Molecular imprinted macroporous chitosan coated mesoporous silica xerogels for hemorrhage control

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 Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR)-Cas9-Based Nanobomb against Carbapenem-Resistant Acinetobacter baumannii Infection through Cascade Reaction and Amplification Synergistic Effect

Carbapenems have been considered to be the preferred antibiotics against Acinetobacter baumannii thus far. However, carbapenem-resistant Acinetobacter baumannii (CRAB) has gradually escalated worldwide, and it frequently causes respiratory and bloodstream infections. Its resistance may lead to high mortality. Thus, there is an urgent need to develop antibacterial drugs. In our research, the pH-sensitive sgRNA-I/L@ZS nanosystem delivered imipenem and better released it in infected tissues to synergistically damage bacteria with nanoparticles. Gene editing of the CRISPR-Cas9 nanosystem amplified the synergistic effect by reversing the drug-resistance of imipenem. Nitric oxide, which l-arginine reacted with ROS to produce in cascade reaction and bacterial infection sites, was beneficial to heal the infected tissues and induce bacteria death for further enhancing antibacterial effects. In addition, this nanocomposite influenced host-bacteria interactions and restrained and destroyed biofilms. The sgRNA-I/L@ZS nanosystem, similar to a nanobomb, was a high-efficiency bactericide against CRAB. Eventually, in acute pneumonia and peritonitis mouse models, the sgRNA-I/L@ZS nanosystem could combat bacteria and protect tissues from infection. It had marked suppressive effects on inflammation and promoted healing and proliferation of infected tissues. This multifunctional nanosystem is expected to be an effective antibacterial agent in the clinic based on good biocompatibility and no toxic side effects. Therefore, developing the nanocomposites will take a favorable step toward solving intractable public health issues.

An improved blood hemorrhaging treatment using diatoms frustules, by alternating Ca and light levels in cultures

Hemorrhage control requires hemostatic materials that are both effective and biocompatible. Among these, diatom biosilica (DBs) could significantly improve hemorrhage control, but it induces hemolysis (the hemolysis rate > 5%). Thus, the purpose of this study was to explore the influence of Ca2+ biomineralization on DBs for developing fast hemostatic materials with a low hemolysis rate. Here, CaCl2 was added to the diatom medium under high light (cool white, fluorescent lamps, 67.5 µmol m-2 s-1), producing Ca-DBs-3 with a particle size of 40-50 μm and a Ca2+ content of Ca-DBs-3 obtained from the higher concentration CaCl2 group (6.7 mmol L-1) of 0.16%. The liquid absorption capacity of Ca-DBs-3 was 30.43 ± 0.57 times its dry weight; the in vitro clotting time was comparable to QuikClot® zeolite; the hemostatic time and blood loss using the rat tail amputation model were 36.40 ± 2.52 s and 0.39 ± 0.12 g, which were 40.72% and 19.50% of QuikClot® zeolite, respectively. Ca-DBs-3 showed no apparent toxicity to L929 cells (cell viability > 80%) and was non-hemolysis (the hemolysis rate < 2%). This study prepared Ca-DBs-3 with a rapid hemostatic effect and good biocompatibility, providing a path to develop diatom biosilica hemostatic materials.

Supplementary Information

The online version contains supplementary material available at 10.1007/s42995-023-00180-3.

Chitosan-coated halloysite nanotube magnetic microspheres for carcinogenic colorectal hemorrhage and liver laceration in albino rats

Carcinogenic colorectal hemorrhage can cause severe blood loss and longitudinal ulcer, which ultimately become fatal if left untreated. The present study was aimed to formulate targeted release gemcitabine (GC)-containing magnetic microspheres (MM) of halloysite nanotubes (MHMG), chitosan (MCMG), and their combination (MHCMG). The preparation of MM by magnetism was confirmed by vibrating sample magnetometry (VSM), the molecular arrangement of NH₂, alumina, and silica groups was studied by X-ray diffraction (XRD) and energy-dispersive spectroscopy (EDS), the hollow spherical nature of the proposed MM was observed by scanning electron microscopy (SEM), functional groups were characterized by Fourier transform infrared (FTIR) spectroscopy and thermochemical modification was studied by thermogravimetric analysis (TGA). In vitro thrombus formation showed a decreasing trend of hemostatic time for MMs in the order of MHMG3 < MCMG3 < MHCMG7, which was confirmed by whole blood clotting kinetics. Interestingly, rat tail amputation and liver laceration showed 3 folds increased clotting efficiency of optimized MHCMG7 compared to that of control. In vivo histopathological studies and cell viability assays confirmed the regeneration of epithelial cells. The negligible systemic toxicity of MHCMG7, more than 90% entrapment of GC and high % release in alkaline medium made the proposed MM an excellent candidate for the control of hemorrhage in colorectal cancer. Conclusively, the healing of muscularis and improved recovery of the colon from granulomas ultimately improved the therapeutic effects of GC-containing MMs. The combination of both HNT and CTS microspheres made them more targeted.

A novel sodium polyacrylate-based stasis dressing to treat lethal hemorrhage in a penetrating trauma swine model

BACKGROUND

Control of massive hemorrhage from penetrating wound sites is difficult in both combat and civilian settings. A new hemostatic dressing, sodium polyacrylate (PAAs)-based bag (PB), based on PAAs is designed for the first aid of massive penetrating hemorrhage. This study aimed to investigate the efficacy of PB in a penetrating trauma model in swine.

