Research On The Control Of The Structure And Performance Of Functional Porous Composite Materials And Their Applications In Trauma Treatment

Rapid hemostasis and wound healing caused by war injury,accident and disaster are two important factors in trauma treatment.It is of great significance to study novel and efficient materials for massive hemorrhage control and wound repair in treating the wounded and saving lives.However,there are many deficiencies in current hemostatic materials:poor stability of biological hemostatic materials when used alone under harsh conditions;polysaccharide hemostatic materials are lacking mechanical strength and only useful in treating low to moderate bleeding,but they are unsuitable in treating massive bleeding;lacking the ability to quickly seal deep,narrow,or irregular wounds induced by explosive devices or gunshot.In addition,current wound dressings are usually single-functioned,and most of them lack of inherent antibacterial properties.Besides,the current wound dressings are not ideal for deep,multi-exudate or chronic wounds.Therefore,aiming at the above problems existing in existing hemostatic materials,PVA porous material is used as matrix to introduce multiple hemostatic mechanisms,such as physical absorption and enrichment,biological stimulation,electrical charge stimulation,and mechanical blocking,to design and fabricate three systems of hemostatic materials.The three systems of hemostatic materials are biological factor anchoring reinforced porous composite material(TCP),double network porous composite material with multiple hemostatic mechanism(PACF)and fiber reinforced shape-adaptive porous composite material(CMCP),respectively.The physicochemical properties,biocompatibility,in vitro hemostatic performance are successively characterized.Finally,the hemostatic efficacy of the three kinds of porous materials is evaluated using animal massive hemorrhage models.In addition,in order to solve the problems existed in current wound dressings,bacterial cellulose(BC)is used as matrix to fabricate a highly flexible and highly transparent porous composite membranes with multiple functions of exudate absorption,permeability,antimicrobial properties and wound healing promotion.The physicochemical properties,biocompatibility and antibacterial properties of the as-prepared membrane are systematically characterized.Finally,then the wound healing properties of the membrane is evaluated in a rat skin full-thickness defect model.Based on the three-dimensional network structure and high liquid absorption characteristics of PVA porous materials,thrombin is uniformly anchored to the surface and internal network of the porous materials through the dual action of physical adsorption and covalent binding.The prepared TCP exhibits good biocompatibility and excellent in vitro hemostatic performance.The hemostatic time of TCP for rat liver hemorrhage is only 31 s.However,when TCP is used for femoral artery bleeding,due to insufficient mechanical strength and structural stability,the wound could not be sealed in time.In addition,after storage at room temperature for more than 12 weeks,the bioactivity of thrombin on TCP decreases dramatically,which makes it impossible to achieve effective hemostasis on liver bleeding.A porous composite material(PACF)with a stable double network structure composed of sodium alginate(SA)and PVA porous material is prepared through the double crosslinking of glutaraldehyde and Ca2+.The pore struture,porosity,surface wettability,surface roughness and Zeta potential of PACF can be regulated and controlled by adjusting the content of SA.The double network structure not only endows PACF with excellent biocompatibility,but also enables it to promote the adhesion of proteins and blood cells,promote rapid thrombosis,activate the coagulation system and finally achieve rapid hemostasis through the synergistic effect of multiple hemostatic mechanisms.Compared with the military hemostats HemCon(?),QuikClot(?)and CELOXTM,PACF has the best hemostatic performance,and it can achieve hemostasis and effectively reduce blood loss in both rat liver hemorrhage model and pig femoral artery transection model.A novel CMC fibers reenforced PVA porous composite material(CMCP)is prepared by crosslinking reaction and supercritical gas foaming technology.CMCP has a unique fiber interspersed three-dimensional porous network structure.CMCP has excellent pressure bearing capacity,anti-fatigue properties,liquid absorption capacity and self-expansion properties.CMCP can generate a dynamic expansion force of up to 8 N and withstand liquid impact force of more than 0.083 MPa during liquid absorption.CMCP can achieve rapid in vitro coagulation through the synergistic effect of multiple hemostatic mechanisms such as promoting blood cell adhesion,aggregation and activation,accelerating thrombosis and activating coagulation system.CMCP self-expands rapidly after contact with blood,and can adapt to change its shape to completely fit the wound cavity.CMCP can quickly and effectively achieve massive bleeding control in a pig femoral artery hemorrhage model,and the hemostatic time is less than 95 s.CMCP does not cause intravascular thrombosis,and can effectively compress the wound bleeding site and prevent wound infection through the shape-adaptive ability.Polyhexamethylene biguanide-polyethylene glycol(PHMB-PEG)micellar droplets are introduced into the nanofiber network of BC,and a composite membrane with smooth surface and porous structure is prepared through a special forming process.The introduction of PHMB-PEG can greatly improve the flexibility,continuous water absorption capacity,water retention capacity,transparency and gas transmittance of the porous composite membrane.PHMB-PBC has multiple antibacterial effects such as bacteria inhibition and anti-adhesion.The porous surface structure and intermolecular interaction endow PHMB-PBC with slow-release antibacterial effect and lasting antibacterial activity.Compared with two commercial dressings,PHMB-PBC shows the shortest wound healing time and the best effect of promoting wound healing in a rat skin full-thickness defect model.During the healing process,no infection,edema or inflammation occur,proving that the PHMB-PBC has excellent antibacterial and anti-infection effects.