Oxidized dextran crosslinked polysaccharide/protein/polydopamine composite cryogels with multiple hemostatic efficacies for noncompressible hemorrhage and wound healing

Polysaccharide hydrogels for skin wound healing

Advances in the development and utilization of polysaccharide materials are highly promising, offering prominent applications in the field of tissue engineering for addressing diverse clinical needs, including wound healing, bone regeneration, cartilage repair, and treatment of conditions such as arthritis. Novel polysaccharide materials are popular owing to their inherent stability, biocompatibility, and repeatability. This review presents an overview of the biomedical applications of natural polysaccharide hydrogels and their derivatives. Herein, we discuss the latest advancements in the fabrication, physicochemical properties, and biomedical applications of polysaccharide-based hydrogels, including chitosan, hyaluronic acid, alginate, and cellulose. Various processing techniques applicable to polysaccharide materials are explored, such as the transformation of polysaccharide hydrogels into electrospun nanofibers, microneedles, microspheres, and nanogels. Furthermore, the use of polysaccharide hydrogels in the context of wound-healing applications, including hemostatic effects, antimicrobial activities, anti-inflammatory properties, and promotion of angiogenesis, is presented. Finally, we address the challenges encountered in the development of polysaccharide hydrogels and outline the potential prospects in this evolving field.

Recent research advances in polysaccharide-based hemostatic materials: A review

Massive bleeding resulting from civil and martial accidents can often lead to shock or even death, highlighting the critical need for the development of rapid and efficient hemostatic materials. While various types of hemostatic materials are currently utilized in clinical practice, they often come with limitations such as poor biocompatibility, toxicity, and biodegradability. Polysaccharides, such as alginate (AG), chitosan (CS), cellulose, starch, hyaluronic acid (HA), and dextran, have exhibit excellent biocompatibility and in vivo biodegradability. Their degradation products are non-toxic to surrounding tissues and can be absorbed by the body. As a result, polysaccharides have been extensively utilized in the development of hemostatic materials and have gained significant attention in the field of in vivo hemostasis. This review offers an overview of the different forms, hemostatic mechanisms, and specific applications of polysaccharides. Additionally, it discusses the future opportunities and challenges associated with polysaccharide-based hemostats.

Utilizing epoxy Bletilla striata polysaccharide collagen sponge for hemostatic care and wound healing

Hemostatic materials that are lightweight and possess good blood absorption performance have been widely considered for use in modern wound care. Natural hemostatic ingredients derived from traditional Chinese medicine have also received extensive attention. Bletilla polysaccharides are valued by researchers for their excellent hemostatic performance and good reactivity. Collagen is favored by researchers due to its high biocompatibility and low immunogenicity. In this study, Bletilla striata polysaccharide, the main hemostatic component of Bletilla striata, was activated by epoxy groups, and epoxidized Bletilla striata polysaccharide (EBSP) was prepared. Then, EBSP was crosslinked with collagen under alkaline conditions, and a new hemostatic material that was an epoxidized Bletilla polysaccharide crosslinked collagen hemostatic sponge was prepared. We demonstrated that endowing collagen with better hemostatic performance, cytocompatibility, and blood compatibility does not destroy its original three-stranded helical structure. Compared with the medical gauze, hemostasis time was shorter (26.75 ± 2.38 s), and blood loss was lower (0.088 ± 0.051 g) in the rat liver injury hemostasis model. In the rat model of severed tail hemostasis, hemostasis time was also shorter (47.33 ± 2.05 s), and the amount of blood loss was lower (0.330 ± 0.122 g). The sponge possessed good hemostatic and healing performance.

An Erythrocyte-Templated Iron Single-Atom Nanozyme for Wound Healing

Iron single-atom nanozymes represent a promising artificial enzyme with superior activity owing to uniform active sites that can precisely mimic active center of nature enzymes. However, current synthetic strategies are hard to guarantee each active site at single-atom state. In this work, an erythrocyte-templated strategy by utilizing intrinsic hemin active center of hemoglobin as sing-atom source for nanozyme formation is developed. By combining cell fixation, porous salinization, and high-temperature carbonization, erythrocytes are successfully served as uniform templates to synthesize nanozymes with fully single-atom FeN4 active sites which derived from hemin of hemoglobin, resulting in an enhanced peroxidase (POD)-like activity. Interestingly, the catalytic activity of erythrocyte-templated nanozyme (ETN) shows dependence on animal species, among which murine ETN performed superior catalytic efficiency. In addition, the as-prepared ETNs display a honeycomb-like network structure, serving as a sponge to accelerate hemostasis based on the interactions with prothrombin and fibrinogen. These features enable ETN to effectively kill methicillin-resistant Staphylococcus aureus (MRSA) by combining POD-like catalysis with near-infrared (NIR) induced photothermal effect, and subsequently suitable to promote wound healing. This study provides a proof-of-concept for facile fabrication of multifunctional nanozymes with uniform single-atom active sites by utilizing intrinsic iron structure characteristics of biogenic source like erythrocytes.

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.

