Study On The Preparation And Applications Of Electrochemical Biosensors Based On Nanogold Composite Materials

Nanomaterials and biotechnology are important fields of science and technology in the 21st century.The Nano-biosensor technology formed by the intersection of the two has became the frontier technology of research.Nanomaterials have special properties such as small size effect,surface effect,quantum dimension effect and macroquantum effect and so on effect.A large number of electrochemical biosensors based on new nanomaterials have been studied and applied,and great progress has been made.These new sensors have the advantages of high sensitivity,such as better selectivity,wide detection range and wider practicability.At present,biosensors based on different new nanomaterials have been applied in the fields of clinical medicine,chemical industry,food and drug safety detection,environmental protection and biotechnology.This dissertation is devoted to the study of protein electrochemical sensing based on five different gold nanoparticles and their composites,including the following five parts:1.The direct electrochemical behavior of myoglobin?Mb? on the gold nanorod?AuNRs? modified electrode was studied.The gold nanorods were immobilized on the carbon ionic liquid electrode?CILE? and coated with Mb to form a selective sensitive membrane.Nafion/Mb/AuNRs/CILE was prepared by immobilization of the gold nanorod solution with Nafion membrane.The structural of AuNRs was observed by scanning electron microscope?SEM? and high transmission electron microscope?TEM?.Comparison of different modified Electrodes by AC Impedance method.Fourier transform of IR and UV-vis absorption spectra showed that Mb maintained the secondary structure of the original protein in the AuNRs composite film,and still had biologicalactivity.Theelectrocatalyticreductionperformanceof Nafion/Mb/AuNRs/CILE to different substrates was also investigated.The electrocatalytic reduction of trichloroacetic acid?TCA?,sodium nitrite?NaNO₂? and potassium bromate?KBrO₃? was good.The wide linear ranges as 10.0³50.0 mmol L^-1,0.05².5 mmol L^-1 and 0.3⁴.0 mmol L^-1 was calculated.The detection limits were 3.33 mmol L^-1,0.016 mmol L^-1 and 0.1 mmol L^-1.The modified electrode designed can also be well applied to the detection of the actual biological sample.2.A new electrochemical biosensor based on gold nano-star?AuNSs? and myoglobin was designed and its electrochemical behavior and electrocatalytic performance were studied.The AuNSs was characterized by transmission electron microscope.The experimental results showed that the stellate structure of AuNSs can load more Mb.Spectroscopic proved that Mb still maintains its bioactive structure in the mixed AuNSs-Mb films.The effect of pH value of PBS on the results of electrochemical experiments was investigated,and the direct electricity of Nafion/Mb/AuNSs/CILE was realized.The electrochemical behavior and the electrocatalytic properties of TCA,NaNO₂ were studied.The electrochemical reduction performance of them was excellent.The Michaelis constants of K_M^apppp were110.12 mmol L^-1 and 4.48 mmol L^-1,respectively.The stability and reproducibility of the electrode are good.3.A newfashioned electrochemical biosensor Nafion/Hb/AuNRs-WS₂/CILE based on gold nanorods tungsten disulfide nanocomposites?AuNRs-WS₂? and hemoglobin was designed and its electrochemical and electrocatalytic applications were studied.The effects of pH of electrolyte solution and scanning rate on the results of cyclic voltammetry were investigated.The direct electrochemical behavior of Nafion/Hb/AuNRs-WS₂/CILE was investigated by electrochemical analysis.The peak shape of oxidation-reduction was good.AuNRs-WS₂ was characterized by scanning electron microscopy?SEM? and visible by UV absorption.The spectra and Fourier transform infrared spectroscopy?FTIR?spectra showed that the protein secondary structure was still maintained after the mixture of Hb and AuNRs-WS₂.The electrochemical characterization of various electrodes was carried out by alternating current impedance method?EIS?.The electrocatalytic performance of the modified electrode for TCA and NaNO₂ obtained low detection limit were 1.0 mmol L^-1 and 0.33 mmol L^-1 and wide linear range as 4.0²40.0 mmol L^-1 and 1.0¹8.0 mmol L^-1.And the K_M^appwere 42.48 mmol L^-1and 2.512 mmol L^-1.The samples containing TCA and NaNO₂ were determined and the recovery was good.4.The coiled carbon nanotubes?CCNTs? were modified by direct drop coating in CILE;then the gold nanoparticles were deposited by electrodeposition to form Au-CCNTs;and then horseradish peroxidase?HRP? was coated with Nafion as protective film.Preparation of Nafion/HRP/Au-CCNTs/CILE.UV and IR spectra showed that HRP maintained the secondary structure of the original protein in the Au-CCNTs composite film,and still had biological activity.The structure and morphology of CCNTs and Au-CCNTs were characterized by scanning electron microscope.The direct electrochemical behavior of Nafion/HRP/Au-CCNTs/CILE in PBS of p H=3 was determined by cyclic voltammetry,and a pair of symmetrical oxidation reduction peaks were observed.The results showed that Au-CCNTs had a good effect on the direct electron transfer of HRP.The electrocatalytic reduction of TCA,Na NO₂ and KBrO₃ by modified electrode was also studied.The linear relationship was obtained.The detection limits were 1.67 mmol L^-1,0.03 mmol L^-1 and1.13 mmol L^-1.5.The modification design and electrochemical and electrocatalytic properties of Nafion/Hb/Au-BPC/CILE were studied.Biomass porous carbon was prepared by vacuum temperature-controlled carbonization method and characterized by scanning electron microscopy?SEM?.UV and IR spectra showed that Hb still maintained its biological activity in the presence of Au-BPC.The electrochemical performance of different modified electrodes was compared and the direct electrochemical behavior of Nafion/Hb/Au-BPC/CILE was realized.The electrocatalytic performance of Nafion/Hb/Au-BPC/CILE on TCA,Na NO₂ and KBrO₃ was studied in the linear range of 10.0 330.0 mmol L^-1,0.1 ¹.0 mmol L^-1 and 0.3 13.0 mmol L^-1,respectively.The detection limits are 3.33 mmol L^-1,0.03 mmol L^-1 and 0.03 mmol L^-1,respectively.The apparent Michaelis constants are 75.3mmol L^-1,1.84 mmol L^-1 and 3.11 mmol L^-1.