Abstract
Nitric oxide (NO) plays an important role in various physiological processes, serving as an endothelial-derived relaxing factor (EDRF), a neurotransmitter, and an immune system mediator. The biological roles of NO have created much interest in the development of direct and selective methods for the detection of this gaseous molecule. In particular, NO easily reacts with superoxide anion radical (O2-·) and generates reactive oxygen species (ROS) and reactive nitrogen species (RNS) such as peroxynitrite (ONOO-) bearing strong oxidative lesions. The ROS and RNS is implicated in many diseases such as inflammation, arteriosclerosis and cancer. Therefore, the determination of NO is subject of intense research. An electrochemical sensor for the detection of NO was developed by electropolymerization of bromo(iron(III) 5,10,15,20-tetrakis(3-thienyl)porphyrin) complexes in the presence of 1-methylimidazole on a glassy carbon electrode. This sensor exhibits significant electrocatalytic activity for the oxidation of NO. A Nafion® membrane coating was used to avoid any interference from nitrite which may exist with NO in the biological systems. The amperometric response for NO was monitored at the electrode potential of 0.80 V versus Ag/AgCl in saline medium. The sensor showed a linear relationship between the current and the NO molarity. In addition, the sensor also operates selectively against interference.
