Hydrophilic Modification And Biosorption Control Of Carbon Fiber Surface Based On Low Temperature Plasma

The interaction between protein and material surface is a natural and complex process.It is not only affected by the nature of protein itself and the environment,but also closely related to the physical and chemical properties of material surface.Carbon fiber has been widely used in biomedical,tissue engineering,environmental engineering and other fields,owing to its large specific surface area,high conductivity,strong corrosion resistance and good biocompatibility.However,the surface of carbon fiber is chemically inert,which limits its application.Thus,the surface modification of carbon fiber is the focus of research.There are various surface modification methods for carbon fiber,including surface oxidation,graft modification and coating modification.Commercial carbon fibers are usually processed in large quantities by strong acid oxidation,which requires long processing time and high processing conditions.Plasma material surface treatment technology has attracted much attention because of its advantages of fast,high efficiency and environmental protection.In this paper,atmospheric pressure plasma jet treatment and acid oxidation method were combined to explore the synergistic effect on the physical and chemical properties of carbon fiber surface.This two-step treatment was supposed to improve the efficiency of surface modification and reduce the conditions required for treatment.The protein adsorption on carbon fiber surface was regulated by studying the protein adsorption amount on the surface with different properties.The main contents are as follows:1.An efficient two-step surface treatment process was proposed.Plasma treatment and nitric acid treatment were combined on carbon fiber surface.The surface properties such as surface morphology,chemical composition and wettability of carbon fibers before and after treatment were characterized respectively,and the amount of protein adsorption was tested.It was found that plasma and acid oxidation treatment can effectively introduce active sites and oxygen-containing functional groups into the surface of materials,and form structural defects.These structural defects can increase the surface adsorption capacity of proteins.Among them,plasma plays an important role of activating carbon fiber surface and promoting its contact with acid solution,thus improving the efficiency of acid oxidation.This work proves that the combination of plasma treatment and acid treatment is an efficient way to modify carbon fibers,which can realize the introduction of active sites,improve the hydrophilicity and enhance the protein adsorption capacity of carbon fibers.It has laid a good foundation for the application of carbon fiber in fields such as tissue engineering scaffolds,enzyme immobilized carrier materials etc.2.Carbon fibers with different surface properties were prepared to achieve controllable surface modification.Carbon fibers were treated with nitric acid,hydrochloric acid and acetic acid respectively(in low concentration)with the assistance of plasma treatment.The effects of acid treatment in the two-step process were analyzed by characterizing the changes of surface morphology,specific surface area,chemical composition and surface energy.It was found that the surface roughness and specific surface area of fiber can be improved by nitric acid and hydrochloric acid at low concentration under the assistance of plasma treatment,while acetic acid has no significant effect on morphology.Plasma can promote the oxidation effect of nitric acid and acetic acid on the carbon fiber surface,and introduce a large number of oxygencontaining functional groups into the surface,such as C-O,C=O and COOH.The introduction of oxygen-containing functional groups can improve the surface energy and surface wettability of carbon fibers.Therefore,the surface of carbon fiber was controllable modified by using different acid.3.The surface protein adsorption regulation of modified carbon fiber was realized.The adsorption of protein on material surface is closely related to material properties.By preparing carbon fibers with different surface properties,the adsorption of protein was tested,and the effects of surface roughness,chemical composition,hydrophilicity and hydrophobicity,surface energy and other factors on protein adsorption were analyzed.It was found that rough surfaces provide adhesion sites for protein attachment,thus enhancing protein adsorption.However,the introduction of oxygen-containing functional groups,such as carboxyl,carbonyl groups etc.,has electrostatic repulsion effect on protein,thereby reducing the adsorption of surface protein.Hydrophilic surface and high surface energy surface can reduce protein adsorption.Therefore,the synergistic effect of plasma treatment and acetic acid can effectively reduce the surface protein adsorption and improve the biocompatibility of carbon fibers.Combining the influencing factors of protein adsorption,controllable protein adsorption amount on the surface of materials can be realized by regulating the physical and chemical properties of the surface.This study provides a theoretical basis for surface modification of biological materials.