxicity to fibroblast HFF-1 cells and good antibacterial activity against S. aureus and E. coli, indicating that it could be used as an oil-soluble-drug carrier.

Carboxymethyl chitosan-gelatin-mesoporous silica nanoparticles containing Myrtus communis L. extract as a novel transparent film wound dressing

Wound healing and health care requirements have attracted more attention, and the need to develop new drug-containing dressings to accelerate wound healing is required. Carboxymethyl chitosan (CMCS)/gelatin-based films with mesoporous silica nanoparticles (MSNs) containing the Myrtus communis L. (Myrtle) aqueous extract were designed to answer this demand. Myrtle aqueous extract included total phenolic content and good free radical scavenging ability in vitro assay. The infrared spectroscopy characterized the functional groups of myrtle extract and biocomposite films. It was found that mesoporous silica nanoparticles increased the tensile strength of the flexible dressings, which is essential in therapeutic uses. MSNs influenced swelling ratio, oxygen, and water vapor permeability that indicates the CMCS/Gelatin/Myrtle/5 % MSNs wound dressing can absorb wound exudates and preserve skin moisture. Also, these biocompatible nanoparticles reduced the cytotoxicity of fibroblast cells due to the decelerated drug release. Correspondingly, silica nanoparticles affected the extract release rate and could accumulate and release the extract prolonged in CMCS/Gelatin/Myrtle/5 % MSNs models. Finally, histological analysis showed collagen growth and fibroblast migration in wounds treated with CMCS/Gelatin/Myrtle/5 % MSNs, causing proper wound contraction and accelerating wound healing in mice models. The results suggest that CMCS/Gelatin/Myrtle/5 % MSNs films have a beneficial application as wound dressings.

Synthesis of multicolor luminescent carbon dots based on carboxymethyl chitosan for cell imaging and wound healing application: In vitro and in vivo studies

The construction of biomaterials that can facilitate wound healing is significantly challenging in the medical field, and bacterial infections increase this complexity. In this study, we selected the biomacromolecule carboxymethyl chitosan as a carbon source and citric acid as an auxiliary carbon source. We prepared carbon quantum dots with multicolor luminescence properties and higher quantum yields (QYs) using a facile one-pot hydrothermal method. We characterized them to select carbon dots (CDs) suitable for cell growth. Subsequently, their biocompatibility with L929 cells, antibacterial properties against Staphylococcus aureus, and efficiency in promoting wound healing in vivo were investigated. Our experimental results showed that CDs at an appropriate concentration had excellent bioimaging ability, were suitable for cell growth, and accelerated the healing of infected wounds. We believe these bioactive CDs have great potential in promoting wound healing.

Carboxymethyl chitosan/polyvinyl alcohol double network hydrogels prepared by freeze-thawing and calcium chloride cross-linking for efficient dye adsorption

The discharge of dye wastewater resulting from rapid industrial development has become a serious environmental concern. Therefore, there is a pressing need to develop efficient methods and technologies for the removal of dye pollutants. This study introduced a double network hydrogel, with varying carboxymethyl chitosan (CMCS) contents and polyvinyl alcohol (PVA), employing a combination of freeze- thawing and calcium chloride cross-linking. The investigation focused on the rheological properties of the hydrogels and their removal ability of acidic blue 93 (AB). The results showed that the strength and viscoelastic modulus of composite hydrogels were positively correlated with the CMCS content, and all composite hydrogels exhibited the typical weak strain overshoot behavior. The pore size of the gel initially decreased and then increased, with the densest pores observed at 4 wt% CMCS, showing the optimal removal ability for AB. The adsorption process followed pseudo second-order kinetic model, dominated by external diffusion, and exhibited inhomogeneous multilayer adsorption. This study unveils the potential of CMCS/PVA gels as adsorbents, offering inspirations for the design and development of polyvinyl alcohol-based gels for applications in the food industry.

