Recent Advances in Hemostasis at the Nanoscale

Superhydrophobic Cellulose Nanofiber Aerogels for Efficient Hemostasis with Minimal Blood Loss

Reducing unnecessary blood loss in hemostasis is a major challenge for traditional hemostatic materials due to uncontrolled blood absorption. Tuning the hydrophilic and hydrophobic properties of hemostatic materials provides a road to reduce blood loss. Here, we developed a superhydrophobic aerogel that enabled remarkably reduced blood loss. The aerogel was fabricated with polydopamine-coated and fluoroalkyl chain-modified bacterial cellulose via a directional freeze-drying method. Primarily, the hydrophobic feature prevented blood from uncontrolled absorption by the material and overflowing laterally. Additionally, the aerogel had a dense network of channels that allowed it to absorb water from blood due to the capillary effect, and fluoroalkyl chains trapped the blood cells entering the channels to form a compact barrier via hydrophobic interaction at the bottom of the aerogel, causing quick fibrin generation and blood coagulation. The animal experiments reveal that the aerogel reduced the hemostatic time by 68% and blood loss by 87 wt % compared with QuikClot combat gauze. The study demonstrates the superiority of superhydrophobic aerogels for hemostasis and provides new insights into the development of hemostatic materials.

Design of chitosan-based drug-loaded laminated materials with superhydrophilic/superhydrophobic properties for simultaneous effective hemostasis and antiadhesion

Hemostatic materials play a crucial role in trauma medicine. However, existing materials have poor hemostatic efficacy and a tendency to adhere to the wound surface, limiting their clinical effectiveness. Herein, a drug-loaded, superhydrophilic/superhydrophobic laminated material (DSLM), consisting of a superhydrophobic inner layer with a micropore array, a superhydrophilic chitosan-based sponge layer loaded with hemostatic/antimicrobial drugs, and a superhydrophobic outer layer, was developed. Furthermore, the DSLM allows unidirectional flow of blood and exudates from the wound bed through the superhydrophobic inner layer while facilitating efficient drug delivery. In addition, it possesses excellent biocompatibility and antiadhesion properties, as confirmed by in vivo and in vitro experiments. Compared with traditional hemostatic materials, the DSLM remarkably increased the survival time by over threefold in the acute femoral transaction wound bleeding model, and simultaneously prevented secondary wound damage by reducing peeling force to one-eighth incomparison to pristine gauze. The DSLM holds promise as a versatile clinical biomaterial for prehospital acute trauma treatment, with its simple structure facilitating manufacturing and expanding applications in biomedicine.

Self-healing, antioxidant, and antibacterial Bletilla striata polysaccharide-tannic acid dual dynamic crosslinked hydrogels for tissue adhesion and rapid hemostasis

Biomaterials capable of achieving effective sealing and hemostasis at moist wounds are in high demand in the clinical management of acute hemorrhage. Bletilla striata polysaccharide (BSP), a natural polysaccharide renowned for its hemostatic properties, holds promising applications in biomedical fields. In this study, a dual-dynamic-bonds crosslinked hydrogel was synthesized via a facile one-pot method utilizing poly(vinyl alcohol) (PVA)-borax as a matrix system, followed by the incorporation of BSP and tannic acid (TA). Chemical borate ester bonds formed around borax, coupled with multiple physical hydrogen bonds between BSP and other components, enhanced the mechanical properties and rapid self-healing capabilities. The catechol moieties in TA endowed the hydrogel with excellent adhesive strength of 30.2 kPa on the surface of wet tissues and facilitated easy removal without residue. Benefiting from the synergistic effect of TA and the preservation of the intrinsic properties of BSP, the hydrogel exhibited outstanding biocompatibility, antibacterial, and antioxidant properties. Moreover, it effectively halted acute bleeding within 31.3 s, resulting in blood loss of 15.6 % of that of the untreated group. As a superior hemostatic adhesive, the hydrogel in this study is poised to offer a novel solution for addressing future acute hemorrhage, wound healing, and other biomedical applications.

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.

Development of an efficient hemostatic material based on cuttlefish ink nanoparticles loaded in cuttlebone biocomposite

Traumatic hemorrhage is one of the main causes of mortality in civilian and military accidents. This study aimed to evaluate the effectiveness of cuttlefish bone (cuttlebone, CB) and CB loaded with cuttlefish ink (CB-CFI) nanoparticles for hemorrhage control. CB and CB-CFI were prepared and characterized using different methods. The hemostasis behavior of constructed biocomposites was investigated in vitro and in vivo using a rat model. Results showed that CFI nanoparticles (NPs) are uniformly dispersed throughout the CB surface. CB-CFI10 (10 mg CFI in 1.0 g of CB) showed the best blood clotting performance in both in vitro and in vivo tests. In vitro findings revealed that the blood clotting time of CB, CFI, and CB-CFI10 was found to be 275.4 ± 12.4 s, 229.9 ± 19.9 s, and 144.0 ± 17.5 s, respectively. The bleeding time in rat liver injury treated with CB, CFI, and CB-CFI10 was 158.1 ± 9.2 s, 114.0 ± 5.7 s, and 46.8 ± 2.7 s, respectively. CB-CFI10 composite resulted in more reduction of aPTT (11.31 ± 1.51 s) in comparison with CB (17.34 ± 2.12 s) and CFI (16.79 ± 1.46 s) (p < 0.05). Furthermore, CB and CB-CFI10 exhibited excellent hemocompatibility. The CB and CB-CFI did not show any cytotoxicity on human foreskin fibroblast (HFF) cells. The CB-CFI has a negative surface charge and may activate coagulation factors through direct contact with their components, including CaCO3, chitin, and CFI-NPs with blood. Thus, the superior hemostatic potential, low cost, abundant, simple, and time-saving preparation process make CB-CFI a very favorable hemostatic material for traumatic bleeding control in clinical applications.

