Electrochemical detection of epinephrine using a biomimic made up of hemin modified molecularly imprinted microspheres

Abstract

In this study, a highly sensitive and selective molecularly imprinted polymer (MIP) was synthesized using a functional monomer, 2,4,6-trisacrylamido-1,3,5-triazine, and its application for electrochemical detection of epinephrine (EP) was demonstrated. This particular monomer was selected based on the interaction energies computed for the formation of a pre-polymer complex using computational studies. Furthermore, EP imprinted microspheres were prepared by precipitation polymerization using hemin as the catalytic centre in order to mimic the active site of an enzyme namely peroxidase. Molecularly imprinted and non-imprinted microspheres were characterized using Fourier transform infrared spectroscopy (FTIR) and field emission scanning electron microscopy (FESEM). An electrochemical sensor for EP detection was fabricated by modifying a gold disc electrode with molecular imprinted microspheres stabilized by a chitosan/Nafion mixture. A linear concentration range from 5 × 10⁻⁸ M to 40 × 10⁻⁶ M with a very low detection limit of 1.2 × 10⁻⁸ M (S/N = 3) is determined for the proposed sensor. Our results clearly demonstrate an efficient sensing capability of imprinted polymer with good reproducibility, stability and higher selectivity for EP detection over its other structural analogues and potential interferents. Essentially, the proposed electrochemical sensor follows a cascade reaction mechanism since it consists of two catalytic sites that aid in EP detection. The analytical applicability of this sensor towards the determination of EP is demonstrated using human blood serum and injection samples.