Blood coagulation evaluation of N -alkylated chitosan

Recent advances in smart hydrogels derived from polysaccharides and their applications for wound dressing and healing

Owing to their inherent biocompatibility and biodegradability, hydrogels derived from polysaccharides have emerged as promising candidates for wound management. However, the complex nature of wound healing often requires the development of smart hydrogels---intelligent materials capable of responding dynamically to specific physical or chemical stimuli. Over the past decade, an increasing number of stimuli-responsive polysaccharide-based hydrogels have been developed to treat various types of wounds. While a range of hydrogel types and their versatile functions for wound management have been discussed in the literature, there is still a need for a review of the crosslinking strategies used to create smart hydrogels from polysaccharides. This review provides a comprehensive overview of how stimuli-responsive hydrogels can be designed and made using five key polysaccharides: chitosan, hyaluronic acid, alginate, dextran, and cellulose. Various methods, such as chemical crosslinking, dynamic crosslinking, and physical crosslinking, which are used to form networks within these hydrogels, ultimately determine their ability to respond to stimuli, have been explored. This article further looks at different polysaccharide-based hydrogel wound dressings that can respond to factors such as reactive oxygen species, temperature, pH, glucose, light, and ultrasound in the wound environment and discusses how these responses can enhance wound healing. Finally, this review provides insights into how stimuli-responsive polysaccharide-based hydrogels can be developed further as advanced wound dressings in the future.

Tri-network PVA/chitosan/gelatin hydrogel modified by tannic acid with self-healing, adhesive and anti-inflammatory properties to accelerate wound healing

Wound inflammation is a key issue in wound healing as it often causes serious complications and delays wound healing. In this study, hemostatic and antimicrobial hydrogels composed of polyvinyl alcohol (PVA), chitosan (CS) and gelatin (Gel) were prepared. Phenylboronic acid (3-CPBA) and tannic acid (TA) were introduced to modify the multinetwork hydrogel to promote wound repair. PGCPT-1.2 hydrogel had a water content of >85 % and was biocompatible. Due to the antibacterial effect of chitosan itself. The PGCPT hydrogel exhibited 100 % antimicrobial activity against both Escherichia coli and Staphylococcus aureus within 12 h. The hydrogel exhibited shape memory behavior and self-healing ability. Histological analysis showed that PGCPT-1.2 hydrogel reduced tumor necrosis factor-α (TNF-α) levels by accelerating collagen deposition. The wound healing rate at day 14 was 97 % ± 0.4 %. PGCPT-1.2 hydrogel dressing with 1.2 % TA addition had the best effect in promoting wound healing, and it is a promising dressing for promoting wound healing and a therapeutic strategy worth developing.

Harnessing the immunomodulatory potential of chitosan and its derivatives for advanced biomedical applications

The success of biomaterial applications in medicine, particularly in tissue engineering, relies on achieving a balance between promoting tissue regeneration and controlling the immune response. Due to its natural origin, high biocompatibility, and versatility, chitosan has emerged as a promising biomaterial especially for immunomodulation purposes. Immunomodulation, refers to the deliberate alteration of the immune system's activity to achieve a desired therapeutic effect either by enhancing or suppressing the function of specific immune cells, signaling pathways, or cytokine production. This modulation opens up the unlimited possibilities for the use of biomaterials, especially about the use of natural polymers such as chitosan. Although numerous chitosan-based immunoregulatory strategies have been demonstrated over the past two decades, the lack of in-depth exploration hinders the full potential of strategies that include chitosan and its derivatives in biomedical applications. Thus, in this review, the possible immunomodulatory effects of chitosan, chitosan derivatives and their potential combined with various agents and therapies are investigated in detail. Moreover, this report includes agents for localized immune response control, chitosan-based strategies with complementary immunomodulatory properties to create synergistic effects that will influence the success of cell therapies for enhanced tissue acceptance and regeneration. Finally, the challenges and outlook of chitosan-based therapies as a powerful tool for improving immunomodulatory applications are discussed for paving the way for further studies.

Regulatory effects of different spacer alkyl chains on the in vitro antioxidant and antibacterial activities of chitosan quaternary ammonium/phosphonium salt derivatives

In this study, three chitosan quaternary phosphonium salts and three chitosan quaternary ammonium salts with varying spacer chain lengths were synthesized. Structure characterization of the obtained products was conducted using Fourier-transform infrared spectroscopy, nuclear magnetic resonance, thermogravimetric analysis, and elemental analysis. Additionally, the in vitro scavenging efficiency of these derivatives against 2,2-diphenyl-1-picrylhydrazyl (DPPH) and superoxide radicals, as well as their antibacterial activities against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus), were evaluated. The results indicated that the scavenging efficiency of the chitosan quaternary phosphonium salt at a concentration of 1.6 mg/mL ranged from 36.9 % to 48.7 % for DPPH free radicals and from 48.3 % to 66.3 % for superoxide free radicals, outperforming that of the chitosan quaternary ammonium salt with long alkyl chains. Furthermore, an increase in the length of the spacer alkyl chain was associated with enhanced antibacterial activities of the corresponding chitosan derivatives. At a concentration of 1.0 mg/mL, the synthesized chitosan derivatives demonstrated antibacterial rates exceeding 90 % against both E. coli and S. aureus. Notably, the CCK-8 assay confirmed that these derivatives are non-toxic to 293 T cells. Among the six derivatives, TPPBOC and DMDOC, characterized by longer spacer alkyl chains, demonstrated superior antioxidant and antibacterial activities. This research establishes a robust theoretical foundation for the development of more effective and safer antioxidants and antibacterial agents, thereby enriching the knowledge base in chitosan chemistry and functional materials, and paving new pathways for the innovation of novel antioxidant and antibacterial materials.

Tuning chitosan properties to enhance blood coagulation

The search for new hemostatic materials remains a priority for researchers, as the problem of uncontrolled hemorrhage during surgical interventions or traumatic injuries represents a significant challenge. The objective of the study was to identify novel polysaccharide structures with enhanced hemostatic properties based on chitosan. The number of chitosan derivatives with two substituents was synthesized and characterized by 1H NMR, FTIR. One of these was a structural analogue of L-DOPA - N-(3,4-dihydroxybenzyl), while the other comprised fragments of different nature, including hydrophobic N-(4-(tetradecyloxy)benzyl), negatively charged groups N-(4-carboxybenzyl) and aminocaproic acid residue. The hemostatic potential of the novel compounds was evaluated in vitro/in vivo on human blood and in mouse model of tail bleeding. Solutions of chitosan derivatives showed the ability to aggregate with blood about 3-5 times higher than chitosan in a neutral saline medium (0.9 % NaCl) and slightly acidic conditions both when (Ca2+) was added and in the case of citrated blood. Chitosan derivatives demonstrated low toxicity (3T3, HepG2 and Huh7) and did not induce plasma coagulation or platelet aggregation at low concentrations. The novel compounds can be used to modify the surface of biomaterials in order to improve their hemostatic properties.