Clays and Wound Healing

Aluminosilicates, such as montmorillonite, kaolinite, halloysite, and diatomite, have a uniform bidimensional structure, a high surface-to-volume ratio, inherent stiffness, a dual charge distribution, chemical inertness, biocompatibility, abundant active groups on the surface, such as silanol (Si-OH) and/or aluminol (Al-OH) groups. These compounds are on the list of U.S. Food and Drug Administration-approved active compounds and excipients and are used for various medicinal products, such as wound healing agents, antidiarrheals, and cosmetics. This review summarizes the wound healing mechanisms related to the material characteristics and the chemical components. Numerous wound dressings with different active components and multiple forms have been studied. Then, medicinal mineral resources for use in hemostatic materials can be developed.

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.

Electrospun organic/inorganic hybrid nanofibers for accelerating wound healing: a review

Electrospun nanofiber membranes hold great promise as scaffolds for tissue reconstruction, mirroring the natural extracellular matrix (ECM) in their structure. However, their limited bioactive functions have hindered their effectiveness in fostering wound healing. Inorganic nanoparticles possess commendable biocompatibility, which can expedite wound healing; nevertheless, deploying them in the particle form presents challenges associated with removal or collection. To capitalize on the strengths of both components, electrospun organic/inorganic hybrid nanofibers (HNFs) have emerged as a groundbreaking solution for accelerating wound healing and maintaining stability throughout the healing process. In this review, we provide an overview of recent advancements in the utilization of HNFs for wound treatment. The review begins by elucidating various fabrication methods for hybrid nanofibers, encompassing direct electrospinning, coaxial electrospinning, and electrospinning with subsequent loading. These techniques facilitate the construction of micro-nano structures and the controlled release of inorganic ions. Subsequently, we delve into the manifold applications of HNFs in promoting the wound regeneration process. These applications encompass hemostasis, antibacterial properties, anti-inflammatory effects, stimulation of cell proliferation, and facilitation of angiogenesis. Finally, we offer insights into the prospective trends in the utilization of hybrid nanofiber-based wound dressings, charting the path forward in this dynamic field of research.

Recent Advances in Topical Hemostatic Materials

Untimely or improper treatment of traumatic bleeding may cause secondary injuries and even death. The traditional hemostatic modes can no longer meet requirements of coping with complicated bleeding emergencies. With scientific and technological advancements, a variety of topical hemostatic materials have been investigated involving inorganic, biological, polysaccharide, and carbon-based hemostatic materials. These materials have their respective merits and defects. In this work, the application and mechanism of the major hemostatic materials, especially some hemostatic nanomaterials with excellent adhesion, good biocompatibility, low toxicity, and high adsorption capacity, are summarized. In the future, it is the prospect to develop multifunctional hemostatic materials with hemostasis and antibacterial and anti-inflammatory properties for promoting wound healing.

A Visible Light Cross-Linked Underwater Hydrogel Adhesive with Biodegradation and Hemostatic Ability

Hydrogel adhesives with integrated functionalities are still required to match their ever-expanding practical applications in the field of tissue repair and regeneration. A simple and effective safety strategy is reported, involving an in situ injectable polymer precursor and visible light-induced cross-linking. This strategy enables the preparation of a hydrogel adhesive in a physiological environment, offering wet adhesion to tissue surfaces, molecular flexibility, biodegradability, biocompatibility, efficient hemostatic performance, and the ability to facilitate liver injury repair. The proposed one-step preparation process of this polymer precursor involves the mixing of gelatin methacryloyl (GelMA), poly(thioctic acid) [P(TA)], poly(acrylic acid)/amorphous calcium phosphate (PAAc/ACP, PA) and FDA-approved photoinitiator solution, and a subsequent visible light irradiation after in situ injection into target tissues that resulted in a chemically-physically cross-linked hybrid hydrogel adhesive. Such a combined strategy shows promise for medical scenarios, such as uncontrollable post-traumatic bleeding.

Recent advances in the application of clay-containing hydrogels for hemostasis and wound healing

INTRODUCTION

Immediate control of bleeding and anti-infection play important roles in wound management. Multiple organ dysfunction syndrome and death may occur if persistent bleeding, hemodynamic instability, and hypoxemia are not addressed. The combination of clay and hydrogel provides a new outlet for wound hemostasis. In this review, the current research progress of hydrogel/clay composite hemostatic agents was reviewed.

AREAS COVERED

This paper summarizes the characteristics of several kinds of clay including kaolinite, montmorillonite, laponite, sepiolite, and palygorskite. The advantages and disadvantages of its application in hemostasis were also summarized. Future directions for the application of hydrogel/clay composite hemostatic agents are presented.

