Preparation And Properties Of Alkylated Chitosan/Polydopamine-Graphene Oxide Composites

Excessive blood loss is one of the initial causes of death.Most of the current hemostatic materials are high in cost,low in hemostatic efficiency,and long time in hemostasis.Therefore,there is an urgent need to develop new high-efficiency and rapid hemostatic materials.Chitosan(CS)can broad-spectrum antibacterial agents,accelerate wound healing,has excellent hemostatic and biocompatibility,and composite materials based on it have high research and development prospects.However,most shell-doped matrix composites have poor hydrophilicity and low hemostatic efficiency.Alkylation modification of shell expansion was used to prepare N-alkylated chitosan(N-CS)to enhance its hemostatic properties.Polydopamine(PDA)was used to improve the biocompatibility of graphene oxide(GO)to prepare basic polydopamine modified graphene oxide(DGO),hydrothermal method and freeze-drying technology were used to composite two materials into different 3D interconnection network structures to prepare two dosage forms of N-CS/DGO,besides,physical and chemical characterization and evaluation of hemostasis performance respectively were carried out.The research results obtained are as follows:1.The nucleophilic addition reaction between dodecanal aldehyde group and chitosan amino group was realized by Schiff base reaction,and then N-CS was reduced using strong reducing agent sodium borohydride.FT-IR and XRD were used to confirm the successful alkylation modification;Hummers method was used to improve the oxidation of graphite to prepare GO,and the synthesis of GO was confirmed by FT-IR,XRD and Raman spectroscopy;DGO with better biocompatibility was obtained by modifying polydopamine and used for the preparation of alkylated chitosan composite hemostatic material;2.N-CS/DGO composite powders with different raw material ratio(5%?DGO?30%)were developed by hydrothermal method combined with vacuum drying method.FT-IR confirmed the synthesis of the material;the contact angle measurement experiment showed that the hydrophobicity of the material was enhanced by alkylation modification,while the hydrophilicity of the material was enhanced after compounding;SEM confirmed that the powder had a interconnected porous structure;The surface area reached 70.2870 m~2/g and the cumulative pore volume reached 0.2366 cm~3/g;Besides,it had good water absorption,suitable degradability,certain bacteriostatic and hemostatic properties.Considering comprehensively,the material had the best hemostatic potential when DGO mass fraction accounted for 15%.At this time,the water absorption rate of the material was 430%,and the degradation rate was appropriate,reaching 88%in five weeks.The antibacterial circles of Escherichia coli and Staphylococcus aureus were 1.92mm and 1.98 mm,respectively.In the in vitro coagulation experiment,the coagulation index reached a minimum of 32%,and the in vitro coagulation time was shortened to 126±6 s,which all showed that the N-CS/DGO material had the potential for hemostasis;3.N-CS/DGO composite sponges with different ratio of raw materials(5%?DGO?30%)were developed by using ultrasonic blending and freeze-drying method,in which DGO was used as the skeleton.Compared with the powder,it can be seen that the composite sponge had better water absorption,degradability and certain bacteriostatic ability.SEM showed that the material had nano-flower structure and can quickly absorb water.Its specific surface area reacheed 103.6 m~2/g,the pore size was mainly distributed below 5 nm,the blood coagulation index was only 29.2%,and the coagulation time was shortened to 113±5 s.Comprehensive consideration of the physical and chemical properties of the sponge,the composite material with DGO mass fraction of 15%was selected as the hemostatic material.At this time,the water vapor transmission rate of the composite sponge was 1.651 kg/(24 h·m~2),which meeted the requirements of the material's permeability,and it can degrade90.92%within 5 weeks,which can last for a long time on the wound.The composite sponge had a rich network structure,can absorb 29.3 times at its own weight of water,and the porosity reached 93.3%.The BET and SEM results were confirmed on the side,which provided a basis for the enhancement of the hemostatic effect.