Construction And Application Of Superoxide Anion Electrochemical Sensor

Superoxide anion（O₂·^-）plays a significant role in physiological process.Under normal condition,the superoxide anion maintains at a very low level in the body.When the body stimulated by the internal and external environment,the dynamic balance will be broken,resulting in abnormal levels of O₂·^-and inducing various diseases.Therefore,accurate and sensitive detection content of O₂·^-in the body is extremely important.Electrochemical method is favored owing to its high sensitivity,rapid response and easy operation.In this paper,combining the excellent mimetic enzyme properties of metal nanoparticles with the electrochemical properties of carbon,we constructed two kind of electrochemical sensors by a simple method for the detection of O₂·^-in cells and serum.The details are as follows:（1）Combined with the excellent catalytic performance of mental nanoparticles and better dispersivity of metal-organic frameworks（MOFs）,MOF（Ag）was synthesized by solvothermal method.And then the Ag NPs@C nanocomposites were obtained by carbonizing at 550℃of MOF（Ag）.The electrochemical sensor（Ag NPs@C/GCE）was constructed and had excellent electrochemical performance for O₂·^-with a linear range of 8 orders of magnitude and a detection limit as low as 10.11 p M（S/N=3）.In addition,the sensor can be used to directly monitor the O₂·^-released from human cervical cancer cells（He La）under normal conditions and induced by malonic acid.At the same time,we also explored the effects of different concentrations of stimulant on cells.The results illustrated the high dose malonic acid can cause oxidative stress on cells.This work provides a new idea for the clinical diagnosis of ROS related diseases.（2）Because of the mimetic enzyme properties of Au NPs and the excellent electrochemical properties of multi-walled carbon nanotubes（MWCNTs）,we prepared Au NPs@MWCNTs composites by one-step reduction method and constructed O₂·^-electrochemical sensor.The structure and electrochemical property of Au NPs@MWCNTs were characterized by transmission electron microscopy（TEM）,X-ray single crystal diffraction（XRD）,cyclic voltammetry（CV）and electrochemical impedance spectroscopy（EIS）.The sensor showed satisfactory results for the detection of O₂·^-due to its large electroactive area,strong catalytic ability and fast electron transfer rate.In addition,the sensor can be used to detect O₂·^-in serum and had great potential in the preliminary diagnosis of related diseases.