Ultrafast self-gelling, superabsorbent, and adhesive chitosan-based hemostatic powders for rapid hemostasis and wound healing

Hemostatic powders are widely used for managing bleeding from wounds with various irregular shapes. However, their limited liquid absorption capacity and difficulty in removal after application remain significant clinical challenges. Herein, we introduce a multifunctional hemostatic powder composed of dually crosslinked poly([2-(methacryloyloxy)ethyl]trimethylammonium chloride-co-acrylic acid) (pMATC-co-AA) and N-[(2-hydroxy-3-trimethylammonium)propyl] chitosan chloride (HTCC), which are integrated via electrostatic interactions and hydrogen bonding. This hemostatic powder exhibits superb liquid-absorbing capacity (94.5 times its own weight in water and 9.1 times in blood), sufficient adhesive properties (5.9 kPa on pig skin), and on-demand removability. It significantly reduces the number of viable Escherichia coli and Staphylococcus aureus by 4.61 and 4.04 orders of magnitude, respectively, thus providing an effective microbiological barrier for the wound. Furthermore, a series of in vivo and in vitro experiments confirm the powder's excellent hemostatic properties. The hydrogel formed on the wound after hemostasis can be removed by saline rinsing on demand, due to its superb liquid-absorbing capacity. Notably, the powder demonstrates good in vivo biocompatibility, with minimal risk of impeding wound healing, and it facilitates the healing process during the later stages. In sum, the hemostatic powder offers a promising solution for trauma bleeding control and acute wound treatment.

Strontium-based quaternary ammonium salt chitosan particles for ultrafast hemostasis of open fracture

The management of open bone defects poses a formidable challenge in clinical practice, primarily due to issues such as profuse bleeding, inflammation, bacterial infections, and compromised bone fracture healing. To tackle these complexities, we have devised a novel hemostatic powder, namely the compound strontium-based chitosan quaternary ammonium salt hemostatic powder (QCS@SrT-TA). This innovative powder leverages the self-assembly of tripolyphosphate and strontium ions, facilitated by a positively charged core cross-linker. Furthermore, its surface has been strategically modified with polyphenol and positively charged macromolecules, imparting unique properties. The mesoporous architecture of QCS@SrT-TA facilitates rapid moisture absorption, enhancing its efficacy. In preclinical studies using rat tail artery amputation and liver bleeding models, QCS@SrT-TA exhibited remarkable performance, significantly reducing both bleeding time and volume (62.39 ± 2.89 mg, 35.33 ± 4.16 s in tail amputation, 63.7 ± 5.19 mg, 62.33 ± 9.61 s in liver bleeding). Notably, the positively charged strontium ions and quaternary ammonium salts within the powder were effective in removing bacteria, minimizing the risk of infection. Beyond hemostasis, QCS@SrT-TA demonstrates additional therapeutic benefits. It polarizes M2 macrophage phenotypes and promotes angiogenesis within bone defect sites, accelerating bone healing processes. Ultimately, a substantially enhanced and notable functional recovery is achieved. In summary, the rapid hemostatic, potent antibacterial, anti-inflammatory, and angiogenesis-promoting characteristics of QCS@SrT-TA hold immense promise as a groundbreaking clinical treatment strategy for open bone defects.

Hydrogel adhesives for tissue recovery

Hydrogel adhesives (HAs) are promising and rewarding tools for improving tissue therapy management. Such HAs had excellent properties and potential applications in biological tissues, such as suture replacement, long-term administration, and hemostatic sealing. In this review, the common designs and the latest progress of HAs based on various methodologies are systematically concluded. Thereafter, how to deal with interfacial water to form a robust wet adhesion and how to balance the adhesion and non-adhesion are underlined. This review also provides a brief description of gelation strategies and raw materials. Finally, the potentials of wound healing, hemostatic sealing, controlled drug delivery, and the current applications in dermal, dental, ocular, cardiac, stomach, and bone tissues are discussed. The comprehensive insight in this review will inspire more novel and practical HAs in the future.

Antibacterial and thermosensitive chitosan-g-poly(N-isopropylacrylamide) copolymer hydrogel containing tannic acid: An injectable therapy for bleeding control

Developing advanced wound dressings improves tissue repair and reduces recovery times. This study introduces a thermo-sensitive hydrogel composed of Chitosan-g-poly (N-isopropylacrylamide) and Tannic acid (CS-PNIPAm-TA), synthesized and characterized using Fourier Transform Infrared Spectroscopy (FTIR) and thermal analysis to confirm successful copolymerization and tannic acid integration. Swelling tests indicated a high capacity for blood absorption, supporting its potential for wound exudate management. Antibacterial testing confirmed the hydrogel's efficacy, with more substantial antibacterial effects observed at higher tannic acid concentrations. Cytotoxicity assessments demonstrated over 90 % cell viability, indicating biocompatibility and fibroblast proliferation. Hemostasis tests in a rat tail injury model showed reduced blood loss and coagulation time, attributed to tannic acid's catalytic effect on the coagulation cascade. In vivo, wound healing assays in a rat model revealed accelerated wound closure compared to controls. These findings suggest that the CS-PNIPAm-TA hydrogel is promising for promoting hemostasis, ensuring biocompatibility, and accelerating wound healing, positioning it as a strong candidate for clinical applications in advanced wound care.

Immunomodulatory bioadhesive technologies

Bioadhesives have found significant use in medicine and engineering, particularly for wound care, tissue engineering, and surgical applications. Compared to traditional wound closure methods such as sutures and staples, bioadhesives offer advantages, including reduced tissue damage, enhanced healing, and ease of implementation. Recent progress highlights the synergy of bioadhesives and immunoengineering strategies, leading to immunomodulatory bioadhesives capable of modulating immune responses at local sites where bioadhesives are applied. They foster favorable therapeutic outcomes such as reduced inflammation in wounds and implants or enhanced local immune responses to improve cancer therapy efficacy. The dual functionalities of bioadhesion and immunomodulation benefit wound management, tissue regeneration, implantable medical devices, and post-surgical cancer management. This review delves into the interplay between bioadhesion and immunomodulation, highlighting the mechanobiological coupling involved. Key areas of focus include the modulation of immune responses through chemical and physical strategies, as well as the application of these bioadhesives in wound healing and cancer treatment. Discussed are remaining challenges such as achieving long-term stability and effectiveness, necessitating further research to fully harness the clinical potential of immunomodulatory bioadhesives.