METHODS

A complex groin penetrating injury was produced in swine by completely excising the femoral vessels and surrounding muscles. After 15-second free bleeding, 18 healthy Guizhou female swine were administered PB (n = 6), CELOX-A (n = 6; Medtrade Products, Crewe, United Kingdom), or standard gauze (n = 6) for hemostatic intervention, followed by 3-minute compression if the bleeding persisted, with subsequent observation continuing for 1 hour. The primary outcomes included initial hemostasis, the incidence of applying manual pressure, and application time.

RESULTS

Sodium polyacrylate could rapidly absorb the liquid to expand, crosslink with a large number of red blood cells, induce cellular morphological alteration, and promote blood coagulation. Sodium polyacrylate-based bag and CELOX-A initiated and sustained hemostasis for 60 minutes, whereas 0% of the standard gauze achieved initial hemostasis. Maximum number of manual compressions were applied in standard gauze (6 of 6 [100%]), followed by CELOX-A (5 of 6 [80%]), while no manual pressure was required in the case of PB (0 of 6 [0%]). Application time for PB (19.0 ± 4.6 seconds) was significantly less than CELOX-A (169.0 ± 73.5 seconds) and standard gauze (187.8 ± 1.7 seconds).

CONCLUSION

We prepared a type of superabsorbent PAAs and made an original hemostatic dressing, PB. It can rapidly achieve durable hemostasis in the groin-penetrating trauma hemorrhage swine model without any external compression. The packet form makes PB easy to deploy and remove from wounds. Therefore, PB could be a promising hemostatic candidate for controlling penetrating hemorrhage.

Biological Application of Novel Biodegradable Cellulose Composite as a Hemostatic Material

Degradable hemostatic materials have unique advantages in reducing the amount of bleeding, shortening the surgical operation time, and improving patient prognosis. However, none of the current hemostatic materials are ideal and have disadvantages. Therefore, a novel biodegradable cellulose-based composite hemostatic material was prepared by crosslinking sodium carboxymethyl cellulose (CCNa) and hydroxyethyl cellulose (HEC), following an improved vacuum freeze-drying method. The resulting cellulose composite material was neutral in pH and spongy with a density of 0.042 g/cm³, a porosity of 77.68%, and an average pore size of 13.45 μm. The composite's compressive and tensile strengths were 0.1 MPa and 15.2 MPa, respectively. Under in vitro conditions, the composites were degraded gradually through petite molecule stripping and dissolution, reaching 96.8% after 14 days and 100% degradation rate at 21 days. When implanted into rats, the degradation rate of the composite was slightly faster, reaching 99.7% in 14 days and 100% in 21 days. Histology showed a stable inflammatory response and no evidence of cell degeneration, necrosis, or abnormal hyperplasia in the tissues around the embedded material, indicating good biocompatibility. In the hemorrhagic liver model, the time to hemostasis and the total blood loss in the cellulose composite group was significantly lower than in the medical gauze group and the blank control group (P < 0.05). These data indicate that the novel cellulose composite is a promising implantable hemostatic material in clinical settings.

Development of silk fibroin‑sodium alginate scaffold loaded silk fibroin nanoparticles for hemostasis and cell adhesion

During wound healing process, it is essential to promote hemostasis and cell adhesion. Herein, we incorporated a scaffold with nanoparticles to improve the hemostatic properties and stimulate cell adhesion. The nanoparticles were prepared by self-assembling of silk fibroin, and the scaffold loaded nanoparticles were synthesized by crosslinking and freeze-drying. Macroscopical images showed that the nanoparticles distributed uniformly and increased the surface roughness of scaffold pore wall. The addition of nanoparticles decreased the pore size, enhanced the compression strength, lowered the degradation rate, and maintained the resilience and water uptake capacity. Compared with pure scaffold, the scaffold loaded nanoparticles revealed higher blood clotting index and promoted platelets adhesion. Furthermore, in vitro tests showed that scaffold loaded nanoparticles exhibited excellent biocompatibility, and stimulation effects on cell proliferation, migration, and adhesion for both L929 cells and HUVECs. Therefore, the scaffold loaded nanoparticles possessed great potential as a wound dressing for efficient hemostasis and subsequent wound healing.

Silk Fibroin Based Formulations as Potential Hemostatic Agents

Effective hemorrhage control is indispensable for life-threatening emergencies in defense fields and civilian trauma. During major injuries, hemostatic agents are applied externally to mimic and accelerate the natural hemostasis process. Commercially available topical hemostatic agents are associated with several limitations, e.g., burning sensation, necrosis, futile in severe injuries, and high costs of the products. In the present study, we developed silk fibroin fiber-based formulations and evaluated their use as a cost-effective potential hemostatic agent with shortened clotting time. Silk fiber-based powder was produced following the alkaline hydrolysis process, wherein Bombyx mori silk fibroin fibers were treated with sodium hydroxide (NaOH) solution that randomly chopped the silk microfibers. Physicochemical reaction parameters, e.g., reaction temperature, molarity of NaOH solution, and incubation time, were optimized to achieve the maximum yield of microfibers. The surface properties of alkaline hydrolyzed silk microfibers (AHSMf) were analyzed by field emission scanning electron microscopy and energy dispersive X-ray studies. The water uptake capacity of AHSMf and the change in pH and temperature (∼30 °C) during blood clotting were analyzed. Further, the hemostatic potential of AHSMf was evaluated by an in vitro whole blood clotting assay using both goat and human blood. The in vitro studies demonstrated a reduced blood clotting time (CT = 20-30 s), prothrombin time (PT = ∼27%), and activated partial thromboplastin time (APTT = ∼14%) in the presence of AHSMf when compared to silk hydrogel powder (devoid of NaOH). Thus, the developed AHSMf could be a promising material to serve as a potential hemostatic agent.

