Coagulopathy-independent, bioinspired hemostatic materials: A full research story from preclinical models to a human clinical trial

Biomimetic and Wound Microenvironment-Modulating PEGylated Glycopolypeptide Hydrogels for Arterial Massive Hemorrhage and Wound Prohealing

Despite great progress in the hydrogel hemostats and dressings, they generally lack resistant vascular bursting pressure and intrinsic bioactivity to meet arterial massive hemorrhage and proheal wounds. To address the problems, we design a kind of biomimetic and wound microenvironment-modulating PEGylated glycopolypeptide hydrogels that can be easily injected and gelled in ∼10 s. Those glycopolypeptide hydrogels have suitable tissue adhesion of ∼20 kPa, high resistant bursting pressure of ∼150 mmHg, large microporosity of ∼15 μm, and excellent biocompatibility with ∼1% hemolysis ratio and negligible inflammation. They performed better hemostasis in rat liver and rat and rabbit femoral artery bleeding models than Fibrin glue, Gauze, and other hydrogels, achieving fast arterial hemostasis of <20 s and lower blood loss of 5-13%. As confirmed by in vivo wound healing, immunofluorescent imaging, and immunohistochemical and histological analyses, the mannose-modified hydrogels could highly boost the polarization of anti-inflammatory M2 phenotype and downregulate pro-inflammatory tumor necrosis factor-α to relieve inflammation, achieving complete full-thickness healing with thick dermis, dense hair follicles, and 90% collagen deposition. Importantly, this study provides a versatile strategy to construct biomimetic glycopolypeptide hydrogels that can not only resist vascular bursting pressure for arterial massive hemorrhage but also modulate inflammatory microenvironment for wound prohealing.

Coagulant Protein-Free Blood Coagulation Using Catechol-Conjugated Adhesive Chitosan/Gelatin Double Layer

Since the discovery of polyphenolic underwater adhesion in marine mussels, researchers strive to emulate this natural phenomenon in the development of adhesive hemostatic materials. In this study, bio-inspired hemostatic materials that lead to pseudo-active blood coagulation, utilizing traditionally passive polymer matrices of chitosan and gelatin are developed. The two-layer configuration, consisting of a thin, blood-clotting catechol-conjugated chitosan (CHI-C) layer and a thick, barrier-functioning gelatin (Geln) ad-layer, maximizes hemostatic capability and usability. The unique combination of coagulant protein-free condition with CHI-C showcases not only coagulopathy-independent blood clotting properties (efficacy) but also exceptional clinical potential, meeting all necessary biocompatibility evaluation (safety) without inclusion of conventional coagulation triggering proteins such as thrombin or fibrinogen. As a result, the CHI-C/Geln is approved by the Ministry of Food and Drug Safety (MFDS, Republic of Korea) as a class II medical device. Hemostatic efficacy observed in multiple animal models further demonstrates the superiority of CHI-C/Geln sponges in achieving quick hemostasis compared to standard treatments. This study not only enriches the growing body of research on mussel-inspired materials but also emphasizes the potential of biomimicry in developing advanced medical materials, contributing a promising avenue toward development of readily accessible and affordable hemostatic materials.

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

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

Alloy nanozyme-reinforced hyaluronic acid-based hydrogel with wound environment-responsive properties for synergistically accelerating infectious wound healing

The recovery of infectious wound tissues presents a significant global health challenge due to the impediments posed by the harsh healing microenvironment, which includes ongoing bacterial invasion, high oxidative stress, inflammatory response, and impaired angiogenesis. To overcome the above issues, we propose a composite hydrogel based on the multiple-crosslinked mechanism involving the covalent network of CC bonds within catechol and maleic-modified HA (CMHA), the self-assembly network of glycyrrhizic acid (GA), and the metal-polyphenol coordination induced by ZHMCe for accelerating infectious wound healing. The resulting CMHA/GA/ZHMCe hydrogels demonstrate enhanced mechanical, adhesive, antioxidative, and antibacterial properties. Importantly, the hydrogel system possesses wound environment-responsive properties that allow it to adapt to the specific therapeutic requirements of different stages by regulating various enzyme activities in the healing of infected wounds. Furthermore, the biocompatible CMHA/GA/ZHMCe shows the ability to promote cell migration and angiogenesis in vitro while reprogramming macrophages toward an anti-inflammatory phenotype due to the effective release of active ingredients. In vivo experiments confirm that the CMHA/GA/ZHMCe hydrogel significantly enhances infectious wound healing by accelerating re-epithelialization, promoting collagen deposition, regulating inflammation, and contributing to vascularization. These findings underscore the therapeutic potential of our hydrogel dressings for the treatment of bacterially infected cutaneous wound healing.

Plant mucus-derived microgels: Blood-triggered gelation and strong hemostatic adhesion

Arrest of bleeding usually applies clotting agents to trigger coagulation procedures or adhesives to interrupt blood flow through sealing the vessel; however, the efficiency is compromised. Here, we propose a concept of integration of hemostasis and adhesion via yam mucus's microgels. The mucus microgels exhibit attractive attributes of hydrogel with uniform size and shape. Their shear-thinning, self-healing and strong adhesion make them feasible as injectable bioadhesion. Exceptionally, the blood can trigger the microgels' gelation with the outcome of super extensibility, which leads to the microgels a strong hemostatic agent. We also found a tight gel adhesive layer formed upon microgels' contacting the blood on the tissue, where there is the coagulation factor XIII triggered to form a dense three-dimensional fibrin meshwork. The generated structures show that the microgels look like hard balls in the dispersed phase into the blood-produced fibrin mesh of a soft net phase. Both phases work together for a super-extension gel. We demonstrated the microgels' fast adhesion and hemostasis in the livers and hearts of rabbits and mini pigs. The microgels also promoted wound healing with good biocompatibility and biodegradability.

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.

