Electrochemical Sensor for Epinephrine Based on a Glassy Carbon Electrode Modified With Carbon Nanotubes/Ag (I) Complex

Epinephrine, also known as adrenaline, is primarily a medication and a hormone. As a medication it is used for a number of conditions including anaphylaxis, cardiac arrest, and superficial bleeding. Inhaled epinephrine may be used to improve the symptoms of croup. It may also be used for asthma when other treatments are not effective. It is given intravenously, by injection into a muscle, by inhalation, or by injection just under the skin. The common side effects of epinephrine include shakiness, anxiety, and sweating. A fast heart rate and high blood pressure may occur. Occasionally it may result in an abnormal heart rhythm [1]. Therefore, determination of epinephrine is interesting for understanding the physiological functions. Electrochemical procedures have been developed to determine epinephrine based on this electrochemical activities. But electrochemical detection of epinephrine at the surface of bare electrodes has a high overpotential, which results in weak electrochemical responses. To solve this problem, various modified electrodes have been developed for the selective determination of epinephrine [2]. Carbon nanotubes (CNTs) have been widely used in electrochemistry due to their unique one-dimensional (1D) structural, electronic, and physical properties. In the field of chemically modified electrode, one of the most important characteristics of CNTs is their reported ability to promote electron-transfer process [3]. The CNT/Ag (I) complex modified glassy carbon electrode (CNT/Ag/GCE) exhibited high sensitivity in the detection of epinephrine (scheme 1, Ag(I) complex). It has been found that oxidation of EP at this modified electrode occurred at less positive potentials than on bare GCE. The anodic peak current observed were directly proportional to epinephrine concentration between the range of 5.0×10−8 and 8.0×10−6 M (LOD = 7.0×10−9 M). At the same time, this electrode also showed favorable electrocatalytic activity toward some other small biomolecules (such as dopamine, ascorbic acid and uric acid), suggesting the potential applications of CNT/Ag(I) complex for constructing biosensors. 34 Scheme 1