Construction Of Carbon Nanocomposite Modified Electrodes And Their Application In The Analysis Of Traditional Chinese Medicine

Nowadays,numerous achievements have been made in the analysis of traditional Chinese medicine（TCM）components in non-electrochemical fields such as chromatography and mass spectrometry,while,it issues efficacy and progress in high sensitivity and stability for electrochemical sensors,which is necessary to complete the scientific research task of accurately determining the active components in TCM and then establishing a comparatively systematic analytical system in the field of electrochemistry.Electrochemical sensors have drawn numerous attentions in the aspect of rapid response,moderate price,real-time online monitoring,high sensitivity and so forth.Now that brilliant electrochemical performance of the sensor is mainly played by the modified material and on account of our research direction and progress of the laboratory,this thesis has purposefully committed to exploring and catching brand new carbon nano-composites with excellently electrical specifications for our three target active ingredients.With single walled carbon nanotubes（SWCNTs）or grapheme oxide（GO）as supporting platform,metal oxide,metal nanoparticles,metal organic frame materials（MOFs）or covalent organic frame materials（COFs）were grafted respectively on the surface of carbon substrates to develop the excellent carbon-based nano-composites,and when working as electrode modified materials,They could respectively exert high adsorption capacity and high catalytic performance for their responding detection object.Crucially,feasible and hypersensitive electrochemical analysis methods have been proposed by using Differential pulse voltammetry（DPV）technique,which rewrote the zero record of sensitive detection for some significant components of TCM（echinacoside and cynarin）by using electrochemical technology.Those works are expressed shortly as follows:（1）This part has successfully designed and constructed one novel high-sensitive electrochemical sensor（ZrO₂-SDS-SWCNTs/GCE）for hyperin determination,and its modified material（ZrO₂-SDS-SWCNTs nano-composite）was prepared through an environmentally friendly and low-cost one-step hydrothermal procedure,where ZrO₂nano-particles were uniformly anchored on the outer tube walls of SWCNTs that functionalized with sodium dodecyl sulfate（SDS）.Electrochemical impedance spectroscopy（EIS）and cyclic voltammetry（CV）were respectively employed to investigate surface properties of the sensor and the electrochemical behavior of hyperin on the sensor surface.With the aid of the superb novel nano-composite,linear range of the new proposed analysis method that based on DPV technique got wider(1.0×10^-93.0×10^-7 mol L^-1)and detection limit（LOD）became lower(5.0×10^-10 mol L^-1)contrasted with the previous reports.（2）This part researched one novel ratiometric sensor with MB encased MOF-5@PGN nano-complex as the brilliant electrode modified material,which worked unexceptionably out as the following course:synthesis of nano-composite MOF-5@PDDA-rGO-Ni（MOF-5@PGN）included the decoration of well-shaped Ni nano-particles（Ni NPs）onto poly diallyldimethylammonium chloride（PDDA）functionalized reduced graphene oxide（rGO）sheets and the construction of cubic porous-morphology MOFs（MOF-5）by in-situ assembly.When the nano-complex MOF-5@PGNcontributedtoconstructtheelectrochemicalsensor MOF-5@PGN/GCE,it devoted a high-sensitive DPV response towards echinacoside,beyond that,the first determination performance of echinacoside in electrochemistry has accordingly proceeded.As for improved analysis method,the MB molecules were encapsulated into cubic MOF-5 frameworks in the as-prepared MOF-5@PGN hybrid with expectation to produce the reference signal,and the attained ratiometric sensor（MB encased MOF-5@PGN/GCE）assisted to develop a new calibration curve with a wider linear range(3.0×10^-81.0×10^-6)and a lower LOD(1.0×10^-8)compared with the result that from MOF-5@PGN/GCE.（3）A new electrochemical sensor TpBD@rGO/GCE was built based on one well-defined COFs material（TpBD）modified graphene oxide nano-composite TpBD@rGO.The fabulous sensor revealed a strong adsorption capacity and extreme cyclic voltammetry（CV）response for cynarin sensing.Besides,the redox mechanism of cynarin on sensor surface and the dynamic process were explored by virtue of CV technology and single potential chronometric study,respectively.As long as it takes,the highly sensitive and credible assay method depending on electrochemical sensor with the aid of DPV technology was firstly put forward for cynarin sensing,and according to the established linear fitting curve,the oxidation peak current of cynarin held a fine linear relationship with its concentration in two ranges:3.0×10^-91.0×10^-7mol L^-1 and 1.0×10^-75.0×10^-66 mol L^-1,with a detection limit（LOD）of 6.73 mol L^-1.Adorably,this method has also been successfully used in actual sample Artichoke leaf for cynarin determination.