Functional Magnetic Graphene Oxide Composites For Separation Of Proteins

Protein is the basic composition of life,it participates in the various life activities.In recent years,protein analysis has attracted widespread attention.A number of protein analysis methods and equipment have been developed.However,protein is usually present in complex sample matrix.Other substances in the matrix such as small organic molecules,inorganic salts and other proteins will cause significant interference in the detection of target protein.Therefore,it is urgent to develop effective sample pretreatment methods to isolate and purify the target protein.Graphene oxide,the novel adsorbent,exhibits potential in the field of protein separation due to its good biocompatibility and controlled surface properties.The oxygenated groups have hydrogen bonding and electrostatic interactions with proteins,and can tune the adsorption capacity and selectivity of target protein via functional modification.However,graphene oxide has a high dispersibility in water,it is difficult to separate the graphene oxide from aqueous solution,which limits its direct use in protein separation.Thus,after the modification of the magnetic particles on the surface of graphene oxide,the material can be quickly separated from the dispersion when an external magnetic field is applied.In this paper,we explored the functionalized modification method of graphene oxide.Amino acids and polyethyleneimine were covalent bonded to the surface of graphene oxide respectively,then the functionalized graphene oxide magnetic composite was successfully synthesized by coprecipitation method.The characterization results showed the successful modification of graphene oxide and the attachment of Fe₃O₄ particles to the surface.The materials were paramagnetic and could be quickly separated from the dispersion under an external magnetic field.In addition,the adsorption properties of the two kinds of composites were investigated,and a series of conditions which affected the adsorption capacities of the materials to the proteins were optimized.The results of adsorption experiments showed that the amino-acid-modified graphene oxide magnetic nanocomposite?AMGO@Fe₃O₄?had a high adsorption capacity for bovine hemoglobin(868.3 mg g^-1)and a better adsorption performance than that of magnetic graphene oxide.The proposed AMGO@Fe₃O₄ could selectively extract BHb from BSA and could be easily recycled and reused more than three times.The proposed composite has been successfully applied to the enrichment and separation of BHb in the real sample of bovine plasma.The polyethyleneimine-modified graphene oxide magnetic nanocomposite?GO-PEI@Fe₃O₄?had a better performance than magnetic graphene oxide in the extraction of BSA.The proposed method possessed good precision,repeatability and stability.It could be used as a simple and efficient separation technique for proteins and exhibited potential applications in real samples.