Hemostatic and antimicrobial properties of chitosan-based wound healing dressings: A review

Uncontrolled bleeding and microbial infections pose significant hurdles in wound healing, and the use of specialized functional dressings is pivotal in overcoming these obstacles. Among the various wound dressings currently under investigation, those based on chitosan and its derivatives have garnered significant attention due to their superior biocompatibility, antimicrobial properties, hemostatic capabilities, and healing promoting ability. In this comprehensive review, we initially delve into the hemostatic capabilities of chitosan, elucidating its interactions with blood cells and plasma proteins. We also dissect the intricate antimicrobial mechanisms of chitosan, which operate through both intracellular and extracellular pathways. The centerpiece of this review is the systematic classification of dressings based on chitosan and its derivatives, across various forms, such as hydrogels, sponges, membranes, fibers, and powders. This is followed by an exhaustive analysis of their hemostatic and antibacterial efficacy in wound healing, providing a robust foundation for further research and the advancement of clinical applications in the field.

Recent advances in modifications, biotechnology, and biomedical applications of chitosan-based materials: A review

Chitosan, a natural polysaccharide with recognized biocompatibility, non-toxicity, and cost-effectiveness, is primarily sourced from crustacean exoskeletons. Its inherent limitations such as poor water solubility, low thermal stability, and inadequate mechanical strength have hindered its widespread application. However, through modifications, chitosan can exhibit enhanced properties such as water solubility, antibacterial and antioxidant activities, adsorption capacity, and film-forming ability, opening up avenues for diverse applications. Despite these advancements, realizing the full potential of modified chitosan remains a challenge across various fields. The purpose of this review article is to conduct a comprehensive evaluation of the chemical modification techniques of chitosan and their applications in biotechnology and biomedical fields. It aims to overcome the inherent limitations of chitosan, such as low water solubility, poor thermal stability, and inadequate mechanical strength, thereby expanding its application potential across various domains. This review is structured into two main sections. The first part delves into the latest chemical modification techniques for chitosan derivatives, encompassing quaternization, Schiff base formation, acylation, carboxylation, and alkylation reactions. The second part provides an overview of the applications of chitosan and its derivatives in biotechnology and biomedicine, spanning areas such as wastewater treatment, the textile and food industries, agriculture, antibacterial and antiviral activities, drug delivery systems, wound dressings, dental materials, and tissue engineering. Additionally, the review discusses the challenges associated with these modifications and offers insights into potential future developments in chitosan-based materials. This review is anticipated to offer theoretical insights and practical guidance to scientists engaged in biotechnology and biomedical research.

Antibacterial chitosan/organic rectorite nanocomposite-conjugated gelatin/β-cyclodextrin hydrogels with improved hemostasis performance for wound repair

Bacterial infections and severe bleeding continue to pose significant challenges in wound repair. There is an urgent need for innovative, nature-inspired hydrogel dressings with antibacterial and hemostatic properties. A Ge-β-CD-CS-OREC conjugate hydrogel was developed by grafting β-CD and CS-OREC nanocomposites into a Ge matrix using EDC/NHS crosslinking, as confirmed by FT-IR and EDX analyses. Compared to single Ge-β-CD cross-linked hydrogels, the addition of CS-OREC enhanced the hydrogel's properties, including increased pore size (60 ± 14 μm), improved wettability (WCA = 28.82 ± 0.6°), enhanced tensile strength (41.3 ± 3.56 KPa), and strong tissue adhesion. Furthermore, this hydrogel demonstrated excellent cytocompatibility when co-cultured with keratinocytes (Kcs) and vascular endothelial cells (VECs). The incorporation of CS chains into OREC interlayers allowed the hydrogel to specifically target bacteria and increase membrane permeability in Pseudomonas aeruginosa (PA), Klebsiella pneumoniae (KP), and Staphylococcus aureus (SA), effectively reducing the bacterial load in infected wounds by 50.24-73.92 % compared to controls in vivo. Further, the hydrogel exhibited superior hemostatic efficiency (78 ± 10 s) over commercial gauze and other gels by enhancing platelet activation and coagulation factor secretion. The hydrogel accelerated tissue regeneration by promoting epithelial maturation and blood vessel regeneration, indicating its clinical potential as promising wound dressing.

Rapid Fluid-Induced-Expanding Chitosan-Derived Hemostatic Sponges with Excellent Antimicrobial and Antioxidant Properties for Incompressible Hemorrhage and Wound Healing

Chitosan-based materials are known for their excellent biocompatibility and inherent hemostatic properties. However, their hemostatic efficiency is significantly affected by poor wettability and mechanical strength. Herein, we developed a novel hemostatic super elastic sponge from mussel-inspired chitosan modified with long alkyl and catechol functional groups (HMCC) via a simple freezing-drying procedure. The incorporation of decanal and catechol in the HMCC sponge significantly enhances its antimicrobial and antioxidant properties and facilitates multiple interactions with blood cells, thus promoting their enrichment for rapid hemostasis. Moreover, HMCC sponges exhibit high compressibility and rapid fluid-induced size recovery capacity, enabling wound shape adaptation to ensure minimizing irritation. In vivo experiments revealed that HMCC sponges possessed enhanced procoagulant, hemostasis abilities, and favorable degradability and could promote wound healing in a rat skin wound model. These results highlight the potential of the HMCC sponge as a promising solution for the clinical management of major bleeding.

Comparative assessment of the effectiveness of low-level laser therapy and chitosan in postoperative pain and bleeding management after primary molar extraction: A randomized clinical study

BACKGROUND

Dental caries, the leading cause of dental pain and the most prevalent chronic childhood disease globally, significantly impacts children's oral health, with prevalence ranging from 16% to 92.2% in India. Untreated caries in deciduous teeth can lead to pain, dietary changes, sleep disturbances, and enamel defects in permanent teeth. Pediatric dentists manage infected pulp with pulp therapy or extraction. Postoperative complications, such as discomfort and bleeding, are common in extraction cases.

AIM

This study aims to compare the analgesic and hemostatic efficacy of chitosan and low-level laser therapy (LLLT) in pediatric extractions, hypothesizing no significant difference between the two.

MATERIALS AND METHODS

This crossover randomized clinical trial was carried out within 87 primary molars from 29 participants. The study participants were randomized into three distinct groups, each with a specific order of interventions: Group A first received the control, followed by laser, and then chitosan; Group B first underwent the laser intervention, followed by chitosan, and finally the control; and Group C first experienced the chitosan intervention, followed by the control, and then laser. After extraction of the primary molar, properly shaped gauze piece, a 940-nm wavelength diode laser (diode Epic, BioLase, USA) was used in a continuous mode with 400 um diameter fiber tip at an approximately 8 mm away from the teeth socket without contact until 1 min, chitosan Sponge of 7 mm was measured using a periodontal probe and was placed into the extraction socket, respectively. Statistical analyses were performed using SPSS version 23 (IBM), with a significance level set at 5%.

