Development of modified electrode based sensors for the determination of some biologically important molecules in body fluids

In this study, development of a modified electrode based sensors for the determination of biologically important molecules like uric acid, serotonin and dopamine, has been aimed. The use of poly(3,4-ethylenedioxythiophene) (PEDOT) ve poly(pyrrole-3-carboxylic acid) p(P3CA) modified pencil graphite elekctrodes as sensors have been investigated. The whole study has been performed at three stages. In the first stage, the preparation of over-oxidized PEDOT nanofibers modified PGE (OO-PEDOT-nf/PGE) for the determination of uric acid has been performed. OO-PEDOT-nf/PGE showed high sensitivity and selectivity towards uric acid. In the second step, the preparation of poly(pyrrole-3-carboxylic acid) modified PGE for the determination of serotonin has been conducted. The prepared electrode showed high sensitivity for serotonin. In the determination of serotonin, to overcome the interferance of electro-active substances like uric acid, the reduction peak of oxidation intermediates of serotonin has been selected as an analytical signal. The selected reduction peak showed high selectivity for serotonin. In the third step, efficiency of poly(pyrrole-3-carboxylic acid) modified over-oxidized PGE (P3CA/OO-PGE) in the determination of dopamine has been examined. The parameters effecting the electrode preparation and measurements have been deeply optimized to increase the efficiency of the modified electrodes. The efficiencies of modified electrodes have been tested in the presence of many diffirent interfering substances. The results showed that the prepared electrodes had the requirements of ideal sensor such as low cost, easy preparation, disposable chracter, low response time, high sensitivity and selectivity. It can be concluded that the prepared modified electrodes can be used as alternative sensors for the deteermination of uric acid, serotonin and dopamine.