Tannic acid-functionalized 3D porous nanofiber sponge for antibiotic-free wound healing with enhanced hemostasis, antibacterial, and antioxidant properties

Developing an antibiotic-free wound dressing with effective hemostasis and antibacterial and antioxidant capacity is highly desirable. In this work, a three-dimensional (3D) chitosan/polyvinyl alcohol-tannic acid porous nanofiber sponge (3D-TA) was prepared via electrospinning. Compared with two-dimensional (2D) fiber membrane, the unique fluffy 3D-TA nanofiber sponge had high porosity, water absorption and retention ability, hemostatic capacity. Furthermore, the 3D sponge functionalized by tannic acid (TA) endow the sponge with high antibacterial and antioxidant capacity without loading antibiotics. In addition, 3D-TA composite sponges have shown highly biocompatibility against L929 cells. The in vivo experiment shows the 3D-TA is enable to accelerate wound healing. This newly 3D-TA sponges hold great potential as wound dressings for future clinical application.

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.

Microbial Exopolysaccharide Composites in Biomedicine and Healthcare: Trends and Advances

Microbial exopolysaccharides (EPSs), e.g., xanthan, dextran, gellan, curdlan, etc., have significant applications in several industries (pharma, food, textiles, petroleum, etc.) due to their biocompatibility, nontoxicity, and functional characteristics. However, biodegradability, poor cell adhesion, mineralization, and lower enzyme activity are some other factors that might hinder commercial applications in healthcare practices. Some EPSs lack biological activities that make them prone to degradation in ex vivo, as well as in vivo environments. The blending of EPSs with other natural and synthetic polymers can improve the structural, functional, and physiological characteristics, and make the composites suitable for a diverse range of applications. In comparison to EPS, composites have more mechanical strength, porosity, and stress-bearing capacity, along with a higher cell adhesion rate, and mineralization that is required for tissue engineering. Composites have a better possibility for biomedical and healthcare applications and are used for 2D and 3D scaffold fabrication, drug carrying and delivery, wound healing, tissue regeneration, and engineering. However, the commercialization of these products still needs in-depth research, considering commercial aspects such as stability within ex vivo and in vivo environments, the presence of biological fluids and enzymes, degradation profile, and interaction within living systems. The opportunities and potential applications are diverse, but more elaborative research is needed to address the challenges. In the current article, efforts have been made to summarize the recent advancements in applications of exopolysaccharide composites with natural and synthetic components, with special consideration of pharma and healthcare applications.

Shape memory and antibacterial chitosan-based cryogel with hemostasis and skin wound repair

Massive damage to the skin can lead to heavy bleeding and potential wound infection. Therefore, the preparation of low-cost wound dressings that meet these requirements by simple methods has a good application prospect. In the study, a shape memory cryogel prepared at low temperatures by mixing chitosan (CS) and citric acid (CA). Silver nanoparticles (Ag NPs) introduced into the cryogel through the reduction of Ag⁺ with tannic acid (TA) as a reducing agent. The CS/CA/Ag cryogel has good mechanical properties and interconnected macroporous structures. The results of hemostasis tests show that CS/CA/Ag cryogel can absorb a large amount of blood and promote blood cell adhesion compared with commercial gelatin sponges and gauze. Meanwhile, CS/CA/Ag cryogel has a good antibacterial ability against S. aureus and E. coli. Furthermore, CS/CA/Ag cryogel significantly promotes wound healing in the full-thickness wound model infected with S. aureus. In conclusion, the cryogel prepared by the simple method has great advantages in rapid hemostasis and promoting wound healing.

Alginate based photothermal cryogels boost ferrous-supply for enhanced antibacterial chemodynamic therapy and accelerated wound healing

Uncontrolled hemorrhage is a main cause of pre-hospital death. Given the importance of hemostatic wound dressings in pre-hospital emergency treatment, novel composite materials are required for fast hemostasis, synergistic bacterial ablation with negligible resistance and wound healing acceleration. Herein, multifunctional SCTF cryogels were fabricated by the simultaneous cross-linking of sodium alginate (SA) and tannic acid (TA) with Fe³⁺ ions. As a result, the prepared SCTF cryogels consisted of Fe³⁺/TA-based metal phenolic networks (MPNs) and Fe³⁺/SA-based 3D skeleton for collagen (CA). MPNs endowed the cryogels with photothermal effect, photothermal-enhanced Fenton activity and pH/photothermal dual-responsive release property of TA and Fe²⁺, which were beneficial for the antibacterial capacity. Due to the intrinsic high porosity, in vitro and in vivo assays demonstrated that SCTF cryogels possessed good hemostatic capacity. Moreover, the synergistic photothermal therapy (PTT), chemodynamic therapy (CDT) and pH/photothermal responsive chemo-therapy dramatically enhanced the bactericidal efficacy of SCTF cryogels both in vitro and in vivo. Eventually, their outstanding healing-accelerating effects were confirmed via animal experiments, which were attributed to the presence of CA and TA. Therefore, the developed composite materials could offer new strategy on exploiting multifunctional wound dressing for clinical applications in the future.

Mussel-inspired nanoparticle composite hydrogels for hemostasis and wound healing

Uncontrolled hemorrhage caused by trauma can easily lead to death. Efficient and safe hemostatic materials are an urgent and increasing need for hemostatic research. Following a trauma, wound healing is induced by various cellular mechanisms and proteins. Hemostatic biomaterials that can not only halt bleeding quickly but also provide an environment to promote wound healing have been the focus of research in recent years. Mussel-inspired nanoparticle composite hydrogels have been propelling the development of hemostatic materials owing to their unique advantages in adhesion, hemostasis, and bacteriostasis. This review summarizes the hemostatic and antimicrobial fundamentals of polydopamine (PDA)-based nanomaterials and emphasizes current developments in hemorrhage-related PDA nanomaterials. Moreover, it briefly discusses safety concerns and clinical application problems with PDA hemostatic nanomaterials.