All-in-One: A Multifunctional Composite Biomimetic Cryogel for Coagulation Disorder Hemostasis and Infected Diabetic Wound Healing

Traditional hemostatic materials are difficult to meet the needs of non-compressible bleeding and for coagulopathic patients. In addition, open wounds are susceptible to infection, and then develop into chronic wounds. However, the development of integrated dressings that do not depend on coagulation pathway and improve the microenvironment of chronic wounds remains a challenge. Inspired by the porous structure and composition of the natural extracellular matrix, adipic dihydrazide modified gelatin (GA), dodecylamine-grafted hyaluronic acid (HD), and MnO2 nanozyme (manganese dioxide)@DFO (deferoxamine)@PDA (polydopamine) (MDP) nanoparticles were combined to prepare GA/HD/MDP cryogels through amidation reaction and hydrogen bonding. These cryogels exhibited good fatigue resistance, photothermal antibacterial (about 98% killing ratios of both Escherichia coli and methicillin-resistant Staphylococcus aureus (MRSA) after 3 min near-infrared irradiation), reactive oxygen species scavenging, oxygen release, and angiogenesis properties. Furthermore, in the liver defect model of rats with coagulopathy, the cryogel displayed less bleeding and shorter hemostasis time than commercial gelatin sponge. In MRSA-infected diabetic wounds, the cryogel could decrease wound inflammation and oxidative stress, alleviate the hypoxic environment, promote collagen deposition, and induce vascular regeneration, showing a better repair effect compared with the Tegaderm™ film. These results indicated that GA/HD/MDP cryogels have great potential in non-compressible hemorrhage for coagulopathic patients and in healing infected wounds for diabetic patients.

A linearly programmable strategy for polymer elastomer mechanics

The mechanical properties of polymer elastomer materials, such as strength and ductility, play important roles in a wide range of applications, including the carrying of major equipment and the construction of infrastructure. However, owing to the widespread disordered physicochemical bonding and unpredictable internal phase separation phenomenon, traditional materials show a complex nonlinear correlation between the material structure and its performance, which makes it difficult to accurately adapt to the performance requirements of various specific application scenarios. In view of the above challenges, this paper innovatively proposes a strategy to achieve linear programmability in the mechanical properties of polymer elastomer materials. Instead of increasing the entropy value of the material, which may be brought about by the traditional physical composite method, this strategy adopts a unique path of introducing special dynamic chain segments (AlPUs). This innovative design leads to a highly ordered microscopic hydrogen bonding arrangement within the elastomer, which effectively reduces the free volume within the material, thus bringing the mechanical response of the material closer to the ideal state. Furthermore, by fine-tuning the content of material components, we are able to achieve linear control of key mechanical indexes, such as tensile strength and elongation at break, which is a significant advantage in terms of precision, range of adjustment, and versatility. The successful implementation of this work opens up a new way toward logical, fine and intelligent design and preparation of polymer materials, providing a solid materials science foundation and unlimited possibilities to promote technological innovation and development in the field of future major equipment and infrastructure.

Water triggered injectable polylactic acid hydrogel based on zwitterionic sulfobetaine modification for incompressible bleeding and tissue anti-adhesion

Massive blood loss is the main cause of prehospital trauma-related death, the development of rapid and effective hemostatic materials is imminent. Injectable hydrogels have the advantages of covering irregular bleeding sites and quickly closing the wound. However, its inherent viscosity can easily precipitate tissue adhesion in vivo and other complications. Based on the anti-protein properties of zwitterion and our previous work about in situ hemostatic/anti-adhesion hydrogel material, we have synthesized a series of injectable hydrogel composed of sulfobetaine-modified polylactic acid (PLA) and gelatin (Gel). These hydrogels could form a smooth film structure by simple water triggering, thereby conferring anti-adhesive properties. We visualized the changes in surface hydrophobicity using fluorescent probes and demonstrated tissue adhesion, rapid hydrophobic interface response, as well as rapid hemostasis for incompressible wounds through in vivo and in vitro experiments. Additionally, we explored the application of hydrogel materials in the scenario of postoperative bleeding, which can effectively prevent unnecessary adhesion through rapid film formation and the anti-protein property of sulfobetaine. We believe that this multifunctional hemostatic hydrogel has the potential to serve as a prehospital emergency treatment of incompressible bleeding and benefit to the postoperative recovery of patients.

3D nanofiber sponge based on natural insect quaternized chitosan/pullulan/citric acid for accelerating wound healing

Extensive traumatic injuries and difficult-to-heal wounds, induced by many circumstances, impose a significant social and economic burden on an annual basis. Thus, innovative wound dressings that encourage wound healing are greatly needed. In this work, we prepared a novel insect chitosan (MCS) using waste pupal shells from housefly (Musca domestica L.) culture. After conducting comparative investigations with commercially available chitosan, it was shown that MCS exhibited comparable qualities and may be used as a substitute source of commercial chitosan. A quaternized chitosan/pullulan/citric acid three-dimensional nanofiber sponge (3D-NS) of natural origin was prepared by electrostatic spinning and gas foaming techniques after MCS was quaternized. In vitro, tests showed that the 3D-NS had a higher liquid absorption capacity than the two-dimensional nanofibrous membrane (2D-NM). Additionally, the 3D-NS showed improved hemostatic, pro-cell proliferation, antibacterial, and anti-inflammatory qualities. In vitro, tests demonstrated that 3D-NS could inhibit the release of inflammatory factors, promote angiogenesis, accelerate collagen deposition, and promote wound contraction. These effects considerably facilitated the healing process of wounds in rats with full-thickness skin damage. In conclusion, the great bioactivity and physicochemical properties of 3D-NS render it an optimal candidate for developing novel wound dressings.

