The Electrochemicalsensor Based On Nano-Materials And Its Applications In The Biological And Evironmental Analysis

Molecular imprinting and immunosensing technology based on nanomaterials, have a number of advantages, such as high specificity, high sensitivity, rapid detection, simple operation, portability and low in cost, which are fascinated by researchers in the sensing field. The paper focused on the applications of nanomaterials in surface molecularly imprinted electrochemical sensor and electrochemical immunosensor. In the article, palladium nanoparticles, carboxyl functionalized multi-walled carbon nanotubes and graphene oxides were used to build the electrochemical sensors, which possess rapid response, high selectivity and sensitivity. And it was successfully applied to the detection of norepinephrine,17p-estradiol and microcystin-LR. The contents of paper include the following three aspects:(1)K2[PdCl2] was slowly reduced to Pd nanoparticles at a high temperature by using a one-pot reduction method, citric acid as the reducing agent, polyvinyl pyrrolidone as a stabilizer. Then the molecular imprinted polymers based on PdNPs (MIP-coated PdNPs) were synthesized by the sol-gel method, using Pd nanomaterial as supporter, norepinephrine (NE) as template molecule, phenyl trimethoxysilane as functional monomer, tetraethylorthosilicate as crosslinking agent. The MiP-coated PdNPs were droped onto the surface of glassy carbon electrode to prepare electrochemical sensor. MIP-coated PdNPs were characterized by Scanning electronic microscopy (SEM), Transmission electron microscope (TEM) and Fourier transform infrared spectrometer (FTIR). The electrochemical characteristics of MIP-coated PdNPs modified electrode were investigated by differential pulse voltammetry (DPV) and cyclic voltammetry. The DPV current response of MIP-coated PdNPs sensor was higher than that of the non-imprinted polymers. In addition, the MIP-coated PdNPs sensor could recognize NE from its relatively similar molecules of dopamine, epinephrine and acetaminophen. The MIP-coated PdNPs sensor had a wide linear range over NE concentration from 0.5 to 80.0 μM with a detection limit of 0.1 μM (S/N=3). The preparation progress for MIP-coated PdNPs was simple, and the prepared MIP-coated PdNPs senor was successfully applied to specificly detection of NE with the combination of molecular imprinting and electrochemical sensing technology.(2) The molecularly imprinted polymers based on carbon nanotubes (MWCNTs-MPIL) were synthesized by using carboxyl multi-walled carbon nanotube as a support material,17β-estradiol (E2) as template molecule, 1-(1’-hydroxy-butane)-3-ethenyl-methylimidazolium hexafluorophosphate as a monomer, (3,3’-(1’,4’-butane)-bis-l-ethenyl-methylimidazolium hexafluorophosphate /EGDMA (the molar ratio is 1:1) as a crosslinking agent, AIBN as initiator. MWCNTs-MIPIL was characterized by SEM, FTIR and TGA. The electrochemical characteristics of MWCNTs-MIPIL sensor were investigated by differential pulse voltammetric (DPV), electrochemical impedance spectroscopy and voltammetry cyclic voltammetry. The MWCNTs-MIPIL sensor exhibited a high adsorption and good selectivity toward E2 compared with some other estrogen compounds. In addition, MWCNTs-MIPIL sensor had high sensibility for E2. The MWCNTs-MIPIL sensor had a wide linear range over E2 concentration from 0.005 to 50.0 μM with a detection limit of 0.0015 μM (S/N=3). The MWCNTs-MIPIL sensor can be successfully applied to the detection of E2 in environmental water sample.(3) Graphene and muti-walled carbon nanotubes composites (GO-MWCNTs) were prepared in this paper, The monoclonal antibody (mAb) was fixed on surface of GO-MWCNTs modified electrode to reparation the immune electrode. It achieved the detection of microcystins-LR (MC-LR) by the antibody-antigen reaction. GO-MWCNTs were characterized by FTIR and SEM. Electrochemical impedance spectroscopy (EIS) and CV methods were applied to characterize the performance of the GO-MWCNTs sensor. Under all of the optimal conditions, the immunosensor exhibited a wide linear response to MC-LR concentration ranging from 0.05 to 5.0 μg/L, with a lowest detection limit of 0.015 μg/L (S/N=3). The propsed strategy was successfully used to detect MC-LR in water samples.