RESULTS

The mean pain score was least for the LLLT group, followed by the Chitosan group and the maximum mean pain score was recorded for the control group and this difference was statistically significant, whereas there was no significant difference regarding the postoperative bleeding after 15 min between three groups. Chitosan was the intervention of choice for both the children and their guardians.

CONCLUSION

Soft-tissue diode lasers can be utilized for postoperative pain management subsequent to deciduous tooth extraction in children. This would reduce the reliance on analgesic medication and eliminate the possibility of adverse effects. Chitosan can serve as a highly effective, dependable, and cost-effective substitute in case of the diode laser's inaccessibility.

Functional potential of chitosan-metal nanostructures: Recent developments and applications

Chitosan (Cs), a naturally occurring biopolymer, has garnered significant interest due to its inherent biocompatibility, biodegradability, and minimal toxicity. This study investigates the effectiveness of various reaction strategies, including acylation, acetylation, and carboxymethylation, to enhance the solubility profile of Cs. This review provides a detailed examination of the rapidly developing field of Cs-based metal complexes and nanoparticles. It delves into the diverse synthesis methodologies employed for their fabrication, specifically focusing on ionic gelation and in-situ reduction techniques. Furthermore, the review offers a comprehensive analysis of the characterization techniques utilized to elucidate the physicochemical properties of these complexes. A range of analytical techniques are utilized, including Ultraviolet-Visible Spectroscopy (UV-Vis), Fourier-Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM) and others. By comprehensively exploring a wide range of applications, the review emphasizes the significant potential of Cs in various scientific disciplines. Diagrams, figures, and tables effectively illustrate the synthesis processes, promoting a clear understanding for the reader. Chitosan-metal nanostructures/nanocomposites significantly enhance antimicrobial efficacy, drug delivery, and environmental remediation compared to standard chitosan composites. The integration of metal nanoparticles, such as silver or gold, improves chitosan's effectiveness against a range of pathogens, including resistant bacteria. These nanocomposites facilitate targeted drug delivery and controlled release, boosting therapeutic bioavailability. Additionally, they enhance chitosan's ability to absorb heavy metals and dyes from wastewater, making them effective for environmental applications. Overall, chitosan-metal nanocomposites leverage chitosan's biocompatibility while offering improved functionalities, making them promising materials for diverse applications. This paper sheds light on recent advancements in the applications of Cs metal complexes for various purposes, including cancer treatment, drug delivery enhancement, and the prevention of bacterial and fungal infections.

Advances in Chitosan Derivatives: Preparation, Properties and Applications in Pharmacy and Medicine

Chitosan (CS) derivatives have been extensively investigated to enhance the physicochemical and biological properties of CS, such as its solubility, biocompatibility, and bioactivity, which are required in various areas of pharmacy and medicine. The present work emphasizes the ongoing research and development in this field, suggesting that the further exploration of CS derivatives could lead to innovative solutions that benefit society. The physicochemical properties, biological activities, methods of preparation, advantages, limitations, intended application areas, and realized practical implementations of particular CS derivatives are summarized and discussed herein. Despite the numerous promising attributes of CS derivatives as reported in this paper, however, challenges like target selectivity, standardization (purity, chitosan structural variability), and cost-effectiveness still need addressing for widespread implementation, especially in drug delivery. Therefore, basic research studies still prevail in CS drug delivery systems. However, for specific applications such as wound healing and tissue engineering, implementations of CS derivatives in practice are found to be more frequent. To obtain a more complex view of the topic, information from the scientific papers reviewed is supplemented with information from actual patents and clinical studies. Both basic research advances and the most successful and important medical implementations of CS derivatives are discussed concerning further challenges and future perspectives.

Fabrication of injectable, adhesive, self-healing, superabsorbent hydrogels based on quaternary ammonium chitosan and oxidized pullulan

Injectable hydrogels, which are polymeric materials that are characterized by their ability to be injected in a liquid form into cavities and subsequently undergo in situ solidification, have garnered significant attention. These materials are extensively used in a range of biomedical applications. This study synthesized several injectable composite hydrogels through the mild Schiff base reaction while imposing different concentrations of quaternary ammonium chitosan and oxidized pullulan. Subsequent characterizations revealed a consistent and coherent porous structure within the hydrogels with smooth inner walls. The hydrogels were also determined to possess good adhesion, mechanical properties, self-healing ability, and injectability. Furthermore, antimicrobial tests against Escherichia coli and Staphylococcus aureus demonstrated antibacterial properties, which improved with increasing concentrations of quaternary ammonium chitosan. Co-culturing with skin fibroblasts demonstrated that the injectable hydrogels exhibited favourable biocompatibility and the capacity to boost cellular activity, thus underscoring its potential for use in biomedical applications.

Novel Biological-Based Strategy for Synthesis of Green Nanochitosan and Copper-Chitosan Nanocomposites: Promising Antibacterial and Hematological Agents

Two novel samples of nanoparticles based on chitosan were greenly synthesized using pomegranate peel extract. The extract served as a nanoparticle precursor, facilitating the precipitation of nanosized chitosan through the ionic gelation method. Additionally, by mixing the green chitosan nanoparticles with copper ions, a nanoscale composite of chitosan and copper oxide was also produced. Structural and morphological investigations (FTIR, XRD, SEM, EDX, and TGA analyses) were performed for greenly synthesized chitosan nanoparticles and their copper oxide composite to determine all the significant characteristics of those nanoparticles. In addition, both samples were tested using some biological investigations, such as antimicrobial activity and hematological effects. The antimicrobial tests yielded promising results for both the green chitosan nanoparticles and the CuO composite when tested using two bacterial strains and two fungal strains. Moreover, the results showed that using a similar concentration of both green-based chitosan samples resulted in a slightly larger inhibition zone and a lower minimum inhibition concentration (MIC) for the copper oxide chitosan composite compared to the chitosan nanoparticles for all microorganisms included in the test. The mean count of blood components (RBCs and platelets), clotting time, and cholesterol levels in three different blood samples were used to indicate the hematological activity of both greenly synthesized nanoparticles. The results verified a slight reduction in blood component count after the addition of green chitosan nanoparticles, but the chitosan copper oxide composite did not have a noticeable effect on the three blood samples. The chitosan nanoparticles were able to cause a considerable reduction in clotting time and cholesterol levels for all blood samples, thus acting as procoagulants. However, the mixing of CuO with chitosan nanoparticles prolonged the rate of clotting in blood samples from hypercholesteremic individuals, and thus, the mixture acted as an anticoagulant agent.

