Preparation Of Functionalized Magnetic Graphene Oxide Nanocomposites And Adsorption Properties For Protein

In recent years,graphene has attracted a lot of attention and was widely used in sensors,biomedicine,optoelectronic materials,electronic devices and supercapacitors due to its unique structure and excellent physicochemical properties.Graphene and its oxides,graphene oxide,both have large surface area and good biocompatibility.In order to further expand the application of graphene in biology,many researchers were dedicated to functionalize graphene oxide surface to improve its biocompatibility.It is appropriate surface modification of GO that not only prevent the agglomeration of graphene oxide,but also enhance its stability and adsorption capacity.At the same time,magnetic nanomaterials were extensively applied to the purification and separation of proteins,owing to their large specific surface area,fast response,easy operation and preparation.The first chapter gave an overview of the progress of the modification of graphene oxide and functionalized magnetic graphene oxide,also summarized the progress of separation and purification of proteins.And discussed the adsorption and separation of proteins in different dimensions of magnetic nanocomposites.In the second chapter,sandwich-like structure of graphene oxide?GO?@SiO₂@C-Ni nanosheets were prepared by combining an extended st?ber method with subsequent carbonization treatment,in which polydopamine was used as reducing agent and carbon source.Firstly,the GO nanosheets were covered with SiO₂interlayer and finally coated with a outer shell of nickel ion doped polydopamine(PDA-Ni²⁺)with an extended st?ber method.Followed by a carbonization to produce the GO@SiO₂@C-Ni nanocomposites with metallic nickel nanoparticles embedded in PDA-derived thin graphic carbon layer.The size and density of nickel nanoparticles on the surface of GO@SiO₂ nanosheets can be effectively adjusted by changing the calcination temperature or the molar ratio between dopamine and nickel salt.Furthermore,nickel nanoparticles decorated on GO@SiO₂@C spheres were empolyed in enrich His-rich proteins?BHb and BSA?via specific metal affinity force between polyhistidine groups and nickel nanoparticles.In the third chapter,graphene oxide?GO?@SiO₂@Fe₃O₄@Cu Silicate nanocomposites were prepared by an extended st?ber method,solvothermal method and hydrothermal reaction.Firstly,the GO nanosheets were coated on both surfaces sequentially by SiO₂ through a classical st?ber method,and then magnetite Fe₃O₄nanoparticles coated onto GO@SiO₂ in one-pot procedure through a solvothermal method.Finally,as-prepared GO@SiO₂@Fe₃O₄ successfully obtained whisker-like copper silicate by hydrothermal reaction.Notably,silica interlayer played a vital role in the formation of such GO@SiO₂@Fe₃O₄@Cu Silicate nanocomposites.The use of a silicon dioxide layer not only prevents the agglomeration of GO but also provides a silicon source for the formation of copper silicate.Furthermore,the introduction of magnetic iron tetroxide particles makes the material superparamagnetism,which greatly facilitate the use of an external magnetic field for composite separation and recycling.In addition,the copper silicate modified on GO@SiO₂@Fe₃O₄ is enriched by the specific metal affinity between polyhistidine and copper ions His proteins?BHb and BSA?.