Serotonin-functionalized starch-based hemostatic sponges enhance platelet activation in the management of non-compressible hemorrhage

Massive hemorrhage poses a serious threat to human health and even life. Access to rapid and potent hemostatic materials is crucial for lowering mortality rates. Starch-based materials exhibit good biocompatibility and are extensively utilized in hemostatic. However, existing starch-based hemostatic products suffer from limited hemostatic efficacy. Serotonin, an indoleamine naturally occurring in the human body, is recognized for its potent platelet-activating properties. Therefore, this study focused on enhancing the procoagulant activity of starch by incorporating serotonin into the starch backbone via esterification and amidation reactions, yielding a novel serotonin-loaded starch-based hemostatic sponge (SLS sponge). The SLS sponges featured exceptional porosity (≥80 %) and water absorption capacity (≥2000 %), which rapidly initiated the coagulation cascade reaction, promoted the adhesion and aggregation of red blood cells and platelets, and intensified platelet activation. This multifaceted approach synergistically enhanced hemostasis via both active and passive coagulation mechanisms. Notably, the SLS sponges adhered firmly to the wound surfaces without pressure. Compared with gelatin sponges, the SLS sponges significantly reduced blood loss by approximately 40.5 % and shortened the time to achieve hemostasis by approximately 28.9 %. These findings indicate that the newly developed SLS sponges are a promising active hemostatic material, particularly effective in managing non-compressible hemorrhages.

Injectable hemostatic hydrogel adhesive with antioxidant, antibacterial and procoagulant properties for hemorrhage wound management

In emergencies, uncontrolled severe bleeding can result in undesired complications and even death of the injured. Designing advanced hemostatic agents is a potential solution for emergency hemostasis, yet it remains challenging to realize the persistent adhesion in a wet wound environment. In this study, based on dynamic reversible Schiff base bond and photo-initiated double-bond polymerization, a novel injectable hemostatic hydrogel (L-COC) consisting of methacrylated carboxymethyl chitosan (CMCSMA), oxidized konjac glucomannan (OKGM) and (+)-catechin hydrate (CH) was synthesized for emergency hemostasis. To our delight, the incorporated CH imparted enhanced blood procoagulantion to the L-COC hydrogel by intensifying the hydrogel-red blood cell interactions. As a result, the hemostatic effect of the engineered L-COC hydrogel was significantly superior to that of fluid gelatin SurgifloTM for liver bleeding wounds in rats (Blood loss: 0.62 ± 0.11 g (L-COC), 0.90 ± 0.08 g (SurgifloTM); hemostasis time: 69.0 ± 2.9 s (L-COC), 84.0 ± 2.2 s (SurgifloTM)). With the favorable antioxidant and antibacterial activities, as well as multifunctional properties, the bio-adhesive L-COC hydrogel and the underlying design principles may facilitate further development of practical hemostatic hydrogels.

Insight into hemostatic performance and mechanism of natural mixed-dimensional Attapulgite clay

Clay minerals have attracted wide attention as biomedical materials due to the unique crystal structure, abundant morphology and good biocompatibility. However, the relevant studies on the abundant natural mixed clay deposits were scarcely reported. Herein, the hemostatic performance of natural mixed-dimensional attapulgite clay (MDAPT) composed of one-dimensional attapulgite and multiple two-dimensional clay were systematically investigated based on the structural evolution using oxalic acid for different time. The results of hemostatic evaluation showed that MDAPT leached by oxalic acid with 1 h presented the shortest clotting time (134 ± 12.17 s), a 15.09 % and 41.74 % reduction of relative hemoglobin absorbance at 180 s and 120 s when compared with the control group, respectively, and an increase of 19.45 % of the blood clotting index in vitro, as well as MDAPT obtained the shortest bleeding time (158.5 ± 6.9 s), nearly 66 % and 31 % reduction blood loss as compared to the blank group and the YNBY group in vivo. This improvement was primarily ascribed to the synergistic effect of lamellar non-expandable illite, and nano rod-like attapulgite. Furthermore, the rapid hemostasis of MDAPT was also due to the joint effect of superhydrophobic property toward blood, minimizing blood loss, surface negative charge, metal ions from MDAPT structural skeleton, promoting an average increase of 21 % for platelet activation. The results suggested that MDAPT could be served as a promising efficient inorganic hemostatic materials, which provided a feasible strategy to realize the high-valued utilization of natural mixed clay resources.

Hemostatic Dressing Immobilized with ε-poly-L-lysine and Alginate Coated Mesoporous Bioactive Glass Prevents Blood Permeation by Pseudo-Dewetting Behavior

The integration of hemostats with cotton fabrics is recognized as an effective approach to improve the hemostatic performance of dressings. However, concerns regarding the uncontrollable absorption of blood by hydrophilic dressings and the risk of distal thrombosis from shed hemostatic agents are increasingly scrutinized. To address these issues, this work develops an advanced dressing (AQG) with immobilized nano-scale mesoporous bioactive glass (MBG) to safely and durably augment hemostasis. The doubly immobilized MBGs, pre-coated with ε-poly-L-lysine and alginate, demonstrate less than 1% detachment after ultrasonic washing. Notably, this MBG layer significantly promotes the adhesion, aggregation, and activation of red blood cells and platelets, adhered five times more red blood cells and 29 times more platelets than raw dressing, respectively. Specially, with the rapid formation of protein corona and amplification of thrombin, dense fibrin network is built on MBG layer and then blocked blood permeation transversely and longitudinally, showing an autophobic pseudo-dewetting behavior and allowing AQG to concentrate blood in situ and culminate in faster hemostasis with lower blood loss. Furthermore, the potent antibacterial properties of AQG extend its potential for broader application in daily care and clinical setting.