Chitosan Hemostatic Dressings: Properties and Surgical Applications

Wounds caused by trauma and/or surgery represent a significant challenge in contemporary medical practice, requiring innovative approaches to promote optimal healing and reduce the risk of bleeding and complications resulting from it. In this context, chitosan, a natural polysaccharide derived from chitin, represents an ideal material for the study and application of medical devices, in the form of dressings, in wound management for pre- and/or post-operative wounds due to its ability to induce hemostasis and its high biocompatibility with biological tissues. The aim of this work was to discuss the structural characteristics, properties and application of chitosan-based hemostatic dressings in hemostatic processes resulting from pre- or post-surgical approaches.

Dehydration-Toughing Dual-Solvent Gels with Viscoelastic Transition for Infectious Wound Treatment

The modulus of traditional biomedical hydrogels increases exponentially meditated by dehydration-stiffing mechanism, which leads to the failure of interface matching between hydrogels and soft tissue wounds. It is found in the study that the dual-solvent gels exhibit dehydration-toughening mechanism with the slowly increasing modulus that are always match the soft tissue wounds. Therefore, dual-solvent glycerol hydrogels (GCFen-gly DGHs) are prepared with hydrophobically modified catechol chitosan (hmCSC) and gelatin based on the supramolecular interactions. GCFen-gly DGHs exhibit excellent water retention capacity with a total solvent content exceeding 80%, permanent skin-like modulus within a range of 0.45 to 4.13 kPa, and stable photothermal antibacterial abilities against S, aureus, E. coli, as well as MRSA. Infectious full-thickness rat skin defect model and tissue section analysis indicate that GCFen-gly DGHs are able to accelerate infectious wound healing by alleviating the inflammatory response, promoting granulation tissue growth, re-epithelialization, collagen deposition, and vascular regeneration. As a result, GCFen-gly DGHs is expected to become the next-generation biological gel materials for infectious wound treatment.

Research progress on chitosan and its derivatives in the fields of corrosion inhibition and antimicrobial activity

Chitosan stands out as the only known polysaccharide of its kind, second only to cellulose. As the second-largest biopolymer globally, chitosan and its derivatives are extensively used in diverse areas such as metal anti-corrosion prevention, food production, and medical fields. Its benefits include environmental friendliness, non-toxicity, cost-effectiveness, and biodegradability. Notably, the use of chitosan and its derivatives has gained substantial attention and has been extensively researched in the fields of metal anti-corrosion prevention and antibacterial applications. By means of chemical modification or synergistic action, the inherent limitations of chitosan can be substantially improved, thereby enhancing its biological and physicochemical properties to meet a wider range of applications and more demanding application requirements. This article offers a comprehensive review of chitosan and its modified composite materials, focusing on the enhancement of their anticorrosion and antibacterial properties, as well as the mechanisms by which they serve as anticorrosion and antibacterial agents. Additionally, it summarizes the synthesis routes of various modification methods of chitosan and their applications in different fields, aiming to contribute to the interdisciplinary development and potential applications of chitosan in various areas.

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.

Electrospun nanofiber membranes for rapid liver hemostasis via N-alkylated chitosan doped chitosan/PEO

The ideal hemostatic agents should be able to stop bleeding quickly and avoid secondary bleeding caused by adhesion with blood clots during dressing change. Herein, a hydrophobic electrospun nanofiber membrane was prepared for achieving hemostasis, rationally targeting both attributes, via doping N-alkylated chitosan (N-CS) grafted with octadecyl into chitosan/polyethylene oxide (PEO). In vitro and in vivo coagulation tests showed that CPNs doped with small amounts of N-CS (CPN31) could significantly shorten hemostasis time and promote the formation of more stable and stronger blood clots. In particular, the whole blood clotting time of CPN31 (58.8 ± 2.2 s) was significantly lower than that of chitosan/PEO (CPN0) nanofiber membrane (67 ± 3.5 s) and the medical sterile gauze (86.7 ± 0.6 s). Furthermore, due to the hemophobic nature of CPNs, blood wetting of the dressing was severely limited and blood can coagulated at the site of liver injury in rats, thus reducing blood loss and allowing rapid removal of the dressing without triggering secondary hemorrhage. The CPN31 exhibited excellent hemostasis properties, easy to remove, blood compatibility, biocompatibility and promoting fibroblast proliferation properties. This hydrophobic CPNs is a promising biological adhesive for hemorrhage control.

Fabricating the multibranch carboxyl-modified cellulose for hemorrhage control

Excessive bleeding is associated with a high mortality risk. In this study, citric acid and ascorbic acid were sequentially modified on the surface of microcrystalline cellulose (MCAA) to increase its carboxyl content, and their potential as hemostatic materials was investigated. The MCAA exhibited a carboxylic group content of 9.52 %, higher than that of citric acid grafted microcrystalline cellulose (MCA) at 4.6 %. Carboxyl functionalization of microcrystalline cellulose surfaces not only plays a fundamental role in the structure of composite materials but also aids in the absorption of plasma and stimulation of platelets. Fourier -transform infrared (FT-IR), thermogravimetric analysis (TGA) and X-ray photoelectron spectroscopy (XPS) spectra confirmed that carboxyl groups were successfully introduced onto the cellulose surface. Physical properties tests indicated that the MCAA possessed higher thermal stability (Tmax = 472.2 °C) compared to microcrystalline cellulose (MCC). Additionally, in vitro hemocompatibility, cytotoxicity and hemostatic property results demonstrated that MCAA displayed good biocompatibility (hemolysis ratio <1 %), optimal cell compatibility (cell viability exceeded 100 % after 72 h incubation), and impressive hemostatic effect (BCIMCAA = 31.3 %). Based on these findings, the hemostatic effect of covering a wound with MCAA was assessed, revealing enhanced hemostatic properties using MCAA in tail-amputation and liver-injury hemorrhage models. Furthermore, exploration into hemostatic mechanisms revealed that MCAA can significantly accelerate coagulation through rapid platelet aggregation and activation of the clotting cascade. Notably, MCAA showed remarkable biocompatibility and induced minimal skin irritation. In conclusion, the results affirmed that MCAA is a safe and potentially effective hemostatic agent for hemorrhage control.

Chemical modification of chitosan for developing of new hemostatic materials: A review

Uncontrolled bleeding that occurs during surgery, trauma, and in combat conditions is critical and require immediate action. Chitosan is a polysaccharide, obtained from natural sources with unique biological properties. It is often used as basis for local hemostatic agents (LHA). We summarized the data on hemostatic properties of chitosan, commercially available chitosan-based products with focus in the field of chemical modification of chitosan. Various approaches are used to enhance hemostatic activity of chitosan-based materials. The approach with chemical modification of chitosan allows changing the properties of the polymer in order to obtain an active macromolecule that contributes to hemostasis. Ongoing research on the mechanism of interaction with blood components in the case of different chitosan derivatives will make it possible to identify promising directions for chemical modification to obtain an effective LHA.