A self-elastic chitosan sponge integrating active and passive hemostatic mechanisms for effectively managing uncontrolled coagulopathic hemorrhage

Developing a self-elastic sponge integrating active and passive hemostatic mechanisms for the effective management of uncontrolled coagulopathic hemorrhage remains a challenge. We here developed a chitosan-based sponge by integrating freeze-drying, chemical decoration of alkyl chains and phosphate groups, and physical loading of thrombin. The sponge exhibited high mechanical strength, self-elasticity, and rapid shape recovery. The sponge facilitated blood cell adhesion, aggregation, and activation through hydrophobic and electrostatic interactions, as well as accelerated blood clotting. The sponge exhibited higher efficacy than commercial gauze and gelatin sponge in managing uncontrolled hemorrhage from heparinized rat tail amputation, liver superficial injury, and liver perforating wound models. In addition, the sponge exhibited favorable biodegradability and biocompatibility. These findings revealed that the developed sponge holds great potential as a novel hemostat for effectively managing uncontrolled coagulopathic hemorrhage from superficial and perforating wounds.

Carbonized Cellulose Aerogel Derived from Waste Pomelo Peel for Rapid Hemostasis of Trauma-Induced Bleeding

Uncontrollable massive bleeding caused by trauma will cause the patient to lose a large amount of blood and drop body temperature quickly, resulting in hemorrhagic shock. This study aims to develop a hemostatic product for hemorrhage management. In this study, waste pomelo peel as raw material is chosen. It underwent processes of carbonization, purification, and freeze-drying. The obtained carbonized pomelo peel (CPP) is hydrophilic and exhibits a porous structure (nearly 80% porosity). The water/blood absorption ratio is significantly faster than the commercial Gelfoam and has a similar water/blood absorption capacity. In addition, the CPP showed a water-triggered shape-recoverable ability. Moreover, the CPP shows ideal cytocompatibility and blood compatibility in vitro and favorable tissue compatibility after long terms of subcutaneous implantation. Furthermore, CPP can absorb red blood cells and fibrin. It also can absorb platelets and activate platelets, and it is capable of achieving rapid hemostasis on the rat tail amputation and hepatectomized hemorrhage model. In addition, the CPP not only can quickly stop bleeding in the rat liver-perforation and rabbit heart uncontrolled hemorrhage models, but also promotes rat liver and rabbit heart tissue regeneration in situ. These results suggest the CPP has shown great potential for managing uncontrolled hemorrhage.

Sticky and Strain-Gradient Artificial Epineurium for Sutureless Nerve Repair in Rodents and Nonhuman Primates

The need for the development of soft materials capable of stably adhering to nerve tissues without any suturing followed by additional damages is at the fore at a time when success in postoperative recovery depends largely on the surgical experience and/or specialized microsuturing skills of the surgeon. Despite fully recognizing such prerequisite conditions, designing the materials with robust adhesion to wet nerves as well as acute/chronic anti-inflammation remains to be resolved. Herein, a sticky and strain-gradient artificial epineurium (SSGAE) that overcomes the most critically challenging aspect for realizing sutureless repair of severely injured nerves is presented. In this regard, the SSGAE with a skin-inspired hierarchical structure entailing strain-gradient layers, anisotropic Janus layers including hydrophobic top and hydrophilic bottom surfaces, and synergistic self-healing capabilities enables immediate and stable neurorrhaphy in both rodent and nonhuman primate models, indicating that the bioinspired materials strategy significantly contributes to translational medicine for effective peripheral nerve repair.

Thermoresponsive Gels with Embedded Starch Microspheres for Optimized Antibacterial and Hemostatic Properties

Apart from single hemostasis, antibacterial and other functionalities are also desirable for hemostatic materials to meet clinical needs. Cationic materials have attracted great interest for antibacterial/hemostatic applications, and it is still desirable to explore rational structure design to address the challenges in balanced hemostatic/antibacterial/biocompatible properties. In this work, a series of cationic microspheres (QMS) were prepared by the facile surface modification of microporous starch microspheres with a cationic tannic acid derivate, the coating contents of which were adopted for the first optimization of surface structure and property. Thermoresponsive gels with embedded QMS (F-QMS) were further prepared by mixing a neutral thermosensitive polymer and QMS for second structure/function optimization through different QMS and loading contents. In vitro and in vivo results confirmed that the coating content plays a crucial role in the hemostatic/antibacterial/biocompatible properties of QMS, but varied coating contents of QMS only lead to a classical imperfect performance of cationic materials. Inspiringly, the F-QMS-4 gel with an optimal loading content of QMS4 (with the highest coating content) achieved a superior balanced in vitro hemostatic/antibacterial/biocompatible properties, the mechanism of which was revealed as the second regulation of cell-material/protein-material interactions. Moreover, the optimal F-QMS-4 gel exhibited a high hemostatic performance in a femoral artery injury model accompanied by the easy on-demand removal for wound healing endowed by the thermoresponsive transformation. The present work offers a promising approach for the rational design and facile preparation of cationic materials with balanced hemostatic/antibacterial/biocompatible properties.

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.

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.

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.

A Janus Gelatin Sponge with a Procoagulant Nanoparticle-Embedded Surface for Coagulopathic Hemostasis

Apart from the wide and safe application of natural polymer-based hemostatic materials/devices, it is still desirable to develop new types of hemostatic materials that can achieve both potent coagulopathic hemostasis and a facile preparation process. In this work, one Janus gelatin sponge (J-ZGS) is readily constructed for both coagulation-dependent and coagulopathic hemostasis by embedding zein nanoparticles on the surface of a self-prepared gelatin sponge (S-GS): zein nanoparticles were facilely prepared by an antisolvent method to achieve procoagulant blood-material interactions, while S-GS was prepared by freeze-drying a foaming gelatin solution. Due to the distinct secondary structure, the optimal zein nanoparticles possessed a higher in vitro hemostatic property than the pristine zein powder and other nanoparticles, the underlying mechanism of which was revealed as the superior RBC/platelet adhesion property in the presence/absence of plasma proteins. Compared with S-GS and a commercial gelatin sponge, J-ZGS achieved a significantly higher in vitro hemostatic property and similarly good blood compatibility/cytocompatibility. Moreover, in vivo artery-injury models confirmed the outstanding hemostatic performance of J-ZGS under both coagulation-dependent and coagulopathic conditions. Our work offers an appealing approach for developing potent hemostatic sponges from natural polymer-based nanoparticles that could be further extended to versatile hemostatic materials for coagulopathic hemostasis.

