Unusual Surface Coagulation Activation Patterns of Crystalline and Amorphous Silicate-Based Biominerals

Bioresorption and Biomineralization of S53P4 Bioactive Glass in Neutral Tris Buffer and Citric Acid Solution

In this study, S53P4 (53SiO2-23Na2O-20CaO-4P2O5) bioactive glass (BG) were prepared through a melt-milling process, and their bioresorption and biomineralization behavior was evaluated by in vitro dissolution under different solution conditions (neutral and acidic). The particle size of S53P4 BG was controlled by milling, and the in vitro dissolution evaluation was performed in tris buffer and citric acid solution for 21 days at 37 °C according to ISO 10993-14 (biological evaluation of medical devices). During dissolution, the ion release rate of S53P4 BG was confirmed to be three times faster in citric acid solution than that in tris buffer. Among them, the ion concentration of calcium and phosphorus initially increased and then gradually decreased, which is due to the biomineralization process. This process formed a new layer of particles on the surface of S53P4 BG, which was identified as a calcium-phosphate-based compound by X-ray diffraction analysis. Furthermore, the thickness of the layer was observed to be 273 nm in tris buffer and 34 nm in citric acid solution by focused-ion beam scanning electron microscopy, and the morphology of the particles comprising this layer was observed to be thicker and longer in tris buffer than that in citric acid solution. This difference is due to the citrate present in the citric acid solution interacting with the released calcium ions and inhibiting the formation of a new layer. Thus, the ion release of S53P4 BG was faster in citric acid solution than that in tris buffer, but the biomineralization process to form the calcium phosphate-based compound was more effective in tris buffer.

Hemostatic Dressing Immobilized with ε-poly-L-lysine and Alginate Coated Mesoporous Bioactive Glass Prevents Blood Permeation by Pseudo-Dewetting Behavior

The integration of hemostats with cotton fabrics is recognized as an effective approach to improve the hemostatic performance of dressings. However, concerns regarding the uncontrollable absorption of blood by hydrophilic dressings and the risk of distal thrombosis from shed hemostatic agents are increasingly scrutinized. To address these issues, this work develops an advanced dressing (AQG) with immobilized nano-scale mesoporous bioactive glass (MBG) to safely and durably augment hemostasis. The doubly immobilized MBGs, pre-coated with ε-poly-L-lysine and alginate, demonstrate less than 1% detachment after ultrasonic washing. Notably, this MBG layer significantly promotes the adhesion, aggregation, and activation of red blood cells and platelets, adhered five times more red blood cells and 29 times more platelets than raw dressing, respectively. Specially, with the rapid formation of protein corona and amplification of thrombin, dense fibrin network is built on MBG layer and then blocked blood permeation transversely and longitudinally, showing an autophobic pseudo-dewetting behavior and allowing AQG to concentrate blood in situ and culminate in faster hemostasis with lower blood loss. Furthermore, the potent antibacterial properties of AQG extend its potential for broader application in daily care and clinical setting.

Calcium Ion-Coupled Polyphosphates with Different Degrees of Polymerization for Bleeding Control

The development of efficient hemostatic materials is crucial for achieving rapid hemorrhage control and effective wound healing. Inorganic polyphosphate (polyP) is recognized as an effective modulator of the blood coagulation process. However, the specific effect of polyP chain length on coagulation is not yet fully understood. Furthermore, calcium ions (Ca2+) are essential for the coagulation process, promoting multiple enzyme-catalyzed reactions within the coagulation cascade. Hence, calcium ion-coupled polyphosphate powders with three different degrees of polymerization (CaPP-n, n = 20, 50, and 1500) are synthesized by an ion-exchange reaction. CaPP exhibits a crystalline phase at a low polymerization degree and transitions to an amorphous phase as the polymerization degree increases. Notably, the addition of Ca2+ enhances the wettability of polyP, and CaPP promotes hemostasis, with varying degrees of effectiveness related to chain length. CaPP-50 exhibits the most promising hemostatic performance, with the lowest blood clotting index (BCI, 12.1 ± 0.7%) and the shortest clotting time (302.0 ± 10.5 s). By combining Ca2+ with polyP of medium-chain length, CaPP-50 demonstrates an enhanced ability to accelerate the adhesion and activation of blood cells, initiate the intrinsic coagulation cascade, and form a stable blood clot, outperforming both CaPP-20 and CaPP-1500. The hemostatic efficacy of CaPP-50 is further validated using rat liver bleeding and femoral artery puncture models. CaPP-50 is proven to possess hemostatic properties comparable to those of commercial calcium-based zeolite hemostatic powder and superior to kaolin. In addition, CaPP-50 exhibits excellent biocompatibility and long-term storage stability. These results suggest that CaPP-50 has significant clinical and commercial potential as an active inorganic hemostatic agent for rapid control of bleeding.

Kaolin loaded gelatin sponges for rapid and effective hemostasis and accelerated wound healing

Severe trauma with massive active blood loss, including liver and spleen rupture, arterial bleeding and pelvic fracture, will lead disability, malformation and even death. Therefore, it is very important to develop new, fast and efficient hemostatic materials. In this study, a novel Gelatin/Kaolin (GE/KA) composite sponge was developed. Meanwhile, to further investigate the effect of kaolin content on sponge properties, we prepared four types of sponges: GE/5% KA, GE/10% KA, GE/15% KA and GE/20% KA. The results of coagulation test in vitro showed that compared to the other groups, there were more activated adhered platelets and red blood cells on the surface of GE/15% KA. The results of hemostasis test in vivo showed that compared to other experimental groups, the GE/15% KA group had significantly less hemostasis time (liver hemostasis model: 69.50 ± 2.81 s; femoral artery hemostasis model: 75.17 ± 3.06 s) and bleeding volume (liver hemostasis model: 219.02 ± 10.39 mg; femoral artery hemostasis model: 948.00 ± 50.69 mg), and was similar to the commercial hemostasis material group. Additionally, the material properties of the sponge were characterized and its biocompatibility was verified as well through cell experiments and in vivo embedding experiments. All these results indicate that the optimal content of kaolin is 15%, which provides a theoretical basis for subsequent research. All in all, the novel GE/KA composite sponge prepared in this study can be used as a multifunctional hemostatic wound dressing for the treatment of complex wounds under various trauma scenes.

Progress and future prospects of hemostatic materials based on nanostructured clay minerals

The occurrence of uncontrolled hemorrhage is a significant threat to human life and health. Although hemostatic materials have made remarkable advances in the biomaterials field, it remains a challenge to develop safe and effective hemostatic materials for global medical use. Natural clay minerals (CMs) have long been used as traditional inorganic hemostatic agents due to their good hemostatic capability, biocompatibility and easy availability. With the advancement of science, technology and ideology, CM-based hemostatic materials have undergone continuous innovations by integrating new inspirations with conventional concepts. This review systematically summarizes the hemostatic mechanisms of different natural CMs based on their nanostructures. Moreover, it also comprehensively reviews the latest research progress for CM-based hemostatic hybrid and nanocomposite materials, and discusses the challenges and developments in this field.