Multifunctional wet-adhesive chitosan/acrylic conduit for sutureless repair of peripheral nerve injuries

The incidence of peripheral nerve injury (PNI) is high worldwide, and a poor prognosis is common. Surgical closure and repair of the affected area are crucial to ensure the effective treatment of peripheral nerve injuries. Despite being the standard treatment approach, reliance on sutures to seal the severed nerve ends introduces several limitations and restrictions. This technique is intricate and time-consuming, and the application of threading and punctate sutures may lead to tissue damage and heightened tension concentrations, thus increasing the risk of fixation failure and local inflammation. This study aimed to develop easily implantable chitosan-based peripheral nerve repair conduits that combine acrylic acid and cleavable N-hydroxysuccinimide to reduce nerve damage during repair. In ex vivo tissue adhesion tests, the conduit achieved maximal interfacial toughness of 705 J m-2 ± 30 J m-2, allowing continuous bridging of the severed nerve ends. Adhesive repair significantly reduces local inflammation caused by conventional sutures, and the positive charge of chitosan disrupts the bacterial cell wall and reduces implant-related infections. This promises to open new avenues for sutureless nerve repair and reliable medical implants.

Antibacterial chitosan-based composite sponge with synergistic hemostatic effect for massive haemorrhage

Uncontrollable acute bleeding and wound infection pose significant challenges in emergency treatment and surgical operations. Therefore, the research and development of highly efficient antibacterial hemostatic agents are of great importance in reducing the mortality rate among patients with massive hemorrhage. In this study, we utilized hydrophobically modified chitosan (HM-CS) and gallic acid chitosan (GA-CS) to create a composite sponge (HM/GA-CS) that exhibits complementary advantages. The composite sponge combines the alkyl chain and polyphenol structure, allowing it to adsorb blood cells and plasma proteins simultaneously. This synergistic effect was confirmed through various tests, including blood cell adhesion, plasma protein barrier behavior, and in vitro hemostatic testing. Furthermore, experiments conducted on a rat liver injury model demonstrated that the composite sponge achieved rapid coagulation within 52 s, resulting in significantly lower bleeding volume compared with traditional gauze. In addition, the incorporation of GA-CS into HM-CS enhanced the antibacterial properties of the composite sponge. The antibacterial rate of the composite sponge against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) reached 100 % and 98.2 %, respectively. To evaluate its biocompatibility, the composite sponge underwent blood compatibility and cell activity tests, confirming its suitability. The HM/GA-CS sponge holds promising applications in managing cases of massive hemorrhage.

Alkylated chitosan-attapulgite composite sponge for rapid hemostasis

This study reported the development of a composite sponge (ACATS) based on alkylated chitosan (AC) and attapulgite (AT) for rapid hemostasis. The well-designed ACATS, with an optimal AC N-alkylation of 5.9 % and an optimal AC/AT mass ratio of 3:1, exhibited a hierarchical porous structure with a favorable biocompatibility. The ACATS can effectively and rapidly stop the uncontrolled bleeding in 235 ± 64 s with a total blood loss of 8.4 ± 4.0 g in comparison with those of Celox as a positive control (602 ± 101 s and 22.3 ± 2.4 g, respectively) using rabbit carotid artery injury model in vivo. ACATS could rapidly interact with blood and its components, including platelets (PLs), red blood cells (RBCs), and coagulation factors, resulting in these blood components rapidly accumulation and the following thrombus formation and coagulation factors activation.

Development of high-capacity surface-engineered MXene composite for heavy metal Cr (VI) removal from industrial wastewater

The substantial quantity of Cr(VI) contaminants in the aqueous atmosphere is a major environmental fear that cannot be overlooked. For the first time, MXene and chitosan-coated polyurethane foam have been employed for wastewater treatment, including heavy metal ions (Cr (VI)) through a fixed-bed column study. It is also the most inexpensive, lightweight, and globally friendly material tested. The Mxene and chitosan-coated polyurethane foam hybrid materials were thoroughly investigated using FTIR (Fourier transform infrared), SEM (scanning electron microscope), XPS (X-ray photoelectron spectroscopy) and XRD (X-ray diffraction). The presence of the rough surface and the pore creation in the Mxene- MX₃@CS₃@PUF should rise its surface area, which is useful to interact the surface-active assembly of MX₃@CS₃@PUF and the Cr(VI) contaminations in the aqueous solution. With the help of the ion exchange mechanism and electrostatic contact, negatively charged MXene hexavalent ions were being adsorbed on the surface. MXene and chitosan have been coated on PUF foam in the form of three different layers, which shows the highest adsorption capacity, where up to ∼70% Cr (VI) was removed in the first 10 min and more than 60% elimination after 3 h when the metal ion concentration was 20 ppm. The electrostatic interaction between the negative charge MXene and the positive charge chitosan on the surface of PUF, which was absent in MX@PUF, is accountable for the high removal efficiency. This was done through a sequence of fixed-bed column studies, which took place in the continuous flowing of wastewater.

Multifunctional Oxidized Dextran Cross-Linked Alkylated Chitosan/Drug-Loaded and Silver-Doped Mesoporous Bioactive Glass Cryogel for Hemostasis of Noncompressible Wounds

Noncompressible wounds resulting from accidents and gunshots are typically associated with excessive bleeding, slow wound healing, and bacterial infection. Shape-memory cryogel presents great potential in controlling the hemorrhaging of noncompressible wounds. In this research, a shape-memory cryogel was prepared using a Schiff base reaction between alkylated chitosan (AC) and oxidized dextran (ODex) and then incorporated with a drug-laden and silver-doped mesoporous bioactive glass (MBG). Hydrophobic alkyl chains enhanced the hemostatic and antimicrobial efficiency of the chitosan, forming blood clots in the anticoagulated condition, and expanding the application scenarios of chitosan-based hemostats. The silver-doped MBG activated the endogenous coagulation pathway by releasing Ca²⁺ and prevented infection through the release of Ag⁺. In addition, the proangiogenic desferrioxamine (DFO) in the mesopores of the MBG was released gradually to promote wound healing. We demonstrated that AC/ODex/Ag-MBG DFO(AOM) cryogels exhibited excellent blood absorption capability, facilitating rapid shape recovery. It provided a higher hemostatic capacity in normal and heparin-treated rat-liver perforation-wound models than gelatin sponges and gauze. The AOM gels simultaneously promoted infiltration, angiogenesis, and tissue integration of liver parenchymal cells. Furthermore, the composite cryogel exhibited antibacterial activity against Staphylococcus aureus and Escherichia coli. Thus, AOM gels show great promise for clinical translation in treating lethal, noncompressible bleeding and the promotion of wound healing.