EXPERT OPINION

Clay can activate the endogenous hemostatic pathway by increasing blood cell concentration and promoting plasma absorption to accelerate the hemostasis. Clay is antimicrobial due to the slow release of metal ions and has a rich surface charge with a high affinity for proteins and cells to promote tissue repair. Hydrogels have some properties such as good biocompatibility, strong adhesion, high stretchability, and good self-healing. Despite promising advances, hydrogel/clay composite hemostasis remains a limitation. Therefore, more evidence is needed to further elucidate the risk factors and therapeutic effects of hydrogel/clay in hemostasis and wound healing.

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.

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

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

A Self-Assembly Pro-Coagulant Powder Capable of Rapid Gelling Transformation and Wet Adhesion for the Efficient Control of Non-Compressible Hemorrhage

Rapid and effective control of non-compressible massive hemorrhage poses a great challenge in first-aid and clinical settings. Herein, a biopolymer-based powder is developed for the control of non-compressible hemorrhage. The powder is designed to facilitate rapid hemostasis by its excellent hydrophilicity, great specific surface area, and adaptability to the shape of wound, enabling it to rapidly absorb fluid from the wound. Specifically, the powder can undergo sequential cross-linking based on "click" chemistry and Schiff base reaction upon contact with the blood, leading to rapid self-gelling. It also exhibits robust tissue adhesion through covalent/non-covalent interactions with the tissues (adhesive strength: 89.57 ± 6.62 KPa, which is 3.75 times that of fibrin glue). Collectively, this material leverages the fortes of powder and hydrogel. Experiments with animal models for severe bleeding have shown that it can reduce the blood loss by 48.9%. Studies on the hemostatic mechanism also revealed that, apart from its physical sealing effect, the powder can enhance blood cell adhesion, capture fibrinogen, and synergistically induce the formation of fibrin networks. Taken together, this hemostatic powder has the advantages for convenient preparation, sprayable use, and reliable hemostatic effect, conferring it with a great potential for the control of non-compressible hemorrhage.

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.

Hemostasis Strategies and Recent Advances in Nanomaterials for Hemostasis

The development of materials that effectively stop bleeding and prevent wound adhesion is essential in both military and medical fields. However, traditional hemostasis methods, such as cautery, tourniquets, and gauze, have limitations. In recent years, new nanomaterials have gained popularity in medical and health fields due to their unique microstructural advantages. Compared to traditional materials, nanomaterials offer better adhesion, versatility, and improved bioavailability of traditional medicines. Nanomaterials also possess advantages such as a high degree and stability, self-degradation, fewer side effects, and improved wound healing, which make them ideal for the development of new hemostatic materials. Our review provides an overview of the currently used hemostatic strategies and materials, followed by a review of the cutting-edge nanomaterials for hemostasis, including nanoparticles and nanocomposite hydrogels. The paper also briefly describes the challenges faced by the application of nanomaterials for hemostasis and the prospects for their future development.

Mussel-inspired methacrylated gelatin-dopamine/quaternized chitosan/glycerin sponges with self-adhesion, antibacterial activity, and hemostatic ability for wound dressings

It is one of the most emergent challenges to prepare wound dressings for quickly and effectively controlling profuse bleeding in clinical surgery and emergent accident. In this work, a novel strategy has been developed to prepare methacrylated gelatin-dopamine (GelMA-DA)/quaternized chitosan (QCS)/glycerol (Gly) composite sponges with good biocompatibility, tissue self-adhesion, antibacterial activity, and hemostatic ability. Results show that the GelMA-DA/QCS/Gly sponges display good biocompatibility and water absorption capacity. The lap shear strength of the GelMA-DA/QCS/Gly sponge with the GelMA-DA content of 5 W/V% is approximately 128.36 ± 8.45, 125.17 ± 7.18, 138.29 ± 7.94, and 113.83 ± 9.28 kPa for skin, liver, muscle, and fat, respectively. The GelMA-DA/QCS/Gly sponge displays better antibacterial activity against Gram positive and negative bacteria than the commercial Gelatin hemostatic sponge and CS hemostatic sponge. Animal experiments using rat tail and liver bleeding model show that the hemostasis time and blood loss in the GelMA-DA/QCS/Gly sponge group is approximately 33.3 ± 6.7 s and 0.19 ± 0.05 g, respectively, which is also better than that of the commercial Gelatin hemostatic sponge and CS hemostatic sponge. These results demonstrate promising potential of the GelMA-DA/QCS/Gly sponges for applications as hemostatic wound dressings in clinical surgery and emergent treatment.

Incorporation of mixed-dimensional palygorskite clay into chitosan/polyvinylpyrrolidone nanocomposite films for enhancing hemostatic activity

Clay mineral-based hemostatic materials have attracted much attention in recent years, but it is scarce to report the hemostatic nanocomposite films containing natural mixed-dimensional clay composed of natural one-dimensional and two-dimensional clay minerals. In this study, the high-performance hemostatic nanocomposite films were facilely prepared by incorporating the natural mixed-dimensional palygorskite clay leached by oxalic acid (O-MDPal) into chitosan/polyvinylpyrrolidone (CS/PVP) matrix. By contrast, the obtained nanocomposite films exhibited the higher tensile strength (27.92 MPa), lower water contact angel (75.40°), better degradation, thermal stability and biocompatibility after incorporation of 20 wt% of O-MDPal, suggesting that O-MDPal contributed to enhancing the mechanical performance and water holding capacity of the CS/PVP nanocomposite films. Compared with the medical gauze and CS/PVP matrix groups, the nanocomposite films also indicated excellent hemostatic performance evaluated by blood loss and hemostasis time indexes based on the mouse tail amputation model, which might be ascribed to the enriched hemostatic functional sites, and hydrophilic surface, robust physical barrier role of nanocomposite films. Therefore, the nanocomposite film exhibited a promising practical application in wound healing.

