Monitoring coagulopathies in fluid resuscitation for trauma or surgery

Sheet-like Janus hemostatic dressings with synergistic effects of cardanol hemostasis and quaternary ammonium salt antibacterial action

It is of utmost importance that bleeding should be stopped and infection be prevented in people with trauma. In this study, an anisotropic Janus mesoporous silica nanosheet (MSNS) with different functional groups was designed and prepared. In order to endow both sides of the MSNS with independent fast hemostasis and effective antibacterial action, the MSNS was modified with cardanol (CA) and 2,3-epoxypropyltrimethylammonium (GTA). The addition of CA significantly improved the hemostatic property of the MSNS. In a SD rat femoral artery injury model, the hemostatic time of CA-MSNS-GTA was 47% shorter than that of the MSNS, attributed to the sealing of the hydrophobic alkyl side chain and the adhesion of phenolic hydroxyl groups in CA. CA-MSNS-GTA could form a three-dimensional network with fibrin to further accelerate the coagulation process. This Janus material exhibited excellent antibacterial effects (∼90%) against Gram-positive bacteria (S. pneumoniae) and Gram-negative bacteria (E. coli) due to the presence of GTA. The cytotoxicity test showed that CA-MSNS-GTA exhibited biosafety, which provided safety guarantee for clinical applications in the future. This Janus dressing with different functions on two opposite sides provides synergetic multifunctional effects during wound healing.

All-Aqueous Microfluidics Fabrication of Multifunctional Bioactive Microcapsules Promotes Wound Healing

Wound healing involves multiple stages of body responses, including hemostasis, inflammation, cell proliferation, and tissue remodeling. New material design satisfying all demands throughout different stages of wound healing is cherished but rarely discussed. Here we introduce all-aqueous multiphase microfluidics as a novel strategy to fabricate self-assembled, multifunctional alkylated chitosan/alginate microcapsules (SAAMs) as novel therapeutic materials for rapid blood coagulation and wound healing. SAAMs are structurally distinguished by their ultrathin shells with polycationic surface for rapid activation of clotting cascade and their internal porous dextran-rich cores for fast absorption of blood and exudate. These features endow SAAMs with excellent hemostatic properties for acute hemorrhage. Moreover, the alkylated chitosan within the microcapsules exhibits persistent antimicrobial activities against bactericidal infections due to their amphiphilic and cationic surfaces. Besides, cytokines can be safely loaded into the organic-solvent-free microcapsules and released precisely to promote the proliferation of epidermal cells, supporting the subsequent development of granulation tissue and suppression of inflammation in the last stages of wound healing. With the ability to fabricate size-tailored soft microcapsules and to realize time-sequential functions for tissue repairing, the presented "all-aqueous microfluidics generation of multifunctional bioactive SAAMs" create a versatile and robust paradigm for wound treatment.

Microfluidic generation of multifunctional core-shell microfibers promote wound healing

Wound healing is a complex physiological process involving four coordinated stages, including hemostasis, anti-inflammatory, repair, and epithelial formation. Herein, multifunctional core-shell alkylated chitosan/calcium alginate microfibers are fabricated as a novel strategy for promoting wound healing by contributing to each four stages in the entire healing process. Taking advantages of the microfluidic technology, the core-shell microfibers can be generated in a continuous and convenient manner through the interfacial assembly between alkylated chitosan and Na-alginate, as well as the simultaneous crosslink between calcium and the alginate. Generated microfibers possess unique internal structure which can effectively promote the absorption of blood and exudate produced during trauma. Moreover, the dodecyl carbon chain and abundant amino groups of alkylated chitosan provide microfibers with excellent hemostatic and antibacterial properties, which can repair acute hemorrhage and destroy bacteria rapidly. Further, the chronic wound healing process of a skin injury model can be significantly promoted by applying the fabricated microfibers. With these sequential functions to guide the whole-stage wound healing, the presented multifunctional core-shell microfibers create a versatile and robust paradigm for comprehensive wound treatment.

Analysis of Safety and Effectiveness of Sodium Alginate/Poly(γ-glutamic acid) Microspheres for Rapid Hemostasis

Most preventable deaths after trauma are related to hemorrhage and occur early after injury. Timely hemostatic treatment is essential to minimize blood loss and improve survival. Among the various treatment methods, the most economical and effective is to use a hemostatic agent. A powdered hemostatic agent can be used for wounds of any shape or depth with high compactness and excellent accumulation effect. Herein, we chose the natural, hydrophilic polymer poly(γ-glutamic acid) (γ-PGA) to form composite hemostatic microspheres with sodium alginate (SA), which show good biocompatibility, water absorptivity, and viscosity. The morphology and structure of the hemostatic microspheres were determined using Fourier transform infrared spectroscopy and scanning electron microscopy. The overall safety, hemolysis, pyrogenic, and intradermal irritation tests were examined. The relationship between hemostatic pressure and hemostatic time during microsphere use was also measured. The hemostatic effect was analyzed with a liver, spleen, and femoral artery bleeding model. The composite microspheres were well tolerated in vivo and exhibited better hemostatic effects in animal experiments than a microporous polysaccharide powder compound. Research results showed that SA/γ-PGA microspheres are materials with good hemostatic effect, high safety, and great potential in clinical applications.

