Preparation Of Nanometer Material Modified Electrode And Its Application To The Detection Of Hydroxyl Radical And Hydrogen Peroxide

Reactive oxygen species?ROS?,such as hydroxyl radicals?·OH?and hydrogen peroxide?H₂O₂?are important compounds in the metabolism of organisms.A higher level of ROS in biological fluids causes cells oxidative stress and generates toxicity,resulting in the occurrence of diseases.In some cases,the production of ROS is one of the defense mechanisms of the probiotics microorganisms against pathogens,and when the body lacks immunity,it can take probiotics added in food to enhance the body's immunity and resist the invasion of pathogenic bacteria,through the production of ROS to enhance the immune capacity of the body,to resist the invasion of pathogenic bacteria.Therefore,rapid and sensitive detection of·OH and H₂O₂ produced by probiotics is helpful for the research and selection of these microorganisms,which is of great significance in the study of physiological processes and foodElectrochemical method has many advantages,such as good stability,fast response,easy operation,high sensitivity,low price,real-time monitoring,miniaturization and so on,as well as electrochemical method has been widely used in food,environment,medicine,biology and other fields.The sensitivity,stability and selectivity of electrochemical modified electrodes depend largely on the structure and performance of electrode materials used in manufacturing,among which electrochemical modified electrodes constructed by nanomaterials such as carbon nanomaterials and metal oxide nanomaterials have become the focus of research.In this paper,three electrochemical modified electrodes were successfully constructed to detect H₂O₂ and·OH,and they were applied in practice?1?Based on the single-walled carbon nanotubes?SWCNT?nanomaterials modified glassy carbon electrode,a novel method for electrochemical detection of·OH was developed,which using 4-hydroxybenzoic acid?4-HBA?.As a capture agent,the content of·OH is indirectly detected by reacting 4-HBA with·OH to a single hydroxylated product,3,4-dihydroxybenzoic acid?3,4-DHBA?.Electrochemical behavior of SWCNT/GCE modified electrode was studied by EIS,CV and square wave voltammetry?SWV?,as well as the concentration of 3,4-DHBA within the range of 0.1-100 ?M had a good linear relationship with the current value.The detection limit was 0.076 ?M,and the modified electrode had a good anti-interference ability to 4-HBA and 2,4-DHBA.The method can be used to detect the content of·OH produced by Fenton reaction,the concentration of·OH within the range of 0.1-7 mM has a good linear relationship with the current value.SWCNT/GCE has a high elelctrochemical signal to 3,4-DHBA and has good stability and reproducibility,which is expected to realize online and in-situ detection of·OH.?2?A novel H₂O₂ electrochemical modified electrode with high selectivity,good reproducibility and high sensitivity was prepared by using copper ferrite-multi-walled carbon nanotube-chitosan?CuFe2O4-MWCNT-CS?nanocomposite.The material and structure of CuFe2O4-MWCNT nanocomposite were characterized by Fourier transform infrared?FTIR?and transmission electron microscopy?TEM?.Electrochemical performance of CuFe2O4-MWCNT-CS/GCE and electrocatalytic effect of H₂O₂ were studied by electrochemical cyclic voltammetry?CV?and electrochemical impedance spectroscopy?EIS?.The amperometry?i-t?method was used to detect the H₂O₂ standard solution,which had a good linear relationship in the range of 5-3010 ?M.The detection limit is 0.39 ?M,and had good anti-interference ability to K⁺,Na⁺,CO₃^2-,Cl-,SO₄^2-,glucose,ascorbic acid.?3?A novel H₂O₂ electrochemical modified electrode with high selectivity,good reproducibility and high sensitivity was prepared by using copper oxide-single-walled carbon nanotube polydiallyldimethylammonium chloride?CuO-SWCNT-PDDA?nanocomposite.The crystal,material and structure of CuO-SWCNT-PDDA nanocomposite were characterized by X-ray diffraction?XRD?,Fourier transform infrared?FTIR?and field emission scanning electron microscopy?FESEM?.Electrochemical performance of CuO-SWCNT-PDDA/GCE and electrocatalytic effect of H₂O₂ were studied by electrochemical cyclic voltammetry?CV?and electrochemical impedance spectroscopy?EIS?.The amperometry?i-t?method was used to detect the H₂O₂ standard solution,which had a good linear relationship in the range of 1-1150 ?M.The detection limit is 0.39 ?M,and had good anti-interference ability to K⁺,Na⁺,Cu²⁺,CO₃^2-,Cl^-,SO₄^2-,glucose,ascorbic acid.?4?Three different modified electrodes SWCNT/GCE,CuFe204-MWCNT-CS/GCE and CuO-SWCNT-PDDA/GCE,were used to detect·OH and H₂O₂ in several bacteria and the accuracy of the three modified electrodes was discussed.Among them,CuFe2O4-MWCNT-CS/GCE was used to detect Lactobacillus plantarum and Lactobacillus bulgaricus.The highest content of H₂O₂ produced by Lactobacillus plantarum can reach about 225 ?M,and H₂O₂ was spiked as well as recovered in Lactobacillus bulgaricus.The rate and RSD value were both good.CuO-SWCNT-PDDA/GCE was used to detect the H₂O₂ content produced by bacteria.After calculation,both Lactobacillus bulgaricus and Lactobacillus plantarum produced H₂O₂,the heighest content can reach out about 280 ?M,and the results were consistent with the colorimetric method as well as H₂O₂ spiked was performed in E.coli,and recovery and RSD values were good.