Conductive imprinted electrochemical sensor for epinephrine sensitive detection and double recognition

Epinephrine (EP), an important derivative of a neurotransmitter in the mammalian central nervous system and monitoring the concentration of EP is significant in biological and chemical researches. In this work, a molecularly imprinted polymer (MIP)/gold nanoparticles (AuNPs) composite (MIP/AuNPs) was modified on glassy carbon electrode (GCE) surface to fabricate a novel electrochemical sensor for EP detection. The modified AuNPs increased the surface area of the electrode and improved the sensitivity of the sensor. 3-thiophene boronic acid (3-TBA), as a monomer of conductive polymer, was employed to electropolymerize MIP in the presence of EP. Scanning electron microscope, cyclic voltammetry, and electrochemical impedance spectroscopy characterization results demonstrated that the prepared sensor possessed sensitive detection and selective recognition abilities toward EP. Unlike the other MW based electrochemical sensors, conductive poly(3-TBA) matrix, as well as the conductive AuNPs can enhance the sensitivity of the sensor. Under the optimal conditions, the sensor can sensitively detect EP with a linear range and limit of detection of 9.0 x 10(-8)-1.0 x 10(-4)mol/L and 7.6 x 10(-8)mol/L, respectively. And the sensor showed double recognition ability to EP due to the following reasons: first, size and shape complementarity between the formed imprinted sites and the template molecules; second, the reversible covalent interaction between boronic acid of 3-TBA and cis-diol of EP. Thus, the sensor can recognize EP from its analogues. And the sensor has been applied to analyze EP in injection samples with satisfactory results.