Porcine liver injury model to assess tantalum-containing bioactive glass powders for hemostasis

This study evaluates compositions of tantalum-containing mesoporous bioactive glass (Ta-MBG) powders using a porcine fatal liver injury model. The powders based on (80-x)SiO₂-15CaO-5P₂O₅-xTa₂O₅ compositions with x = 0 (0Ta/Ta-free), 1 (1Ta), and 5 (5Ta) mol% were made using a sol-gel process. A class IV hemorrhage condition was simulated on the animals; hemodynamic data and biochemical analysis confirmed the life-threatening condition. Ta-MBGs were able to stop the bleeding within 10 min of their application while the bleeds in the absence of any intervention or in the presence of a commercial agent, Arista^TM (Bard Davol Inc., Rhode Island, USA) continued for up to 45 min. Scanning electron microscopy (SEM) imaging of the blood clots showed that the presence of Ta-MBGs did not affect clot morphology. Rather, the connections seen between fibrin fibers of the blood clot and Ta-MBG powders point towards the powders' surfaces embracing fibrin. Histopathological analysis of the liver tissue showed 5Ta as the only composition reducing parenchymal hemorrhage and necrosis extent of the tissue after their application. Additionally, 5Ta was also able to form an adherent clot in worst-case scenario bleeding where no adherent clot was seen before the powder was applied. In vivo results from the present study agree with in vitro results of the previous study that 5Ta was the best Ta-MBG composition for hemostatic purposes. Graphical abstract.

Insights into the Role of Biopolymer-Based Xerogels in Biomedical Applications

Xerogels are advanced, functional, porous materials consisting of ambient, dried, cross-linked polymeric networks. They possess characteristics such as high porosity, great surface area, and an affordable preparation route; they can be prepared from several organic and inorganic precursors for numerous applications. Owing to their desired properties, these materials were found to be suitable for several medical and biomedical applications; the high drug-loading capacity of xerogels and their ability to maintain sustained drug release make them highly desirable for drug delivery applications. As biopolymers and chemical-free materials, they have been also utilized in tissue engineering and regenerative medicine due to their high biocompatibility, non-immunogenicity, and non-cytotoxicity. Biopolymers have the ability to interact, cross-link, and/or trap several active agents, such as antibiotic or natural antimicrobial substances, which is useful in wound dressing and healing applications, and they can also be used to trap antibodies, enzymes, and cells for biosensing and monitoring applications. This review presents, for the first time, an introduction to biopolymeric xerogels, their fabrication approach, and their properties. We present the biological properties that make these materials suitable for many biomedical applications and discuss the most recent works regarding their applications, including drug delivery, wound healing and dressing, tissue scaffolding, and biosensing.

Ultra-small gold nanoclusters assembled on plasma polymer-modified zeolites: a multifunctional nanohybrid with anti-haemorrhagic and anti-inflammatory properties

Hemostatic agents are pivotal for managing clinical and traumatic bleeding during emergency and domestic circumstances. Herein, a novel functional hybrid nanocomposite material consisting of plasma polymer-modified zeolite 13X and ultra-small gold nanoclusters (AuNCs) was fabricated as an efficient hemostatic agent. The surface of zeolite 13X was functionalised with amine groups which served as binding sites for carboxylate terminated AuNCs. Protein corona studies revealed the enhanced adsorption of two proteins, namely, coagulation factors and plasminogen as a result of AuNCs immobilization on the zeolite surface. The immune response studies showed that the hybrid nanocomposites are effective in reducing inflammation, which combined with a greater attachment of vitronectin, may promote wound healing. The hemostatic potential of the nanocomposite could be directly correlated with their immunomodulatory and anti-haemorrhagic properties. Together, the hybrid nanoengineered material developed in this work could provide a new avenue to tackle life-threatening injuries in civilian and other emergencies.

Origami Paper-Based Electrochemical (Bio)Sensors: State of the Art and Perspective

In the last 10 years, paper-based electrochemical biosensors have gathered attention from the scientific community for their unique advantages and sustainability vision. The use of papers in the design the electrochemical biosensors confers to these analytical tools several interesting features such as the management of the solution flow without external equipment, the fabrication of reagent-free devices exploiting the porosity of the paper to store the reagents, and the unprecedented capability to detect the target analyte in gas phase without any sampling system. Furthermore, cost-effective fabrication using printing technologies, including wax and screen-printing, combined with the use of this eco-friendly substrate and the possibility of reducing waste management after measuring by the incineration of the sensor, designate these type of sensors as eco-designed analytical tools. Additionally, the foldability feature of the paper has been recently exploited to design and fabricate 3D multifarious biosensors, which are able to detect different target analytes by using enzymes, antibodies, DNA, molecularly imprinted polymers, and cells as biocomponents. Interestingly, the 3D structure has recently boosted the self-powered paper-based biosensors, opening new frontiers in origami devices. This review aims to give an overview of the current state origami paper-based biosensors, pointing out how the foldability of the paper allows for the development of sensitive, selective, and easy-to-use smart and sustainable analytical devices.

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.

Hemostatic strategies for uncontrolled bleeding: A comprehensive update

Uncontrolled bleeding remains the leading cause of morbidity and mortality across the entire macrocosm. It refers to excessive loss of blood that occurs inside of body, due to unsuccessful platelet plug formation at the injury site. It is not only limited to the battlefield, but remains the second leading cause of death amongst the civilians, as a result of traumatic injury. Startlingly, there are no effective treatments currently available, to cater the issue of internal bleeding, even though early intervention is of utmost significance in minimizing the mortality rates associated with it. The fatal issue of uncontrolled bleeding is ineffectively being dealt with the use of pressure dressings, tourniquet, and surgical procedures. This is not a practical approach in combat arenas or in emergency situations, where the traumatic injury inflicted is deep inside the body, and cannot be addressed externally, by the application of topical dressings. This review focuses on the traditional hemostatic agents that are used to augment the process of hemostasis, such as mineral zeolites, chitosan based products, biologically active agents, anti-fibrinolytics, absorbable agents, and albumin and glutaraldehyde, as well as the micro- and nano-based hemostatic agents such as synthocytes, thromboerythrocytes, thrombosomes, and the synthetic platelets.

