Construction And Properties Of Novel Superoxide Anion Electrochemical Sensors

Reactive oxygen species(ROS)are a general term for relatively short live oxygen free radicals and other oxygenated substances with oxygen radical reactivity,and are a normal product of aerobic metabolism.ROS participates in the normal physiological activities of cells in the living body.However,when the body's redox balance is broken,the reactive oxygen species content will increase,which will lead to various diseases such as nervous system diseases,cardiovascular diseases,lung diseases,various inflammations and cancers.Superoxide anion(O₂^·-)is one of the important ROS.The change of the intracellular O₂^·-concentration has a significant impact on health.Therefore,fast,reliable,sensitive and real-time detection of O₂^·-has critical research significance.Most of the methods currently used to detect ROS are traditional indirect methods,which are time-consuming and expensive.The electrochemical sensor is widely used with the advantages of simple structure,easy operation,fast detection speed and low cost.In this experiment,several non-enzymatic O₂^·-electrochemical sensors were constructed,and the details are as follows:1)A nanostructured transition metal phosphate phosphate,i.e.nickel nanorod(Ni(PO₄)NRs),was synthesized by a simple and environmentally friendly hydrothermal method.Ni(PO₄)NRs and carboxylated multi-walled carbon nanotubes(C-MWCNTs)were modified onto a glassy carbon electrode(GCE)by drop coating to construct an O₂^·-electrochemical sensor.The sensor exhibits high sensitivity(4.68×10⁴?A m M^-1 cm^-2)and lower detection limit(0.170?M at S/N=3),and good selectivity.In addition,the sensing platform can be used for detection of O₂^·-released from human breast cancer cells(MCF-7)with good real-time detection capabilities.2)Cobalt cyanide(Co[Fe(CN)₆]·10H₂O)was prepared by coprecipitation method.Reduced graphene oxide(r GO)were prepared by Hummers method.Co[Fe(CN)₆]·10H₂O and r GO were modified to a glassy carbon electrode in a certain mass ratio to prepare an enzyme-free O₂^·-electrochemical sensor.Due to the synergistic effect of Co[Fe(CN)₆]and r GO,the prepared electrochemical sensor shows good catalytic performance for the electrochemical reduction of O₂^·-with a sensitivity of 9.18×10⁴?A m M^-1 cm^-2.The limit of detection is 0.354?M(S/N=3).The sensor has good selectivity,stability and reproducibility,and is successfully applied to the detection of O₂^·-released from MCF-7.3)The O₂^·-electrochemical sensor was constructed mainly by using nickel ferricyanide(Ni HCF)as a modification material.Under the optimal experimental conditions,the catalytic activity of Ni HCF/GCE for O₂^·-was studied.It was found that the response current of O₂^·-at Ni HCF/GCE had a good linear relationship with O₂^·-concentration in the range of 1?1100?M.Sensitivity of the sensor was 3.08×10⁴?A m M^-1 cm^-2,and the limit of detection was 0.317?M(S/N=3).The electrochemical sensor exhibits good selectivity,reproducibility and stability for O₂^·-.