Tranexamic acid-loaded catechol-modified hyaluronic acid/carboxymethyl chitosan double cross-linked porous gel micropowders for rapid hemostasis and wound healing

Acquiring rapid and effective hemostasis remains a critical clinical challenge. Current researches focus on concentrating blood components to speed up the hemostatic while ignore the effect of anti-fibrinolysis in promoting blood coagulation. Herein, we designed a novel tranexamic acid (TA)-loaded physicochemical double cross-linked multifunctional catechol-modified hyaluronic acid-dopamine/carboxymethyl chitosan porous gel micropowders (TA&Fe3+@HA-DA/CMCS PGMs) for rapid hemostasis and wound healing. TA&Fe3+@HA-DA/CMCS PGMs exhibited high water absorption rate (505.9 ± 62.1 %) and rapid hemostasis (79 ± 4 s) in vivo. Catechol groups, Fe3+ and the protonated amino groups of CMCS induced bacterial death. Moreover, TA&Fe3+@HA-DA/CMCS PGMs displayed sufficient adhesion to a variety of wet rat tissues. TA&Fe3+@HA-DA/CMCS PGMs on various bleeding wounds, including rat liver injury and tail severed models showed excellent hemostasis performance. The TA&Fe3+@HA-DA/CMCS PGMs could promote the healing of full-thickness skin wounds on the backs of rats. The advantages of TA&Fe3+@HA-DA/CMCS PGMs including rapid hemostasis, effective wound healing, good tissue adhesion, antibacterial properties and ease of use make it potentially valuable in clinical application.

Thermo-assisted fabrication of a novel shape-memory hyaluronic acid sponge for non-compressible hemorrhage control

Hyaluronic acid (HA), a major component of skin extracellular matrix, provides an excellent framework for hemostatic design; however, there still lacks HA materials tailored with superior mechanical properties to address non-compressible hemorrhages. Here, we present a solvent-free thermal approach for constructing a shape-memory HA sponge for this application. Following facile thermal incubation around 130 °C, HA underwent cross-linking via esterification with poly(acrylic acid) within the sponge pre-shaped through a prior freeze-drying process. The resulting sponge system exhibited extensively interconnected macropores with a high fluid absorption capacity, excellent shape-memory property, and robust mechanical elasticity. When introduced to whole blood in vitro, the HA sponges demonstrated remarkable hemostatic properties, yielding a shorter coagulation time and lower blood clotting index compared to the commercial gelatin sponge (GS). Furthermore, in vivo hemostatic studies involving two non-compressible hemorrhage models (rat liver volume defect injury or femoral artery injury) achieved a significant reduction of approximately 64% (or 56%) and 73% (or 70%) in bleeding time and blood loss, respectively, which also outperformed GS. Additionally, comprehensive in vitro and in vivo evaluations suggested the good biocompatibility and biodegradability of HA sponges. This study highlights the substantial potential for utilizing the designed HA sponges in massive bleeding management.

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.

A 3D-Printed Cuttlefish Bone Elastomeric Sponge Rapidly Controlling Noncompressible Hemorrhage

Developing a self-expanding hemostatic sponge with high blood absorption and rapid shape recovery for noncompressible hemorrhage remains a challenge. In this study, a 3D-printed cuttlefish bone elastomeric sponge (CBES) is fabricated, which combined ordered channels and porous structures, presented tunable mechanical strength, and shape memory potentials. The incorporation of cuttlefish bone powder (CBp) plays key roles in concentrating blood components, promoting aggregation of red blood cells and platelets, and activating platelets, which makes CBES show enhanced hemostatic performance compared with commercial gelatin sponges in vivo. Moreover, CBES promotes more histiocytic infiltration and neovascularization in the early stage of degradation than gelatin sponges, which is conducive to the regeneration and repair of injured tissue. To conclude, CBp loaded 3D-printed elastomeric sponges can promote coagulation, present the potential to guide tissue healing, and broaden the hemostatic application of traditional Chinese medicine.

A Laparoscopically Compatible Rapid-Adhesion Bioadhesive for Asymmetric Adhesion, Non-Pressing Hemostasis, and Seamless Seal

Bioadhesive hydrogels offer unprecedented opportunities in hemostatic agents and tissue sealing; however, the application of existing bioadhesive hydrogels through narrow spaces to achieve strong adhesion in fluid-rich physiological environments is challenged either by undesired indiscriminate adhesion or weak wet tissue adhesion. Here, a laparoscopically compatible asymmetric adhesive hydrogel (aAH) composed of sprayable adhesive hydrogel powders and injectable anti-adhesive glue is proposed for hemostasis and to seal the bloody tissues in a non-pressing way, allowing for preventing postoperative adhesion. The powders can seed on the irregular bloody wound to rapidly absorb interfacial fluid, crosslink, and form an adhesive hydrogel to hemostatic seal (blood clotting time and tissue sealing in 10 s, ≈200 mm Hg of burst pressure in sealed porcine tissues). The aAH can be simply formed by crosslinking the upper powder with injectable glue to prevent postoperative adhesion (adhesive strength as low as 1 kPa). The aAH outperforms commercial hemostatic agents and sealants in the sealing of bleeding organs in live rats, demonstrating superior anti-adhesive efficiency. Further, the hemostatic seamless sealing by aAH succeeds in shortening the time of warm ischemia, decreasing the blood loss, and reducing the possibility of rebleeding in the porcine laparoscopic partial nephrectomy model.

