Graphene-based Composite Sponge For Trauma Hemostasis

Excessive bleeding usually increases the risk of suffering hemorrhagic shock coagulopathy,infection,and multiple organ failures.As reported,hemorrhage results in 30%-4O%of deaths and is the leading cause of trauma-associated death.Thus,applying hemostatic agents is important for rapid and effective control of hemorrhage.Recently,cross-linker graphene hemostatic sponge(CGS)was developed and showed outstanding hemostatic performance.Compared with the common used hemostatic agents,the CGS has many advantages,such as facile preparation,low cost,ultra-light weight,portability,stability and nontoxicity.Physical adsorption is the main hemostatic mechanism of the CGS.It can fast absorb plasma,enrich hemocytes and platelets on the wound surface that accelerate blood coagulation.To improve the hemostatic performance of the CGS,composite strategy was used in the study.A series of novel graphene composite sponges were developed by chemical modification,adding biological hemostatic agent and physical mixing.In the synergy of different hemostatic mechanisms,the graphene composite sponges exhibit outstanding hemostatic performance.First,2,3-diaminopropionic acid(DapA)was used as the cross-linker to prepare a DapA cross-linked graphene sponge(DCGS).EDS,EA and Zeta potential tests revealed that DapA can effectively increase the amount of carboxylic acid groups and enhance negative charge of the DCGS,and as a result,blood cells and platelets are activated on the surface of the DCGS.In the synergy of fast absorption and charge stimulation,the hemostatic efficiency of the DCGS has been significantly improved.It stops bleeding within 166 s,which is 35 s shorter than the CGS,suggesting that synergy effect is in favor of hemostasis.Therefore,this work provides a new direction for the development of graphene-based hemostatic materials by using a double(or multi)mechanism for hemostasis.Second,polydopamine(PDA)cross-linked graphene oxide(GO)hemostatic sponge(DCGO)was prepared according to the theory proposed above.Blood cell evaluations verified that the DCGO can be an effective agonist for activating platelet.Therefore,the DCGO can fast stop bleeding within 100 s in the synergy of sponge’s fast absorption and charge stimulation.The hemostatic efficiency of the DCGO is 58%superior than that of GO sponge.PDA cross-linked network can not only maintain the oxidation degree of the DCGO,but also enhance sponge’s mechanical strength.The mechanical stability of the DCGO ensure its absorbability.500 g of weight(350 times of DCGO’s weight)can stand on the surface of the DCGO without destroying the formation of the DCGO,suggesting that this strategy is in favor of developing graphene-based composite with high mechanical strength.Third,we developed a facile spray method for preparing a thrombin/cross-linked graphene sponge(TCGS).The spraying process is a soft and efficient method to introduce thrombin into CGS and effectively protecting the biological activity of thrombin.CGS is also proved to be an ideal thrombin carrier because its high specific area and porous structure insure the immobilized thrombin fully contacting with blood cells to perform high-efficient catalytic capacity.In the synergy of fast plasma absorption and optimal thrombin stimulation,TCGS exhibits outstanding hemostatic performance.It ultrafast stops bleeding within 100 s.In addition,in-depth insight demonstrated that the physical absorbability and the biological stimulation should be balanced.Thought adding more thrombin could increase the hemostatic stimulation,the excessive thrombin would block the pore structure of TCGS,resulting in low hemostatic efficiency.Therefore,the synergy effect is crucial for the TCGS composite.This study not only introduces a strategy for the combination of biologies and graphene hemostatic materials,but also provides a deeper understanding of the hemostatic synergy-effect of graphene-based hemostatic materials.At last,we developed a graphene-montmorillonite(MMT)composite sponge(GMCS)by the method of physical mixture.The GMCS can rapidly stop bleeding in 85 s in rabbit artery injury test with the synergy effect of fast adsorption and MMT’s stimulation.Although the addition amount of MMT is too small to compare to the way of using MMT powders directly,its hemostatic action is fully played out within the GMCS.A synergy effect is remarkably showed in this composite,where the dimension changes of blood distribution play a crucial role.More importantly,the GMCS reduced the biotoxicity of MMT and did not cause in vivo thrombus or blood clot in the vessels.Biocompatibility evaluations further highlighted the cytocompatibility of this GMCS material.Therefore,we anticipated that this study could not only provide a new strategy for MMT used in the hemostatic field again,but also open a new avenue to develop a superb GMCS-type hemostat used for trauma therapy.In this study,we used composite stagey to develop a series of graphene-based hemostatic sponges,which effectively stop bleeding with different kinds of hemostatic mechanisms.These graphene-stimuli composite sponge can act as a platform to introduce different hemostatic mechanisms,providing broad space for future development of novel hemostatic materials.