| Based on the properties of simple preparation,low cost and high selectivity and sensitivity,electrochemical biosensor was widely used in the fields of environment,food and medicine,etc.Hence,in order to realize the wide application of electrochemical biosensor,it is very important to make specific modification for bare electrode.Carbon nanomaterials were widely used as modified materials for electrochemical biosensors due to their good conductivity,large specific surface area and favorable biocompatibility.Moreover,carbon nanomaterials can change the microstructure of the surface of bare electrode and improve the selectivity and sensitivity of modified electrode.In this work,carbon nanomaterials and other nanomaterials were composited to build electrochemical biosensors and to study the electrocatalytic properties for small biomolecules.The main contents of this work were as follows:(1)A carbon quantum dots/overoxidized poly(2-aminopyridine)(CQDs/PAPox)composite modified electrode was successfully fabricated through electrochemical polymerization and electrochemical oxidation.Electrochemical responses of as-prepared modified electrodes were investigated by cyclic voltammetry and differential pulse voltammetry.The results indicated that as-prepared CQDs/PAPox modified electrode was successfully used for the simultaneous determination of guanine(GU)and adenine(AD).Owing to the synergistic effect of CQDs and PAPox,two oxidation peaks well separated from each other and the peak potential separation of GU-AD was 320 mV.In addition,the currents of the oxidation peaks showed a linear dependence on the concentrations of GU and AD in the ranges of 1.0-116 and 1.0-128 μM,respectively,with detection limits of 0.48 and 0.35 μM(S/N = 3).(2)A poly(bromocresol green)(PBG)/CQDs composite modified electrode was successfully fabricated by electropolymerization.Electrochemical responses of as-prepared modified electrodes were evaluated by cyclic voltammetry and differential pulse voltammetry.As-prepared PBG/CQDs modified electrode was successfully applied in the simultaneous determination of GU and AD,owing to large surface area and favorable electrocatalysis effect of PBG and CQDs.Two oxidation peaks were observed at 0.81 and 1.13 V for GU and AD.Besides,PBG/CQDs modified electrode was highly selective towards the determination of GU and AD,and interfering substances had no significant interference.(3)A poly(glycine)(PGLY)/graphene oxide(GO)(PGLY/GO)composite modified electrode was successfully fabricated by simple electropolymerization.Electrochemical responses of as-prepared modified electrode were evaluated by cyclic voltammetry and differential pulse voltammetry.As-prepared PGLY/GO modified electrode was successfully applied in the simultaneous determination of GU and AD.Owing to the synergistic effect of PGLY and GO.the oxidation peaks of both GU and AD well separated from each other and the peak potential separation was 300 mV.Moreover,the currents of the oxidation peaks showed a linear dependence on the concentrations of GU and AD in the ranges of 0.15-48 and 0.090-103 μM,respectively,with detection limits of 0.026 and 0.030 μM(S/N = 3).(4)A NiO/GO modified electrode was fabricated by electrodeposition.Electrochemical responses of as-prepared modified electrodes were evaluated by cyclic voltammetry and differential pulse voltammetry.The results indicated that as-prepared NiO/GO modified electrode was successfully applied in the simultaneous determination of ascorbic acid(AA),dopamine(DA)and uric acid(UA).Three oxidation peaks well separated from each other and the potential separations of oxidation peaks of AA-DA and DA-UA were 120 and 160 mV,respectively,owing to the synergistic effect of NiO and CQDs.Besides,the currents of the oxidation peaks showed a linear dependence on the concentrations of of AA,DA and UA were obtained in the concentration range of 0.40～700,2.0～60 and 2.0～120 μM,respectively,with the detection limits of 0.55,0.10 and 0.14 μM(S/N = 3).To sum up,four nanocomposites modified electrodes(PAPox/CQDs,PBG/CQDs,PGLY/GO and NiO/GO)were prepared respectively by electrochemical methods,and were used to detect GU,AD,AA,DA and UA,etc.The results showed that these four kinds of modified electrodes had favorable selectivity,reproducibility and stability for GU,AD,AA,DA and UA,etc. |