Tuning Blood-Material Interactions to Generate Versatile Hemostatic Powders and Gels

Polymer-based hemostatic materials/devices have been increasingly exploited for versatile clinical scenarios, while there is an urgent need to reveal the rational design/facile approach for procoagulant surfaces through regulating blood-material interactions. In this work, degradable powders (PLPS) and thermoresponsive gels (F127-PLPS) are readily developed as promising hemostatic materials for versatile clinical applications, through tuning blood-material interactions with optimized grafting of cationic polylysine: the former is facilely prepared by conjugating polylysine onto porous starch particle, while F127-PLPS is prepared by the simple mixture of PLPS and commercial thermosensitive polymer. In vitro and in vivo results demonstrate that PLPS2 with the optimal-/medium content of polylysine grafts achieve the superior hemostatic performance. The underlying procoagulant mechanism of PLPS2 surface is revealed as the selective fibrinogen adsorption among the competitive plasma-protein-adsorption process, which is the foundation of other blood-material interactions. Moreover, in vitro results confirm the achieved procoagulant surface of F127-PLPS through optimal PLPS2 loading. Together with the tunable thermoresponsiveness, F127-PLPS exhibits outstanding hemostatic utilization in both femoral-artery-injury and renal-artery-embolization models. The work thereby pioneers an appealing approach for generating versatile polymer-based hemostatic materials/devices.

Bioadhesive Technology Platforms

Bioadhesives have emerged as transformative and versatile tools in healthcare, offering the ability to attach tissues with ease and minimal damage. These materials present numerous opportunities for tissue repair and biomedical device integration, creating a broad landscape of applications that have captivated clinical and scientific interest alike. However, fully unlocking their potential requires multifaceted design strategies involving optimal adhesion, suitable biological interactions, and efficient signal communication. In this Review, we delve into these pivotal aspects of bioadhesive design, highlight the latest advances in their biomedical applications, and identify potential opportunities that lie ahead for bioadhesives as multifunctional technology platforms.

The In Vivo Fate of Polycatecholamine Coated Nanoparticles Is Determined by a Fibrinogen Enriched Protein Corona

Polycatecholamine coatings have attracted significant attention in the past 10 years owing to their ability to functionalize a wide range of materials. Here we apply the use of such coatings to drug nanocrystals, made from a poorly soluble drug compound, to postfunctionalize the nanocrystal surface with the aim of providing steric stabilization and extending their circulation time after intravenous injection. We show that both polydopamine and polynorepinephrine can be used to successfully modify drug nanocrystals and subsequently incorporate end-functionalized PEG to the surface. Even though high grafting densities of PEG were achieved, we observed rapid clearance and increased liver uptake for polycatecholamine functionalized drug nanocrystals. Using both surface sensitive model systems and protein corona profiling, we determine that the rapid clearance was correlated with an increase in adsorption of proteins involved in coagulation to the polycatecholamine surface, with fibrinogen being the most abundant. Further analysis of the most abundant proteins revealed a significant increase in thiol-rich proteins on polycatecholamine coated surfaces. The observed interaction with coagulation proteins highlights one of the current challenges using polycatecholamines for drug delivery but might also provide insights to the growing use of these materials in hemostatic applications.

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

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

Hydrophobic Polystyrene-Modified Gelatin Enhances Fast Hemostasis and Tissue Regeneration in Traumatic Brain Injury

Hemostatic sealant is required to deal with blood loss, especially in the scenario of traumatic brain injury (TBI), which presents high rates of morbidity and disability. Hemostasis in surgery with traditional gelatin-based sealants often leads to blood loss and other issues in brain because of the hydrophilic gelatin swelling. Herein, hydrophobic effects on the hemostasis in TBI surgery are studied by tuning the chain length of polystyrene (PS) onto methylacrylated gelatin (Gel-MA). The hydrophobicity and hemostatic efficiency can be tuned by controlling the length of PS groups. The platelet activation of modified sealants Gel-MA-2P, Gel-MA-P, and Gel-MA-0.5P is as much as 17.5, 9.1, and 2.1 times higher than Gel-MA in vitro. The hemostatic time of Gel-MA-2P, Gel-MA-P, and Gel-MA-0.5P groups is 2.0-, 1.6-, and 1.1-folds faster than that in Gel-MA group in TBI mice. Increased formation of fibrins and platelet aggregation can also be observed in vitro by scanning electron microscopy. Animal's mortality is lowered by 46%, neurologic deficiency is reduced by 1.5 times, and brain edema is attenuated by 10%. Protein expression is further investigated to exhibit toxic iron-related processes caused by delayed hemostasis and activation of platelets via PI3K/PKC-α signaling. The hydrophobic Gel-MA has the potential in hemostatic TBI and promotes nervous system recovery in brain with the potentials in clinics.

Tough and On-Demand Detachable Wet Tissue Adhesive Hydrogel Made from Catechol Derivatives with a Long Aliphatic Side Chain

Wet adhesion is critical in cases of wound closure, but it is usually deterred by the hydration layer on tissues. Inspired by dopamine-mediated underwater adhesion in mussel foot proteins, wet tissue adhesives containing catechol with 2-3 carbons side chains are reported mostly. To make wet adhesion of this type of adhesives much tougher, catechol derivatives with a long aliphatic side chain (≈10 atoms length) are synthesized. Then, a series of strong wet tissue adhesive hydrogels are prepared through photoinduced copolymerization of acrylic acid with synthetic monomers. The adhesive hydrogel has a high cohesion strength, that is, tensile strength and strain, and toughness of ≈1800 kPa, ≈540%, and ≈4100 kJ m-3 , respectively. Its interfacial toughness on wet and underwater porcine skin is respectively ≈1300 and ≈1100 J m-2 , and its adhesion strength to wet porcine skin is ≈153 kPa. These values are much higher than those of dopamine-based adhesives in the same conditions, demonstrating that the long aliphatic side chain on catechol can greatly improve the wet tissue-adhesion. Additionally, the tough interfacial adhesion can be broken on demand with 5 wt.% aqueous urea solution. This adhesive hydrogel is highly promising in safe wound closure.

