A novel electrochemical sensor for epinephrine based on three dimensional molecularly imprinted polymer arrays

In this work, a novel electrochemical sensor for epinephrine, which uses three dimensional molecularly imprinted polymer arrays (3-D MIP arrays) as the sensing materials, was reported for the first time. ZnO nanorods (ZNRs) were deposited on indium tin oxide coated polyethylene terephthalate (ITO/PET) film and used as high-surface 3-D scaffolds for 3-D MIP arrays deposition. The 3-D MIP arrays were prepared by electropolymerization of pyrrole onto ZNRs on ITO/PET film in the presence of epinephrine as template molecule. Due to the imprinted sites are located at the surface, as well as high specific surface area, these 3-D MIP arrays have good imprinted sites accessibility to template molecule. These 3-D MIP arrays are quite attractive for sensors, because each rod of arrays is accessible to analyte and can be used as sensing unit, thus yielding highly sensitive and efficient signal. 3-D MIP arrays based electrochemical sensor was characterized using scanning electron microscopy (SEM), electrochemical impedance spectroscopy (EIS) and differential pulse voltammetry (DPV). Results indicated that this 3-D MIP arrays based electrochemical sensor exhibits high sensitivity and good selectivity for epinephrine. Under optimized conditions, the oxidation peak current of epinephrine showed two linear dynamic ranges (1–10 μM and 10–800 μM) using DPV method. Moreover, this electrochemical sensor has been successfully applied to the determination of epinephrine in epinephrine hydrochloride injections with satisfied recoveries (97.1% to 102.2%) and precision (2.2% to 4.5% of RSD).