Research On Molecular Imprinting-electrochemiluminescence For Determination Of Endocrine Disrupting Chemicals In Environment

There are many different kinds of environmental endocrine disruptors(EDCs),which had complicated structures and forms,and they has been a serious threat to survival environment for human beings.Therefore,how to improve the sensitivity and selectivity of EDCs detection methods has become the most attractive research topic in environmental analytical chemistry.In this study,the Molecularly Imprinted Polymer-Electrochemiluminescence(MIP-ECL)sensor with high selectivity and high sensitivity for the determination of EDCs in water,such as 17β-estradiol(E2),Bisphenol A(BPA)and nonylphenol(NP),was established by combination of molecular imprinting technique(MIT)and ECL.Firstly,Ru(bpy)32+/MWCNTs-Nafion-SiO2 modified electrode was prepared by immobilizing ruthenium bipyridine(Ru(bpy)32+)on the Nafion modified gold electrode doped with multi-walled carbon nanotubes(MWCNTs)and nanosilica(SiO2).The molecularly imprinted polymers(MIPs)were further modified on the electrode to obtain MIP-ECL sensor for determination of E2 in the water.The detection conditions such as pH value,scanning speed and accumulation time were optimized as follows:scanning speed of 100 mV/s,phosphate buffer solution of pH=7.4 and accumulation time of 20 min.The sensor showed both the sensitivity of ECL and the selectivity of MIT.It had a good linear relationship within the range of 0.03～2 μg/L,the detection limit of 0.0060 μg/L.The sensor has been successfully applied to the determination of E2 in the water samples with the recoveries from 88.7%to 105.0%.Secondly,in order to improve the sensitivity of the Ru(bpy)32+/MWCNTs/TiO2-Nafion modified electrode,MIP-ECL sensor were acquired by modifying the MIPs by sol-gel method on the electrode.Under the best detection conditions,in the phosphate buffer solution(pH=7.4)containing different concentrations of BPA,the ECL intensity was detected after accumulating for 20 min.The proposed sensor not only exhibited high sensitivity,wide linear range(0.01～2μg/L)and low detection limit(0.0041 μg/L),but also displayed great selectivity,stability and reproducibility.The results showed that the sensor could be successfully applied to the detection of BPA in environmental water.Finally,the surface of gold electrode was primarily modified by Si-Ti nanocomposites andMWCNTs,then Ru(bpy)32+ was immobilized onto the modified electrode surface.Subsequently,the MIPs were fabricated on the surface of the electrode,using NP as the template molecule,phenyl methoxysilane as functional monomer and tetraethoxysilane as the cross linking agent.The electrochemical and ECL behaviors of the sensor was characterized by cyclic voltammetry,ECL intensity and electrochemical impedance spectroscopy.The results showed that the addition of Si-Ti nanocomposites and MWCNTs could significantly improve,electrochemical and ECL performance of sensor.Under detection conditions,a linear ranging from 0.02～2 μg/L for the detection of NP was observed with the detection limit of 0.0021 μg/L.The sensor not only exhibited high sensitivity and selectivity,but also showed good stability and reproducibility.Moreover,The sensor was successfully applied to the determination of NP in environmental water samples with recovery ranging from 86.1%to 98.5%.