A self-gelling powder based on polyacrylic acid/polyacrylamide/quaternate chitosan for rapid hemostasis

Epidermal growth factor-loaded, dehydrated physical microgel-formed adhesive hydrogel enables integrated care of wet wounds

Integrated wound care, a sequential process of promoting wound hemostasis, sealing, and healing, is of great clinical significance. However, the wet environment of wounds poses formidable challenges for integrated care. Herein, we developed an epidermal growth factor (EGF)-loaded, dehydrated physical microgel (DPM)-formed adhesive hydrogel for the integrated care of wet wounds. The DPMs were designed using the rational combination of hygroscopicity and reversible crosslinking of physical hydrogels. Unlike regular bioadhesives, which consider interfacial water as a barrier to adhesion, DPMs utilize water to form desirable adhesive structures. The hygroscopicity allowed the DPMs to absorb interfacial water and subsequently, the interfacial adhesion was realized by the interactions between tissue and DPMs. The reversible crosslinks further enabled DPMs to integrate into hydrogels (DPM-Gels), thus achieving wet adhesion. Importantly, the water-absorbing gelation mode of DPMs enabled facile loading of biologically active EGF to promote wound healing. We demonstrated that the DPM-Gels possessed wet tissue adhesive performance, with about 40 times the wet adhesive strength of fibrin glue and about 4 times the burst pressure of human blood pressure. Upon application at the injury site, the EGF-loaded DPM-Gels sequentially promoted efficient wound hemostasis, stable sealing, and quick healing, achieving integrated care of wet wounds.

Tissue-adhesive, stretchable and compressible physical double-crosslinked microgel-integrated hydrogels for dynamic wound care

Integrated wound care through sequentially promoting hemostasis, sealing, and healing holds great promise in clinical practice. However, it remains challenging for regular bioadhesives to achieve integrated care of dynamic wounds due to the difficulties in adapting to dynamic mechanical and wet wound environments. Herein, we reported a type of dehydrated, physical double crosslinked microgels (DPDMs) which were capable of in situ forming highly stretchable, compressible and tissue-adhesive hydrogels for integrated care of dynamic wounds. The DPDMs were designed by the rational integration of the reversible crosslinks and double crosslinks into micronized gels. The reversible physical crosslinks enabled the DPDMs to integrate together, and the double crosslinked characteristics further strengthen the formed macroscopical networks (DPDM-Gels). We demonstrated that the DPDM-Gels simultaneously possess outstanding tensile (∼940 kJ/m3) and compressive (∼270 kJ/m3) toughness, commercial bioadhesives-comparable tissue-adhesive strength, together with stable performance under hundreds of deformations. In vivo results further revealed that the DPDM-Gels could effectively stop bleeding in various bleeding models, even in an actual dynamic environment, and enable the integrated care of dynamic skin wounds. On the basis of the remarkable mechanical and appropriate adhesive properties, together with impressive integrated care capacities, the DPDM-Gels may provide a new approach for the smart care of dynamic wounds. STATEMENT OF SIGNIFICANCE: Integrated care of dynamic wounds holds great significance in clinical practice. However, the dynamic and wet wound environments pose great challenges for existing hydrogels to achieve it. This work developed robust adhesive hydrogels for integrated care of dynamic wounds by designing dehydrated, physical double crosslinked microgels (DPDMs). The reversible and double crosslinks enabled DPDMs to integrate into macroscopic hydrogels with high mechanical properties, appropriate adhesive strength and stable performance under hundreds of external deformations. Upon application at the injury site, DPDM-Gels efficiently stopped bleeding, even in an actual dynamic environment and showed effectiveness in integrated care of dynamic wounds. With the fascinating properties, DPDMs may become an effective tool for smart wound care.