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.

Polysaccharide-based nanocomposites for biomedical applications: a critical review

Polysaccharides (PSA) have taken specific position among biomaterials for advanced applications in medicine. Nevertheless, poor mechanical properties are known as the main drawback of PSA, which highlights the need for PSA modification. Nanocomposites PSA (NPSA) are a class of biomaterials widely used as biomedical platforms, but despite their importance and worldwide use, they have not been reviewed. Herein, we critically reviewed the application of NPSA by categorizing them into generic and advanced application realms. First, the application of NPSA as drug and gene delivery systems, along with their role in the field as an antibacterial platform and hemostasis agent is discussed. Then, applications of NPSA for skin, bone, nerve, and cartilage tissue engineering are highlighted, followed by cell encapsulation and more critically cancer diagnosis and treatment potentials. In particular, three features of investigations are devoted to cancer therapy, i.e., radiotherapy, immunotherapy, and photothermal therapy, are comprehensively reviewed and discussed. Since this field is at an early stage of maturity, some other aspects such as bioimaging and biosensing are reviewed in order to give an idea of potential applications of NPSA for future developments, providing support for clinical applications. It is well-documented that using nanoparticles/nanomaterials above a critical concentration brings about concerns of toxicity; thus, their effect on cellular interactions would become critical. We compared nanoparticles used in the fabrication of NPSA in terms of toxicity mechanism to shed more light on future challenging aspects of NPSA development. Indeed, the neutralization mechanisms underlying the cytotoxicity of nanomaterials, which are expected to be induced by PSA introduction, should be taken into account for future investigations.

Nano-Enabled Chronic Wound Healing Strategies: Burn and Diabetic Ulcer Wounds

The human skin serves as the body’s first line of defense against the environment. Diabetes mellitus (DM) and 2nd–4th degree burns, on the other hand, affect the skin’s protective barrier features. Burn wounds, hypermetabolic state, and hyperglycemia compromise the immune system leading to chronic wound healing. Unlike acute wound healing processes, chronic wounds are affected by reinfections which can lead to limb amputation or death. The conventional wound dressing techniques used to protect the wound and provide an optimal environment for repair have their limitations. Various nanomaterials have been produced that exhibit distinct features to tackle issues affecting wound repair mechanisms. This review discusses the emerging technologies that have been designed to improve wound care upon skin injury. To ensure rapid healing and possibly prevent scarring, different nanomaterials can be applied at different stages of healing (hemostasis, inflammation, proliferation, remodeling).

Design of nanoconstructs that exhibit enhanced hemostatic efficiency and bioabsorbability

Hemorrhage is a prime cause of death in civilian and military traumatic injuries, whereby a significant proportion of death and complications occur prior to paramedic arrival and hospital resuscitation. Hence, it is crucial to develop hemostatic materials that are able to be applied by simple processes and allow control over bleeding by inducing rapid hemostasis, non-invasively, until subjects receive necessary medical care. This tutorial review discusses recent advances in synthesis and fabrication of degradable hemostatic nanomaterials and nanocomposites. Control of assembly and fine-tuning of composition of absorbable (i.e., degradable) hemostatic supramolecular structures and nanoconstructs have afforded the development of smart devices and scaffolds capable of efficiently controlling bleeding while degrading over time, thereby reducing surgical operation times and hospitalization duration. The nanoconstructs that are highlighted have demonstrated hemostatic efficiency pre-clinically in animal models, while also sharing characteristics of degradability, bioabsorbability and presence of nano-assemblies within their compositions.

Graphene-ophicalcite heterogeneous composite sponge for rapid hemostasis

Synergistic functionalization of interface coagulation stimulation and liquid absorption capacity is the key to improve the hemostatic efficiency of hemostats. Herein, we prepared a graphene-ophicalcite (OPH) heterogeneous composite sponge (GOCS) by using the heterogeneous gradient composite strategy. The sponge took cross-linked graphene sponge (CGS) as the main skeleton, allowing the OPH to be controllably positioned on the surface of GOCS. The heterogeneous strategy gave full play to the advantages of the material. On the one hand, GOCS had excellent liquid absorption ability, which enriched blood cells and other coagulation components at the wound interface after contacting blood. On the other hand, the OPH at the interface obviously activated platelets and rapidly triggered coagulation cascade reactions, exhibiting fast response and feedback characteristics for coagulation signals. Under the synergistic effects, the blood clotting index value of GOCS was reduced to 33.87 ± 9.97%, which was significantly lower than those of OPH (46.33 ± 16.85%) and CGS (67.53 ± 5.35%). Importantly, GOCS rapidly stopped bleeding within 51 s in the rat femoral artery model, suggesting its great potential in the field of hemostasis. Therefore, this study provides a new idea for the design and preparation of hemostatic materials via heterogeneous strategy.