Targeted siRNA Delivery by Bioinspired Cancer Cell Membrane-Coated Nanoparticles with Enhanced Anti-Cancer Immunity

Introduction

Cell-membrane nanocarriers are usually constructed by modifying the nanoparticle surface with cell membrane extracts, which has a direct benefit in endowing targeting capacity to nanocarriers based on their original cell types. However, delivering nucleic acid cargos by cell membrane-based nanoparticles is difficult owing to the strong negative charge of the cell membrane fraction. In this study, we developed a cancer cell membrane-based drug delivery system, the cMDS, for efficient siRNA delivery. Meanwhile, the cancer-specific immune response stimulated by the gene vector itself could offer synergistic anti-cancer ability.

Methods

The cMDS was prepared by ultrasound, and its transfection efficiency and anti-cancer ability were examined using cultures of CT26 cells. MTT and red blood cell hemolysis tests were performed to assess the safety of cMDS, while its targeted gene delivery and strong immune stimulation were investigated in a subcutaneous tumor model. Moreover, the detailed anti-cancer immune stimulation mechanisms of cMDS are uncovered by protein chip analysis.

Results

The cMDS was spherical core-shell structure. It showed high transfection efficiency and anti-cancer ability in vitro. In animal experiments, intravenously administered cMDS/siStat3 complex efficiently suppress the growth of colon cancer. Moreover, the result of protein chip analysis suggested that cMDS affect the migration and chemotaxis of immune cells.

Conclusion

The cMDS shows obvious tumor tissue-specific accumulation properties and strong immune stimulation ability. It is an advanced targeted gene delivery system with potent immunotherapeutic properties.

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.

A Mechanically Resilient and Tissue-Conformable Hydrogel with Hemostatic and Antibacterial Capabilities for Wound Care

Hydrogels are used in wound dressings because of their tissue-like softness and biocompatibility. However, the clinical translation of hydrogels remains challenging because of their long-term stability, water swellability, and poor tissue adhesiveness. Here, tannic acid (TA) is introduced into a double network (DN) hydrogel consisting of poly(vinyl alcohol) (PVA) and poly(acrylic acid) (PAA) to realize a tough, self-healable, nonswellable, conformally tissue-adhesive, hemostatic, and antibacterial hydrogel. The TA within the DN hydrogel forms a dynamic network, enabling rapid self-healing (within 5 min) and offering effective energy dissipation for toughness and viscoelasticity. Furthermore, the hydrophobic moieties of TA provide a water-shielding effect, rendering the hydrogel nonswellable. A simple chemical modification to the hydrogel further strengthens its interfacial adhesion with tissues (shear strength of ≈31 kPa). Interestingly, the TA also can serve as an effective hemostatic (blood-clotting index of 58.40 ± 1.5) and antibacterial component, which are required for a successful wound dressing. The antibacterial effects of the hydrogel are tested against Escherichia coli and Staphylococcus aureus. Finally, the hydrogel is prepared in patch form and applied to a mouse model to test in vivo biocompatibility and hemostatic performances.

Advances in haemostatic sponges: Characteristics and the underlying mechanisms for rapid haemostasis

In traumatized patients, the primary cause of mortality is uncontrollable continuous bleeding and unexpected intraoperative bleeding which is likely to increase the risk of complications and surgical failure. High expansion sponges are effective clinical practice for the treatment of wound bleeding (irregular/deep/narrow) that are caused by capillaries, veins and even arterioles as they possess a high liquid absorption ratio so can absorb blood platelets easily in comparison with traditional haemostasis treatments, which involve compression, ligation, or electrical coagulation etc. When in contact with blood, haemostatic sponges can cause platelet adhesion, aggregation, and thrombosis, preventing blood from flowing out from wounds, triggering the release of coagulation factors, causing the blood to form a stable polymerized fibre protein, forming blood clots, and achieving the goal of wound bleeding control. Haemostatic sponges are found in a variety of shapes and sizes. The aim of this review is to facilitate an overview of recent research around haemostatic sponge materials, products, and technology. This paper reviews the synthesis, properties, and characteristics of haemostatic sponges, together with the haemostasis mechanisms of haemostatic sponges (composite materials), such as chitosan, cellulose, gelatin, starch, graphene oxide, hyaluronic acid, alginate, polyethylene glycol, silk fibroin, synthetic polymers silver nanoparticles, zinc oxide nanoparticles, mesoporous silica nanoparticles, and silica nanoparticles. Also, this paper reviews commercial sponges and their properties. In addition to this, we discuss various in-vitro/in-vivo approaches for the evaluation of the effect of sponges on haemostasis.

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.

Catechol-chitosan/carboxymethylated cotton-based Janus hemostatic patch for rapid hemostasis in coagulopathy

Uncontrolled bleeding is the leading cause of death, and the death risk of bleeding from coagulopathy is even higher. By infusing the relevant coagulation factors, bleeding in patients with coagulopathy can be clinically treated. However, there are not many emergency hemostatic products accessible for coagulopathy patients. In response, a Janus hemostatic patch (PCMC/CCS) with a two-layer structure of partly carboxymethylated cotton (PCMC) and catechol-grafted chitosan (CCS) was developed. Ultra-high blood absorption (4000 %) and excellent tissue adhesion (60 kPa) were both displayed by PCMC/CCS. The proteomic analysis revealed that PCMC/CCS has significantly contributed to the creative generation of FV, FIX, and FX, as well as to the substantial enrichment of FVII and FXIII, re-paving the initially blocked coagulation pathway of coagulopathy to promote hemostasis. The in vivo bleeding model of coagulopathy demonstrated that PCMC/CCS was substantially more effective than gauze and commercial gelatin sponge at achieving hemostasis in just 1 min. The study provides one of the first investigations on procoagulant mechanisms in anticoagulant blood conditions. Rapid hemostasis in coagulopathy will be significantly affected by the results of this experiment.

