Rational selection of the monomer for molecularly imprinted polymer preparation for selective and sensitive detection of 3-methylindole in water

3-Methylindole (3-MI) is a recalcitrant and toxic substance that can cause damages to human and animal lung cells and may have a pronounced effect on mood and stress levels. Rapid and sensitive detection of 3-MI is therefore of great important for its environmental safety evaluation. A novel electrochemical sensor for the determination of 3-MI was fabricated based on electropolymerization of molecular imprinted polymer (MIP) film on a glassy carbon electrode (GCE). Rational selection of the suitable monomers was conducted by evaluation of the interaction between each monomer and template using the density functional theory method. The results indicated that the stabilization energy of 3-MI-o-Phenylenediamine (o-PD) complex is greater than that obtained from other evaluated monomers, hence o-PD was used to prepare the MIP sensor. The imprinted layer was systematically characterized by cyclic voltammetry (CV), electrochemical impendence spectroscopy (EIS), scanning electron microscopy (SEM) and atomic force microscopy (AFM). Under optimal experimental conditions, a linear relationship was observed between the peak current change of the electrochemical probe [Fe (CN)6]3- and the concentration of 3-MI over the range 0.01-1.2 M, with a detection limit of 4 nM. This sensor also exhibited superb selectivity to 3-MI as minimum interferences were observed from other structurally similar compounds, thus it was successfully applied for the determination of 3-MI in real samples.