Self-healing hydrogel based on polyphosphate-conjugated pectin with hemostatic property for wound healing applications

Self-healing hydrogels have important application in hemostasis and wound repairing. In this research, pectin based self-healing hydrogel was fabricated with conjugated polyphosphate for hemostatic and wound healing applications. The hydrogel formed without any stimulus and hydrogel kept its biocompatibility; at the same time, the hydrogel degraded completely by enzyme and in vivo. The polyphosphate conjugated hydrogel also showed self-healing property and sustained release performance with strong coagulation characteristic. More importantly, the in vivo experiment revealed that the polyphosphate conjugated hydrogel reduced the blood loss and hemostasis time in hemorrhage model; meanwhile, the hydrogel accelerated the wound repairing rate of the open wound by preventing bacterial invasion. Altogether, the PolyP conjugated hemostatic pectin-based hydrogel is a good candidate as wound dressing material applied in clinic or open wound repairing.

Keratin-based wound dressings: From waste to wealth

Keratin is a natural protein with a high content of cysteine residues (7-13%) and is widely found in hair, wool, horns, hooves, and nails. Keratin possesses abundant cell-binding motifs such as leucine-aspartate-valine (LDV), glutamate-aspartate-serine (EDS), and arginine-glycine-aspartate (RGD), which benefit cell attachment and proliferation. It has been confirmed that keratin plays important roles in every stage of wound healing, including hemostasis, inflammation, proliferation, and remodeling, making keratin-based materials good candidates for wound dressings. In combination with synthetic and natural polymers, keratin-based wound dressings in the forms of films, hydrogels, and nanofibers can be achieved with improved mechanical properties. This review focuses on the recent development of keratin-based wound dressings. Firstly, the physicochemical and biological properties of keratin, are systematically discussed. Secondly, the role of keratin in wound healing is proposed. Thirdly, the applications of keratin-based wound dressings are summarized, in terms of the forms and functionalization. Finally, the current challenges and future development of keratin-based wound dressings are presented.

A hemostatic keratin/alginate hydrogel scaffold with methylene blue mediated antimicrobial photodynamic therapy

Uncontrollable bleeding and infection are two of the most common causes of trauma-related death. Yet, developing safe materials with high hemostatic and antibacterial effectiveness remains a challenge. Keratin-based biomaterials have been reported to exhibit the functions of enhancing platelet binding and activating and facilitating fibrinogen polymerization. In this study, we designed a hemostatic material with good biodegradability, biocompatibility, hemostatic ability, and antibacterial function to solve the shortcomings of common hemostatic materials. Methylene blue-loaded keratin/alginate composite scaffolds were prepared by the freeze-gelation method. The composite scaffolds exhibited over 1600% liquid absorption, well-interconnected pores, good biocompatibility, and biodegradability. We find that the keratin/alginate composite scaffolds' synergistic action may significantly reduce hemostasis time. To prevent infection, the drug-loaded scaffolds generated high burst release by absorbing wound exudate in the early stages of wound healing. The results obtained by the antimicrobial photoinactivation assay in vitro suggest that an antimicrobial photodynamic effect might be triggered, thereby preventing the fast growth of colonies.

Addressing the Shortcomings of Polyphenol-Derived Adhesives: Achievement of Long Shelf Life for Effective Hemostasis

For rapid and effective hemostasis of uncontrollable bleeding, versatile hemostatic agents have been emerging. Among them, polyphenol-derived adhesives have attracted those hemostatic materials due to instantaneous formation of sticky barriers by robust interactions between the material and the serum proteins from wound. However, a critical challenge in such phenolic materials lies in long-term storage due to spontaneous oxidation under humid environments, leading to changes in hemostatic capability and adhesive strength. Here, we report a transparent hemostatic film consisting of gallol-conjugated chitosan (CHI-G) for minimizing the phenolic oxidation even for 3 months and maintaining strong tissue adhesiveness and its hemostatic ability. The film undergoes a phase transition from solid to injectable hydrogels at physiological pH for efficiently stopping internal and external hemorrhage. Interestingly, the hemostatic capability of the CHI-G hydrogels after 3 month storage depends on (i) the folded microstructure of the polymer with optimal gallol modification and (ii) an initial phase of either a solution state or a solid film. When the hydrogels are originated from the dehydrated film, their successful hemostasis is observed in a liver bleeding model. Our finding would provide an insight for design rationale of hemostatic formulations with long shelf-life.

Silk Fibroin-Based Biomaterials for Hemostatic Applications

Hemostasis plays an essential role in all surgical procedures. Uncontrolled hemorrhage is the primary cause of death during surgeries, and effective blood loss control can significantly reduce mortality. For modern surgeons to select the right agent at the right time, they must understand the mechanisms of action, the effectiveness, and the possible adverse effects of each agent. Over the past decade, various hemostatic agents have grown intensely. These agents vary from absorbable topical hemostats, including collagen, gelatins, microfibrillar, and regenerated oxidized cellulose, to biologically active topical hemostats such as thrombin, biological adhesives, and other combined agents. Commercially available products have since expanded to include topical hemostats, surgical sealants, and adhesives. Silk is a natural protein consisting of fibroin and sericin. Silk fibroin (SF), derived from silkworm Bombyx mori, is a fibrous protein that has been used mostly in fashion textiles and surgical sutures. Additionally, SF has been widely applied as a potential biomaterial in several biomedical and biotechnological fields. Furthermore, SF has been employed as a hemostatic agent in several studies. In this review, we summarize the several morphologic forms of SF and the latest technological advances on the use of SF-based hemostatic agents.