Less-Suture Vascular Anastomosis: Development of Alternative Protocols with Multifunctional Self-Wrapping, Transparent, Adhesive, and Elastic Biomaterials

Blood vessel anastomosis by suture is a life-saving, yet time-consuming and labor-intensive operation. While suture-less alternatives utilizing clips or related devices are developed to address these shortcomings, suture anastomosis is still overwhelmingly used in most cases. In this study, practical "less-suture" strategies are proposed, rather than ideal "suture-less" methods, to reflect real-world clinical situations. In the case of rat artery (d = 0.64 mm) anastomosis, the less-suture anastomosis involves the application of thin, adhesive, transparent, and self-wrapping films to the site. This surprisingly reduces the number of stitches required from ten (without films) to four (with films), saving 27 min of operating time per vessel. Furthermore, the decreased number of stitches largely alleviates fibrosis-mediated wall-thickening. Thus, a less-suture strategy is particularly useful for anastomosis of multiple vessels in emergency conditions and small-diameter vessels.

Injectable, self-healing hydrogel adhesives with firm tissue adhesion and on-demand biodegradation for sutureless wound closure

Tissue adhesives have garnered extensive interest as alternatives and supplements to sutures, whereas major challenges still remain, including weak tissue adhesion, inadequate biocompatibility, and uncontrolled biodegradation. Here, injectable and biocompatible hydrogel adhesives are developed via catalyst-free o-phthalaldehyde/amine (hydrazide) cross-linking reaction. The hydrogels demonstrate rapid and firm adhesion to various tissues, and an o-phthalaldehyde-mediated tissue adhesion mechanism is established. The hydrogel adhesives show controlled degradation profiles of 6 to 22 weeks in vivo through the incorporation of disulfide bonds into hydrogel network. In liver and blood vessel injury, the hydrogels effectively seal the incisions and rapidly stop bleeding. In rat and rabbit models of full-thickness skin incision, the hydrogel adhesives quickly close the incisions and accelerate wound healing, which exhibit efficacies superior to those of commercially available fibrin glue and cyanoacrylate glue. Thus, the hydrogel adhesives show great potential for sutureless wound closure, hemostasis sealing, and prevention of leakage in surgical applications.

UV cross-linked injectable non-swelling dihydrocaffeic acid grafted chitosan hydrogel for promoting wound healing

Hydrogels are widely used as wound dressings for wound healing, but when hydrogels absorb wound exudate, swelling occurs and compresses the surrounding tissue, affecting healing. A chitosan injectable (CS/4-PA/CAT) hydrogel based on catechol and 4-glutenoic acid was prepared to avoid swelling and promote wound healing. After cross-linking by UV light, pentenyl groups formed hydrophobic alkyl chains which give the hydrogel a hydrophobic network and thus control its swelling. CS/4-PA/CAT hydrogels retained their non-swelling for a long time in PBS solution at 37 °C. CS/4-PA/CAT hydrogels had good injectable and adhesive properties, and had a good killing effect on E. coli and S. aureus and could remove the bacterial biofilms of E. coli and S. aureus. CS/4-PA/CAT hydrogels had good in vitro coagulation function by absorbing red blood cells and platelets. When used in a whole skin injury model, CS/4-PA/CAT-1 hydrogel stimulated fibroblast migration, promoted epithelialization and accelerated collagen deposition to promote defect healing, and showed good hemostatic effects in liver and femoral artery defects in mice. In summary, the non-swelling injectable hydrogel with free radical scavenging, rapid hemostasis, and antibacterial effects would be a promising treatment for defect repair.

Chitosan-Based Biomaterials for Hemostatic Applications: A Review of Recent Advances

Hemorrhage is a detrimental event present in traumatic injury, surgery, and disorders of bleeding that can become life-threatening if not properly managed. Moreover, uncontrolled bleeding can complicate surgical interventions, altering the outcome of surgical procedures. Therefore, to reduce the risk of complications and decrease the risk of morbidity and mortality associated with hemorrhage, it is necessary to use an effective hemostatic agent that ensures the immediate control of bleeding. In recent years, there have been increasingly rapid advances in developing a novel generation of biomaterials with hemostatic properties. Nowadays, a wide array of topical hemostatic agents is available, including chitosan-based biomaterials that have shown outstanding properties such as antibacterial, antifungal, hemostatic, and analgesic activity in addition to their biocompatibility, biodegradability, and wound-healing effects. This review provides an analysis of chitosan-based hemostatic biomaterials and discusses the progress made in their performance, mechanism of action, efficacy, cost, and safety in recent years.

Super-Elastic Carbonized Mushroom Aerogel for Management of Uncontrolled Hemorrhage

Uncontrolled hemorrhage is still the most common cause of potentially preventable death after trauma in prehospital settings. However, there rarely are hemostatic materials that can achieve safely and efficiently rapid hemostasis simultaneously. Here, new carbonized cellulose-based aerogel hemostatic material is developed for the management of noncompressible torso hemorrhage, the most intractable issue of uncontrolled hemorrhage. The carbonized cellulose aerogel is derived from the Agaricus bisporus after a series of processing, including cutting, carbonization, purification, and freeze-drying. In vitro, the carbonized cellulose aerogels with porous structure show improved hydrophilicity, good blood absorption, and coagulation ability, rapid shape recoverable ability under wet conditions. And in vivo, the carbonized aerogels show effective hemostatic ability in both small and big animal serious hemorrhage models. The amount of blood loss and the hemostatic time of carbonized aerogels are all better than the positive control group. Moreover, the mechanism studies reveal that the good hemostatic ability of the carbonized cellulose aerogel is associated with high hemoglobin binding efficiency, red blood cell absorption, and platelets absorption and activation. Together, the carbonized aerogel developed in this study could be promising for the management of uncontrolled hemorrhage.