Tentative identification of key factors determining the hemostatic efficiency of diatom frustule

It is increasingly essential to develop excellent materials for rapid hemorrhage control. Our previous study showed that centric diatoms such as frustules were superior to QuikClot® in hemostasis, however, related studies in pennate diatoms are still scarce. The morphological and physicochemical properties of pennate diatoms are quite different from those of centric diatoms, meaning that significant differences may also be observed from their hemostatic effects. Thus, the hemostasis effects of four pennate diatom frustules (Cocconeiopsis orthoneoides, Navicula avium, Navicula sp., and Pleurosigma indicum) were investigated in this study. Herein, all diatom frustules demonstrated outstanding hemostasis performance. For example, the in vitro coagulation time of C. orthoneoides (100.33 ± 9.5 s) was 32.4% lower than that of QuikClot®. Meanwhile, the hemostatic times of C. orthoneoides in the rat tail amputation and femoral artery models were 82 s and 180 s, respectively, only around one-half and one-third of the QuikClot® values. Moreover, the blood loss amounts of C. orthoneoides in the rat tail amputation and femoral artery model were 73.4% and 61% less than that of QuikClot®. Besides that, diatom frustules also exhibited favorable biocompatibility (hemolysis ratio <5%, MEFs cell viabilities >80%, and no inflammation). To find out the key factors underlying the hemostatic effect of frustules, Pearson correlation analysis was further performed in this study. The results demonstrated that the coagulation reaction time (R) was negatively correlated with the specific surface area and liquid absorbability but positively with the diatom pore diameter. The angle α, indicating the clot formation rate, was negative to the diatom size and pore diameter. Additionally, MA also showed a negative correlation with the BET value. This study can enrich our knowledge about the application potential of diatoms in the field of bleeding control and is helpful in deepening our understanding about the hemostatic mechanism of frustules.

Fabricating poly(vinyl alcohol)/gelatin composite sponges with high absorbency and water-triggered expansion for noncompressible hemorrhage and wound healing

Composite sponges obtained from PVA and gelatin were synthesized by thiol–ene chemistry and used for controlling noncompressible hemorrhage.

Click-Grafting of Cardanol onto Mesoporous Silica/Silver Janus Particles for Enhanced Hemostatic and Antibacterial Performance

Janus particles with obvious chemical compartition can perform their functions independently, so they have attracted much attention in biomedical materials. Herein, a mesoporous silica/silver Janus nanoparticle modified with cardanol (C-MSN@Ag) was designed and synthesized via redox and click chemical reactions and was further evaluated as a highly efficient hemostatic dressing. This Janus structure endowed C-MSN@Ag with both prominent hemostatic and antibacterial performance. The hemostatic time of C-MSN@Ag on rat liver laceration was up to 40% shorter than that of MSN and MSN@Ag because of adhesion of phenolic compounds on the tissue and the blocking effect of the hydrophobic alkyl chains from cardanol. Besides, C-MSN@Ag could promote coagulation by forming a three-dimensional network with fibrin more quickly than MSN and MSN@Ag. Additionally, due to the released silver ions and phenolic hydroxyl groups of cardanol, C-MSN@Ag exhibited a broad-spectrum antibacterial rate (∼99%) against both Escherichia coli and Staphylococcus aureus. C-MSN@Ag also possessed non-cytotoxicity. This work not only provides a way for the fabrication of silica-based Janus hemostatic agents by the atom-economical click reaction but also gives a direction for the application of the sustainable naturally occurring cardanol.

Design and synthesis of a new topical agent for halting blood loss rapidly: A multimodal chitosan-gelatin xerogel composite loaded with silica nanoparticles and calcium

Uncontrolled hemorrhage often causes death during traumatic injuries and halting exsanguination topically is a challenge. Here, an efficient multimodal topical hemostat was developed by (i) ionically crosslinking chitosan and gelatin with sodium tripolyphosphate for (ii) fabricating a robust, highly porous xerogel by lyophilization having 86.7 % porosity, by micro-CT and large pores ∼30 μm by SEM (iii) incorporating 0.5 mg synthesized silica nanoparticles (SiNPs, 120 nm size, -22 mV charge) and 2.5 mM calcium in xerogel composite that was confirmed by FTIR analysis with peaks at 3372, 986 and 788 cm^-1, respectively. XPS analysis displayed the presence of SiNPs (Si2p peak for silicon) and calcium (Ca2p1, Ca2p3 transition peaks) in the composite. Interestingly, in silico percolation simulation for composite revealed interlinked 800 μm long-conduits predicting excellent absorption capacity and validated experimentally (640 % of composite dry weight). The composite achieved >16-fold improved blood clotting in vitro than commercial Celox and Gauze through multimodal interaction of its components with RBCs and platelets. The composite displayed good platelet activation and thrombin generation activities. It displayed high compressive strength (2.45 MPa) and withstood pressure during application. Moreover, xerogel composite showed high biocompatibility. In vivo application of xerogel composite to lethal femoral artery injury in rats achieved hemostasis (2.5 min) significantly faster than commercial Celox (3.3 min) and Gauze (4.6 min) and was easily removed from the wound. The gamma irradiated composite was stable till 1.5 yr. Therefore, the xerogel composite has potential for application as a rapid topical hemostatic agent.