Bio-based chitosan-based film as a bifunctional fire-warning and humidity sensor

Early fire detection is an efficient method to mitigate disastrous fire loss. However, developing smart low-temperature fire-warning sensors that better diminish fire hazards, especially those caused by household appliances, is still challenging. Herein, a salts-modified chitosan (salts-modified CS) based sensor with integrated fire-warning and humidity-monitoring capability is proposed using an easy assembling method. This sensor can respond to temperatures as low as 50 °C and a flame within 2 s quickly and detect relative humidity (RH) range above 50 % at 50 °C and 75 °C sensitively. This system can be reusable for multiple ignitions and works in high-humidity environments (>50 %). Furthermore, the comparison between different salts-modified CS films is carried out to elucidate the mechanism of the formation of electric current under the joint driven by temperature and humidity. Moreover, real-time temperature and RH monitoring can be achieved with a wireless transmission section. This design shows a promising approach for multifunctional CS-based sensors and paves a path to developing a new generation of smart fire-warning detectors.

Carboxymethyl chitosan-TK resistant starch complex ameliorates type 2 diabetes by regulating the gut microbiota

Carboxymethyl chitosan and resistant starch exhibit good performance in diabetes regulation. We prepared carboxymethyl chitosan - resistant starch complex. Test the properties of composite resistant starch by using X-ray diffraction, water contact angle, infrared spectroscopy, and scanning electron microscopy, interactions with intestinal microbiota and mouse experiments were also conducted. The results indicated that the composite resistant starch had a good effect on promoting the proliferation of probiotics on Bifidobacterium and a significant inhibitory effect on Escherichia coli than resistant starch (P < 0.05). After administration, the water intake and weight of diabetic mice were significantly reduced. The blood glucose of diabetic mice was also reduced, and oral glucose tolerance showed that the glucose degradation rates of composite resistant starch were significantly improved compared to model mice. Cholesterol, triglycerides, high-density lipoprotein and low-density lipoprotein were significantly lower than those in the diabetes group (P < 0.05). The diversity of the gut microbiota was also proven.

Carboxymethyl chitosan dopamine conjugates: Synthesis and evaluation for intranasal anti Parkinson therapy

With respect to the Parkinson's disease (PD), herein, we aimed at synthetizing and characterizing two novel macromolecular conjugates where dopamine (DA) was linked to N,O-carboxymethyl chitosan or O-carboxymethyl chitosan, being both conjugates obtained from an organic solvent free synthetic procedure. They were characterized by FT-IR, 1H NMR spectroscopies, whereas thermal analysis (including Differential Scanning Calorimetry and Thermal Gravimetric Analysis) revealed good stability of the two conjugates after exposure at temperatures close to 300 °C. Release studies in simulated nasal fluid elucidated that a faster release occurred since O-carboxymethyl chitosan-DA conjugate maybe due to the less steric hindrance exerted by the polymeric moiety. The CMCS-DA conjugates prepared in aqueous medium may self-assembly to form polymeric micelles and/or may form polymeric nanoparticles. TEM and Photon correlation spectroscopy lent support for polymeric nanoparticle formation. Moreover, such CMCS-DA conjugates showed antioxidant activity, as demonstrated by DPPH radical scavenging assay. Finally, cytocompatibility studies with neuroblastoma SH-SY5Y cells showed no cytotoxicity of both conjugates, whereas their uptake increased from 2.5 to 24 h and demonstrated in 40-66 % of cells.

Solvent-less carboxymethylation-induced electrostatic crosslinking of chitosan

The successful N-carboxymethylation and concomitant crosslinking of solid chitosan upon heating its mixture with solid monochloroacetic acid, without the use of solvents or catalysts, is reported. The N-carboxymethylation was confirmed through the analysis of the partially depolymerized product using NMR spectroscopy, as well as a control reaction with lysine. This transformation was facilitated by the nucleophilic nature of the free amine group in the repeating unit of chitosan, which possesses lone pair of electrons capable of attacking the carbon center bearing the leaving group and displacing the leaving group in a concerted manner. The crosslinking, on the other hand, was established by the observed insolubility in aqueous acidic solutions, even when subjected to prolonged heating at 60 °C. This crosslinking occurs due to the electrostatic interactions between the carboxylate groups and the adjacent ammonium groups, as supported by evidence from FTIR spectroscopy and a control reaction involving ethyl chloroacetate. The resulting crosslinked carboxymethyl chitosan demonstrated its usefulness in the adsorption of methyl orange and fluorescein, as well as functioning as an organic catalyst for aza-Michael addition, Hantzsch reaction, and substituted perimidine synthesis.