Colorimetric pH-responsive and hemostatic hydrogel-based bioadhesives containing functionalized silver nanoparticles

Here we develop and characterize a dual-cross-linked pH-responsive hydrogel based on the carboxyethyl chitosan-oxidized sodium alginate (CAO) containing silver nanoparticles (Ag NPs) functionalized with tannic acid/red cabbage (ATR). This hybrid hydrogel is formed via covalent and non-covalent cross-linking. The adhesive strength measured in contact with cow skin and compression strength is measured more than 3 times higher than that of CAO. Importantly, the incorporation of 1 ​wt% ATR into CAO significantly enhances the compression strength of CAO from 35.1 ​± ​2.1 ​kPa to 97.5 ​± ​2.9 ​kPa. Moreover, the cyclic compression tests confirm significantly higher elastic behavior of CAO after the addition of ATR-functionalized NPs to CAO. The CAO/ATR hydrogel is pH-sensitive and indicated remarkable color changes in different buffer solutions. The CAO/ATR also shows improved hemostatic properties and reduced clotting time compared to the clotting time of blood in contact with CAO hydrogel. In addition, while CAO/ATR is effective in inhibiting the growth of both Gram-positive and Gram-negative bacteria, CAO is only effective in inhibiting the growth of Gram-positive bacteria. Finally, the CAO/ATR hydrogel is cytocompatible with L929 fibroblasts. In summary, the resulting CAO/ATR hydrogel shows promising results in designing and constructing smart wound bioadhesives with high cytocompatibility, antibacterial properties, blood coagulation ability, and fast self-healing properties.

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.

A Super Tough, Rapidly Biodegradable, Ultrafast Hemostatic Bioglue

Death happening due to massive hemorrhage has been involved in military conflicts, traffic accidents, and surgical injuries of various human disasters. Achieving rapid and effective hemostasis to save lives is crucial in urgent massive bleeding situations. Herein, a covalent cross-linked AG-PEG glue based on extracellular matrix-like amino-gelatin (AG) and PEG derivatives is developed. The AG-PEG glue gelatinizes fast and exhibits firm and indiscriminate close adhesion with various moist tissues upon being dosed. The formed glue establishes an adhesive and robust barrier to seal the arterial, hepatic, and cardiac hemorrhagic wounds, enabling it to withstand up to 380 mmHg blood pressure in comparison with normal systolic blood pressure of 60-180 mmHg. Remarkably, massive bleeding from a pig cardiac penetrating hole with 6 mm diameter is effectively stopped using the glue within 60 s. Postoperative indexes of the treated pig gradually recover and the cardiac wounds regrow significantly at 14 days. Possessing on-demand solubility, self-gelling, and rapid degradability, the AG-PEG glue may provide a fascinating stop-bleeding approach for clinical hemostasis and emergency rescue.

Bioabsorbable Fibrillar Gauze Dressing Based on N-Carboxyethyl Chitosan Gelling Fibers for Fatal Hemorrhage Control

Death from lethal hemorrhage remains a major problem in various emergency scenarios. There is a continuous interest in the development of absorbable hemostatic dressings that can control hemorrhage rapidly and can be left in the wound site without removal. In this study, we report a hemostatic gauze dressing based on N-carboxyethyl chitosan (CECS) gelling fibers. The CECS fibrillar gauze combines ultra-hydrophilic, cationic chemical property of the fiber components with the fluffy nonwoven material form, exhibiting good conformability for wound filling, high fluid uptaking capacity, and enhanced blood-concentrating effect. In a swine femoral artery injury model, the CECS fibrillar gauze achieves shorter time to hemostasis and less blood loss compared with commercially available hemostatic dressings. This chitosan gelling fiber gauze demonstrates comparable bioabsorbability to clinically used absorbable hemostat and thus may be applied to treat fatal hemorrhage both in emergency medical services and in internal surgical procedures.

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.

A self-gelling starch-based sponge for hemostasis

Uncontrolled bleeding remains one of the direct causes of high mortality. There is an urgent need for developing emergency hemostats capable of coping with uncontrolled bleeding. The commercial starch-based hemostatic powder (PerClot®) requires compression during application, which limits its application in hemostasis of irregular and non-compressed wounds. Herein, a boronic acid-modified thiol starch sponge (St-SP sponge) with self-gelling properties was developed for hemorrhage control. The results show that the St-SP sponge could quickly absorb blood, self-gel and self-heal to seal the bleeding sites. In addition, the St-SP sponge can rapidly initiate the coagulation cascade and promote the adhesion and aggregation of erythrocytes and platelets. The St-SP sponge exhibited significantly improved in vitro and in vivo hemostatic abilities as compared with PerClot. Notably, the St-SP sponge attained complete hemostasis without any compression in 61.5 s and made a great difference compared to PerClot (169 s) for the irregular wound constructed on the rabbit liver. In addition, the St-SP sponge had good hemocompatibility and cytocompatibility. It turns out that the newly developed St-SP sponge is a promising material for first-aid hemostasis of irregular and non-compressed wounds.

A natural biological adhesive from snail mucus for wound repair

The discovery of natural adhesion phenomena and mechanisms has advanced the development of a new generation of tissue adhesives in recent decades. In this study, we develop a natural biological adhesive from snail mucus gel, which consists a network of positively charged protein and polyanionic glycosaminoglycan. The malleable bulk adhesive matrix can adhere to wet tissue through multiple interactions. The biomaterial exhibits excellent haemostatic activity, biocompatibility and biodegradability, and it is effective in accelerating the healing of full-thickness skin wounds in both normal and diabetic male rats. Further mechanistic study shows it effectively promotes the polarization of macrophages towards the anti-inflammatory phenotype, alleviates inflammation in chronic wounds, and significantly improves epithelial regeneration and angiogenesis. Its abundant heparin-like glycosaminoglycan component is the main active ingredient. These findings provide theoretical and material insights into bio-inspired tissue adhesives and bioengineered scaffold designs.

Superwetting Injectable Hydrogel with Ultrastrong and Fast Tissue Adhesion for Minimally Invasive Hemostasis

Injectable hydrogels have recently emerged as alternatives to sutures for various clinical indications. However, existing injectable hydrogels are unsuitable for hemostasis in minimally invasive surgery because of their weak interfacial adhesion and complex/prolonged processing. Herein, a superwetting injectable hydrogel composed of oppositely charged polysaccharides is developed. The spontaneous spreading of the injectable hydrogel on the surfaces achieves complete wetting and forms tight interfacial contact by absorbing the interfacial water. The superwetting ability and subsequent covalent crosslinking perform fast and ultrastrong wet adhesion (140 kPa) on the tissue surface. Ex vivo porcine and in vivo rat models show that the hydrogel successfully leads to the aggregation of erythrocytes for targeted hemostasis (in less than 12 s) without requiring external adjuncts, and no postsurgical adhesions to the peripheral tissues. This further demonstrates that hydrogel can act as an effective hemostasis agent in laparoscopic surgery in a rabbit model. Overall, the strong wet adhesion, antibacterial properties, and easy operability make this injectable hydrogel a promising candidate for hemostasis applications, as it can successfully combine clinical efficacy and transformation opportunities for minimally invasive surgery.