A glimpse on the function of chitosan as a dental hemostatic agent

Managing a bleeding patient can be a challenge during dental surgery. Profuse hemorrhage due to platelet defects, coagulation disorders, vascular anomalies, medication-induced patients, as well as inherited bleeding ailments result in soft tissue hematoma, septic shock, compromised airway, and in some severe cases, death could occur. A vast array of surgical hemostatic agents are available to stop bleeding, including chitosan-based hemostatic agents. Chitosan has an advantage over other topical hemostatic materials for its ability to promote shorter bleeding times and assist in healing. Massive behind-the-scene research and development efforts are ongoing to increase the performance of chitosan as a hemostatic agent. Numerous studies on chitosan use in dental hemostasis have registered it as being safe, biodegradable, biocompatible, promoting healing, antimicrobial and bioactive. This article reviews the application of chitosan in managing hemostasis in dental patients.

Tantalum-containing mesoporous bioactive glass powder for hemostasis

This study evaluates the hemostatic properties of tantalum-containing mesoporous bioactive glasses (Ta-MBGs) through a suite of in-vitro methods: hemolysis percentage, zeta potential, blood coagulation assays (Activated Partial Thromboplastin Time - APTT and Prothrombin Time - PT) and cytotoxicity tests. Five compositions of Ta-MBG, with x mol% Ta₂O₅ added to the glass series (80-x)SiO₂-15CaO-5P₂O₅-xTa₂O₅ where x=0 (0Ta), x=0.5 (0.5Ta), x=1 (1Ta), x=5 (5Ta), and x=10 (10Ta) mol%, were synthesised. The hemostatic potential of all the Ta-MBGs was confirmed by their negative zeta potential (-23 to -31 mV), which enhances the intrinsic pathway of blood coagulation. The hemolysis percentages of all Ta-MBGs except 10Ta showed statistically significant reductions compared to the same experiments carried out both in the absence of a sample ('no treatment' group) and in the presence of 10Ta. These observations validate the consideration of Ta-MBGs as hemostatic agents as they do not cause significant lysis of red blood cells. Cytotoxicity analysis revealed that Ta-MBGs had no effect on bovine fibroblast viability. Furthermore, a reduction in both APTT (a test to evaluate the intrinsic pathway of coagulation) and PT (a test to evaluate the extrinsic pathway) signified enhancement of hemostasis: 5Ta caused a significant reduction in APTT compared to 'no treatment', 1Ta and 10Ta and a significant reduction in PT compared to 0Ta. Therefore, we conclude that 5mol% of Ta optimised the hemostatic properties of these mesoporous bioactive glasses.

Fabrication of Chitosan-Reinforced Multifunctional Graphene Nanocomposite as Antibacterial Scaffolds for Hemorrhage Control and Wound-Healing Application

Accidents on battlefields and roads often lead to hemorrhage and uncontrolled bleeding. Hence, immediate hemorrhage control remains of great importance to reduce mortality and socioeconomic loss. Herein, nanobiocomposite scaffolds (film and sponge) have been fabricated for the first time through the incorporation of a graphene-silver-polycationic peptide (GAP) nanocomposite into chitosan (Cs). Ten different scaffolds viz. Cs, Cs-GAP25, Cs-GAP50, Cs-GAP75, and Cs-GAP100 were prepared in the form of films and sponges. Cs-GAP100 nanobiocomposite sponge exhibited excellent porosity, fluid absorption, and blood clotting capacity, whereas Cs-GAP100 nanobiocomposite film showed excellent mechanical strength and poor degradation property. The presence of graphene in GAP provided a unique mechanical property and prevented the natural degradation, whereas silver nanoparticles and polycationic peptide provided an efficient antimicrobial property to the scaffolds. The high surface area of graphene and the hydrophilic nature of the polycationic peptide also imparted high fluid and blood absorption capacity to Cs-GAP nanobiocomposite scaffolds. The in vitro whole blood clotting assay demonstrated that clotting efficacy improved with the concentration of GAP nanocomposite and Cs-GAP100 nanobiocomposite sponge significantly (p value <0.003) reduced the clotting time to 60 s, as compared to the pristine chitosan dressings. On the other side, the Cs-GAP100 nanobiocomposite film showed an excellent wound-healing property. The Cs-GAP100 nanobiocomposite demonstrated profound antibacterial activity against Escherichia coli and Staphylococcus aureus. The intracellular reactive oxygen species (ROS) assay explained the interfacial interaction of Cs-GAP100 nanobiocomposite and bacterial cells, resulting in cell damage and finally cell death. The obtained information thus provided a novel safe-by-design concept for fabrication of Cs-GAP100 nanobiocomposite scaffolds and demonstrated potential development of antibacterial hemostatic and wound dressing in traumacare management.

Emerging chitin nanogels/rectorite nanocomposites for safe and effective hemorrhage control

Excessive bleeding due to trauma, surgery and diseases may cause severe mortalities. Here, an emerging chitin nanogel/rectorite nanocomposite is developed for effective hemorrhage control. Chitin chains are intercalated into rectorite and subsequent mechanical high speed stirring generates chitin nanogels, which assemble on the surface of the rectorite nanoplates through electrostatic interactions to form a sandwich structure. The in vitro experiments reveal that the nanocomposite exhibits favorable biocompatibility and negligible hemolysis (<3.5%) as compared to rectorite (40%). The nanocomposite stops bleeding in 121 s in rat tail incision and exhibits higher hemostatic activity in the rabbit artery injury model as compared to a commercialized chitosan hemostat, Celox. The efficient blood clotting activity is attributed to the induction of a coagulation cascade by rectorite and the quick adsorption and aggregation of platelets and red blood cells by chitin. The enhanced biocompatibility and hemostatic activity of the chitin/rectorite nanocomposite make it a safe and cost effective hemostat to control bleeding.

