Preparation of gold electrode based electrochemical sensors for epinephrine detection

In this thesis, it is aimed to prepare electrochemical sensors based on gold electrodes for the determination of the hormone epinephrine, which is an important neurotransmitter in the diagnosis of neurological disorders. For this, gold disc (AuE) and gold screen-printed (AuSPE) electrodes selected as working electrodes were modified with cysteine (CYS), carboxyl-functionalized multi-walled carbon nanotube (MWCNT-COOH) and silver nanoparticles (AgNPs). The surface properties of the prepared AuE/CYS-MWCNT/AgNPs and AuSPE/CYS-MWCNT/AgNPs electrodes were investigated by Scanning Electron Microscopy (SEM) technique, and their electrochemical characterization was investigated by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) techniques. data were compared with unmodified electrodes. Operating conditions such as suitable cysteine concentration, pH were optimized, and performance factors such as reproducibility and stability of the sensors response and the effects of other species on the response were studied. Working ranges for epinephrine for two types of sensors prepared under suitable conditions were determined as 0.0008-0.8 mmol L-1 and 0.003-8 0.0008-0.8 mmol L-1, respectively. These sensors were used for the determination of epinephrine in synthetic serum samples and % recovery values were calculated.