Nanochitin and Nanochitosan: Chitin Nanostructure Engineering with Multiscale Properties for Biomedical and Environmental Applications

Nanochitin and nanochitosan (with random-copolymer-based multiscale architectures of glucosamine and N-acetylglucosamine units) have recently attracted immense attention for the development of green, sustainable, and advanced functional materials. Nanochitin and nanochitosan are multiscale materials from small oligomers, rod-shaped nanocrystals, longer nanofibers, to hierarchical assemblies of nanofibers. Various physical properties of chitin and chitosan depend on their molecular- and nanostructures; translational research has utilized them for a wide range of applications (biomedical, industrial, environmental, and so on). Instead of reviewing the entire extensive literature on chitin and chitosan, here, recent developments in multiscale-dependent material properties and their applications are highlighted; immune, medical, reinforcing, adhesive, green electrochemical materials, biological scaffolds, and sustainable food packaging are discussed considering the size, shape, and assembly of chitin nanostructures. In summary, new perspectives for the development of sustainable advanced functional materials based on nanochitin and nanochitosan by understanding and engineering their multiscale properties are described.

Nanofibrous hemostatic materials: Structural design, fabrication methods, and hemostatic mechanisms

Development of rapid and effective hemostatic materials has always been the focus of research in the healthcare field. Nanofibrous materials which recapitulate the delicate nano-topography feature of fibrin fibers produced during natural hemostatic process, offer large length-to-diameter ratio and surface area, tunable porous structure, and precise control in architecture, showing great potential for staunching bleeding. Here we present a comprehensive review of advances in nanofibrous hemostatic materials, focusing on the following three important parts: structural design, fabrication methods, and hemostatic mechanisms. This review begins with an introduction to the physiological hemostatic mechanism and current commercial hemostatic agents. Then, it focuses on recent progress in electrospun nanofibrous hemostatic materials in terms of composition and structure control, surface modification, and in-situ deposition. The article emphasizes the development of three-dimensional (3D) electrospun nanofibrous materials and their emerging evolution for improving hemostatic function. Next, it discusses the fabrication of self-assembling peptide or protein-mimetic peptide nanofibers, co-assembling supramolecular nanofibers, as well as other nanofibrous hemostatic agents. Further, the article highlights the external and intracavitary hemostatic management based on various nanofiber aggregates. In the end, this review concludes with the current challenges and future perspectives of nanofibrous hemostatic materials. STATEMENT OF SIGNIFICANCE: This article reviews recent advances in nanofibrous hemostatic materials including fabrication methods, composition and structural control, performance improvement, and hemostatic mechanisms. A variety of methods including electrospinning, self-assembly, grinding and refining, template synthesis, and chemical vapor deposition, have been developed to prepare nanofibrous materials. These methods provide robustness in control of the nanofiber architecture in the forms of hydrogels, two-dimensional (2D) membranes, 3D sponges, or composites, showing promising potential in the external and intracavitary hemostasis and wound healing applications. This review will be of great interest to the broad readers in the field of hemostatic materials and multifunctional biomaterials.

Influence of Cedar Essential Oil on Physical and Biological Properties of Hemostatic, Antibacterial, and Antioxidant Polyvinyl Alcohol/Cedar Oil/Kaolin Composite Hydrogels

Polyvinyl alcohol (PVA) is a safe and biodegradable polymer. Given the unique physical and chemical properties of PVA, we physically cross-linked PVA with kaolin (K) and cedar essential oil (Ced) using the freeze-thawing approach to fabricate PVA/Ced/K sponge hydrogels as hemostatic, antibacterial, and antioxidant wound healing materials. The physicochemical characteristics of PVA/Ced/K hydrogels, including water swelling profiles and gel fractions, were surveyed. Additionally, the functional groups of hydrogels were explored by Fourier transform infrared spectroscopy (FTIR), while their microstructures were studied using scanning electron microscopy (SEM). Furthermore, the thermal features of the hydrogels were probed by thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC). Evidently, alterations in cedar concentrations resulted in significant variations in size, water uptake profiles, and hydrolytic degradation of the hydrogels. The incorporation of cedar into the PVA/K endowed the hydrogels with significantly improved antibacterial competency against Bacillus cereus (B. cereus) and Escherichia coli (E. coli). Moreover, PVA/Ced/K exhibited high scavenging capacities toward ABTS^•+ and DPPH free radicals. Beyond that, PVA/Ced/K hydrogels demonstrated hemocompatibility and fast blood clotting performance in addition to biocompatibility toward fibroblasts. These findings accentuate the prospective implementation of PVA/Ced/K composite hydrogel as a wound dressing.

Multifunctional 3D platforms for rapid hemostasis and wound healing: Structural and functional prospects at biointerfaces

354Fabrication of multifunctional hemostats is indispensable against chronic blood loss and accelerated wound healing. Various hemostatic materials that aid wound repair or rapid tissue regeneration has been developed in the last 5 years. This review provides an overview of the three-dimensional (3D) hemostatic platforms designed through the latest technologies like electrospinning, 3D printing, and lithography, solely or in combination, for application in rapid wound healing. We critically discuss the pivotal role of micro/nano-3D topography and biomaterial properties in mediating rapid blood clots and healing at the hemostat-biointerface. We also highlight the advantages and limitations of the designed 3D hemostats. We anticipate that this review will guide the fabrication of smart hemostats of the future for tissue engineering applications.

