Study Of PAHs-Electrochemical Sensors Based On π-Conjugated Stacking Systems

Electrochemical sensors have important valuable applications among medicine, foodscience, environmental science, military and so on. Graphene has excellent properties inelectrical, magnetical, optical, thermal and catalytic. They can greatly improve theperformance of electrochemical sensors due to their surface effect, special quantum size effectand macroscopic quantum tunnel effect. Conducting polypyrrole has high conductivity,nonlinear optical properties, Optical electrical properties, luminescence properties, magneticalproperties, inexpensive and high energy efficiency properties. Conductive polypyrrole as wellas graphene has high π electron density and huge π-π conjugate system, make them havepotential application in selective enrichment and detection of polycyclic aromatichydrocarbons (PAHs). Therefore, this paper is focusing on the research of preparation ofcontrollable nanomaterials and polypyrrole and their usage in preparing electrochemicalsensors based on π-conjugated stacking system. Single-layer graphene and polypyrroleelectrochemical sensors were prepared, characterized. In addition, the catalytic activity of PPymodified electrode was measured using1-hydroxypyrene which is a biomarker of polycyclicaromatic hydrocarbons. The details are described as follows:(1) Electropolymerization of polypyrrole (PPy) using cysteine-Pb nanowires as templatewas prepraed. As-prepared PPy was characterized by scanning electron microscopy (SEM)and Fourier-transform infrared spectra (FTIR). The catalytic activity of PPy modifiedelectrode was measured by cyclic voltammetric (CV) technique. The results show that themethod can reduce the influence of poly time and the as-prepared Ppy has larger specificsurface area and macroporous structure. And template-based Ppy will adsorb more1-hydroxyrene (1-OHP, a widely used biomarker for evaluation of polycyclic aromatichydrocarbons (PAHs) exposure) via π-π conjugation. The holes in the template-based Ppyacted as microelectrode. The current response of1-hydroxyrene at template-basedelectropolymerization of PPy modified electrode is considerably larger than that of directelectropolymerized electrode. The peak currents of1-OHP obtained by differentialpulsevoltammetry were linear with the concentrations of1-OHP in a range of0.5-12μM (R2=0.9918) with a detection limit of0.18μM (S/N=3) and a sensitivity of3.4μA μM-1cm-2. Inaddition, the electrochemical sensor with conjugate system had a good stability, selectivityand reproducibility. The results showed that the electrochemical sensor can be used in thedetermination of OH-PAHs.(2) Natural flake graphite as material for synthesis of monolayer graphene nano films.Bifunctional modular unit of alkyne-functionalized pyrene is synthesized. The dosage ofgraphene was determined via fluorescence spectra of alkyne-functionalized pyrene. Graphenewas non-covalently functionalized on Au substrate through π-π interaction and click chemistry.The as-prepared materials and sensor were characterized by Laser Confocal Micro RamanSpectrometer (RAM), Scanning Electron Microscope (SEM), Fourier-transform InfraredSpectra (FTIR), Atomic Force Microscope (AFM), Cyclic Voltammetry (CV) andElectrochemical Impedance Spectroscopy (EIS). The results show that graphene can be non-covalently functionalized on Au substrate through π-π interaction and click chemistry.This strategy may facilitate new ways to design graphene-based electrochemical devices. Thecatalysis of1-OHP showed that this new electrochemical sensor also had great potential in thedetection of OH-PAHs.