Preparation of Super Absorbent and Highly Active Fish Collagen Sponge and its Hemostatic Effect in vivo and in vitro

Effective control of acute wound hemorrhage caused by battlefields, car accidents, natural disasters can highly improve patients’ survival rates. Nevertheless, hemostatic materials on present market have various defects and limitations. This study utilizes tilapia to extract macromolecular type I collagen to prepare a new hemostatic sponge for controlling acute wound bleeding. The extracted fish collagen has high purity, uniform molecular size and high hydroxyproline content. The peptide chain structure and natural high-level structure are intactly preserved. The infrared absorption spectrum showcases that it preserves all the characteristic absorption bands of type I collagen. The developed hemostatic sponge has a uniform honeycomb-shaped porous structure and high water absorption capacity. The biological safety test illustrates that the sponge cell has good compatibility and it will not trigger any inflammatory reaction or immune rejection reactions in the body. The sponge cell could be degraded gradually and completely, which has good biocompatibility and degradation performance. The result of in vitro experiments shows that certain groups or structures in fish collagen molecules can combine specific sites on the surface of blood cells and platelets, which can quickly activate platelets and coagulation system to obtain better coagulation function. The result of In vivo experiments further shows that the fish collagen sponge has fast coagulation speed and low bleeding during the hemostasis process of rabbit ear arteries and rat liver wounds, which proves that it has excellent coagulation performance.

Advances in Hemostatic Wound Dressings: Clinical Implications and Insight

ABSTRACT

Hemorrhagic shock is one of the leading causes of prehospital death in the armed forces. In this state, the body begins to shut down because of blood volume depletion. In both civilian and military trauma, a significant number of hemorrhage deaths occur in the first several hours after injury. Researchers all over the globe are working to develop relatively inexpensive and easy-to-transport products to prevent soldiers from going into hemorrhagic shock. For example, many advances have been made during the last several years toward the development of ideal hemostatic dressings. No current hemostatic agents meet all of the requirements, but the ideal dressing would fulfill many important measures: minimizes or stops blood flow within minutes, contains hemostatic agents to enhance blood clotting, is easy to apply, does not need preapplication preparation, has a reasonably long shelf life, is safe to use, prevents bacterial or viral transmission, is stable at extreme temperatures, and is inexpensive. For this literature review, the authors conducted an extensive search of academic scientific databases for relevant keywords and assessed and summarized the results. This review aimed to identify recent advances in hemostatic wound dressings; summarize the currently available dressings and their supporting literature; and discuss the compositions, mechanisms of action, and clinical relevance of each category of dressing. In addition, case studies and suggestions for future research into hemorrhage control with new hemostatic agents are provided.

Hemostatic biomaterials to halt non-compressible hemorrhage

Non-compressible hemorrhage is an unmet clinical challenge, which occurs in inaccessible sites in the body where compression cannot be applied to stop bleeding. Current treatments reliant on blood transfusion are...

Microfluidic-based functional materials: new prospects for wound healing and beyond

Microfluidics has been applied to fabricate high-performance functional materials contributing to all physiological stages of wound healing. The advances of microfluidic-based functional materials for wound healing have been summarized.

Hydrogel-Based Biomaterials Engineered from Natural-Derived Polysaccharides and Proteins for Hemostasis and Wound Healing

Rapid and effective hemostasis is of great importance to improve the quality of treatment and save lives in emergency, surgical practice, civilian, and military settings. Traditional hemostatic materials such as tourniquets, gauze, bandages, and sponges have shown limited efficacy in the management of uncontrollable bleeding, resulting in widespread interest in the development of novel hemostatic materials and techniques. Benefiting from biocompatibility, degradability, injectability, tunable mechanical properties, and potential abilities to promote coagulation, wound healing, and anti-infection, hydrogel-based biomaterials, especially those on the basis of natural polysaccharides and proteins, have been increasingly explored in preclinical studies over the past few years. Despite the exciting research progress and initial commercial development of several hemostatic hydrogels, there is still a significant distance from the desired hemostatic effect applicable to clinical treatment. In this review, after elucidating the process of biological hemostasis, the latest progress of hydrogel biomaterials engineered from natural polysaccharides and proteins for hemostasis is discussed on the basis of comprehensive literature review. We have focused on the preparation strategies, physicochemical properties, hemostatic and wound-healing abilities of these novel biomaterials, and highlighted the challenges that needed to be addressed to achieve the transformation of laboratory research into clinical practice, and finally presented future research directions in this area.

Highly resilient, biocompatible, and antibacterial carbon nanotube/hydroxybutyl chitosan sponge dressing for rapid and effective hemostasis

Uncontrolled hemorrhage is the leading cause of trauma death. The development of safe and efficient hemostatic agents that can rapidly and effectively control bleeding is of great significance to rescue the injured. However, the mechanical, absorptive, and antibacterial properties of conventional two-dimensional hemostatic agents are not satisfactory. Herein, a series of effective three-dimensional hemostatic dressings (JWCNT/HBC sponges) are developed by chemical modification of joint-welded carbon nanotube (JWCNT) sponges with hydroxybutyl chitosan (HBC) for hemorrhage hemostasis. The JWCNT/HBC sponges exhibit high elasticity, porous structure, and suitable blood-absorption and blood-maintaining performance. Moreover, the introduction of HBC endows the JWCNT/HBC sponges with favorable blood compatibility and good antibacterial activity. The sponge treated with 0.5% HBC (JWCNT/0.5%HBC sponge) displays better antiseptic capability, faster blood clotting ability in vitro and shorter hemostasis time in vivo than the commercial gelatin sponge. The JWCNT/HBC sponges combine the advantages of JWCNT sponges and HBC in the adhesion and activation of platelets and red blood cells, thus becoming a good medical material for trauma hemostasis.