Marine-derived polysaccharides and their therapeutic potential in wound healing application - A review

Polysaccharides originating from marine sources have been studied as potential material for use in wound dressings because of their desirable characteristics of biocompatibility, biodegradability, and low toxicity. Marine-derived polysaccharides used as wound dressing, provide several benefits such as promoting wound healing by providing a moist environment that facilitates cell migration and proliferation. They can also act as a barrier against external contaminants and provide a protective layer to prevent further damage to the wound. Research studies have shown that marine-derived polysaccharides can be used to develop different types of wound dressings such as hydrogels, films, and fibres. These dressings can be personalised to meet specific requirements based on the type and severity of the wound. For instance, hydrogels can be used for deep wounds to provide a moist environment, while films can be used for superficial wounds to provide a protective barrier. Additionally, these polysaccharides can be modified to improve their properties, such as enhancing their mechanical strength or increasing their ability to release bioactive molecules that can promote wound healing. Overall, marine-derived polysaccharides show great promise for developing effective and safe wound dressings for various wound types.

Rheological insights on Carboxymethyl cellulose hydrogels

Hydrogels are copiously studied for tissue engineering, drug delivery, and bone regeneration owing to their water content, mechanical strength, and elastic behaviour. The preparation of stable and mechanically strengthened hydrogels without using toxic crosslinkers and expensive approaches is immensely challenging. In this study, we prepared Carboxymethyl cellulose based hydrogels with different polymer concentration via a less expensive physical crosslinking approach without using any toxic crosslinkers and evaluated their mechanical strength. In this hydrogel system, the carbopol concentration was fixed at 1 wt/v% and the Carboxymethyl cellulose concentration was varied between 1 and 5 wt/v%. In this hydrogel system, Carbopol serves as the crosslinker to bridge Carboxymethyl cellulose polymer through hydrogen bonds. Rheological analysis was employed in assessing the mechanical properties of the prepared hydrogel, in particular, the viscoelastic behaviour of the hydrogels. The viscoelastic nature and mechanical strength of the hydrogels increased with an increase in the Carboxymethyl cellulose polymer concentration. Further, our results suggested that gels with Carboxymethyl cellulose concentration between 3 wt/v % and 4 wt/v % with yield stresses of 58.83 Pa and 81.47 Pa, respectively, are potential candidates for use in transdermal drug delivery. The prepared hydrogels possessed high thermal stability and retained their gel network structure even at 50 °C. These findings are beneficial for biomedical applications in transdermal drug delivery and tissue engineering owing to the biocompatibility, stability, and mechanical strength of the prepared hydrogels.

Injectable hydrogels derived from marine polysaccharides as cell carriers for large corneal epithelial defects

Injectable hydrogels have been employed for sutureless repair of corneal epithelial defects, which can perfectly fit the defect sites and minimize the associated discomfort. However, numerous hydrogels are ineffective in treating large corneal epithelial defects and still suffer from poor biocompatibility or weak applicability when used as cell carriers. Herein, hydroxypropyl chitin/carboxymethyl chitosan (HPCT/CMCS) temperature-sensitive hydrogels are fabricated, and their physicochemical properties and suitability for corneal epithelial repair are investigated. The results demonstrate that HPCT/CMCS hydrogels have excellent temperature sensitivity between 20 and 25 °C and a transparency of over 80 %. Besides, HPCT/CMCS hydrogels can promote cell proliferation and facilitate cell migration of primary rabbit corneal epithelial cells (CEpCs). A rabbit large corneal epithelial defect model (6 mm) is established, and CEpCs are transplanted into defect sites by HPCT/CMCS hydrogels. The results suggest that HPCT/CMCS/CEpCs significantly enhance the repair of large corneal epithelial defects with a healing rate of 99.6 % on day 8, while reducing inflammatory responses and scarring formation. Furthermore, HPCT/CMCS/CEpCs can contribute to the reconstruction of damaged tissues and the recovery of functional capacities. Overall, HPCT/CMCS hydrogels may be a feasible corneal cell carrier material and can provide an alternative approach to large corneal epithelial defects.

