Construction And Hemostasis Mechanism Of Antibacterial Hemostatic Materials For First Aid

Excessive blood loss is the main cause of death in war wounds,traffic accidents,natural disasters and surgical treatment,it is especially important for the rapid and effective hemostasis of moderate and severe bleeding.At present,the rapid hemostasis products on the market are mainly aluminosilicates and chitosan,but there are still defects such as aluminosilicates which are easy to cause vascular embolization and unstable hemostatic effects of chitosan.Therefore,it is an urgent need to develop new hemostasis methods and hemostatic products that can safely and efficiently control moderate to severe bleeding.This thesis focuses on the development of emergency life-saving hemostasis materials,material hemostasis mechanism,antibacterial properties and biocompatibility researchs.A silica nanoparticle coated with polydopamine(PDA/SiNP)with good antibacterial performance was developed for hemorrhage control.PDA/SiNP formed a porous network and rendered material with phenol hydroxyls,aminos,proper hydrophobicity.The clotting time of blood was shortened by nearly 150 seconds for PDA/SiNP compared with that of commercial Celox in vitro hemostasis.Not only the PDA/SiNP achieved adequate hemostasis,but also blood loss was remarkably reduced in the femoral artery and vein injury,liver injury SD rat models.PDA/SiNP could significantly adhere platelets,aggregate erythrocytes,and accelerate coagulation by activating the extrinsic pathway of the coagulation cascade.Importantly,PDA/SiNP exhibited long-lasting inhibition of Escherichia coli even after 208 h.Also,the hemolysis and exothermic effects of PDA/SiNP with low cytotoxicity was much lower.Moreover,the dissolution behaviors in vitro indicated that the weight loss of PDA/SiNP could attain approximately 40%just after 24 h.An aldehyde dextran(DA)sponge with proper absorption,adhesion,antibacterial and wound-healing properties was designed by lyophilization for hemorrhage control.DA sponge with pore size of～30-50 μm and porosity over 90%,not only absorbed blood quickly(～54 g/g),but also possessed strong tissue adhesion(～51 kPa).The clotting time of blood was shortened by nearly 344 seconds for DA sponge compared with that of Celox in vitro hemostasis.Furthermore,DA sponge achieved effective hemostasis and remarkable blood loss reduction in the ear vein,femoral artery,liver injuries of rabbit models.DA sponge could significantly accelerate coagulation by rapid wound block,fast cells aggregation and initiation,and high coagulation factors concentration.Importantly,this hemostat exhibited excellent inhibition effects on Escherichia coli and Staphylococcus aureus,and significantly promoted wound healing without skin irritation in rabbit full-thickness skin injury model.The hemolysis and cytotoxicity of DA sponge with no irritation and sensitization to skin were very low.Improtantly,DA sponge could be completely degraded in vivo in 2 days,and had no significant effect on the organs of SD rats after degradation.A poly aldehyde dextran(DA)/montmorillonite(MMT)composite sponge(DAM)with commendable tissue adhesion,antibacterial,and wound healing performances was fabricated for massive hemorrhage control.DAM sponge(～46 kPa)maintained excellent wet tissue adhesion of DA sponge.Under the synergistic action of DA and MMT,DAM sponge could achieve immediate coagulation compared with Celox.Therefore,DAM sponge achieved mostasis in limited lifesaving time,especially decreasing nearly 95%blood loss in the femoral artery and vein incision of rat model.DAM sponge could rapidly seal the wound,and promote cells aggregation and adhesion,quickly activate and enlarge the whole coagulation system,and achieve efficient and rapid hemostasis.Furthermore,the antibacterial activity of DAM sponge was comparable to that of DA sponge and also contributed to wound healing.Importantly,DAM sponge could effectively avoid the destruction of red blood cells and side effects of embolism caused by MMT leakage.