Facile Synthesis of Multifunctional Mesoporous Starch-Based Microparticle for Effective Hemostasis and Wound Healing

Uncontrolled hemorrhage and infection are the principal causes of mortality associated with trauma in both military and civilian medical settings. Modified starch granules have emerged as a safe hemostatic agent for irregular and noncompressible wounds, but their performance is constrained by limited hemostasis efficiency and modest antibacterial activity. This study reported a directed self-assembly approach for a multifunctional mesoporous starch-based microparticle loaded with chitosan and calcium ions (Ca@MSMP) used for rapid hemostasis and wound healing. Directed self-assembly of uniform Ca@MSMP with a hierarchical hollow structure in the presence of chitosan was confirmed by scanning electron microscopy (SEM) analysis and pore structure analysis. The resulting Ca@MSMP exhibited a well-defined spherical shape and uniform size of 1 μm and demonstrated excellent antibacterial activity (>95%) without hemolytic activity. Importantly, Ca@MSMP enhanced blood coagulation and platelet aggregation via the synergistic effect of rapid calcium release and chitosan-mediated electrostatic interactions, leading to a significant decrease in blood loss and reduction in hemostasis time in rat tail amputation and liver injury models. In comparative analyses, Ca@MSMP significantly outperformed the commercial hemostatic agent Quickclean, notably enhancing the healing of full-thickness skin wounds in vivo by effectively preventing infection. These results underscore the potential of this innovative hemostatic material in diverse clinical scenarios, offering effective solutions for the management of bleeding in wounds that are irregularly shaped and noncompressible.

Alginate based hemostatic materials for bleeding management: A review

Severe bleeding has caused significant financial losses as well as a major risk to the lives and health of military and civilian populations. Under some situations, the natural coagulation mechanism of the body is unable to achieve fast hemostasis without the use of hemostatic drugs. Thus, the development of hemostatic materials and techniques is essential. Improving the quality of life and survival rate of patients and minimizing bodily damage requires fast, efficient hemostasis and prevention of bleeding. Alginate is regarded as an outstanding hemostatic polymer because of its non-immunogenicity, biodegradability, good biocompatibility, simple gelation, non-toxicity, and easy availability. This review summarizes the basics of hemostasis and emphasizes the recent developments regarding alginate-based hemostatic systems. Structural modifications and mixing with other materials have widely been used for the improvement of hemostatic characteristics of alginate and for making multifunctional medical devices that not only prevent uncontrolled bleeding but also have antibacterial characteristics, drug delivery abilities, and curing effects. This review is hoped to prepare critical insights into alginate modifications for better hemostatic properties.

Synthesis of ultrathin hybrid membranes via the co-polymerization of acrylic acid, styrene and molybdenum disulfide and their high adsorption selectivity for lead(II) in the mixture of metal ions

Lead(II) is a potential carcinogen of heavy-metal ions (HIs). With the wide application of Pb-bearing products including lead alloy products, and new-energy lead-ion batteries, lead pollution has become a tricky problem. To solve such a difficulty, novel ultrathin MoS2-vinyl hybrid membranes (MVHMs) with a "spring" effect were synthesized via co-polymerization of acrylic acid, styrene and molybdenum disulfide (MoS2) and their adsorptions for HIs were explored. The "spring" effect derived from the interaction between the tendency of the short polyacrylic acid (PAA) chain connected with MoS2 to spread outward and the coulomb force between layers from MoS2 (s-MoS2), which enlarge the spacing of MoS2 layers without changing the number of layers after membrane formation, which changes the swelling membrane to a dense membrane and reduces the original thickness from 0.5 cm to 0.011 mm in the thickness direction. The adsorption experiment revealed that these MVHMs had super adsorption performance and high selectivity for Pb2+ by comparison with other five metal ions: Cu2+, Cd2+, Ni2+, Cr3+ and Zn2+. Especially, the adsorption quantity of MVHMs for Pb2+ could approach 2468 mg/g and the maximum adsorption ratio of qe[Pb2+]/qe[Cu2+] can reach 10.909. These values were much larger than the data obtained with the adsorbents reported in the last decade. A variety of models are applied to evaluate the effect of ionic groups. It was confirmed that -COOH plays a key role in adsorption of HIs and s-MoS2 also has a certain contribution. Conversely, ion exchange plays only a minor role during the period of adsorption process. Effective diffusion coefficient (Deff) of Pb(II) had the largest values among these metal ions. Hence, these hybrid membranes are promising adsorbents for the removal of Pb2+ from water containing various ions.