Green Synthesis of Carboxymethyl Chitosan-Based CuInS2 QDs with Luminescent Response toward Pb2+ Ion and Its Application in Bioimaging

Polysaccharide-based QDs have attracted great attention in the field of biological imaging and diagnostics. How to get rid of the high heavy metal toxicity resulting from conventional Cd- and Pb-based QDs is now the main challenge. Herein, we offer a simple and environmentally friendly approach for the "direct" interaction of thiol-ending carboxymethyl chitosan (CMC-SH) with metal salt precursors, resulting in CuInS2 QDs based on polysaccharides. A nucleation-growth mechanism based on the LaMer model can explain how CMC-CuInS2 QDs are formed. As-prepared water-soluble CMC-CuInS2 QDs exhibit monodisperse particles with sizes of 5.5-6.5 nm. CMC-CuInS2 QDs emit the bright-green fluorescence at 530 nm when excited at 466 nm with the highest quantum yield of ∼18.0%. Meanwhile, the fluorescence intensity of CMC-CuInS2 QD aqueous solution is quenched with the addition of Pb2+ and the minimal limit of detection is as little as 0.4 nM. Furthermore, due to its noncytotoxicity, great biocompatibility, and strong biorecognition ability, CMC-CuInS2 QDs can be exploited as a possible cell membrane imaging reagent. The imaging studies also demonstrate that CMC-CuInS2 QDs are suitable for Pb2+ detection in live cells and living organisms (zebrafish). Thus, this work offers such an efficient, green, and practical method for creating low-toxicity and water-soluble QD nanosensors for a sensitive and selective detection of toxic metal ion in live cells and organisms.

Double network structure via ionic bond and covalent bond of carboxymethyl chitosan and poly(ethylene glycol): Factors affecting hydrogel formation

The factors were studied that affect the formation of DN hydrogel, which was prepared using a water-based, environmental-friendly system. The DN hydrogel was designed and prepared based on a cross-linked, polysaccharide-based, polymer carboxymethyl chitosan (CMCS) via an ionic crosslinking reaction for the first network structure. UV irradiation created a radical crosslinking reaction of poly(ethylene glycol) from a double bond at the chain end for the second network structure. It was found that the optimum hydrogel was produced using 9.5 %v/v of 1000PEGGMA, CMCS 5%w/v, and CaCl₂ 3%w/v. The results showed the highest percentage of the gel fraction was 87.84 % and the hydrogel was stable based on its rheological properties. Factors affecting the hydrogel formation were the concentration and molecular weight of PEGGMA and the concentrations of CMCS and calcium chloride (CaCl₂). The DN hydrogel had bioactivity due to its octacalcium phosphate (OCP) hydroxyapatite crystal form. In addition, the composite DN scaffold with a conductive polymer of chitosan-grafted-polyaniline (CS-g-PANI) had conduction of 2.33 × 10^-5 S/cm when the concentration of CS-g-PANI was 3 mg/ml, confirming the semi-conductive nature of the material. All the results indicated that DN hydrogel could be a candidate to apply in tissue-engineering applications.

Evaluation of the Anti-Inflammatory Pain Effect of Ginsenoside-Conjugated O-Carboxymethyl Chitosan Particles

Nanoparticle delivery of functional molecules or vaccines is an effective method for the treatment of many diseases. This study aims to design ginsenoside Rh2-conjugated O-carboxymethyl chitosan (O-CMC/Rh2) as a drug delivery system and explore its anti-nociceptive effects. O-CMC/Rh2 was synthesized with an esterification reaction, and its chemical composition and morphology were evaluated using proton nuclear magnetic resonance (1H NMR), the attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy, and scanning electron microscopy (SEM). In addition, the in vitro cumulative release of Rh2 from the O-CMC/Rh2 was also evaluated under different pH conditions. The results showed that the ginsenoside Rh2 was successfully conjugated to the O-CMC matrix and exhibited a highly porous structure after conjugation, facilitating the release of Rh2 from O-CMC. Complete Freund's adjuvant (CFA) and burn injury-induced pain models were used to evaluate the anti-nociceptive effects of O-CMC/Rh2 on inflammatory pain. O-CMC/Rh2 reduced CFA-induced pain hypersensitivity in a dose-dependent manner and had a longer analgesic effect than Rh2. In addition, O-CMC/Rh2 also relieved the chronic pain induced by bury injury. These results indicated that O-CMC/Rh2 could be useful in reducing inflammatory pain, thus possessing a potential medicinal application in pain therapy.