Silver-decorated mesostructured cellular silica foams as excellent antibacterial hemostatic agents for rapid and effective treatment of hemorrhage

Uncontrolled bleeding, such as deep, narrow or irregular wound hemorrhage, has been a major cause of death in peacetime and wartime. Besides, traditional hemostatic agents are lack of antibacterial properties, which could not provide effective protection on open wound. In this paper, a novel antibacterial hemostatic agent composed of mesostructured cellular silica foams (MCF) decorated with silver ions (MCF-Ag) was synthesized by hydrothermal method. Hemorrhage wound infected with Escherichia coli was applied to evaluate its antibacterial and hemostatic performance both in vitro and in vivo. Both MCF and MCF-Ag showed excellent hemostasis in vitro and in vivo. The MCF-Ag demonstrated significant antibacterial effect. By contrast, no obvious antibacterial effect was observed from the MCF. The above results demonstrate that the MCF-Ag is an excellent antibacterial hemostatic agent with splendid water absorption and antibacterial capacity.

In-vitro and in-vivo evaluation of modified sodium starch glycolate for exploring its haemostatic potential

The control of blood flow from breached blood vessels during surgery or trauma is challenging. With the existing treatment options being either expensive or ineffective, the development of a haemostat that overcome such drawbacks would be beneficial. With an aim to develop an ideal haemostat, the potential of sodium starch glycolate (SSG), a commonly used pharmaceutical disintegrant was modified to obtain porous microparticles (pSSG). The biodegradability, cyto-compatibility and haemo-compatibility of the modified particles were confirmed using appropriate studies. In comparison to starch and SSG, the irregular shaped pSSG demonstrated spontaneous and significant fluid absorption (3500+500 %) and formed a physical barrier to blood flow. In addition, significant blood cells aggregation and platelet activation was observed in the modified micoparticles leading to rapid clot formation. In-vivo studies on liver and abdominal artery injury models in rats indicated the superior haemostatic potential of pSSG over SSG and starch. The results indicated that pSSG can be explored further in clinical evaluation as a hemostat.

Research status and development potential of composite hemostatic materials

Through the discussion of the coagulation mechanism of compositehemostatic materials, the future development potential of hemostatic materials is proposed.

Absorbable nanocomposites composed of mesoporous bioglass nanoparticles and polyelectrolyte complexes for surgical hemorrhage control

Absorbable polyelectrolyte complexes-based hemostats are promising for controlling hemorrhage in iatrogenic injuries during surgery, whereas their hemostatic efficacy and other performances require further improvement for clinical application. Herein, spherical mesoporous bioglass nanoparticles (mBGN) were fabricated, and mBGN-polyelectrolyte complexes (composed of carboxymethyl starch and chitosan oligosaccharide) nanocomposites (BGN/PEC) with different mBGN contents were prepared via in situ coprecipitation followed by lyophilization. The effect of various mBGN content (10 and 20 wt%) on morphology, zeta potential, water absorption, degradation behavior and ion release were systematically evaluated. The in vitro degradability was dramatically promoted and a more neutral environment was achieved with the incorporation of mBGN, which is preferable for surgical applications. The in vitro coagulation test with whole blood demonstrated that the incorporation of mBGN facilitated blood clotting process. The plasma coagulation evaluation indicated that BGN/PEC had increased capability to accelerate coagulation cascade via the intrinsic pathway than that of the PEC, while have inapparent influence on the extrinsic and common pathway. The in vivo hemostatic evaluation in a rabbit hepatic hemorrhage model revealed that BGN/PEC with 10 wt% mBGN (10BGN/PEC) treatment group had the lowest blood loss, although its hemostatic time is close to that of 20BGN/PEC treatment group. The cytocompatibility evaluation with MC3T3-L1 fibroblasts indicated that 10BGN/PEC induced a ~25% increase of cell viability compared to the PEC at days 4 and 7, indicating improved biocompatibility. These findings support the promising application of absorbable BGN/PEC with optimized mBGN content as internal hemostats and present a platform for further development of PEC-based hemostats.

Recent Advances in Hemostasis at the Nanoscale

Rapid and effective hemostatic materials have received wide attention not only in the battlefield but also in hospitals and clinics. Traditional hemostasis relies on materials with little designability which has many limitations. Nanohemostasis has been proposed since the use of peptides in hemostasis. Nanomaterials exhibit excellent adhesion, versatility, and designability compared to traditional materials, laying a good foundation for future hemostatic materials. This review first summarizes current hemostatic methods and materials, and then introduces several cutting-edge designs and applications of nanohemostatic materials such as polypeptide assembly, electrospinning of cyanoacrylate, and nanochitosan. Particularly, their advantages and working mechanisms are introduced. Finally, the challenges and prospects of nanohemostasis are discussed.

