The hemostatic performance and mechanism of palygorskite with structural regulate by oxalic acid gradient leaching

Palygorskite (Pal) is a naturally available one-dimensional clay mineral, featuring rod-shaped morphology, nanoporous structure, permanent negative charges as well as abundant surface hydroxyl groups, exhibiting promising potential as a natural hemostatic material. In this study, the hemostatic performance and mechanisms of Pal were systematically investigated based on the structural regulate induced by oxalic acid (OA) gradient leaching from perspectives of structure, surface attributes and ion release.In vitroandin vivohemostasis evaluation showed that Pal with OA leaching for 1 h exhibited a superior blood procoagulant effect compared with the raw Pal as well as the others leached for prolonging time. This phenomenon might be ascribed to the synergistic effect of the intact nanorod-like morphology, the increase in the surface negative charge, the release of metal ions (Fe3+and Mg2+), and the improved blood affinity, which promoted the intrinsic coagulation pathway, the fibrinogenesis and the adhesion of blood cells, thereby accelerating the formation of robust blood clots. This work is expected to provide experimental and theoretical basis for the construction of hemostatic biomaterials based on clay minerals.

Preparation and Hemostatic Effect of Micro-Nanograded Porous Particles Doped with Dopamine-Based Water-Triggered Intelligent Composite Adhesives

The wet environment of water or tissue in bleeding wounds poses significant challenges to the adhesion performance of existing hemostatic adhesives. An intelligent composite adhesive prepared by doping starch-based silicate micro-nanograded porous particles (MBC@CMS) with dopamine-hyperbranched polymers (HPD, 7800 Mw) synthesized by the Michael addition reaction could be triggered by water to form a glue (MBC@CMS-HPD). The results indicated that MBC@CMS-HPD could still have adhesion properties under running water washing and water immersion and could effectively seal the water outlet. The results of the glue-forming mechanism showed that MBC@CMS-HPD had better wettability than water, which could eliminate water molecules at the wet adhesive surface. When contacted with water, the agglomeration of the HPD hydrophobic chain increases the exposure of the catechol group, and the relative atomic mass of the N element on the surface increases from 2.8 to 4.8%. The adhesion of MBC@CMS-HPD was enhanced and stable. MBC@CMS-HPD showed significant hemostasis effects in five injury bleeding models of Sprague-Dawley (SD) rats and New Zealand rabbits. Especially in the fatal femoral artery bleeding model of New Zealand rabbits, MBC@CMS-HPD reduced the amount of bleeding by 75% and shortened the bleeding time by 78% compared with the a-cyanoacrylate adhesives. The results of the coagulation mechanism showed that compared with HPD, MBC@CMS-HPD could activate both endogenous and exogenous coagulation pathways. Among them, after contact with blood, HPD formed a gel to close the blood outlet, and MBC@CMS entered the wound to activate the internal and external coagulation pathways. In addition, HPD and MBC@CMS had good histocompatibility and degradability, which has the potential to be applied to different wounds.

Development potential of extracellular matrix hydrogels as hemostatic materials

The entry of subcutaneous extracellular matrix proteins into the circulation is a key step in hemostasis initiation after vascular injury. However, in cases of severe trauma, extracellular matrix proteins are unable to cover the wound, making it difficult to effectively initiate hemostasis and resulting in a series of bleeding events. Acellular-treated extracellular matrix (ECM) hydrogels are widely used in regenerative medicine and can effectively promote tissue repair due to their high mimic nature and excellent biocompatibility. ECM hydrogels contain high concentrations of extracellular matrix proteins, including collagen, fibronectin, and laminin, which can simulate subcutaneous extracellular matrix components and participate in the hemostatic process. Therefore, it has unique advantages as a hemostatic material. This paper first reviewed the preparation, composition and structure of extracellular hydrogels, as well as their mechanical properties and safety, and then analyzed the hemostatic mechanism of the hydrogels to provide a reference for the application and research, and development of ECM hydrogels in the field of hemostasis.

Application and outlook of topical hemostatic materials: a narrative review

Bleeding complications can cause significant morbidities and mortalities in both civilian and military conditions. The formation of stable blood clots or hemostasis is essential to prevent major blood loss and death from excessive bleeding. However, the body's self-coagulation process cannot accomplish timely hemostasis without the assistance of hemostatic agents under some conditions. In the past two decades, topical hemostatic materials and devices containing platelets, fibrin, and polysaccharides have been gradually developed and introduced to induce faster or more stable blood clot formation, updating or iterating traditional hemostatic materials. Despite the various forms and functions of topical hemostatic materials that have been developed for different clinical conditions, uncontrolled hemorrhage still causes over 30% of trauma deaths across the world. Therefore, it is important to fabricate fast, efficient, safe, and ready-to-use novel hemostatic materials. It is necessary to understand the coagulation process and the hemostatic mechanism of different materials to develop novel topical hemostatic agents, such as tissue adhesives and sealants from various natural and synthetic materials. This review discusses the structural features of topical hemostatic materials related to the stimulation of hemostasis, summarizes the commercially available products and their applications, and reviews the ongoing clinical trials and recent studies concerning the development of different hemostatic materials.