Bilirubin Report

Electrochemical behavior and Square Wave Voltammetric Determination of Bilirubin Based on Nafion/Graphene Oxide Nanocomposite Glassy Carbon Electrode

Hayati Filik(*), Asiye Aslıhan Avan, Sevda Aydar

Istanbul University, Faculty of Engineering, Department of Chemitry, 34320 Avcılar Istanbul, Turkey

Abstract

A highly sensitive electrochemical sensor for the determination of bilirubin at the Nafion-electrochemically reduced graphene oxide (Nafion/ER-GO) modified glassy carbon electrode is reported. The electrochemical oxidation behaviors of bilirubin (BR) at the Nafion/ER-GO modified glassy carbon electrode were studied in acetone 0.05 M H2SO4 containing as the supporting electrolyte. The Nafion/ER-GO modified glassy carbon electrode exhibited

Free heme, which is toxic, is degraded via cleavage of its tetrapyrrolole ring by heme oxygenase. Bilirubin exists in two forms in the body: indirect (unconjugated) and direct (conjugated). Indirect bilirubin, which doesn't dissolve in water, must travel to the liver to be changed into the soluble form, direct bilirubin. Normal levels of bilirubin in blood serum of adult range from 10−5 M to 10−6 M [1]. When the amount of bilirubin in the body exceeds the binding capacity of albumin, extra free bilirubin binds and deposits to various tissues, especially in the brain with deleterious effects. The importance of bilirubin analysis in clinical chemistry is related to diagnosis and prediction of haemolytic disorders in adults as well as in newborn infants

All the experiments were carried out at room temperature. Bilirubin were purchased from Sigma (St. Louis, MO, USA), and they were all used as received. The desired weight of bilirubin was initially dissolved in a minimal amount of 0.1 M sodium hydroxide. Standard stock solutions (1.0×10−2 mol L−1) of the compounds (dopamine, ascorbic acid, uric acid and tocopherol) were prepared by dissolving appropriate amounts in ethanol. The solutions were protected from light and stored at 4°C. Before use, all sample solutions were prepared by appropriate dilutions to the desired concentration with distilled water. All potentials reported were versus the Ag/AgCl (3 M KCl). All of the measurements were carried out without removing dissolved oxygen. For all the electrochemical studies, 0.05 M H2SO4 was used as the supporting electrolyte unless specially stated. Graphene oxide (GO) was synthesized from natural graphite by a modified Hummers method [25,26]. Nafion/ER-GO-modified glassy carbon electrode was prepared according to a literature reported procedure