Bioactive Glasses Enriched with Strontium or Zinc with Different Degrees of Structural Order as Components of Chitosan-Based Composite Scaffolds for Bone Tissue Engineering

The development of innovative biomaterials with improved integration with bone tissue and stimulating regeneration processes is necessary. Here, we evaluate the usefulness of bioactive glasses from the SiO2-P2O5-CaO system enriched with 2 wt.% SrO or ZnO in the manufacturing of chitosan-based scaffolds. Bioglasses produced using the sol-gel method were subjected to thermal treatment in different regimes. Chitosan/bioglass composites were produced with a weight ratio. Bioglasses were evaluated via TG-DTA, FTIR, and SEM-EDS before and after incubation in simulated body fluid (SBF). The release of ions was tested. The cytocompatibility of the composites in contact with MG63 osteoblast-like cells was evaluated. The results showed that the presence of the crystalline phase decreased from 41.2-44.8% for nonmodified bioglasses to 24.2-24.3% for those modified with ZnO and 22.0-24.2% for those modified with SrO. The samples released Ca2+, Zn2+, and/or Sr2+ ions and were bioactive according to the SBF test. The highest cytocompatibility was observed for the composites containing nonmodified bioglasses, followed by those enriched with SrO bioglasses. The least cytocompatible were the composites containing ZnO bioglasses that released the highest amount of Zn2+ ions (0.58 ± 0.07 mL/g); however, those that released 0.38 ± 0.04 mL/g were characterised by acceptable cytocompatibility. The study confirmed that it is feasible to control the biological performance of chitosan/bioglass composites by adjusting the composition and heat treatment parameters of bioglasses.

Synthesis and fluorescent property of carboxymethyl chitosan with different degrees of carboxymethylation and its application for fluorescence turn-on detection of Cd(II) ion

Recently, carboxymethyl chitosan (CMCS) has proved to be an intrinsically fluorescent material with aggregation-induced emission characteristic. In order to elucidate the influence of CMCS's chemical structure and solution behavior on its fluorescent intensity, two series of CMCS with different degrees of carboxymethylation (DCM) are synthesized by adjusting the mass ratio of monochloroacetic acid and sodium hydroxide to chitosan at various reaction temperature and time, and then characterized using Fourier-transform infrared spectroscopy and nuclear magnetic resonance. Their solution behaviors at different pH values are studied via zeta potential and ultraviolet-visible measurements. The data reveal that the isoelectronic point (IEP) of a CMCS decreases with increasing DCM, and all the CMCSs have good water solubility at pH range below their IEPs. Fluorescence spectra indicate that a CMCS shows the highest fluorescent intensity in a slightly acidic environment next to its IEP, and the photoluminescence of a CMCS solution increases significantly after heat treatment above T = 70 °C. Furthermore, we compare for the first time the use of heated CMCS solutions for the fluorescence turn-on detection of cadmium ion in pure and tap water, respectively. The limit of detection is found to be ca. 1 μM for the Cd2+ in pure water.

Potential Medicinal Value of Rhein for Diabetic Kidney Disease

Diabetic kidney disease (DKD) is the primary cause of mortality among diabetic patients. With the increasing prevalence of diabetes, it has become a major concern around the world. The therapeutic effect of clinical use of drugs is far from expected, and therapy choices to slow the progression of DKD remain restricted. Therefore, research on new drugs and treatments for DKD has been a hot topic in the medical field. It has been found that rhein has the potential to target the pathogenesis of DKD and has a wide range of pharmacological effects on DKD, such as anti-nephritis, decreasing blood glucose, controlling blood lipids and renal protection. In recent years, the medical value of rhein in the treatment of diabetes, DKD and renal disease has gradually attracted worldwide attention, especially its potential in the treatment of DKD. Currently, DKD can only be treated with medications from a single symptom and are accompanied by adverse effects, while rhein improves DKD with a multi-pathway and multi-target approach. Therefore, this paper reviews the therapeutic effects of rhein on DKD, and proposes solutions to the limitations of rhein itself, in order to provide valuable references for the clinical application of rhein in DKD and the development of new drugs.

