| In recent years,more and more synthetic antioxidants were added to food in order to extend the shelf-life duration of foodstuff and to facilitate the storage of food.However,there are often some news about food safety problems that excessive antioxidants and illegal antioxidants were added to various food were reported,which might seriously endanger to people's health and life.Therefore,it is important to detect accurately the content of antioxidants in food.To overcome the problem that the detection of target was wasy to disturbed by other substances in food,the new method for detecting target specifically was studied by many researchers.Molecularly imprinted electrochemical sensor?MIECS?is fabricated by molecularly imprinted polymer?MIP?modified on the surface of the working electrode,combing the electrochemical method such as cyclic voltammetry?CV?and differential pulse voltammetry?DPV?and other electrochemical methods to obtain the content of the target molecule,which is very fast and efficient.Nano material were used mangy filed for their advantage such as,large surface area,good biocompatibility,good conductivity,good catalytic activity.In this paper,nano materials were used as substrate and provided a platform for imprintig reaction,and three kinds of MIP for antioxidant based on nano materials were prepared by surface molecular imprinting technique,whose imprinted sites were all sitted in the surface of MIP.It is easy to clear away the target molecules from surface MIP and to overcome mass transfer resistance to get imprinted cavity in the adsorption process.By using the surface MIP to fabricated MIECS,the detection effect of MIECS to the target molecules was studied by electrochemical method to achieve that dtection for antioxidant was quickly,accurately,sensitively and specifically.This paper was divided into fsix chapters,each chapter is as follows:In the first chapter,the harm of antioxidant,priniciple,detection method to antioxidant,molecualr imprinting technolgy,MIP based on nano materials,the research of MIECS and MIECS for antioxidant.The research status,significance,main research contents and innovations of this article were stated.In the second chapter,the reagents,instruments,experiment content and characterization were introduced.In the chapter three,Muti-wall carbon nanotube?MWCNT?were used tomodifyglassycarbonelectrode?GCE?,MIPfilmfor tert-Butylhydroquinone?TBHQ?waspreparedbyelectrochemical polymerization in the sodium perchlorate solution containing functional monomer pyrrole and target molecule TBHQ.Using CV and electrochemical impedance spectroscopy?EIS?to study the conductivity changes in the process of fabricated MIECS and to verify the molecular imprinted polymer membrane were preparated successfully.The electrochemical response of MIECS to target molecules was studied by DPV.The repeatability,specificity and stability of the MIECS was also disscussed.The results showed that the MIECS showed good linear response to TBHQ from 2×10-8 to 1×10-5 M and from 1×10-5 to 1×10-4 M,with the detection limit of 1×10-8M.In the chapter four,a novel surface MIECS for the detection of 4-hexylresorcinol?4-HR?was prepared by dispersing a MIP on GCE modified by MWCNT.Molecular imprinting polymer based on Si O2 was prepared by using polyethyleneimine?PEI?that were grafted to Si O2 nanoparticles as functional polymer,4-HR as a template and ethylene glycol diglycidyl ether?EGDE?as a cross-linker.The MIP was obtained after the removal of 4-HR and the etching of Si O2.The obtained MIP was characterized by Fourier transform infrared spectroscopy?FT-IR?and the MIECS was characterized by CV and DPV.The sensor exhibited a remarkable enhancement of current response since the charge transfer process was facilitated by the etching of Si O2 nanoparticles and the modification of GCE with MWCNT.The sensor showed specific recognition ability to 4-HR rather than other antioxidant with an excellent repeatability since the recognition sites were distributed on the surface of the polymer.The linear range of the calibration curve was1×10-8-1×10-5M with a detection limit of 5×10-9M?S/N=3?,superior to the other electrochemical sensors reported in the literature.The fabricated sensor exhibited a good performance in the determination of 4-HR in real samples as well.In the chapter five,the surface MIP?MIP/MWCNT?for propyl gallate?PG?was prepared by using PEI?grafted onto the surface of acidified MWCNT?as the functional monomer,PG as target molecule and EGDE as crosslinking agent.The structure of MIP/MWCNT was characterized by FTIR,X-Ray Diffraction spectrum?XRD?and so on.In addition,the performance of the MIECS was studied by electrochemical analysis.The experimental results showed that the linear range of the sensor to PG was from 1×10-8-1×10-5M,with the detection limit of 2.5×10-9M.In the chapter six,makes a summary of the whole paper,and prospects the development of Molecular Imprinted Electrochemical sensors for antioxidant. |
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