Application Of Graphene Fiber Microelectrodes Modified By Cobalt-based Nanoarray In Dopamine Electrochemical Biosensors

Dopamine(DA)is one of the neurotransmitters that initiate neuronal signal transduction in the human physiological system.Its metabolic abnormality leads to severe neurodegenerative diseases.The metabolic level of neurotransmitter in the human body is at the nmol level.It is very important to develop an efficient and sensitive analysis and diagnosis technology for DA detection in real physiological samples.Microelectrodes have the advantages of small size,electrochemical stability,which are of great research value in electroanalysis and detection of small biological molecules.Compared with metal fiber and traditional carbon fiber materials,graphene fiber(GF)has the advantages of large specific surface area,adjustable structure,high conductivity,good stability and biocompatibility,and high mechanical strength,which has greater potential value in electrochemical biosensors.Therefore,in this paper,GF are used as the substrate material,we developed two flexible functionalized GF microelectrodes through heteroatom doping and array structure design and an electrochemical sensor system for ultra-sensitive DA detection was constructed,exploring the application research of body fluids and nerve cells.The study content of this paper mainly includes two aspects:(1)In order to functionalize GF and explore the application of microfluidic technology in the detection of trace body fluids.PA-GF was prepared by wet spinning using graphene oxide(GO)nanosheets as the building block and PA as the phosphorus source.Through solvothermal and high-temperature pyrolysis,cobalt tetroxide nano wire array(Co₃O₄ NWA)was grown on phosphor doping GF microelectrodes.The large specific surface area and good catalytic activity of Co₃O₄ NWA and good conductive carrier of P-GF microelectrodes make good electrocatalytic activity for DA with a sensitivity of 17.5?A cm^-2?M^-1,The detection limit was as low as 0.4?M.In view of the easy integration of the microfluidic chip,an electrochemical microfluidic sensor chip was prepared to realize the sensitive detection of DA in human urine.(2)In order to further improve the electrocatalytic activity of GF on DA and explore the application of nerve cell detection Using GF as the substrate material,the cobalt phosphide nanowire array(Co P NWA)modifying GF microelectrode was obtained through two steps of solvothermal and low-temperature phosphating.Under the optimal conditions,the sensitivity was 21.4?A cm^-2?M^-1and the detection limit was as low as 0.024?M.The microelectrode realized the sensitive detection of DA in human urine and serum and detected in situ the current signal of DA released by human neuroma cells SHSY-5Y under a certain K⁺concentration stimulation,providing a new way of rapid diagnosis and detection of neurological diseases.