What else should hemostatic materials do beyond hemostasis: A review

Massive blood loss due to injury is the leading cause of prehospital deaths in disasters and emergencies. Hemostatic materials are used to realize rapid hemostasis and protect patients from death. Researchers have designed and developed a variety of hemostatic materials. However, in addition to their hemostatic effect, hemostatic materials must be endowed with additional functions to meet the practical application requirements in different scenarios. Here, strategies for modifications of hemostatic materials for use in different application scenarios are listed: effective positioning at the site of deep and narrow wounds to stop bleeding, resistance to high blood pressure and wound movement to maintain wound formation, rapid and easy removal from the wound without affecting further treatment after hemostasis is completed, and continued function when retained in the wound as a dressing (such as antibacterial, antiadhesion, tissue repair, etc.). The problems encountered in the practical use of hemostatic materials and the strategies and progress of researchers will be further discussed in this review. We hope to provide valuable references for the design of more comprehensive and practical hemostatic materials.

Self-Oxidated Hydrophilic Chitosan Fibrous Mats for Fatal Hemorrhage Control

Enriching erythrocytes and platelets in seconds and providing a fast seal in bleeding sites is vital to fatal hemorrhage control. Herein, hydrophilic chitosan fibrous mats (CECS-D mats) are fabricated by introducing hydrophilic carboxyethyl groups and subsequent catechol groups onto chitosan fibers. Due to strong hydrophilicity, CECS-D mats exhibit rapid liquid-absorption capacity, especially instantaneous absorptivity to the rabbit blood, which can achieve erythrocyte and platelet aggregations quickly by concentrating blood, thus promoting the formation of blood clots. Furthermore, the mats are self-oxidated to form quinone-amine adducts or quinone multimers by adjusting pH conditions, which not only provides tissue adhesion but also induces erythrocyte aggregation and platelet adhesion, further enhancing the seal and triggering quick closure to achieve fast hemostasis. Therefore, the mats reveal superior hemostatic performance in rabbit liver and spleen models over CECS mats and gauze. Especially in the fatal femoral artery injury model of rabbits, the mats reduce the blood loss by ∼75% and shortened the bleeding time by ∼50% compared with CECS mats, which have been reported to have the same hemostatic effect as commercialized Celox products in a swine femoral artery injury model. Besides, the mats are cytocompatible and degradable as well as antibacterial. This chitosan mat is a promising hemostatic material for fatal hemorrhage control.

A ZIF-8-encapsulated interpenetrated hydrogel/nanofiber composite patch for chronic wound treatment

Designing wound dressings necessitates the crucial considerations of maintaining a moist environment and implementing effective bacterial control. Furthermore, developing a three-dimensional framework emulating the extracellular matrix (ECM) confers advantages in fostering cellular migration and proliferation. Inspired by this, hydrogel/nanofiber composites have been demonstrated as promising materials for wound dressings. The composites also overcome the disadvantages of poor mechanical properties and rapid release of traditional pure hydrogels. In this study, we constructed a calcium alginate hydrogel/polylactic acid nanofiber (CAH/PLANF) composite with an interpenetrated network. Additionally, the synthesis of zeolitic imidazolate framework-8 (ZIF-8) incorporated into the composite system endowed the system with enhanced mechanical properties and photodynamic antibacterial attributes. The obtained composite patch (ZIF-8@CAH/PLANF) exhibited excellent swelling, strong mechanical properties, low cytotoxicity, and durable photodynamic antibacterial effect with an antibacterial efficacy of higher than 99.99%. Finally, bacterial infection and wound healing properties were investigated in vivo, and the ZIF-8@CAH/PLANF patch was proven to have the ability to fight infection and accelerate wound healing.

Development of alginate macroporous hydrogels using sacrificial CaCO3 particles for enhanced hemostasis

Polymeric hydrogels have increasingly garnered attention in the field of hemostasis. However, there remains a lack of targeted development and evaluation of non-dense polymeric hydrogels with physically incorporated pores to enhance hemostasis. Here, we present a facile route to macroporous alginate hydrogels using acid-induced CaCO3 dissolution to provide Ca2+ for alginate gelation and CO2 bubbles for subsequent macropore formation. The as-prepared pore structure in the hydrogels and its formation mechanisms were characterized through microscopic imaging and nitrogen adsorption/desorption tests. Functional analyses revealed that the macroporous hydrogels exhibited improved rheology, blood absorption, coagulation factor delivery, and platelet aggregation. Ultimately, the introduction of pores significantly enhanced the hemostatic effectiveness of alginate hydrogels in vivo, as demonstrated in rat tail amputation and liver injury models, leading to a reduction in blood loss of up to 77 % or a decrease in bleeding time of up to 88 %. Notably, hydrogels with higher porosity achieved with a CaCO3 to alginate ratio of 40 % outperformed those with lower porosity in the aforementioned properties. Furthermore, these improvements were found to be biocompatible and elicited minimal inflammation. Our findings underscore the potential of a simple porous hydrogel design to enhance hemostasis efficacy by physically incorporating macropores.

Multiple Non-Covalent Cross-Linked Multifunctional Strong Hemostatic Agent for Dynamic Exposure Hemostasis

Trauma requires immediate hemostasis during primary care, as well as durable hemostasis that can withstand dynamic wound exposure. Although current hemostatic materials can treat bleeding sites in emergency situations, their mechanical strength and storage conditions limit their practical application. The simultaneous combination of good mechanical properties, storage stability, biocompatibility, and rapid hemostasis of hemostatic materials remains a challenge. In this paper, a novel hemostatic material based on multiple non-covalent bond crosslinking, which has excellent mechanical properties, good biocompatibility, storage stability, and rapid hemostasis ability, is reported. Under the drive of multiple non-covalent bonds, the flowability of hydrogel micro-modules (HM) decreases rapidly within 20 s after exposure to physiological saline. The HM form a gel barrier with a tensile strength of 62.10 kPa and an elongation at break of 1976% under multiple non-covalent bonding. Furthermore, the mechanical properties do not change significantly after 30 days of storage. Cell viability is maintained at over 80% after 3 days of incubation with the cells, and the hemolysis test shows a very low hemolysis rate (2.08%). The hemostatic gel formed by HM effectively prevents secondary bleeding in dynamic hemostasis experiments simulating transportation. This work provides a hemostatic material with comprehensive properties for practical applications.

