Application Research Of Cu²⁺ And Ag⁺ Based On All-Solid-State Potentiometric Analysis Sensing Technology

An all-solid-state potential sensor is a kind of electrochemical sensor.The potential sensor is a sensing technique that utilizing the potential of the ion selective electrode to vary with the amount of ions being measured in the solution.All solid-state ion selective electrodes?ASS-ISEs?without internal filling are the main research direction of all-solid-state potential sensors,which are different from conventional ion-selective electrodes.All-solid-state ion-selective electrodes have the advantages of being freely positionable,easy to miniaturize,simple to prepare,and fast in response,and have been rapidly developed in the fields of environmental monitoring,disease monitoring,and detection of experimental processes in recent years.Factors such as water layer,charge transfer impedance and electric double layer between the substrate electrode and the selective sensitive film affect the stability of the all-solid ion selective electrode.To improve this situation,a classical all-solid state electrode containing a solid contact layer has been developed.All solid-state ion selective electrodes,which are usually composed of a solid contact layer with high hydrophobicity and high ion-electron conduction efficiency and a polymer sensitive membrane.In addition,new all-solid-state potential sensors such as aptamer base potential sensors,biomolecular base potential sensors,paper electrodes and wearable potential sensors.In this paper,we mainly construct a new all-solid-state potential sensor and a classical all-solid-state ion-selective electrode and study its practical application.The main research work of this thesis is as follows:?1?A novel all-solid ion selective electrode?ASS-ISE?was constructed based on phytic acid-coated silver?PA@Ag?composite nanomaterials.The sensitive film formed by PA@Ag owning a negative charge that can attract positively charged Cu²⁺.causes a potential change.PA with excellent conductivity and complexing ability can selectively recognize metal ions and convert charged ions into electrical signals to the electrode surface.The present of silver nanoparticles can connect a plurality of phytic acid molecules to form a network structure,which can greatly improve the conductivity and stability of the film layer.Real-time and rapid detection of Cu²⁺was carried out by open-circuit potential method.After optimizing the thickness of PA@Ag film,this ASS-ISE gave a near Nernstian behavior?31.3±1.8 mV/dec?towards the variation of Cu²⁺concentration in the range of 1.0×10^-5 mol/L to1.0×10^-3 mol/L with a detection limit of 2.7×10^-6 mol/L,and presented excellent selectivity and stability.Furthermore,it was applied in the analysis of Cu²⁺in environmental waters with the satisfactory recoveries,and the results were consistent well with those obtained by inductively coupled plasma atomic emission spectrometer,providing a promising alternative for the on-site detection of Cu²⁺with simplicity and reliability.?2?A polypyrrole/carbon nanotube?PPY-CNT?copolymer was developed as solid contact?SC?for the an all-solid silver ion selective electrode?Ag⁺-ISMs?.First,the pyrrole monomer and carbon nanotube are dissolved in a sodium dodecyl sulfate solution?SDS?and deposited on the GCE to obtain a polypyrrole/carbon nanotube copolymer by cyclic voltammetry.Then,a silver ion selective membrane dissolved in THF was drop on top of SC,and an all solid PPY-CNT/Ag⁺-ISMs electrode was obtained after the THF volatilization.Polypyrrole has good electrical conductivity and hydrophobicity,while carbon nanotubes exhibit outstanding capacitive and hydrophobic properties.The copolymers avoid their respective defects,synergistically exert ion-electron transport and avoid formation of water layers.The open-circuit potential test results show that the PPY-MWCNTs/Ag⁺-ISMs/GCE response with a near Nermstian slope of 48.0±1.7 mV/dec in 1.0×10^-6 mol/L-1.0×10^-22 mol/L.The electrode potential stability obtained by the reverse chronopotentiometry and the water layer test evaluation between the electrode sensitive film and the substrate electrode indicate that the high redox and high capacitance of PPY-MWCNTs effectively avoid the formation of the water layer and greatly improve the stability of PPY-MWCNTs/Ag+-ISMs/GCE electrodes.?3?In this section,a sensor based on the characteristics of nano-silver oxidation.was constructed for indirect detection of thrombin.The sensor is based on silver nanoparticle functionalized SiO₂?Ag@SiO₂?as a signal amplification component,Aptamer29/Ag@SiO₂ as a probe.And the sandwich structure Ag@SiO₂/Apt2/thrombin/Apt 1/Fe₃O₄ was constructed by the specific binding of thrombin with two-stage aptamers.Subsequently,the magnetic separation was carried out using the magnetic properties of Fe₃O₄,and the silver nanoparticles were oxidized to silver nanoparticles under the oxidation of nitric acid.Finally,the corresponding thrombin concentration was detected by PPY-MWCNTs/Ag⁺-ISMs/GCE we prepared.Quantitative detection of thrombin was achieved by quantitative relationship between the concentration of silver nanoparticles and the concentration of thrombin.Under optimal conditions,the solid-state electrode PPY-MWCNTs/Ag⁺-ISM/GCE exhibits a linear relationship with the Ag@SiO₂/Apt 2/thrombin/Apt 1/Fe₃O₄ system.The linear response slope is 20.7 mV/dec,which is close to the concentration of Ag⁺obtained by direct oxidation of Ag@SiO₂ by HNO₃.This application provides preliminary evidence for further application of all-solid-state electrodes to complex biological protein systems.