Silk composite interfacial layer eliminates rebleeding with chitosan-based hemostats

Chitosan foams are among the approved hemostats for pre-hospital hemorrhagic control but suffer from drawbacks related to mucoadhesiveness and rebleeding. Herein, we have developed a designer bilayered hemostatic foam consisting of a bioactive layer composed of silica particles (≈300 nm) and silk fibroin to serve as the tissue interfacing component on a chitosan foam. The foam composition was optimized based on the in vitro clotting behavior and cytocompatibility of individual components. In vivo analysis in a rat model demonstrated that the developed hemostat could achieve rapid clotting (31 ± 4 s), similar to a chitosan-based hemostat, but the former had significantly lower blood loss. Notably, removal of the bilayered hemostat prevented rebleeding, unlike the chitosan foam, which was associated with markedly higher incidences of rebleeding (50 %) and left behind material residue. Thus, the designer bilayered foam presented here is a potent inducer of blood clotting whilst affording easy removal with minimal rebleeding.

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.

Preparation and application of chitosan-based medical electrospun nanofibers

Chitosan is a kind of polysaccharide cationic polymer, which has excellent biocompatibility, biodegradability and biological activity. In recent years, chitosan has been widely used as medical materials because of its non-toxicity, non-immunogenicity and rich sources. This paper reviews chitosan chemistry, the basic principles and influence of electrospinning technology, the blending of chitosan with polyethylene oxide, polyvinyl alcohol, polycaprolactone, polylactic acid, protein, polysaccharide and other polymer materials, the blending of chitosan with oxides, metals, carbon-based and other inorganic substances for electrospinning, the application of chitosan electrospinning nanofibers in medical field and its mechanism in clinical application. In order to provide reference for the in-depth study of electrospinning technology in the field of medical and health.

Microwave assisted preparation of a hemostatic gauze with mesoporous silica through in-situ synthesis

The medical disinfection cotton gauze is the most frequently used medical consumables for wound care. Here this ordinary commercial gauze was upgraded to a hemostatic gauze, which was loaded with mesoporous silica through in-situ synthesis and further microwave treatment. The original cotton gauze was pretreated with NaOH solutions for surface activation, soaked in double-silica source precursor solution for moderate in-situ synthesis, treated with microwave for quick template removement and dehydration. The final obtained hemostatic gauze (MS-G₁) showed superior physical, biocompatible and hemostatic advantages. The newborn mesoporous silica was firmly anchored onto the cotton fiber surface with <20% leaching after 10 min of sonication. The microwave treatment not only shortened the time for template removal but also promotes the formation of mesoporous structure. The clotting blood time (CBT) of MS-G₁ were only (62.00 ± 5.56 s), which was 23.14% shorter than that of original medical gauze, and even 3.6% shorter than Combat Gauze (CG). MS-G₁ also showed excellent biocompatibility in cytotoxicity tests of L-929 cells, with a 116% proliferation rate at the concentration of 5 mg/mL. Furthermore, the hemostatic performance was explored on a rabbit wound model of hemorrhagic liver injury, and MS-G₁ showed both shorter hemostasis time (113.75 s) and less blood loss (1.69 g) than that of CG (180.00 s, 5.13 g). The hemostatic gauze anchored with mesoporous silica was expected to be an excellent prehospital hemostatic dressing for field first aid.

Progress in Research of Chitosan Chemical Modification Technologies and Their Applications

Chitosan, which is derived from chitin, is the only known natural alkaline cationic polymer. Chitosan is a biological material that can significantly improve the living standard of the country. It has excellent properties such as good biodegradability, biocompatibility, and cell affinity, and has excellent biological activities such as antibacterial, antioxidant, and hemostasis. In recent years, the demand has increased significantly in many fields and has huge application potential. Due to the poor water solubility of chitosan, its wide application is limited. However, chemical modification of the chitosan matrix structure can improve its solubility and biological activity, thereby expanding its application range. The review covers the period from 1996 to 2022 and was elaborated by searching Google Scholar, PubMed, Elsevier, ACS publications, MDPI, Web of Science, Springer, and other databases. The various chemical modification methods of chitosan and its main activities and application research progress were reviewed. In general, the modification of chitosan and the application of its derivatives have had great progress, such as various reactions, optimization of conditions, new synthetic routes, and synthesis of various novel multifunctional chitosan derivatives. The chemical properties of modified chitosan are usually better than those of unmodified chitosan, so chitosan derivatives have been widely used and have more promising prospects. This paper aims to explore the latest progress in chitosan chemical modification technologies and analyze the application of chitosan and its derivatives in various fields, including pharmaceuticals and textiles, thus providing a basis for further development and utilization of chitosan.

Antibacterial biomaterials for skin wound dressing

Bacterial infection and the ever-increasing bacterial resistance have imposed severe threat to human health. And bacterial contamination could significantly menace the wound healing process. Considering the sophisticated wound healing process, novel strategies for skin tissue engineering are focused on the integration of bioactive ingredients, antibacterial agents included, into biomaterials with different morphologies to improve cell behaviors and promote wound healing. However, a comprehensive review on anti-bacterial wound dressing to enhance wound healing has not been reported. In this review, various antibacterial biomaterials as wound dressings will be discussed. Different kinds of antibacterial agents, including antibiotics, nanoparticles (metal and metallic oxides, light-induced antibacterial agents), cationic organic agents, and others, and their recent advances are summarized. Biomaterial selection and fabrication of biomaterials with different structures and forms, including films, hydrogel, electrospun nanofibers, sponge, foam and three-dimension (3D) printed scaffold for skin regeneration, are elaborated discussed. Current challenges and the future perspectives are presented in this multidisciplinary field. We envision that this review will provide a general insight to the elegant design and further refinement of wound dressing.

Hydrophobic and self-recoverable cellulose nanofibrils/N-alkylated chitosan/poly(vinyl alcohol) sponge for selective and versatile oil/water separation

A highly hydrophobic and self-recoverable sponge was prepared with cellulose nanofibrils (CNFs), N-alkylated chitosan (NCS), and poly (vinyl alcohol) (PVA), which was then endowed with hydrophobic properties via simple thermal chemical vapor deposition (CVD). The three-dimensional (3D) interconnected microstructure of the prepared CNF/NCS/PVA sponge was found to have 96% porosity, ultra-low density (16.61-50.91 mg/cm³) and high hydrophobicity (water contact angle of 147°), which can absorb various organic solvents with an absorption capacity of 19.05-51.08 times of its original weight. Besides, the sponge could bear 80% strain and be cyclically compressed 50 times under the strain of 50%. The sponge can effectively separate oil/water mixtures and water-in-oil emulsions with high separation efficiency and fluxes. Moreover, the sponge could keep its good stability in various acidic, saline and mechanical abrasion conditions. The green preparation and good separation efficiency suggest a potential application of recyclable and versatile CNF/NCS/PVA sponges in oil/water separation.