Biomimetic hydroxyapate/polydopamine composites with good biocompatibility and efficiency for uncontrolled bleeding

Uncontrolled bleeding is thought to be the most deadly cause of pre-hospital, traffic, and military accidents death. However, the popular commercial hemostats can only realize the hemostasis of mild bleeding. Therefore, we developed polydopamine (PDA) composite materials (PMs), which applied hydroxyapatite as the parent body. The PMs were produced via lyophilization and functionalized with amino, phenol hydroxyls groups, which endowed hydrophobicity to materials. This ensured a high aggregation ability of blood cells to the PMs and they were tested to be as high as 300% compared with the negative control group. The clotting time was shortened to 79.7% compared with the usually used commercial hemostat (Celox) in the test of in vitro hemostasis. Through the results of PT and APTT tests, blood coagulation index test, and the analysis of intracellular Ca²⁺ activation, we further understood the mechanism of the hemostasis of the materials, which explained the low blood loss and quick coagulation time of the PM hemostats in detail. Besides, the low hemolysis and cytotoxicity of the PMs suggested the good biocompatibility of the hemostats, which was further proved by the regular morphology maintained by erythrocytes in the hemolysis tests. The study of nanoscale composites led the research for the methods of hemostasis.

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.

Chitosan-glucan complex hollow fibers reinforced collagen wound dressing embedded with aloe vera. II. Multifunctional properties to promote cutaneous wound healing

This study presents an innovative multifunctional system in fabricating new functional wound dressing (FWD) products that could be used for skin regeneration, especially in cases of infected chronic wounds and ulcers. The innovation is based on the extraction, characterization, and application of collagen (CO)/chitosan-glucan complex hollow fibers (CSGC)/aloe vera (AV) as a novel FWS. For the first time, specific hollow fibers were extracted with controlled inner (500-900 nm)/outer (2-3 µm) diameters from mycelium of Schizophyllum commune. Further on, research and evaluation of morphology, hydrolytic stability, and swelling characteristics of CO/CSGC@AV were carried out. The obtained FWS showed high hydrolytic stability with enhanced swelling characteristics compared to native collagen. The hemostatic effect of FWS increased significantly in the presence of CSGC, compared to native CO and displayed excellent biocompatibility which was tested by using normal human dermal fibroblast (NHDF). The FWS showed high antibacterial activity against different types of bacteria (positive/negative grams). From in vivo measurements, the novel FWS increased the percentage of wound closure after one week of treatment. All these results imply that the new CO/CSGC@AV-FWD has the potential for clinical skin regeneration and applying for controlled drug release.

Porous chitosan microspheres containing zinc ion for enhanced thrombosis and hemostasis

Quick hemostats for non-lethal massive traumatic bleeding in battlefield and civilian accidents are important for reducing mortality and medical costs. Chitosan (CS) has been widely used as a clinic hemostat. To enhance its hemostatic efficiency, Zn²⁺ in the form of zinc alginate (ZnAlg) was introduced to CS to make porous CS@ZnAlg microspheres with ZnAlg component on the surface. Such microspheres were prepared by successive steps of micro-emulsion, polyelectrolyte adhesion, and thermally induced phase separation. Their structure and hemostatic performance were analyzed by SEM, FT-IR, XPS and a series of in vitro hemostatic experiments including thromboelastography analysis. The composite microspheres had an outer and internal interconnected porous structure. Their size, surface area, and water absorption ratio were ca. 70μm, 48m²/g, and 1850%, respectively. Compared to the neat chitosan microspheres, the CS@ZnAlg microspheres showed shorter onset of clot formation, much faster in vitro and in vivo whole blood clotting, bigger clot, less blood loss, and shorter hemostatic time in the rat liver laceration and tail amputation models. The synergetic hemostatic effects from (1) the electrostatic attraction between chitosan component and red blood cells, (2) the activation of coagulation factor XII by Zn²⁺ of zinc alginate component, and (3) physical blocking by microsphere matrix, contributed to the enhanced hemostatic performance of CS@ZnAlg microspheres.

A novel approach to modeling acute normovolemic hemodilution

Acute normovolemic hemodilution (ANH) was introduced as a blood conservation technique to reduce patient exposure to allogenic blood transfusion during surgery. Despite years of research and experience, the best practice procedure, efficacy and safety of ANH remain in question. In this work, a numerical model is developed for the ANH procedure based upon a multi-compartmental, fluid model of the body. The model also analyzes the most commonly used acellular fluids for ANH or for fluid therapy following hemorrhage. The model allows user input of critical ANH parameters, providing the ability to simulate the patient׳s response in real time to many clinical scenarios, using various types of resuscitation fluids. First, the patient׳s response to a representative, clinical ANH protocol and surgery was simulated. Then, the effect of several variables was investigated including: type/amount of resuscitation fluid, number of blood units collected during ANH, and amount of surgical blood loss. Our simulations highlighted the importance of osmotic molecules within the blood in preventing excessive fluid retention and initiating fluid clearance after surgery. The developed model can be utilized as a tool to simulate and optimize a variety of proposed protocol related to the ANH procedure and surgery. It can also be utilized as an educational or training tool to become familiar with the ANH procedure.