Antibacterial conductive polyacrylamide/quaternary ammonium chitosan hydrogel for electromagnetic interference shielding and strain sensing

The utilization of biomass-based conductive polymer hydrogels in wearable electronics holds great promise for advancing performance and sustainability. An interpenetrating network of polyacrylamide/2-hydroxypropyltrimethyl ammonium chloride chitosan (PAM/HACC) was firstly obtained through thermal-initiation polymerization of AM monomers in the presence of HACC. The positively charged groups on HACC provide strong electrostatic interactions and hydrogen bonding with the PAM polymer chains, leading to improved mechanical strength and stability of the hydrogel network. Subsequently, the PAM/HACC networks served as the skeletons for the in-situ polymerization of polypyrrole (PPy), and then the resulting conductive hydrogel demonstrated stable electromagnetic shielding performance (40 dB), high sensitivity for strain sensing (gauge factor = 2.56). Moreover, the incorporation of quaternary ammonium chitosan into PAM hydrogels enhances their antimicrobial activity, making them more suitable for applications in bacterial contamination or low-temperature environments. This conductive hydrogel, with its versatility and excellent mechanical properties, shows great potential in applications such as electronic skin and flexible/wearable electronics.

Recent advances of chitosan as a hemostatic material: Hemostatic mechanism, material design and prospective application

Uncontrolled hemorrhage arising from surgery or trauma may cause morbidity and even mortality. Therefore, facilitating control of severe bleeding is imperative for health care worldwide. Among diverse hemostatic materials, chitosan (CS) is becoming the most promising material owing to its non-toxic feature, as well as inherently hemostatic performance. However, further enhancing hemostatic property of CS-based materials without compromising more beneficial functions remains a challenge. In this review, representative hemostatic mechanisms of CS-based materials are firstly discussed in detail, mostly including red blood cells (RBCs) aggregation, platelet adherence and aggregation, as well as interaction with plasma proteins. Also, various forms (involving powder/particle, sponge, hydrogel, nanofiber, and other forms) of CS-based hemostatic materials are systematically summarized, mainly focusing on their design and preparation, characteristics, and comparative analysis of various forms. In addition, varied hemostatic applications are described in detail, such as skin wound hemostasis, liver hemostasis, artery hemostasis, and heart hemostasis. Finally, current challenges and future directions of functional design of CS-based hemostatic materials in diverse hemostatic applications are proposed to inspire more intensive researches.

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.

Robust and Wet Adhesive Self-Gelling Powders for Rapid Hemostasis and Efficient Wound Healing

Healing traumatic wounds is arduous, leaving miscellaneous demands for ideal wound dressings, such as rapid hemostasis, superior wet tissue adhesion, strong mechanical properties, and excellent antibacterial activity. Herein, we report a self-gelling, wet adhesive, stretchable (polyethylenimine/poly(dimethylammonium chloride)/(poly(acrylic acid)/poly(sodium styrenesulfonate)/alkylated chitosan)) ((PEI/PDDA)/(PAA/PSS)/ACS) powder as a new option. The self-gel utilizes noncovalent interactions among in situ formed PDDA/PSS nanoparticles and PEI/PAA polymetric matrices to earn sensational mechanical properties and tensile strength while incorporating ACS to obtain fast hemostasis and therapeutic capacities. The powder can form a hydrogel patch in situ within 3 s upon liquid absorption, capable of resisting pressure higher than twice the blood pressure. Deposition of the self-gelling powders on various wounds, such as rat liver and femoral artery wounds, can stop bleeding in 10 s and lessen the amount of bleeding 6-fold plus in corresponding models. Furthermore, the self-gelling powders can significantly advance the chronic wound healing process by displaying a high wound healing rate and a low inflammatory response and promoting the formation of new blood vessels and tissue regeneration. The satisfactory mechanical properties, strong wet adhesion, sufficient antibacterial properties, ease of usage, adaptability to complex wounds, rapid hemostasis, and superior therapeutic capacities of (PEI/PDDA)/(PAA/PSS)/ACS self-gelling powders render them as a profound wound dressing biomaterial.

