| Graphene?GN?has received extensive attention because of its excellentphysicochemical properties.As an accurate,simple preparation and low cost detection device,electrochemical biosensor has been widely used in the fields of biology,medicine,and environmental monitoring.Using the GN as a sensing element to build a new sensor not only increases the sensitivity of the sensor,but also enriches the sensor type.This article mainly studies the preparation and functionalization of GN modified electrodes,preparation of electrochemical sensors and detection of rutin and HIV.The main research contents are as follows:1.The modified Hummers process was used to prepare graphite oxide?GO?,whichwas then reduced with hydrazine hydrate to obtain GN.FT-IR,XRD,Raman and SEM were used to study its structure and morphology.The results show that a large number of oxygen-containing functional groups have been removed after the reduction of GO.The resulting graphene is thin and fluffy,which is favorable for the immobilization of biomolecules.2.Poly-L-cysteine/graphene/Nafion modified electrode?poly-L-Cys/GN/Nafion?was prepared by electrochemical polymerization.DPV and CV methods were used to study the electrochemical behavior of rutin on the modified electrode and its influencing factors.The results showed that the electrochemical reaction of rutin on the modified electrode was a reversible process controlled by adsorption,and two electron transfer occurred during the reaction.The study also found that the number of scanning cycles has a certain influence on the performance of electropolymerization and its modified electrodes.Under optimal conditions,the peak current of rutin has a linear relationship with its concentration in the range of 10?M to 0.02?M.The established electrochemical sensor based on poly-L-Cys/GN/Nafion composite film was applied to the detection of compound rutin tablets with satisfactory results.3.Polyaniline/graphene?PANI/GN?nanocomposites were prepared by reversedphase polymerization and used to modify glassy carbon electrodes?GCE?.The single-stranded DNA?ssDNA?probe was then immobilized on the modified electrode and designated ssDNA/PANI/GN/GCE.Through the?-?*stacking interaction,the negatively charged target HIV-1 phospho-skeleton was hybridized with the probe DNA to form double-stranded DNA.The electrochemical impedance spectroscopy?EIS?was used to detect the changes in impedance before and after hybridization.The results showed that in the range of 5.0×10-16mol/L to 1.0×10-10mol/L,the impedance difference?Ret before and after hybridization showed a good linear relationship with the logarithm logC of the target HIV concentration.The linear equation was:?Ret???=273log C+4579,the correlation coefficient R2=0.9930?S/N=3?,and the detection limit is 1.0×10-1616 mol/L.The prepared sensor has outstanding stability and reproducibility.4.Graphene was obtained by electrochemical reduction method,and AuNP wasdeposited by electrochemical deposition method.A DNA sensor based on AuNP/RGO/GCE was obtained.The electrochemical behavior of this sensor was studied using CV and EIS.The results showed that there was a linear relationship between the impedance difference?Ret before and after hybridization and the logarithm logC of target HIV concentration in the range of 1.0×10-16mol/L to 1.0×10-11mol/L.The linear equation was:?Ret???=53.26log C+879.63,the correlation coefficient R2=0.9616?S/N=3?,and the detection limit is 3.2×10-17mol/L.Compared with the sensors assembled in Chapter 4,the AuNP/GN/GCE based DNA sensors exhibit better sensitivity and stability. |
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