Peptide-immobilized starch/PEG sponge with rapid shape recovery and dual-function for both uncontrolled and noncompressible hemorrhage

It is challenging for traditional hemostatic sponges to meet the clinic demand for both uncontrolled and noncompressible hemorrhage. With the aim to develop a rapid shape recovery material with both active and passive hemostatic performance, a dual-functional hemostatic sponge (TRAP-Sp) with a macroporous structure and good mechanical properties for controlling massive and noncompressible hemorrhage was prepared by chemically immobilizing thrombin-receptor-agonist-peptide (TRAP) onto a starch/polyethylene glycol (PEG) sponge. The TRAP2-Sp1 showed the best hemostatic performance among all samples in both rat artery uncontrollable hemorrhage and liver defect noncompressible hemorrhage models. When analyzing the hemostatic mechanism of TRAP-Sp, the high water absorption capacity of the sponge contributed to absorbing plasma, concentrating blood cells, and enhancing blood coagulation. After absorbing water, the shape-fixed TRAP-Sp with sufficient mechanical strength and high resilience can rapidly expand and apply pressure to the wound. TRAP immobilized on the sponge could activate the adhered platelets in an active pathway. Additionally, evaluation of cytotoxicity, hemolysis, and histology further highlighted the adequate biocompatibility of TRAP-Sp. With excellent hemostatic performance and biosafety, this sponge could be a potential candidate as a topical hemostatic agent for uncontrolled and noncompressible hemorrhage. STATEMENT OF SIGNIFICANCE: There is a need for innovative hemostatic materials for both uncontrolled and noncompressible hemorrhage. This manuscript describes a rapid shape recovery hemostatic sponge with both active and passive hemostatic performances synthesized by foaming technique, cross-linking reaction, and chemical immobilization of thrombin-receptor-agonist-peptide (TRAP). On contact with blood, the shape-fixed sponge can not only rapidly recover its original shape and concentrate platelets and RBCs but also activate the adhered platelets efficiently. The dual-functional sponge has excellent hemostatic efficacy in rat femoral artery hemorrhage and can control noncompressible hemorrhage in penetrating liver wound. Thus, we believe that this sponge could be a potential candidate as a topical hemostatic agent for uncontrolled and noncompressible hemorrhage.

N-alkylated chitosan/graphene oxide porous sponge for rapid and effective hemostasis in emergency situations

N-alkylated chitosan (AC) sponges and graphene oxide (GO) sponges are promising candidates for emergency hemostat. However, AC sponges have weak mechanical strength and GO sponges may induce toxicity. To overcome these problems, a series of AC/GO composite spongs (ACGS) were prepared with various ratios (GO/AC, 0%, 5%, 10%, and 20%) using a dilute solution freeze phase separation and drying process. The sponges exhibit excellent absorption capacity, mechanical stability, and biocompatibility. In serial in vitro clotting tests, the higher the ratio of GO, the better the coagulation efficiency. ACGS with 20% ratio of GO (ACGS20) has shorter hemostatic time than Celox in a rabbit femoral injury test. Moreover, ACGS20 can accelerate erythrocyte and platelet adhesion. CD62p and intracellular Ca²⁺ measurements show that ACGS20 can promote the release of intracellular Ca²⁺ and stimulate platelet activation. These results suggest that ACGS20 is a good candidate composition for a safe and efficacious hemostatic dressing.

Mesoporous silica nanoparticles carried on chitosan microspheres for traumatic bleeding control

Chitosan has been made into various hemostats, but their hemostatic efficiency for controlling severe traumatic bleeding is still inadequate. The aim of this work is to make quick hemostats by incorporating mesoporous silica nanoparticles into chitosan. Porous chitosan-silica composite microspheres (CSMS-S) with high hemostatic efficacy were fabricated through a combination of the microemulsion, thermally induced phase separation, and surfactant templating method. A large number of mesoporous silica nanoparticles were formed on and within the CSMS-S microspheres, which had abundant surface and inner macropores. The synergetic two hemostatic mechanisms from chitosan and mesoporous silica nanoparticles let CSMS-S composite microspheres with proper amount of silica displayed better hemostatic potential than the single component porous chitosan microspheres (CSMS). Within a same time interval, the whole blood clotting kinetics showed that CSMS-S could form larger blood clots than CSMS. The hemostatic time of CSMS-S was down to 97 s from 114 s of CSMS in the rat liver laceration model. The cytotoxicity and histological analysis proved that CSMS-S was a safe hemostatic agent without noticeable adverse effects on tissues around the wound. Our results demonstrate that CSMS-K is a promising quick hemostatic agent for traumatic hemorrhaging control.

Influence of the physicochemical characteristics of diatom frustules on hemorrhage control

Diatom frustules are good resources for hemostasis agent production.

Well-ordered mesoporous silica and bioactive glasses: promise for improved hemostasis

Mesoporous silica and bioactive glasses with unique textural properties are new generations of inorganic hemostats with efficient hemostatic ability.

Urushiol-functionalized mesoporous silica nanoparticles and their self-assembly into a Janus membrane as a highly efficient hemostatic material

Quick hemostasis plays a very important role in preventing hemorrhagic shock and death by controlling blood loss from trauma in civil and military accidents. An ideal quick hemostat should have tissue-adhesive functional groups, clotting factor activating components, and a plasma non-permeable hydrophobic layer. Inspired by the adhesive behavior of mussels, a novel efficient hemostat of urushiol-functionalized mesoporous silica nanoparticles (MSN@U) with a core-shell structure was synthesized and their hemostatic performance was evaluated for the first time. MSN@U could form an amphipathic Janus membrane (a hydrophobic layer and a hydrophilic layer in one membrane) by interfacial self-assembly. The morphology and structure of MSN@U were characterized. The results showed that MSN@U possessed a large specific surface area of 448.91 m2 g-1 and a rich porous structure with an average pore diameter of 3.94 nm. The hydrophilic catechol groups and the long hydrophobic alkyl groups of urushiol allowed MSN@U to self-assemble at the blood/air interface. The former made MSN@U tightly adhere onto blood vessel tissue through covalent bonds, while the latter formed a hydrophobic barrier layer which hindered blood from oozing. Meanwhile, MSN@U would accelerate clotting cascade reactions. These three effects made MSN@U a very quick hemostat with a hemostatic time of 22 ± 2 s on a rat liver laceration. Both in vitro and in vivo tests showed that they had a better hemostatic effect and blood compatibility than MSN. Cell viability evaluations indicated that MSN@U had no cytotoxicity. MSN@U will be a safe and promising hemostatic agent for clinical applications.