Functional hemostatic hydrogels: design based on procoagulant principles

Uncontrolled hemorrhage results in various complications and is currently the leading cause of death in the general population. Traditional hemostatic methods have drawbacks that may lead to ineffective hemostasis and even the risk of secondary injury. Therefore, there is an urgent need for more effective hemostatic techniques. Polymeric hemostatic materials, particularly hydrogels, are ideal due to their biocompatibility, flexibility, absorption, and versatility. Functional hemostatic hydrogels can enhance hemostasis by creating physical circumstances conducive to hemostasis or by directly interfering with the physiological processes of hemostasis. The procoagulant principles include increasing the concentration of localized hemostatic substances or establishing a physical barrier at the physical level and intervention in blood cells or the coagulation cascade at the physiological level. Moreover, synergistic hemostasis can combine these functions. However, some hydrogels are ineffective in promoting hemostasis or have a limited application scope. These defects have impeded the advancement of hemostatic hydrogels. To provide inspiration and resources for new designs, this review provides an overview of the procoagulant principles of hemostatic hydrogels. We also discuss the challenges in developing effective hemostatic hydrogels and provide viewpoints.

Preparation and application of hemostatic microspheres containing biological macromolecules and others

Bleeding from uncontrollable wounds can be fatal, and the body's clotting mechanisms are unable to control bleeding in a timely and effective manner in emergencies such as battlefields and traffic accidents. For irregular and inaccessible wounds, hemostatic materials are needed to intervene to stop bleeding. Hemostatic microspheres are promising for hemostasis, as their unique structural features can promote coagulation. There is a wide choice of materials for the preparation of microspheres, and the modification of natural macromolecular materials such as chitosan to enhance the hemostatic properties and make up for the deficiencies of synthetic macromolecular materials makes the hemostatic microspheres multifunctional and expands the application fields of hemostatic microspheres. Here, we focus on the hemostatic mechanism of different materials and the preparation methods of microspheres, and introduce the modification methods, related properties and applications (in cancer therapy) for the structural characteristics of hemostatic microspheres. Finally, we discuss the future trends of hemostatic microspheres and research opportunities for developing the next generation of hemostatic microsphere materials.

Hydrogel-Transformable Antioxidant Poly-γ-Glutamic Acid/Polyethyleneimine Hemostatic Powder for Efficient Wound Hemostasis

Hemostatic powder, which can absorb large amounts of water and tends to produce repeated hydration with tissue, has been clinically proven as an ideal engineering material for treating wounds and tissues. We herein designed a polypeptide-based hemostatic powder. A water-soluble polypeptide, γ-polyglutamic acid (γ-PGA), was mixed with the polyethyleneimine (PEI), N-hydroxysuccinimide, and 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide. The solution of these polymers was lyophilized to harvest the γ-PGA/PEI powder (PP hemostatic powder). When deposited on a bleeding wound, the PP hemostatic powder can quickly absorb a large amount of blood and interstitial fluid, concentrate coagulation factors, coagulate blood cells, and eventually form a stable mechanical hydrogel. The wound bleeding time of the PP hemostatic powder group was 1.8 ± 0.4 min, significantly lower than that of the commercial chitosan hemostatic powder group (2.8 ± 0.4 min). The PP hemostatic powder was endowed with antioxidant capacity by introducing protocatechuic aldehyde, which can effectively inhibit inflammation and promote wound healing. Therefore, via preparation through a facile lyophilization method, the PP hemostatic powder is expected to find a wide application prospect as a qualified hemostatic powder.

Multifunctional chitosan-based gel sponge with efficient antibacterial, hemostasis and strong adhesion

Developing wound dressings with solid adhesive properties that enable efficient, painless hemostasis and prevent wound infection remain a huge challenge. Herein, the tris(hydroxymethyl) methyl glycine-modified chitosan derivative (CTMG) was prepared and freeze-dried after simply adjusting the concentration of CTMG to obtain the chitosan-based gel sponge with desired multi-hollow structure, special antibacterial and biocompatibility. The adhesion strength on porcine skin was impressive up to 113 KPa, much higher than fibrin glue. It can withstand the pressure that far exceeds blood pressure. CTMG exhibits bacteriostatic abilities as demonstrated in a bacteriostatic assay, and alongside biocompatibility, as shown in cytotoxicity and hemolytic assays. Moreover, CTMG gel sponge showed hemostatic properties in both in vivo and in vitro hemostasis experiments. During an experiment on liver hemorrhage in rats, CTMG gel sponge proved to be more effective in controlling bleeding than other hemostatic sponges available on the market, indicating its promising hemostatic properties. CTMG gel sponge possesses the potential to function as a wound dressing and hemostatic material, making it suitable for various clinical applications.

