Application And Research Of Four Nanomaterials Modified Electrodes In Protein Sensors

Nanomaterials consist of fine particles and are characterized by nanoscale ultrafine solids,at least in one direction,with a grain size typically in the 1-100 nm range.When the grain of the material is within this range,the crystal and electronic structure of the material will change,which will produce effects that macroscopic objects do not have,such as small size effects,quantum effects and so on.Different nanomaterials have unique characteristics in electrical,optical,and chemical fields and are widely used in clinical,military,and biological fields.Studying the electron transfer and electrocatalysis of protein active centers helps people to better understand life activities.The combination of nanomaterials and proteins can promote the reaction of protein active centers,and it is of great significance for the construction of third generation biosensors for studying the mechanism of living bodies.In this dissertation,four kinds of nanomaterials were used as modifiers to prepare four kinds of nanomaterials modified electrodes for the study of the electrochemical behavior of myoglobin(Mb)and hemoglobin(Hb).1.Synthesis of three-dimensional graphene(3DGR)nanomaterials by hydrothermal method and further used as electrode modification.Because 3DGR shows better properties than 2D graphene,such as higher conductivity,larger specific surface area and good biocompatibility.A biosensor was prepared by immobilizing myoglobin(Mb)on the electrode surface with chitosan(CTS).The spectral results show that the Mb immobilized on the 3DGR nanomaterial maintains its original structure.The cyclic voltammogram of CTS/Mb/3DGR/CILE in p H 4.0 buffer solution shows a reversible redox peak,indicating that Mb has achieved direct electrochemistry on the electrode.Using CTS/Mb/3DGR/CILE as the working electrode,a novel third-generation electrochemical biosensor was constructed and used for the electrochemical detection of trichloroacetic acid(TCA).Experiments show that the established method has many advantages such as high sensitivity,wide detection range,low detection limit,stability and good reproducibility.2.Preparation of tin oxide-three-dimensional graphene(Sn O2-3DGR)nanocomposites.Sn O2-3DGR was drop on the surface of the electrode to construct a Sn O2-3DGR/CILE electrochemical sensing platform,and Mb was further assembled on the interface.Based on the Mb/Sn O2-3DGR good performance of electrocatalytic reduction of trichloroacetic acid(TCA).An electrochemical biosensor for rapid detection of TCA was prepared.The linear range of the biosensor was: 5.0~94.0mmol/L.The detection limit was 1.67 mmol/L(3σ).The prepared biosensor has good biocompatibility,high sensitivity,simple prepared,environment-friendly and low cost,and can achieve high-efficiency detection of TCA.3.An ionic liquid-modified carbon paste electrode(CILE)was used as a substrate electrode.Nitrogen-doped graphene quantum dots(N-GQDs)and Hb were mixed in a certain proportion and then modified on the surface of CILE to construct an electrochemical biosensor(Nafion/Hb/N-GQDs/CILE).N-GQDs have quantum confinement effect and edge effect,which make them have good application prospects in protein sensors.The Nafion/Hb/N-GQDs/CILE was used to study the electrocatalytic properties of TCA,Na NO2 and H2O2.The electrocatalytic range of N-GQDs modified electrode for TCA,Na NO2 and H2O2 was 3.0~170.0 mmol/L,0.2~2.0 mmol/L,and 5.0~20.0 mmol/L.4.Nano-carbon nitride(C3N4)is a new kind of semiconductor material with chemical stability,which has been widely used in electrocatalysis.A C3N4/CILE modified electrode was prepared by using C3N4 as an electrode modifier and Mb and Nafion were further immobilized on the modified electrode to obtain a Nafion composite film modified electrode Nafion/Mb/C3N4/CILE.The electrochemical electrode was used to characterize the modified electrode.The results showed that the presence of nanomaterial on the surface of the electrode increased the specific surface area of the electrode.A reversible redox peak is observed in the cyclic voltammetry test,indicating that the direct electrochemical behavior of Mb is achieved at the electrode surface,which is the typical electrochemical behavior of Fe(III)/Fe(II)redox couple in Mb.The presence of nano-C3N4 on the surface of the electrode provides a special interface for Mb to accelerate electron transfer.The direct electrochemical behavior of Mb was studied by calculating the electrochemical parameters.Under theselected conditions,the Mb modified electrode exhibited good electrocatalytic activity for TCA and H2O2 with linear ranges of 0.8~64.0 mmol/L and 2.0~14.0 mmol/L,respectively.