The Fabrication And Application Of Electrochemical Sensors Based On Three Kinds Of Metal Ion Doped Nanomaterials

As a kind of biological small molecules,dopamine?DA?is very important information transfer material existing in the mammalian central nervous system.The extremely abnormal level of DA was studied to be closely related to various diseases,such as heart disease,Parkinson's disease,neuromuscular disorders and various neurological diseases.DA can be used for the performances to cure loss of hematic disease,cardiogenic and septic shock in clinical practice.Therefore,the research on the determination method of DA has been highly concerned.Phenol is the persistent organic pollutant that will cause severe pollution of air,soil and water.Up to now,bisphenol A?BPA?is detected in the water and life items around the world.The environmental behavior and risk assessment of BPA have become the research focus in environment field.So monitoring the content of BPA has great significant not only to human health but also environmental protection.Until now,various analytical methods have been built to determinate biological small molecules and phenolics.The electrochemical method has been widely applied to detect them due to its low cost,fast response,high sensitivity,time-saving and convenient operation.The construction of sensing interface is the key for electrochemical detection.In this work,the novel electrochemical sensing interfaces are developed and used for the electrochemical detection of DA and BPA based on the three novel kinds of chemically modified electrodes.This study has a certain scientific significance on enlarging the application scope of electrochemical sensing interface and a broad prospect in the clinical medicine and environmental monitoring.This paper is divided into five chapters and the main contents are includedas follows:La-doped ZnWO₄ nanospheres are successfully synthesized by a hydrothermal synthesis method and further investigated by X-ray diffraction?XRD?,scanning electron microscopy?SEM?and energy dispersive X-ray spectroscopy?EDS?.A novel electrochemical sensor has been fabricated by carbon paste electrode?CPE?coated with the prepared La-doped ZnWO₄ nanospheres.Electrochemical impedance spectroscopy?EIS?,cyclic voltammetry?CV?and differential pulse voltammetry?DPV?are applied to characterize electrochemical properties of the sensor?La-doped ZnWO₄/CPE?.By using DPV method,low detection limits of DA and UA are obtained to be 0.04?mol·L^-1and 0.03 ?mol·L^-1?S/N = 3?,with the linear calibration curves over the concentration ranges of 0.10⁴3.03 ?mol·L^-1 and 0.08¹06.65 ?mol·L^-1,respectively.Furthermore,the sensor is employed to detect DA and UA with good selectivity and sensitivity,and the interference experiment as well as the practical sample analysis is also well performed.Na-doped WO3 nanorods are successfully prepared via a hydrothermal synthesis method and further characterized by XRD,SEM and EDS.A novel and sensitive electrochemical sensor has been fabricated for determination of bisphenol A?BPA?based on the as-synthesized nanomaterials modified CPE.EIS,CV and DPV are applied to demonstrate the electrochemical performances of Na-doped WO3 modified CPE?Na-doped WO3/CPE?.By using the DPV technology,the linear calibration curve is obtained within a wide concentration range from 0.0810 ?mol·L^-1 to 22.5 ?mol·L^-1 with the low detection limit of 0.028 ?mol·L^-1?S/N = 3?for BPA.Moreover,the sensor also show good anti-interference ability in the interference study and satisfactory recovery in the practical sample analysis.Thus,the proposed sensor could be advantageously employed for the determination of BPA in environmental science.Ce-doped ZnFe₂O₄ nanorods are successfully synthesized by a precipitation synthesis route and used for the fabrication of Ce-doped ZnFe₂O₄ modified CPE?Ce-doped ZnFe₂O₄/CPE?to determinate BPA.SEM,EDS,XRD and EIS are applied to characterize as-synthesized nanomaterials and modified electrodes.CV responses of BPA under different p H and scan rate indicate that Ce-doped ZnFe₂O₄/CPE has good electrocatalytic property.Meanwhile,by DPV method,the good linear relationship isshowed within a wide concentration range from 0.072 ?mol·L^-1to 21.11 ?mol·L^-1with the low detection limit of 0.025 ?mol·L^-1?S/N = 3?for BPA.The anti-interference ability,stability and repeatability of the sensor are also well evaluated.Ce-doped ZnFe₂O₄/CPE has advantages of wide linear range,low detection limit and high sensitivity,which makes it better than the traditional electrode.