Hydro-Sensitive, In Situ Ultrafast Physical Self-Gelatinizing, and Red Blood Cells Strengthened Hemostatic Adhesive Powder with Antibiosis and Immunoregulation for Wound Repair

Immediate and effective hemostatic treatments for complex bleeding wounds are an urgent clinical demand. Hemostatic materials with characteristics of adhesion, sealing, anti-infection, and concrescence promotion have drawn growing concerns. However, pure natural multifunctional hemostatic materials with in situ ultrafast self-gelation are rarely reported. In this study, a hydro-sensitive collagen/tannic acid (ColTA) natural hemostatic powder is developed that can in situ self-gel to form adhesive by the non-covalent crosslinking between tannic acid (TA) and collagen (Col) in liquids. The physical interactions endow ColTA adhesive with the characteristics of instantaneous formation and high adhesion at various substrate surfaces. Crucially, ColTA powder adhesive shows an enhanced adhesion performance in the presence of blood due to the electrostatic interactions between ColTA adhesive and red blood cells, conducive to effective in situ sealing and rapid hemostasis. The biocompatible and hemocompatible ColTA adhesive can effectively control bleeding and seal the wounds of the caudal vein, liver, heart, and femoral arteries in rats. Furthermore, the low-cost and ready-to-use ColTA adhesive powder also possesses good antibacterial and inhibiting biofilm formation ability, and can efficiently regulate immune response by the NF-κB pathway to promote wound repair, making it a highly promising hemostatic material with great potential for biomedical applications.

Injectable spontaneously formed asymmetric adhesive hydrogel with controllable removal for wound healing

Healing large-scale wounds has been a long-standing challenge in the field of biomedicine. Herein, we propose an injectable oxidated sodium alginate/gelatin/3,3'-dithiobis(propionic hydrazide)-aurum (Alg-CHO/gelatin/DTPH-Au) hydrogel filler with asymmetric adhesion ability and removability, which is formed by the Schiff-base reaction between aldehyde-based sodium alginate and multi-amino crosslinkers (gelatin and DTPH), combined with the coordination interaction between Au nanoparticles and disulfide bond of DTPH. Consequently, the prepared Alg-CHO/gelatin/DTPH-Au hydrogel exhibits high mechanical properties and injectable behaviors owing to its multiple-crosslinked interactions. Moreover, because various types of interaction bonding form on the contact side with the tissue, denser crosslinking of the upper layer relative to the lower layer occurs. Combined with the temperature difference between the upper and lower surfaces, this results in asymmetric adhesive properties. Owing to the photothermal effect, the reversible coordination interaction between Au nanoparticles and DTPH and the change in the triple helix structure of gelatin to a coil structure impart the filler-phased removability and antibacterial ability. The choice of all natural polymers also allows for favorable degradability of the wound filler and outstanding biocompatibility. Based on these features, this versatile wound filler can achieve a wide range of applications in the field of all-skin wound repair.

Rapid hemostatic antibacterial self-gelling powder based on methacryloylsulfonyl betaine and quaternized carboxymethyl chitosan

Hemostatic powders can be used for deep wounds and wounds with irregular shapes that are frequently inaccessible to traditional hemostatic dressings like hemostatic gauze, sponges, and foams. In this study, sulfobetaine methacrylate (SBMA) and quaternized carboxymethyl chitosan (QCCS) were combined to create an antibacterial hemostatic hydrogel through photopolymerization under green LED irradiation, which was then changed into PSBMA/QCCS powder. PSBMA/QCCS powder could quickly form hydrogel with strong wet adhesion. The internal structure, water absorption capacity, and adhesion properties of the powder were evaluated. The coagulation ability, antimicrobial properties, and biocompatibility of the powder were also characterized. The PSBMA/QCCS powder could aggregate blood cells and platelets to enhance hemostasis. Meanwhile, PSBMA/QCCS powder also showed effective antibacterial ability against both gram-positive bacteria (Staphylococcus aureus) and gram-negative bacteria (Escherichia coli). In summary, PSBMA/QCCS powder is a promising hemostatic agent with the characteristics of quick hemostasis, tough wet adhesion, satisfactory biocompatibility, considerable antibacterial effect, and adaptability to any irregularly shaped wounds.