Advanced bioactive nanomaterials for biomedical applications

Bioactive materials are a kind of materials with unique bioactivities, which can change the cellular behaviors and elicit biological responses from living tissues. Bioactive materials came into the spotlight in the late 1960s when the researchers found that the materials such as bioglass could react with surrounding bone tissue for bone regeneration. In the following decades, advances in nanotechnology brought the new development opportunities to bioactive nanomaterials. Bioactive nanomaterials are not a simple miniaturization of macroscopic materials. They exhibit unique bioactivities due to their nanoscale size effect, high specific surface area, and precise nanostructure, which can significantly influence the interactions with biological systems. Nowadays, bioactive nanomaterials have represented an important and exciting area of research. Current and future applications ensure that bioactive nanomaterials have a high academic and clinical importance. This review summaries the recent advances in the field of bioactive nanomaterials, and evaluate the influence factors of bioactivities. Then, a range of bioactive nanomaterials and their potential biomedical applications are discussed. Furthermore, the limitations, challenges, and future opportunities of bioactive nanomaterials are also discussed.

Effects of degree of deacetylation on hemostatic performance of partially deacetylated chitin sponges

Chitin/chitosan hemostatic materials have long been studied for uncontrolled hemorrhage, an urgent clinical problem due to severe blood-vessel damage or hemophilia. As one of the basic structural parameters of chitin, the degree of deacetylation (DD) significantly affects the material's physical, chemical, as well as biological properties. In this study, partially deacetylated chitins with a wide range of DD (23-81%) were prepared by homogeneous deacetylation, and sponges with these various chitins were fabricated by freeze-drying to study the effects of DD on their hemostatic properties. Among all sponge samples, the chitosan sponge with a DD of 48% showed the highest water absorption, whole blood adsorption, RBC adsorption rate, and the best hemostatic performance in an uncontrolled bleeding model of the rat femoral artery, demonstrating that a certain proportion of acetyl amino and amino groups could also activate the coagulation system and promote the adhesion of platelet and erythrocyte.

Epinephrine-entrapped chitosan nanoparticles covered by gelatin nanofibers: A bi-layer nano-biomaterial for rapid hemostasis

Uncontrolled hemorrhage accounts for significant death risk both in trauma and surgery. Various bleeding control techniques have been emerged to augment hemostasis, which still has several limitations and drawbacks. In this study, epinephrine-entrapped chitosan nanoparticles were electrosprayed on a base pad and covered by a gelatin nanofiber layer (E-CS-Gl. Physico-chemical characteristics, hemocompatibility, cytotoxicity, and blood coagulation tests were studied in-vitro, and blood coagulation and hemostasis potential tests were performed in-vivo. The in-vitro results showed that the prepared nano-biomaterial is cytocompatible against HuGu cells. Also, hemocompatibility studies showed that PT and aPTT times did not change in comparison with the controls. Further blood coagulation study indicated that E-CS-Gl provides an ultimate interface to induce red blood cell absorption and aggregation, resulting in augmented blood coagulation. E-CS-Gl also caused rapid clotting in rat models of ruptured femoral artery and liver compared to controls. Findings exhibited that E-CS-Gl is a safe and effective hemostatic agent and provides a new approach for fast and safe hemorrhage control.

Fast acting hemostatic agent based on self-assembled hybrid nanofibers from chitosan and casein

Hemorrhage is a leading cause of preventable death in both military combat and civilian accidents. To overcome these challenges, an affordable and effective bandage is must required substance. A novel strategy is reported for developing chitosan-casein (CC) based self-assembled nanofibrous polyelectrolyte complex (PEC) for rapid blood clotting. The amide group (1630 cm^-1) and phosphate group (910 cm^-1) of chitosan-casein can form PEC at pH 8.2 ± 0.2. The PECs contain intertwined nanofibers (≤100 nm diameter) with a high surface area. Increasing chitosan percentage from 30% (CC30) to 50% (CC50) or 70% (CC70) results, increase in zeta potential of PEC from -9.14 ± 3.3 to 7.46 ± 3.7 and 14.8 ± 3.3 mV, respectively. Under in vitro conditions, the CC30, CC50, and CC70 PECs allow platelet adhesion and rapidly absorbs blood fluid to form mechanically stable blood clots within 9 ± 3, 16 ± 3, and 30 ± 4 s, respectively, which are better than Celox™ (90 ± 3 s). In vivo application of PEC (CC50) causes clotting within 37 ± 6 s of large (1 cm) arterial incision in rabbit models. The PEC is biocompatible with promising hemostatic efficiency. This is the first report of nanofibrous PEC from chitosan and casein for rapid clotting, to the best of our knowledge.

Biosafety risk assessment of nanoparticles: Evidence from food case studies

Nanotechnology provides a wide range of benefits in the food industry in improving food tastes, textures, sensations, quality, shelf life, and food safety. Recently, potential adverse effects such as toxicity and safety concerns have been associated with the increasing use of engineered nanoparticles in food industry. Additionally, very limited information is known concerning the behavior, properties and effects of food nano-materials in the gastrointestinal tract. There is explores the current advances and provides insights of the potential risks of nanoparticles in the food industry. Specifically, characteristics of food nanoparticles and their absorption in the gastrointestinal tract, the effects of food nanoparticles against the gastrointestinal microflora, and the potential toxicity mechanisms in different organs and body systems are discussed. This review would provide references for further investigation of nano-materials toxicity effect in foods and their molecular mechanisms. It will help to develop safer foods and expand nano-materials applications in safe manner.