Platelet-Inspired Intravenous Nanomedicine for Injury-Targeted Direct Delivery of Thrombin to Augment Hemostasis in Coagulopathies

Severe hemorrhage associated with trauma, surgery, and congenital or drug-induced coagulopathies can be life-threatening and requires rapid hemostatic management via topical, intracavitary, or intravenous routes. For injuries that are not easily accessible externally, intravenous hemostatic approaches are needed. The clinical gold standard for this is transfusion of blood products, but due to donor dependence, specialized storage requirements, high risk of contamination, and short shelf life, blood product use faces significant challenges. Consequently, recent research efforts are being focused on designing biosynthetic intravenous hemostats, using intravenous nanoparticles and polymer systems. Here we report on the design and evaluation of thrombin-loaded injury-site-targeted lipid nanoparticles (t-TLNPs) that can specifically localize at an injury site via platelet-mimetic anchorage to the von Willebrand factor (vWF) and collagen and directly release thrombin via diffusion and phospholipase-triggered particle destabilization, which can locally augment fibrin generation from fibrinogen for hemostatic action. We evaluated t-TLNPs in vitro in human blood and plasma, where hemostatic defects were created by platelet depletion and anticoagulation. Spectrophotometric studies of fibrin generation, rotational thromboelastometry (ROTEM)-based studies of clot viscoelasticity, and BioFlux-based real-time imaging of fibrin generation under simulated vascular flow conditions confirmed that t-TLNPs can restore fibrin in hemostatic dysfunction settings. Finally, the in vivo feasibility of t-TLNPs was tested by prophylactic administration in a tail-clip model and emergency administration in a liver-laceration model in mice with induced hemostatic defects. Treatment with t-TLNPs was able to significantly reduce bleeding in both models. Our studies demonstrate an intravenous nanomedicine approach for injury-site-targeted direct delivery of thrombin to augment hemostasis.

Biodegradable Block Copolymer-Tannic Acid Glue

Bioadhesives are becoming an essential and important ingredient in medical science. Despite numerous reports, developing adhesive materials that combine strong adhesion, biocompatibility, and biodegradation remains a challenging task. Here, we present a biocompatible yet biodegradable block copolymer-based waterborne superglue that leads to an application of follicle-free hair transplantation. Our design strategy bridges self-assembled, temperature-sensitive block copolymer nanostructures with tannic acid as a sticky and biodegradable polyphenolic compound. The formulation further uniquely offers step-by-step increases in adhesion strength via heating-cooling cycles. Combining the modular design with the thermal treating process enhances the mechanical properties up to 5 orders of magnitude compared to the homopolymer formulation. This study opens a new direction in bioadhesive formulation strategies utilizing block copolymer nanotechnology for systematic and synergistic control of the material's properties.

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.

Non‐compressible wounds are a major source of high mortality in trauma victims. Here the authors report on the creation of xerogels impregnated with liquid adhesives which can rapidly absorb fluids promoting blood clotting while forming adhesions to tissue and demonstrate the xerogel in ex vivo and in vivo models.

Rational Design of Intelligent and Multifunctional Dressing to Promote Acute/Chronic Wound Healing

Currently, the clinic's treatment of acute/chronic wounds is still unsatisfactory due to the lack of functional and appropriate wound dressings. Intelligent and multifunctional dressings are considered the most advanced wound treatment modalities. It is essential to design and develop wound dressings with required functions according to the wound microenvironment in the clinical treatment. This work summarizes microenvironment characteristics of various common wounds, such as acute wound, diabetic wound, burns wound, scalded wound, mucosal wound, and ulcers wound. Furthermore, the factors of transformation from acute wounds to chronic wounds were analyzed. Then we focused on summarizing how researchers fully and thoroughly combined the complex microenvironment with modern advanced technology to ensure the usability and value of the dressing, such as photothermal-sensitive dressings, microenvironment dressing (pH-sensitive dressings, ROS-sensitive dressings, and osmotic pressure dressings), hemostatic dressing, guiding tissue regeneration dressing, microneedle dressings, and 3D/4D printing dressings. Finally, the revolutionary development of wound dressings and how to transform the existing advanced functional dressings into clinical needs as soon as possible have carried out a reasonable and meaningful outlook.

Janus mucosal dressing with a tough and adhesive hydrogel based on synergistic effects of gelatin, polydopamine, and nano-clay

There are many problems and challenges related to the treatment of highly prevalent oral mucosal diseases and oral drug delivery because of a large amount of saliva present in the oral cavity, the accompanying oral movements, and unconscious swallowing in the mouth. Therefore, an ideal oral dressing should possess stable adhesion and superior tough strength in the oral cavity. However, this fundamental requirement greatly limits the use of synthetic adhesive dressings for oral dressings. Here, we developed a mussel-inspired Janus gelatin-polydopamine-nano-clay (GPC) hydrogel with controlled adhesion and toughness through the synergistic physical and chemical interaction of gelatin (Gel), nano-clay, and dopamine (DA). The hydrogel not only exhibits strong wet adhesion force (63 kPa) but also has high toughness (1026 ± 100 J m^-3). Interfacial adhesion of hydrogels is achieved by modulating the interaction of catechol groups of the hydrogel with specific functional groups (e.g., NH₂, SH, OH, and COOH) on the tissue surface. The matrix dissipation of the hydrogel is regulated by physical crosslinking of gelatin, chemical crosslinking of gelatin with polydopamine (Michael addition and Schiff base formation), and nano-clay-induced constraint of the molecular chain. In addition, the GPC hydrogel shows high cell affinity and favors cell adhesion and proliferation. The hydrogel's instant and strong mucoadhesive properties provide a long-lasting therapeutic effect of the drug, thereby enhancing the healing of oral ulcers. Therefore, mussel-inspired wet-adhesion Janus GPC hydrogels can be used as a platform for mucosal dressing and drug delivery systems. STATEMENT OF SIGNIFICANCE: It is a great challenge to treat oral mucosal diseases due to the large amount of saliva present in the oral cavity, the accompanying oral movements, unconscious swallowing, and flushing of drugs in the mouth. To overcome the significant limitations of clinical bioadhesives, such as weakness, toxicity, and poor usage, in the present study, we developed a simple method through the synergistic effects of gelatin, polydopamine, and nano-clay to prepare an optimal mucosal dressing (Janus GPC) that integrates Janus, adhesion, toughness, and drug release property. It fits effectively in the mouth, resists saliva flushing and oral movements, provides oral drug delivery, and reduces patient discomfort. The Janus GPC adhesive hydrogels have great commercial potential to support further the development of innovative therapies for oral mucosal diseases.