Preparation Of Electrochemical Sensor Based On Molecularly Imprinted Polymer And Its Application

It is an important research field to develop fast, selective and sensitive methods for the detection of environmental pollutants. In recent years, molecularly imprinted polymer has gained increasing attention as recognition elements in sensors research due to its high affinity to tempelate molecules, excellent chemical and mechanical stability. In this paper, two novel electrochemical sensors based on molecularly imprinted polymer were developed for the detection of ofloxacin and bisphenol A. The main contents include:Molecularly imprinted polymer/mesoporous carbon nanoparticles (MCNs@MIP) were prepared through covalent grafting of the MIP polymer onto the surface of mesoporous carbon nanoparticles by precipitation polymerization using ofloxacin as a tempelate. MCNs@MIP nanoaprticles were well monodispersed, with a diameter of～220nm by electron microscope analysis. Furthermore, a novel modified electrode was prepared by using the MCNs@MIP nanoparticles as electrode sensing material for electrochemical detection of ofloxacin. The modified electrode showed good electrochemical activity and selective response to ofloxacin in aqueous solutions. High sensitivity and selectivity were attributed to good conductivity and large specific surface area of MCNs and specific recognition of MIP to ofloxacin. Some affecting factors were optimized such as the amount of the MCN@MIPs, pH value of supporting electrolyte and accumulation time. Under the optimized conditions, there was a linear relationship between the peak currents in cyclic voltammetry measurement and ofloxacin concentrations in the range of0.5～100μmol/L (r=0.9946), with a limit of detection (S/N=3) of80nmol/L. The proposed method was applied for the detection of ofloxacin in the spiked sea water and human urine samples, with recoveries of93.7%and86.8%, respectively. The relative standard derivations were2.1%and5.9%, respectively.A novel graphene quantum dots/polypyrrole/MIP (GQDs/PPy/MIP) modified electrode was prepared by elcetro-polymerization using bisphenol A as a template, pyrrole as functional monomer in the presence of graphene quantum dots. The novel electrode was evaluated by K3[Fe(CN)6] solution and showed high electrochemical activity. The electrode was used for the detection of bisphenol A by differential pulse voltammetry (DPV). The detection principle was based on the decrease of K3[Fe(CN)6] peak currents in DPV analysis after bisphenol A binding into the imprinted sites. Preparation of the electrode and detection conditions were optimized such as the volume of GQDs, electro-polymerization voltage and cycle times, accumulate time, and pH value of accumulation solution. Under the optimized condition, there was a linear relationship between the decrease of K3[Fe(CN)6] peak currents and bisphenol A concentrations in the range of0.1～60μmol/L (r=0.9956), with a limit of detection (S/N=3) of40nmol/L. The proposed sensor was applied for the detection of bisphenol A in the spiked sea water and tap water, with recoveries of93.7%and94.5%, respectively. The relative standard derivations were3.53%and1.71%, respectively.