| Graphene,amonolayer of sp~2 hybridized carbon atoms packed into a dense honeycomb crystal structure,has attracted considerable attention in recent years due to its unique physicochemical properties such as large surface area to volume ratio,strong mechanical strength,acceptable biocompatibility,excellent thermal and electricalconductivity.Using graphene as electrode material to build new electrochemical sensor.Not only the types of sensors construction materials enriched,but also improving the performance of the sensor because of the unique physicochemical properties of graphene.This paper mainly studied the preparation and characterization of graphene and its application in electrochemical sensor.The main contents are as follows:Graphene oxide was prepared by modified Hummers method,it was oscillated with ultrasonic and then reduced by green and environmental L-cysteine.The structure and properties of graphene was characterized by using FT-IR,XRD,Raman,SEM and TG technique.The results showed that the graphene oxide was reduced to graphene with L-cysteine.A large number of oxygen bearing functional groups such as C=O,-OH,-COOH and C-O-C have been removed,a part of the sp3 bonding carbon atoms of graphene oxide into sp~2 carbon atoms.Graphene was split into lamellar structure and it has good thermal stability,in addition,graphene was made by this method exhibits good dispersion in Nafion.A poly(p-aminobenzene sulfonic acid)/graphene(p-ABSA/GN)modified electrode was fabricated by electropolymerization of poly(p-aminobenzene sulfonic acid)on a glassy carbon electrode with graphene.The electrochemical behaviors of rutin at the modified electrode was studied by differential pulse voltammetry(DPV).The rusults show that compared with p-ABSA modified electrode and GN modified electrode,the modified electrode significantly improves the detection sensitivity of rutin.Under the optimized conditions,the peak current value and concentration of rutin in range of 5.0×10-8mol/L to 1.0×10-5mol/L showed a good linear relationship,the detection limit of 2.2×10-8mol/L(3σ).The modified electrode has high sensitivity and good stability,The modified electrodewas applied to assessing the contents of rutin tablets with recoveries of 96.35%to 99.28%.Graphene was droped on glassy carbon electrode to prepare graphene modified electrode(GN/GCE),and then it was further decorated with poly L-tryptophanby by using cyclic voltammetry method to obtain a modified electrode denoted as p-L-Trp/GN/GCE.The electrochemical behavior of dopamine at the modified electrode was studied and a DPV method was developed for the determination of dopamine.Results show that p-L-Trp/GN/GCE modified electrode has a good catalytic effect on dopamine.The peak current and the concentration of dopamine in the 2.0×10-7mol/L to 1.0×10-4mol/L showed good linear relationship,Linear equation:Ipa=-0.398c-1.150(R2=0.997),the detection limit was 6.0×10-8 mol/L,This modified electrode has good stability and reproducibility and applied to the analysis of dopamine in the presence of ascorbic acid.The prepared of graphene samples were dissolved in 0.2%Nafion solution to foam stable suspensions,graphene/Nafion modified glassy carbon electrode was fabricated and the sequence of HIV was determined by electrochemical impedance spectrum(EIS).The modified electrode and probe HIV bases have strongπ-πinteraction,the probe HIV adsorbed to electrode surface and the impedance value increased.After hybridization,the dsDNA will be released from the surface of graphene,and with the decrease of the impedance value.It can be seen that the value ofΔRet and HIV log(cHIV)on 1.0×10-13 mol/L to 1.0×10-10mol/L showed a good linear relationship,and the linear equation wasΔRet(Ω)=-7131gc-5283(R2=0.985).The limit of detection was 2.3×10-14mol/L mol/L(3σ).The sensor has good selectivity,it can identify the single base mismatch target HIV. |
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