Application Of Electrode Modified With Nano-scale Nickel-/Cobalt-containing Compound In Determination Of Several Small Molecules

This thesis introduces the principles,classification and application prospect of electrochemical sensors.The electrodes modified with carbon-based nanomaterials,nano-scale cobalt-/nickel-containing compound and their composites are summarized.The quantitative detections of glucose,vitamin B2(V_B2),and hydrogen peroxide?H₂O₂?were achieved using three types of modified glassy carbon electrodes based on the redox reactions and catalytic actions of nickel-/cobalt-containing compounds with nanostructure.The contents of the above small molecules in the cell microenvironment upon high glucose-induced vascular endothelial cell damage were analyzed.The main works were listed as follows:1.Well-dispersed poly?cysteine?-Ni?OH?₂ nanocomposite(?Pcys-Ni?OH?₂?was synthesized on the surface of a glassy carbon electrode?GCE?modified with graphene by cyclic voltammetry.The surface of the modified electrode was analyzed by scanning electron microscopy,infrared spectroscopy and X-ray photoelectron spectroscopy.The nickel-based nanomaterial exhibited a good electrocatalytical activity for oxidation of glucose in a strongly alkaline medium.The current change druing chronoamperometric measurement showed a linear dependence on the glucose concentration from 1.0?M to 0.10 mM and that from 0.20mM to 2.0 mM with a detection limit of 0.35?M?S/N=3?,and the sensitivity was 1092?A mM^-1 cm^-2.So an enzyme-free glucose sensor with high sensitivity and selectivity was constructed.The fabricated sensor was successfully applied in the determination of glucose level in human serum samples.The analysis on cell lysate reveals that the high-glucose medium could induce the enhancement of glucose content in human umbilical vein endothelial cells?HUVECs?and this glucose accumulation in these cells was one of important reasons for the cell injury.2.CoO_x-Au nanocomposite was prepared on the surface of a GCE modified with multi-wall carbon nanotubes?MWCNTs?via electrodeposition and redox reaction.The MWCNTs/CoO_x-Au film was characterized by scanning electron microscopy,energy spectrum analysis and X-ray photoelectron spectroscopy.The electrochemical behaviors of V_B22 on GCE,GCE/CoO_x-Au,GCE/MWCNTs,GCE/MWCNTs/CoO_x-Au were investigated,respectively.The quantitative analysis of V_B22 was realized using GCE/MWCNTs/CoO_x-Au.Under the optimal measurement conditions,a broad linear range from 5 nM to 50?M,a low detection limit of 1.7 nM and a high sensitivity of 764?A mM^-1 cm^-2were obtained.The developed sensor was employed in the detection of V_B2 content in a commercially available vitamin B2 tablet.The analysis on HUVECs cell culture medium showed that the uptake capacity of cells to V_B2 was significantly weakened after HUVECs suffered from injury in the presence of high-concentration glucose.3.Polytoluidine blue-cobalt film was prepared on the MWCNTs-immobilized GCE using cyclic voltammetry and the electrochemical performance of the modified electrodes was investigated.A method with high sensitivity and good selectivity for the enzyme-free detection of H₂O₂ was proposed based on the interconversion between cobalt-containing hydroxide Co?OH?₂ and CoOOH in a strongly alkaline medium and its electrocatalytic activity for the oxidation of H₂O₂.The current signal during chronoamperometric measurement exhibited a good linear response to the H₂O₂ concentration in range of 1.0?M-3 mM with a detection limit of 0.15?M?S/N=3?and a sensitivity of 273?A mM^-1cm^-2.The modified electrode was successfully applied in the detection of H₂O₂ content in a disinfectant sample.