Engineering Hydrogel Adhesion for Biomedical Applications via Chemical Design of the Junction

Hydrogel adhesion inherently relies on engineering the contact surface at soft and hydrated interfaces. Upon contact, adhesion normally occurs through the formation of chemical or physical interactions between the disparate surfaces. The ability to form these adhesion junctions is challenging for hydrogels as the interfaces are wet and deformable and often contain low densities of functional groups. In this Review, we link the design of the binding chemistries or adhesion junctions, whether covalent, dynamic covalent, supramolecular, or physical, to the emergent adhesive properties of soft and hydrated interfaces. Wet adhesion is useful for bonding to or between tissues and implants for a range of biomedical applications. We highlight several recent and emerging adhesive hydrogels for use in biomedicine in the context of efficient junction design. The main focus is on engineering hydrogel adhesion through molecular design of the junctions to tailor the adhesion strength, reversibility, stability, and response to environmental stimuli.

Hemostatic performance of chitosan-based hydrogel and its study on biodistribution and biodegradability in rats

Hemostasis is of great significance regardless of the smooth operation or postoperative recovery. Therefore, it is urgent to develop a hemostatic material with excellent biodegradability and biocompatibility. It is well known that both carboxymethyl chitosan and hyaluronic acid with biodegradability and biocompatibility have wound healing promoting property. Here, a degradable chitosan-based hydrogel was prepared based on carboxymethyl chitosan and cross-linked by oxidized hyaluronic acid. The hemostatic performance of the hydrogel in rat liver resection injury was evaluated which results showed that the hydrogel exhibited comparable hemostatic properties compared with Fibrin Sealant. In addition, the hydrogel proved to be rapidly absorbed by the body without significant accumulation in vivo, demonstrating good biodegradability and biocompatibility. The overall results suggested the hydrogel will be a promising hemostatic hydrogel for controlling bleeding.

Rapid Hemostasis Resulting from the Synergism of Self-Assembling Short Peptide and O-Carboxymethyl Chitosan

The development of novel hemostatic agents with distinct modes of action from traditional ones remains a formidable challenge. Self-assembling peptide hydrogels have emerged as a new hemostatic material, not only because of their inherent biocompatibility and biodegradability but also their designability. Especially, rational molecular design can make peptides and their hydrogelation responsive to biological cues. In this study, we demonstrated that transglutaminase-catalyzed reactions not only occurred among designed short peptide I₃QGK molecules but also between the peptide and a natural polysaccharide O-carboxymethyl chitosan. Because Factor XIII in the blood can rapidly convert into activated transglutaminase (Factor XIIIa) upon bleeding, these enzymatic reactions, together with the electrostatic attraction between the two hemostatic agents, induced a strong synergetic effect in promoting hydrogelation, blood coagulation, and platelet adhesion, eventually leading to rapid hemostasis. The study presents a promising strategy for developing alternative hemostatic materials and methods.

Hemostatic nanotechnologies for external and internal hemorrhage management

An uncontrolled hemorrhage can easily lead to death during surgery and military operations. Despite the significant advances in hemostatic research, there is still an urgent and increasing need for safer and more effective hemostatic materials. Recently, nanotechnologies have been receiving increasing interest owing to their unique advantages and have been propelling the developement of hemostatic materials. This review summarizes the fundamentals of hemostasis and emphasizes the recent developments regarding hemorrhage-related hemostatic nanotechnologies. In terms of external accessible hemorrhage management, natural and synthetic polymers and inorganic components that have been used in traditional hemostats provide novel nanoscale solutions. Regarding internal noncompressible hemorrhage management, current research endeavors are dedicated to the development of substitutes for blood components, and nanoformulated hemostatic drugs. This review also briefly discusses the main and persistent problems of hemostatic nanomaterials, including safety concerns and clinical translation challenges. This review is hoped to provide critical insight into hemostatic nanomaterial development.

In-situ Electrospinning for Intestinal Hemostasis

INTRODUCTION

During routine surgery, rapid hemostasis, especially the rapid hemostasis of internal organs, is very important. The emergence of in-situ electrospinning technology has fundamentally solved this problem. It exhibits a high speed of hemostasis, and no bleeding occurs after surgery. Thus, it is of great significance. The use of sutures in some human organs, such as the intestines and bladder, is inadequate because fluid leakage occurs due to the presence of pinholes.

METHODS

Three types of large intestine wounds with an opening of about 1 cm were investigated. They were untreated, treated by needle and threaded, and treated by hand-held electrospinning, respectively.

RESULTS

The results show that hand-held electrospinning technique effectively prevented the exudation of fluids in the intestinal tract. The average diameter of the nanofibrous membrane was about 0.5 μm with hole of several micrometers. It can be elongated 90% without breakage. The hand-held electrospinning device could be used with nitrile gloves, preventing the risk of infection caused by exposed hands.

DISCUSSION

This work can provide a reference for future animal experiments and clinical experiments. However, safety should be investigated before application.