An injectable, self-healable, antibacterial, and pro-healing oxidized pullulan polysaccharide/carboxymethyl chitosan hydrogel for early protection of open abdominal wounds

Open abdomen (OA) is an effective method for treating critical abdominal conditions such as severe abdominal infections. The temporary abdominal closure (TAC) technique is often used to temporarily restore the physiological environment of the abdominal cavity and maintain the homeostatic balance of the abdominal cavity. However, most of the common TAC materials available today lack bio-responsiveness, tend to abrade the intestinal canal, and lead to delayed tissue healing of the wound. Hydrogels could mimic the extracellular matrix and have shown significant potential in life science fields such as tissue regeneration, wound repair, and controlled drug release. In this study, a composite hydrogel scaffold was constructed by the Schiff base reaction of oxidized pullulan polysaccharide with carboxymethyl chitosan. The hydrogel exhibited excellent self-healing, cellular biocompatibility, and antibacterial and anti-inflammatory abilities, and in experiments it reduced secondary damage caused by friction between tissue and patch, thereby preventing serious complications such as intestinal fistula, promoted M1-M2 polarization of macrophages, reduced the inflammatory response, regulated the inflammatory microenvironment in vivo, promoted angiogenesis and granulation tissue regeneration, and accelerated wound healing. Therefore, our hydrogel provides a new strategy for material-assisted wound protection during OA and has potential clinical applications.

Coordination-driven robust antibacterial coatings using catechol-conjugated carboxymethyl chitosan

To prevent bacterial contamination on solid surfaces, a simple yet efficient antibacterial coating was developed in a substrate-independent manner by using the catechol-conjugated carboxymethyl chitosan (CMC-DOPA). The CMC-DOPA was firstly synthesized via an aza-Michael reaction with methyl acrylate and the subsequent acyl substitution with dopamine. The coating strategy consists of spin-coating-assisted deposition of CMC-DOPA on polydopamine-coated substrates and coordination-driven crosslinks between catechol groups and Fe3+ ions in sequence, producing the multilayered CMC-DOPA films. The film thickness was controllable depending on the concentration of CMC-DOPA. Compared to bare controls, the CMC-DOPA-coated substrates reduced the bacterial adhesion by up to 99.8 % and 96.2 % for E. coli and S. aureus, respectively. It is demonstrated that the CMC-DOPA coating can be a robust antibacterial coating across various pH environments, inhibiting bacterial adhesion by 78.7 %, 95.1 %, and 93.2 %, respectively, compared to the control, even after 7 days of acidic, physiological, and alkaline pH treatment. The current coating approach could be applied to various substrates including silicon dioxide, titanium dioxide, and polyurethane. Given its simple and versatile coating capability, we think that the coordination-driven CMC-DOPA coating could be useful for various medical devices and implants.

A Photocurable Polysaccharide-Based Hydrogel Delivery of Polydeoxyribonucleotide-Loaded Vectors for Wound Treatment

The wounds caused by war, accidents, and diseases require timely and effective treatment. Polysaccharides, as natural macromolecules, have good biocompatibility and unique functions, and are excellent substrates for constructing new wound dressings. Short-chain chitosan (SCS) has good water solubility and, importantly, retains a large number of active amino groups. We first introduce double bonds to SCS. This chitosan derivative can be entangled with sodium alginate (SA) through electrostatic interaction. The flowing sol can be applied to a wound with an irregular shape. Under the initiation of a photoinitiator, the internal double bonds are broken and cross-linked to form a gel. The prepared hydrogel wound dressing exhibited good antibacterial properties and can provide a microenvironment conducive to wound repair. A polydeoxyribonucleotide (PDRN) has been proven to have encouraging therapeutic effects for wound healing. PDRN can be condensed by branched polyethylenimine (PEI) to form a nucleic acid delivery system, which can be efficiently uptaken by cells. The cooperation of hydrogel and nucleic-acid-based therapy presented good results in a mouse full-thickness skin wound model.