Typical structure, biocompatibility, and cell proliferation bioactivity of collagen from Tilapia and Pacific cod

Aquatic collagens, as the alternative sources of mammalian collagen, have received increasing attention due to its low-cost, low-antigenicity, biocompatibility, and biodegradability. Pepsin-soluble collagens were extracted from the skins of Oreochromis mossambicus (Om-PSC) and Gadus macrocephalus (Gm-PSC), and their structural properties and bioactivities were probed to reveal their potential applications in biomedical material for tissue engineering. The results of Fourier transforms-infrared spectroscopy (FT-IR), circular dichroism (CD), X-ray diffraction (XRD), ultraviolet (UV) and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) demonstrated that Om-PSC and Gm-PSC had similar and intact triple helical structures. The amino acid composition and peptide profiles revealed Om-PSC and Gm-PSC were identified as type I collagen with the typical repetitive sequence of (Gly-X-Y) _n. However, the denaturation temperature (T_d) was determined to be 29.7 ℃ of Om-PSC, much higher than that of Gm-PSC (17.3 ℃). Toxicological experiments demonstrated Om-PSC and Gm-PSC both had good biocompatibility and cytocompatibility, which met the requirements of medical materials. Fluorescence imaging and cell cycle distribution revealed Om-PSC and Gm-PSC could promote the proliferation of fibroblast and osteoblast cells. Therefore, Om-PSC and Gm-PSC showed the advantages in medical materials.

Bioinspired Design of Sericin/Chitosan/Ag@MOF/GO Hydrogels for Efficiently Combating Resistant Bacteria, Rapid Hemostasis, and Wound Healing

Due to the spread of drug-resistant bacteria in hospitals, the development of antibacterial dressings has become a strategy to control wound infections caused by bacteria. Here, we reported a green strategy for in situ biomimetic syntheses of silver nanoparticles@organic frameworks/graphene oxide (Ag@MOF-GO) in sericin/chitosan/polyvinyl alcohol hydrogel. Ag@MOF-GO was synthesized in situ from the redox properties of tyrosine residues in silk sericin without additional chemicals, similar to a biomineralization process. The sericin/chitosan/Ag@MOF-GO dressing possessed a high porosity, good water retention, and a swelling ratio. The hemolysis rate of the composite was 3.9% and the cell viability rate was 131.2%, which indicated the hydrogel possessed good biocompatibility. The composite also showed excellent lasting antibacterial properties against drug-sensitive and drug-resistant pathogenic bacteria. The composite possessed excellent hemostatic activity. The coagulation effect of the composite may be related to its effect on the red blood cells and platelets, but it has nothing to do with the activation of coagulation factors. An in vitro cell migration assay confirmed and an in vivo evaluation of mice indicated that the composite could accelerate wound healing and re-epithelialization. In summary, the composite material is an ideal dressing for accelerating hemostasis, preventing bacterial infection, and promoting wound healing.

A composite sponge based on alkylated chitosan and diatom-biosilica for rapid hemostasis

Rapid control of bleeding is of great significance in military trauma and traffic accidents. In this study, alkylated chitosan (AC) and diatom biosilica (DB) were combined to develop a safe and effective hemostatic composite sponge (AC-DB sponge) for hemorrhage control. Due to the procoagulant chemical structure of AC-DB sponge, it exhibited rapid hemostatic ability in vitro (clotting time was shortened by 78% than that of control group), with favorable biocompatibility (hemolysis ratio < 5%, no cytotoxicity). The strong interface effect between AC-DB sponge and blood induced the erythrocyte and platelets activation, deformation and aggregation, intrinsic coagulation pathway activation, resulting in significant coagulation acceleration. AC-DB sponge had excellent performance in in vivo assessments with shortest clotting time (106.2 s) and minimal blood loss (328.5 mg). All above results proved that AC-DB sponge had great potential to be a safe and rapid hemostatic material.

Cellulose fibers-reinforced self-expanding porous composite with multiple hemostatic efficacy and shape adaptability for uncontrollable massive hemorrhage treatment

Uncontrollable hemorrhage leads to high mortality and thus effective bleeding control becomes increasingly important in the military field and civilian trauma arena. However, current hemostats not only present limitation when treating major bleeding, but also have various side effects. Here we report a self-expanding porous composites (CMCP) based on novel carboxymethyl cellulose (CMC) fibers and acetalized polyvinyl alcohol (PVA) for lethal hemorrhage control. The CMC fibers with uniform fibrous structure, high liquid absorption and procoagulant ability, are evenly interspersed inside the composite matrix. The obtained composites possess unique fiber-porous network, excellent absorption capacity, fast liquid-triggered self-expanding ability and robust fatigue resistance, and their physicochemical performance can be fine-tuned through varying the CMC content. In vitro tests show that the porous composite exhibits strong blood clotting ability, high adhesion to blood cells and protein, and the ability to activate platelet and the coagulation system. In vivo hemostatic evaluation further confirms that the CMCP presents high hemostatic efficacy and multiple hemostatic effects in swine femoral artery major hemorrhage model. Additionally, the CMCP will not fall off from the injury site, and is also easy to surgically remove from the wound cavity after the hemostasis. Importantly, results of CT tomography and 3D reconstruction indicate that CMCP can achieve shape adaptation to the surrounding tissues and the wound cavities with different depths and shapes, to accelerate hemostasis while protecting wound tissue and preventing infection.

Chestnut-like macro-acanthosphere triggered hemostasis: a featured mechanism based on puncturing red blood cells

Acute hemorrhage that occurs after trauma is a life-threatening condition. Hence, to halt massive bleeding, there is a critical need to develop a suitable therapy. In this study, we developed self-propelling chestnut-like particles (Pro-MAS) comprising a macro-acanthosphere (MAS) coated with calcium carbonate and protonated tranexamic acid to puncture red blood cells (RBCs) and thus activate hemostasis. In vitro assessments revealed that Pro-MAS was biocompatible, biodegradable, and nontoxic; furthermore, it was capable of puncturing RBCs to release procoagulants and activate platelet aggregation for hemostasis. Animal tests showed that self-propelling Pro-MAS effectively traveled through blood flow to the deep ends of wounds; hemorrhage was controlled within 90 s and 4 min in the injured liver and bleeding femoral artery, respectively. Compared with a commercial hemostat, superior hemostasis was achieved with Pro-MAS, which could be ascribed to its functional and structural features. Overall, traveling Pro-MAS possessed sufficient impact force to puncture RBCs and sufficient momentum to reach the targeted bleeding sites. The present study demonstrated the ability of a novel platform, self-propelling MAS particles, to trigger hemostasis by puncturing RBCs. To the best of our knowledge, this is the first trial in which the release of endogenous procoagulants is promoted without the addition of exogenous procoagulants for severe hemorrhage control.

