Modified fluorine-doped tin oxide electrode with inorganic ruthenium red dye-multiwalled carbon nanotubes for simultaneous determination of a dopamine, uric acid, and tryptophan

Abstract

For the first time, a modified F-doped SnO2 electrode with ruthenium red (RuRe) inorganic dye immobilized on a multi-walled carbon nanotube was been developed. The RuRe maintained high activity on this nanomaterial, catalyzing the oxidation of dopamine (DA), uric acid (UA) and tryptophan (Trp) in a simultaneous determination, which was electrochemically reduced at 0.377, 0.552 and 0.841V versus SCE on the biosensor surface. The measurements were carried out using cyclic voltammetry in phosphate buffer solution with pH 3.0. Under optimum conditions, the biosensor showed linear response up to 283μM for DA and 433μM for UA and Trp with limit of detection 0.15, 0.14 and 0.14μM for DA, UA and Trp, respectively. The analytical performance of this sensor has been evaluated for simultaneous detection of DA, UA and Trp in human serum and urine samples.