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.

Antibacterial and hemostatic chitin sponge directly constructed from Pleurotus Eryngii via top-down approach

Chitin, the second most abundant polysaccharide on earth, possesses unique characteristics, including biosafety, biodegradability, and procoagulant activity, making it an attractive material for hemostasis. However, the conventional bottom-up construction of chitin-based materials is intricate and time-consuming. In this study, we have developed a top-down strategy to prepare a 3D porous chitin-based hemostatic sponge with exceptional hemostatic properties and antibacterial activity, directly from the spongy Pleurotus eryngii. The top-down method involves deproteinization, in situ quaternization, and tannin acid crosslinking. The obtained sponge has an interconnected microporous structure with high porosity (89.7 ± 3.2 %), endowing it with high water absorption (2047 ± 105 %) and rapid water-triggered shape-memory behavior (< 2 s). The sponge exhibits superior blood coagulant activity and outperforms standard medical gauze, gelatin sponge, and chitosan sponge in both topical artery and non-compressive liver puncture wound. In addition, the sponge exhibited significant antibacterial activity against both gram-positive Staphylococcus aureus and gram-negative Escherichia coli. In summary, this study provides a straightforward and practical approach for constructing an antibacterial and hemostatic chitin sponge that could be a valuable option for treating bleeding wounds.

Laponite nanoparticle-crosslinked carboxymethyl cellulose-based injectable hydrogels with efficient underwater-specific adhesion for rapid hemostasis

Tissue adhesives have attracted intense and increasing interest due to their multiple biomedical applications. Despite the rapid development of adhesive hydrogels, huge challenges remain for materials that can ensure strong adhesion and seal hemostasis in aqueous and blood environments. To address this issue, we have developed an innovative design of PAA-based coacervate hydrogel with strong wet adhesion capability through a simple mixture of PAA copolymers with oxidized-carboxymethylcellulose (OCMC), and tannic acid (TA) as the main components, and structurally enhanced with natural clays (Laponite XLG). The absorbed TA provides solid adhesion to dry and wet substrates via multiple interactions, which endows the XLG-enhanced coacervate with the desired underwater adhesive strength. More importantly, the dielectric constant is introduced to evaluate the polarity of the tested samples, which may be used as guidance for the design of mussel-inspired adhesives with even better underwater adhesive properties. In vivo hemorrhage experiments further confirmed that the hydrogel adhesive dramatically shortened the hemostatic time to tens of seconds. Overall, the persistent adhesion and acceptable cytocompatibility of the hydrogel nanocomposite make it a promising alternative suture-free approach for rapid hemostasis at different length scales and is expected to be extended to clinical application for other organ injuries.

Natural polymer-based bioadhesives as hemostatic platforms for wound healing

Medical adhesives are advanced but challenging alternatives to wound closure and repair, especially in mitigating uncontrolled hemorrhage. Ideal hemostatic adhesives need to meet good biocompatibility and biodegradability, adequate mechanical strength, and strong tissue adhesion functionality under wet and dynamic conditions. Considering these requirements, natural polymers such as polysaccharide, protein and DNA, attract great attention as candidates for making bioadhesives because of their distinctive physicochemical performances and biological properties. This review systematically summarizes the advances of bioadhesives based on natural polysaccharide, protein and DNA. Various physical and chemical cross-linking strategies have been introduced for adhesive synthesis and their hemostatic applications are introduced from the aspect of versatility. Furthermore, the possible challenges and future opportunities of bioadhesives are discussed, providing insights into the development of high-performance hemostatic materials.

Progress and future prospects of hemostatic materials based on nanostructured clay minerals

The occurrence of uncontrolled hemorrhage is a significant threat to human life and health. Although hemostatic materials have made remarkable advances in the biomaterials field, it remains a challenge to develop safe and effective hemostatic materials for global medical use. Natural clay minerals (CMs) have long been used as traditional inorganic hemostatic agents due to their good hemostatic capability, biocompatibility and easy availability. With the advancement of science, technology and ideology, CM-based hemostatic materials have undergone continuous innovations by integrating new inspirations with conventional concepts. This review systematically summarizes the hemostatic mechanisms of different natural CMs based on their nanostructures. Moreover, it also comprehensively reviews the latest research progress for CM-based hemostatic hybrid and nanocomposite materials, and discusses the challenges and developments in this field.

Biologically Derived Nanoarchitectonic Coatings for the Engineering of Hemostatic Needles

Bleeding after venipuncture could cause blood loss, hematoma, bruising, hemorrhagic shock, and even death. Herein, a hemostatic needle with antibacterial property is developed via coating of biologically derived carboxymethyl chitosan (CMCS) and Cirsium setosum extract (CsE). The rapid transition from films of the coatings to hydrogels under a wet environment provides an opportunity to detach the coatings from needles and subsequently seal the punctured site. The hydrogels do not significantly influence the healing process of the puncture site. After hemostasis, the coatings on hemostatic needles degrade in 72 h without inducing a systemic immune response. The composition of CMCS can inhibit bacteria of Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus by destroying the membrane of bacteria. The hemostatic needle with good hemostasis efficacy, antibacterial property, and safety is promising for the prevention of bleeding-associated complications in practical applications.

