Electrochemical Sensors Based On Aniline-derived Polymer/Graphene Nanocomposites

Based on the special properties of synthetic simple,materials cheap,high chemical stability and excellent electrochemical performance of the aniline-derived conducting polymer,electrochemical sensors based on aniline-derived conducting polymer/graphene nanocomposites modified electrodes were prepared and used for the electrochemical determination of neurotransmitter molecules,such as dopamine(DA)and5-hydroxytryptamine(5-HT).Three novel electrochemical sensors of high sensitivity and good selectivity were constructed.The main contents are as follows:(1)A nanocomposite of polyaniline/reduced graphene oxide(PANI-rGO)was synthesized via a hydrothermal method.The product was characterized by Fourier-transform infrared(FT-IR),Raman spectra,X-ray diffraction(XRD),Scanning electron microscopy(SEM)and Transmission electron microscopy(TEM).Then the hybrid material of PANI-rGO and Nafion was prepared and used to modify glassy carbon electrode(GCE)surface and obtained PANI-rGO-NF/GCE.The electrochemical behavior of DA on the modified electrode was studied.It was found that PANI-rGO-NF/GCE had better catalytic activity toward redox process of DA than GCE,PANI-NF/GCE,rGO-NF/GCE and PANI-rGO-NF/GCE.Under the optimal conditions,selective detection of DA in a linear concentration range of 0.01 to 60.0 ?M(R = 0.996)and 60.0 ?mol/L to 180.0 ?mol/L(R =0.996)were obtained with the limit of 0.024 ?M(3S/N).Selective experiments showed the modified electrode had no response to ascorbic acid(AA)and uric acid(UA),leading to a high analytical performance toward DA,and had good repeatability and stability.In addition,the modified electrode was also applied to detect the levels of DA in dopamine hydrochloride injection with satisfactory results.(2)The poly(p-aminobenzene sulfonic acid)modified electrode(Pp-ABSA/GCE)was prepared by electropolymerized method,then the hybrid material PANI-rGO was dropped on the surface of Pp-ABSA/GCE,and obtained PANI-rGO/Pp-ABSA/GCE.Using [Fe(CN)6]3-/4-as a probe,GCE,Pp-ABSA/GCE,r GO/Pp-ABSA/GCE and PANI-rGO/Pp-ABSA/GCE were characterized by cyclic voltammetry(CV).The results showed that the PANI-rGO/Pp-ABSA/GCE not only had great surface area but also had excellent conductivity.The modified electrode for the trace determination of 5-HT,and the results showed that the electrode had good catalytic activity to process of oxidation reaction of 5-HT.(3)Under the best conditions,the peak currents of 5-HT were linearly correlated with the concentration of 5-HT in the range from 0.1 ?mol/L to 100.0 ?mol/L(R= 0.996)with a detection limit of 0.032 ?mol/L(S/N=3).At the same time,when the concentration of DA and AA for 50 times or UA for 10 times as much as 5-HT,which did not interfere the detection of 5-HT on the modified electrode.The modified electrode was applied to detect5-HT level in the human blood serum and obtained satisfactory results,and had good repeatability and could keep at least more than four weeks.(4)The graphene oxide/zinc oxide composites(GO/ZnO)was synthesized by the ultrasonic method and dropped on the surface of Pp-ABSA/GCE,and obtained GO/ZnO/Pp-ABSA/GCE.The modified electrode for the simultaneous electrochemical determination of DA and 5-HT in the presence of AA.The results showed that the modified electrode had better electrochemical response for the detection of DA and 5-HT than Pp-ABSA/GCE,GO/Pp-ABSA/GCE and ZnO/Pp-ABSA/GCE.Under the optimum conditions,the oxidation peak currents of DA and 5-HT were linearly correlated to their concentrations in the ranges of 1.0 ?mol/L to 20.0 ?mol/L and 1.0 ?mol/L to 20.0 ?mol/L,the detection limits for DA and 5-HT were estimated to be 0.12 ?mol/L and 0.23 ?mol/L,(S/N = 3),respectively.The modified electrode was used to detect the 5-HT of serum on biological samples which had good detection effect,and the modified electrodes had good stability and high selectivity.