Investigation of the Effects of Molecular Parameters on the Hemostatic Properties of Chitosan

Hemorrhea is one of the major problems in war, trauma care, and surgical operation that threaten the life of the injured and patients. As a novel polymeric hemostatic agent, biodegradable chitosan can stop bleeding through a variety of approaches. In this paper, chitosan with various molecular parameters was prepared from chitin as raw material through deacetylation, oxidative degradation, hydrophilic modification, and salt formation reactions. The influence of different polymer parameters on the hemostatic effects of chitosan was investigated by in vitro coagulation time and dynamic coagulation assay. The results showed that when the molecular weights were high (10⁵⁻10⁶) and approximate, the coagulation effect of chitosan improved with a decrease of the deacetylation degree and achieved a prominent level in a moderate degree of deacetylation (68.36%). With the same degree of deacetylation, the higher the molecular weight of chitosan, the better the procoagulant effect. The substituent derivatives and acid salts of chitosan showed significant procoagulant effects, especially the acid salts of chitosan. In addition, the hemostasis mechanism of chitosan with various parameters was preliminarily explored by analyzing the plasma recalcification time (PRT). The efforts in this paper laid a basis for further study of the structure⁻activity relationship and the mechanism of chitosan hemostasis.

Strategies to overcome the polycation dilemma in drug delivery

Because of polycationic auxiliary agents such as chitosan, polyethyleneimine and cell penetrating peptides as well as cationic lipids assembling to polycationic systems, drug carriers can tightly interact with cell membranes exhibiting a high-density anionic charge. Because of these interactions the cell membrane is depolarized and becomes vulnerable to various uptake mechanisms. On their way to the target site, however, the polycationic character of all these drug carriers is eliminated by polyanionic macromolecules such as mucus glycoproteins, serum proteins, proteoglycans of the extracellular matrix (ECM) and polyanionic surface substructures of non-target cells such as red blood cells. Strategies to overcome this polycation dilemma are focusing on a pH-, redox- or enzyme-triggered charge conversion at the target site. The pH-triggered systems are making use of a slight acidic environment at the target site such as in case of solid tumors, inflammatory tissue and ischemic tissue. Due to a pH shift from 7.2 to slightly acidic mainly amino substructures of polymeric excipients are protonated or shielding groups such as 2,3 dimethylmaleic acid are cleaved off unleashing the underlying cationic character. Redox-triggered systems are utilizing disulfide linkages to bulky side chains such as PEGs masking the polycationic character. Under mild reducing conditions such as in the tumor microenvironment these disulfide bonds are cleaved. Enzyme-triggered systems are targeting enzymes such as alkaline phosphatase, matrix metalloproteinases or hyaluronidase in order to eliminate anionic moieties via enzymatic cleavage resulting in a charge conversion from negative to positive. Within this review an overview about the pros and cons of these systems is provided.

Injectable negatively charged gelatin microsphere-based gels as hemostatic agents for intracavitary and deep wound bleeding in surgery

Gelatin, as natural macromolecular material, has been used in biomedical fields widely. In this study, various injectable gelatins A, B, and their compound AB microsphere-based gels (A-GMGs, B-GMGs and AB-GMGs) were prepared through water-in-oil emulsion method for hemostasis, and the effects of blood coagulation in vitro and surgical hemostasis (a deep liver wound model) in vivo were evaluated. Furthermore, the influences of gelatin sorts, the size of microsphere, zeta potential (ZP) and viscoelastic properties on hemostasis were also assessed. Results showed that the gelatin microspheres (GMs) exhibited smooth surface, good sphericity and the particle size of a rough normal distribution. GMs carried negative charges and their electronegativity was stronger than that of gelatin A (GA) and gelatin B (GB) raw materials. Rheological analysis showed that a decreasing particle size of the microspheres led to stronger gel strength, and solid-like gels were exhibited under low stress conditions and liquid-like gels were exhibited under high stress conditions. The blood clotting time of B-GMGs was within 60 s, which exhibited a significantly higher blood clotting effect compared with control groups. The hemostasis assay in vivo showed that the gels had better hemostatic effect on a deep liver wound bleeding model compared with control groups, especially B-GMGs. However, in vivo and vitro hemostatic experiments, particle size of GMs had no obvious influence on the hemostatic effect of the gels. In addition, the CCK-8 assay of bone marrow mesenchymal stem cells of murine (mMSCs) indicated non-cytotoxicity of GMs for cells. These results demonstrated that the gelatin microsphere-based gels (GMGs) had potential to be an effective hemostatic material for intracavitary and deep wound bleeding in surgery.

Chitosan-Based Composite Materials for Prospective Hemostatic Applications

Effective hemostasis is vital to reduce the pain and mortality of patients, and the research and development of hemostatic materials are prerequisite for effective hemostasis. Chitosan (CS), with good biodegradability, biocompatibility and non-toxicity, has been widely applied in bio-medicine, the chemical industry, the food industry and cosmetics. The excellent hemostatic properties of CS have been extensively studied. As a result, chitosan-based composite hemostatic materials have been emerging. In this review, the hemostatic mechanism of chitosan is briefly discussed, and then the progress of research on chitosan-based composite hemostatic materials with multiple forms such as films, sponges, hydrogels, particles and fibers are introduced. Finally, future perspectives of chitosan-based composite hemostatic materials are given. The objective of this review is to provide a reference for further research and development of effective hemostatic materials.