The hemostatic effect and wound healing of novel collagen-containing polyester dressing

Collagen plays an important role in hemostasis and tissue repair processes. Traditional passive wound dressings like gauze, bandage, and cotton wool could hardly fit the open wounds and exerted no active effect on wound healing. Even worse, they would adhere to the skin tissue, causing dehydration and second injury upon replacement. Polyester is commonly used in the medical field and is a safe and inexpensive polymer. Due to the hydrophobic surface, polyester does not adhere to tissue; however, polyester does not have the hemostatic properties. We designed a material composed of collagen and polyester, encapsulated hydrolyzed collagen in polyester particles, and made collagen-polyester non-woven fabric by melt blowing method, The collagen content was 1% and the collagen-polyester dressing exhibited a hydrophobic nature, preventing moisture from sticking to its surface. The purpose of this study was to compare the hemostatic effect of collagen-polyester nonwovens with conventional polyester pads, and to observe the adhesion of the pads to the wound. The wound healing and shrinkage rates of collagen-polyester dressings and conventional pads were compared in a rat wound healing test. The hemostatic test showed that the polyester pads containing 1% collagen significantly shortened the bleeding time compared with the traditional polyester pads, and retained the hydrophobicity and non-adhesion properties. The collagen-polyester dressing had better angiogenesis and granulation degree than the control group on the 14th day, and reduced the wound shrinkage rate. Collagen polyester dressings have excellent hemostasis, regeneration, shrinkage reduction and non-adhering for wounds. Overall, the novel collagen-containing polyester dressing is ideal choice for wound dressings.

Development of polydopamine functionalized porous starch for bleeding control with the assistance of NIR light

Efficient hemorrhage control of severe wound injuries is an urgent medical need, deserving agents with promising blood coagulation and biocompatible characteristics. Current work developed polydopamine (PDA) functionalized porous starch powder (PS-PDA) for emergency bleeding treatment. The micro-morphology and elements, chemical groups, and porosity of PS-PDA were systematically characterized. Its comparison with porous starch (PS) revealed the promising potential of this composite in medical practice. On one hand, PS-PDA showed superior surface area and biomineralization affinity over PS, along with comparable hemo/cyto-compatibility. On the other hand, the photothermal effect of PDA under near Infrared (NIR) light paved the possibility to accelerate blood coagulation in situ. In vivo studies indicated PS-PDA can significantly reduce blood loss and improvement of hemostasis efficiency accompanied by NIR light exposure. These results suggest that this newly developed PS-PDA powder can serve as a promising hemostatic material for bleeding wound control.

Sea Cucumber-Inspired Aerogel for Ultrafast Hemostasis of Open Fracture

The symptomatic management of hemorrhagic shock complicated by open fractures is a great challenge, because it is also complicated by complex wound bleeding, bacterial infection, and bone defects. Inspired by the water absorption and cross-sectional microstructure of sea cucumbers, in this study, a new sea cucumber-like aerogel (GCG) is proposed. Its aligned porous structure and composition can stop bleeding rapidly and effectively with a blood clotting index of 3.73 ± 1.8%. More importantly, the data of in vivo hemostasis test in an amputating rat tail hemostatic model (15.69 ± 2.45 s, 26.95 ± 8.43 mg) and liver puncture bleeding model (23.77 ± 2.68 s, 36.22 ± 16.92 mg) also indicate the excellent hemostatic performance of GCG. In addition, GCG also shows a significant inhibitory effect on S. aureus and E. coli, which can prevent the occurrence of postoperative osteomyelitis. Not only that, after filling in the bone defect, it is shown that this GCG aerogel completely degrades eight weeks after surgery and induces new bone ingrowth, achieving functional regeneration after hemostasis of an open fracture defect. Generally, because of its combination of hemostatic, antibacterial, and osteogenic activities, this new aerogel is a promising option for open fractures treatment.

Short Peptide Nanofiber Biomaterials Ameliorate Local Hemostatic Capacity of Surgical Materials and Intraoperative Hemostatic Applications in Clinics

Short designer self-assembling peptide (dSAP) biomaterials are a new addition to the hemostat group. It may provide a diverse and robust toolbox for surgeons to integrate wound microenvironment with much safer and stronger hemostatic capacity than conventional materials and hemostatic agents. Especially in noncompressible torso hemorrhage (NCTH), diffuse mucosal surface bleeding, and internal medical bleeding (IMB), with respect to the optimal hemostatic formulation, dSAP biomaterials are the ingenious nanofiber alternatives to make bioactive neural scaffold, nasal packing, large mucosal surface coverage in gastrointestinal surgery (esophagus, gastric lesion, duodenum, and lower digestive tract), epicardiac cell-delivery carrier, transparent matrix barrier, and so on. Herein, in multiple surgical specialties, dSAP-biomaterial-based nano-hemostats achieve safe, effective, and immediate hemostasis, facile wound healing, and potentially reduce the risks in delayed bleeding, rebleeding, post-operative bleeding, or related complications. The biosafety in vivo, bleeding indications, tissue-sealing quality, surgical feasibility, and local usability are addressed comprehensively and sequentially and pursued to develop useful surgical techniques with better hemostatic performance. Here, the state of the art and all-round advancements of nano-hemostatic approaches in surgery are provided. Relevant critical insights will inspire exciting investigations on peptide nanotechnology, next-generation biomaterials, and better promising prospects in clinics.

Gelatin Methacryloyl-Based Sponge with Designed Conical Microchannels for Rapidly Controlling Hemorrhage and Theoretical Verification

It remains a challenge to develop effective hemostatic products in battlefield rescue for noncompressible massive hemorrhage. Some previous research had concentrated on the modification of different materials to improve the hemostasis ability of sponges. Herein, to investigate the relationship between the taper of microchannels and hemostatic performance of porous sponges, gelatin methacryloyl-based sponges with designed conical microchannels and a disordered porous structure were prepared using the 3D printing method and freeze-drying technology. Experiments and theoretical model analysis demonstrated that the taper and distribution of microchannels in the sponge affected the water and blood absorption properties, as well as the expansion ability. In treatment of SD rat liver defect and SD rat liver perforation wound, GS-1 sponge with the taper (1/15) microchannels exhibited an excellent hemostatic effect with blood loss of 0.866 ± 0.093 g and a hemostasis time of 280 ± 10 s. Results showed that the hemostatic capacities of GelMA sponges were increased with the bottom diameter (taper) of conical microchannels. This is a potential strategy to develop designed taper sponges with designed taper microchannels for rapidly controlling hemorrhage.