Biomimetic hydroxyapate/polydopamine composites with good biocompatibility and efficiency for uncontrolled bleeding

Uncontrolled bleeding is thought to be the most deadly cause of pre-hospital, traffic, and military accidents death. However, the popular commercial hemostats can only realize the hemostasis of mild bleeding. Therefore, we developed polydopamine (PDA) composite materials (PMs), which applied hydroxyapatite as the parent body. The PMs were produced via lyophilization and functionalized with amino, phenol hydroxyls groups, which endowed hydrophobicity to materials. This ensured a high aggregation ability of blood cells to the PMs and they were tested to be as high as 300% compared with the negative control group. The clotting time was shortened to 79.7% compared with the usually used commercial hemostat (Celox) in the test of in vitro hemostasis. Through the results of PT and APTT tests, blood coagulation index test, and the analysis of intracellular Ca²⁺ activation, we further understood the mechanism of the hemostasis of the materials, which explained the low blood loss and quick coagulation time of the PM hemostats in detail. Besides, the low hemolysis and cytotoxicity of the PMs suggested the good biocompatibility of the hemostats, which was further proved by the regular morphology maintained by erythrocytes in the hemolysis tests. The study of nanoscale composites led the research for the methods of hemostasis.

Chitosan/alginate/hyaluronic acid polyelectrolyte composite sponges crosslinked with genipin for wound dressing application

Wound dressing composed of polyelectrolyte complexes (PECs), based on chitosan/alginate/hyaluronic acid (CS/ALG/HYA) crosslinked by genipin, was prepared by freeze-dried molding. Genipin as excellent natural biological crosslinker was chose for high biocompatibility and improving mechanical properties of materials. The CS/ALG/HYA sponges (CAHSs) were characterized by FTIR, XRD, DSC and SEM. Porosity, swelling behavior and mechanical properties and in vitro degradation of CAHSs were investigated. The cytotoxicity assay was carried out on HUVEC cells in vitro and the result proves the good biocompatibility of CAHSs. Hemolysis tests indicated that the prepared CAHSs were non-hemolytic material (hemolysis ratio < 5%, no cytotoxicity). PT and aPPT coagulation tests demonstrated that CAHS2 and CAHS3 could both activate the extrinsic and intrinsic coagulation pathway and thus accelerated blood coagulation. Further, in a rat full-thickness wounds model, the CAHS2 sponge significantly facilitates wound closure compared to other groups. CAHSs exhibited adjustable physical, mechanical and biological properties. Thus, the chitosan-based polyelectrolyte composite sponges exhibit great potential as promising wound dressings.

Green Synthesis of A Novel MXene–CS Composite Applied in Treatment of Cr(VI) Contaminated Aqueous Solution

The considerable amount of Cr(VI) pollutants in the aqueous environment is a significant environmental concern that cannot be ignored. A series of novel Mxene–CS inorganic–organic composite nanomaterials synthesized by using the solution reaction method was applied to treat the Cr(VI) contaminated water. The Mxene–CS composites were characterized through SEM (scanning electron microscope), XRD (X–ray diffraction), XPS (X–ray photoelectron spectroscopy), and FTIR (Fourier transform infrared). The XRD patterns (observed at 2θ of 18.1°, 35.8°, 41.5°, and 60.1°) and the FT–IR spectra (-NH2 group for 1635 and 1517 cm−1, and -OH group for 3482 cm−1) illustrated that CS was successfully loaded on the Mxene. The effects of solution pH, the dosage of Mxene–CS, and duration time on the adsorption of Cr(VI) by synthesized Mxene–CS were investigated. The removal efficiency of Cr(VI) was increased from 12.9% to 40.5% with Mxene–CS dosage ranging from 0.02 to 0.12 g/L. The adsorption process could be well fitted by the pseudo–second–order kinetics model, indicating chemisorption occurred. The Langmuir isotherm model could be better to describe the process with a maximum adsorption capacity of 43.1 mg/g. The prepared novel Mxene–CS composite was considered as an alternative for adsorption of heavy metals from wastewater.

Ag@MOF-loaded chitosan nanoparticle and polyvinyl alcohol/sodium alginate/chitosan bilayer dressing for wound healing applications

In this paper, Ag-Metal-organic framework loaded chitosan nanoparticles (0.1%Ag@MOF/1.5%CSNPs) and polyvinyl alcohol/sodium alginate/chitosan (PACS) were used as the upper and lower layers to successfully prepare a bilayer composite dressing for wound healing. The performance of bilayer dressing was evaluated. The lower layer (PACS) had uniform pore size distribution, good water retention, swelling, water vapor permeability, and biocompatibility while PACS had almost no antibacterial activity. The upper layer (Ag@MOF/CSNPs) possessed excellent antibacterial activity and poor biocompatibility. As the upper layer, it can avoid direct contact with the skin and inhibit microbial invasion. In addition, the bilayer can adhere to a large number of red blood cells and platelets, promoting blood coagulation and cell proliferation. Ag@MOF, CSNPs, Ag@MOF/CSNPs and bilayer showed antibacterial activity in ascending order, due to the synergistic antibacterial action of the upper and lower layer. In vivo evaluation showed that both bilayer and PACS could significantly accelerate the wound healing, and the bilayer dressing showed more complete re-epithelialization with less inflammatory cells. In summary, this new bilayer composite is an ideal dressing for accelerating wound healing.

How Do Amphiphilic Biopolymers Gel Blood? An Investigation Using Optical Microscopy

Amphiphilic biopolymers such as hydrophobically modified chitosan (hmC) have been shown to convert liquid blood into elastic gels. This interesting property could make hmC useful as a hemostatic agent in treating severe bleeding. The mechanism for blood gelling by hmC is believed to involve polymer-cell self-assembly, i.e., insertion of hydrophobic side chains from the polymer into the lipid bilayers of blood cells, thereby creating a network of cells bridged by hmC. Here, we probe the above mechanism by studying dilute mixtures of blood cells and hmC in situ using optical microscopy. Our results show that the presence of hydrophobic side chains on hmC induces significant clustering of blood cells. The extent of clustering is quantified from the images in terms of the area occupied by the 10 largest clusters. Clustering increases as the fraction of hydrophobic side chains increases; conversely, clustering is negligible in the case of the parent chitosan that lacks hydrophobes. Moreover, the longer the hydrophobic side chains, the greater the clustering (i.e., C₁₂ > C₁₀ > C₈ > C₆). Clustering is negligible at low hmC concentrations but becomes substantial above a certain threshold. Finally, clustering due to hmC can be reversed by adding the supramolecule α-cyclodextrin, which is known to capture hydrophobes in its binding pocket. Overall, the results from this work are broadly consistent with the earlier mechanism, albeit with a few modifications.