Abstract

A sensitive electrochemical sensor for warfarin was prepared based on molecular imprinting strategy by electropolymerization qof o-phenylenediamine (o-PD) on a glassy carbon electrode via cyclic voltammetry (CV). In order to enhance the electrode sensitivity and electronic transmission, multiwall carbon nanotubes (MWCNT) containing carboxylic functional group (f-MWCNTs) were introduced on glassy carbon electrode (GCE). Thin film of molecularly imprinted polymer (MIP) with specific binding sites for warfarin was cast on the modified electrode using electrochemical deposition. In order to form a double layer with MIP layer as an insulating electrolyte, Au nanoparticles (AuNPs) was introduced at the MIP surface to form final modified electrode (AuNP/MIP/f-MWCNT/GCE). The properties of AuNP/MIP/f-MWCNT/GCE were studied in the presence of K₃Fe(CN)₆ as a probe for signal transduction and also by the use of electrochemical impedance spectroscopy (EIS). AuNP/MIP/f-MWCNT/GCE exhibits fast binding kinetics and good selectivity to template due to their high ratio of surface imprinted sites, large surface-to-volume ratios and large affinity to template. The modified electrode was used to detect the concentration of warfarin with a linear range and detection limit (S/N = 3) of 0.031–0.616 ng mL⁻¹ and 0.024 ng mL⁻¹, respectively. Finally, the modified electrode was successfully applied to determine warfarin in human serum sample.