Multifunctional and Tunable Coacervate Powders to Enable Rapid Hemostasis and Promote Infected Wound Healing

Hemostatic powders provide an important treatment approach for time-sensitive hemorrhage control. Conventional hemostatic powders are challenged by the lack of tissue adhesiveness, insufficient hemostatic efficacy, limited infection control, and so forth. This study develops a hemostatic powder from tricomponent GTP coacervates consisting of gelatin, tannic acid (TA), and poly(vinyl alcohol) (PVA). The physical cross-linking by TA results in facile preparation, good storage stability, ease of application to wounds, and removal, which provide good potential for clinical translation. When rehydrated, the coacervate powders rapidly form a cohesive layer with interconnected microporous structure, competent flexibility, switchable wet adhesiveness, and antibacterial properties, which facilitate the hemostatic efficacy for treating irregular, noncompressible, or bacteria-infected wounds. Compared to commercial hemostats, GTP treatment results in significantly accelerated hemostasis in a liver puncture model (∼19 s, >30% reduction in the hemostatic time) and in a tail amputation model (∼38 s, >60% reduction in the hemostatic time). In the GTP coacervates, gelatin functioned as the biodegradable scaffold, while PVA introduced the flexible segments to enable shape-adaptability and interfacial interactions. Furthermore, TA contributed to the physical cross-linking, adhesiveness, and antibacterial performance of the coacervates. The study explores the tunability of GTP coacervate powders to enhance their hemostatic and wound healing performances.

Polysaccharides based rapid self-crosslinking and wet tissue adhesive hemostatic powders for effective hemostasis

Hemostatic powders with flexible shape are widely used for the noncompressible and inaccessible hemorrhage wounds. However, current hemostatic powders display poor wet tissue adhesion and fragile mechanical strength of the powder-supported blood clots, leading to compromised hemostasis efficacy. Herein, a bi-component of carboxymethyl chitosan (CMCS) and aldehyde-modified hyaluronic acid grafted with catechol groups (COHA) was designed. Upon absorption of blood, the bi-component powders (CMCS-COHA) spontaneously self-crosslinks into an adhesive hydrogel within 10 s, tightly adhering to wound tissue to form a pressure-resistant physical barrier. During gelation, the hydrogel matrix captures and locks the blood cells/platelets to generate a robust thrombus in the bleeding sites. Compared with traditional hemostatic powder Celox™, CMCS-COHA displays superior blood coagulation and hemostatic performance. More importantly, CMCS-COHA has inherent cytocompatibility and hemocompatibility. These prominent advantages in rapid and effective hemostasis, adaptability to fit irregulate defective wound, easy preservation, facile usage, and bio-safety, make CMCS-COHA a promising hemostatic in emergency situations.

Morphological, cytotoxicity, and coagulation assessments of perlite as a new hemostatic biomaterial

Hemorrhage control is vital for clinical outcomes after surgical treatment and pre-hospital trauma injuries. Numerous biomaterials have been investigated to control surgical and traumatic bleeding. In this study, for the first time, perlite was introduced as an aluminosilicate biomaterial and compared with other ceramics such as kaolin and bentonite in terms of morphology, cytotoxicity, mutagenicity, and hemostatic evaluations. Cellular studies showed that perlite has excellent viability, good cell adhesion, and high anti-mutagenicity. Coagulation results demonstrated that the shortest clotting time (140 seconds with a concentration of 50 mg mL^-1) was obtained for perlite samples compared to other samples. Therefore, perlite seems most efficient as a biocompatible ceramic for hemorrhage control and other biomaterial designs.

A Choline Phosphoryl-Conjugated Chitosan/Oxidized Dextran Injectable Self-Healing Hydrogel for Improved Hemostatic Efficacy

The development of injectable hydrogels with good biocompatibility, self-healing, and superior hemostatic properties is highly desirable in emergency and clinical applications. Herein, we report an in situ injectable and self-healing hemostatic hydrogel based on choline phosphoryl functionalized chitosan (CS-g-CP) and oxidized dextran (ODex). The CP groups were hypothesized to accelerate hemostasis by facilitating erythrocyte adhesion and aggregation. Our results reveal that the CS-g-CP/ODex hydrogels exhibit enhanced blood clotting and erythrocyte adhesion/aggregation capacities compared to those of the CS/ODex hydrogels. The CS-g-CP₅₀/ODex₇₅ hydrogel presents rapid gelation time, good mechanical strength and tissue adhesiveness, satisfactory bursting pressure, and favorable biocompatibility. The hemostatic ability of the CS-g-CP₅₀/ODex₇₅ hydrogel was significantly improved compared to that of the CS/ODex hydrogel and commercial fibrin sealant in the rat tail amputation and liver/spleen injury models. Our study highlights the positive and synergistic effects of CP groups on hemostasis and strongly supports the CS-g-CP₅₀/ODex₇₅ hydrogel as a promising adhesive for hemorrhage control.

Liquid-infused microstructured bioadhesives halt non-compressible hemorrhage

Non-compressible hemorrhage is an unmet clinical challenge that accounts for high mortality in trauma. Rapid pressurized blood flows under hemorrhage impair the function and integrity of hemostatic agents and the adhesion of bioadhesive sealants. Here, we report the design and performance of bioinspired microstructured bioadhesives, formed with a macroporous tough xerogel infused with functional liquids. The xerogel can rapidly absorb interfacial fluids such as whole blood and promote blood clotting, while the infused liquids facilitate interfacial bonding, sealing, and antibacterial function. Their synergy enables the bioadhesives to form tough adhesion on ex vivo human and porcine tissues and diverse engineered surfaces without the need for compression, as well as on-demand instant removal and storage stability. We demonstrate a significantly improved hemostatic efficacy and biocompatibility in rats and pigs compared to non-structured counterparts and commercial products. This work opens new avenues for the development of bioadhesives and hemostatic sealants.