Use of Gold Nanoparticles for Electrochemical Detection of Dopamine

Dopamine is both a neurotransmitter and a hormone. It has been used to analyze cognitive function. Due to its significance in neurodegenerative conditions, a comprehensive understanding of how this neurotransmitter affects the brain is needed. Previous research has demonstrated success in novel therapeutics to treat neurodegenerative diseases via the use of dopamine, including using L-DOPA and carbi-DOPA to manage Parkinson's disease (Iversen et al 2007). Electrochemical techniques, specifically cyclic voltammetry, have shown great promise in understanding the reactivity of its molecular complexes and detection in neural tissue. Gold nanoparticles have been used as markers in the ultrasensitive detection of Dopamine in tissue samples. In this study, a nanostructured electrochemical biosensor is being developed to detect Dopamine in neural tissue sample.

Dopamine solutions were prepared using dilution methods at varying concentrations (0 μM, 20 uM, 40 uM, 60 uM, 80 uM, and 100 uM) with phosphate buffer solution. Cyclic voltammetry was conducted using silver/silver chloride (Ag/AgCl) as the reference electrode. Platinum electrode was employed as the counter electrode. Glassy carbon electrode was used as the working electrode. An initial set of experiments were run using the bare glassy carbon electrode. Gold nanoparticles were adsorbed onto the glassy carbon electrode overnight for the second set of experiments

A series of cyclic voltammetry experiments were carried out at scan rates of 50 V/s, 100 V/s, 150 V/s, 200 V/s, and 250 V/s for varying molar concentrations of Dopamine in phosphate buffer pH 7.2. Figure 1 below demonstrates the reaction of Dopamine using a bare glassy carbon electrode. A second set of experiments was performed using a glassy carbon electrode with gold nanoparticles. There were little to no differences in the peaks for oxidation and reduction, indicating that the dopamine present is not detected or not actively participating in the electrochemical reaction. Another set of experiments was performed using a glassy carbon electrode with gold nanoparticles.

Previous studies show great promise in using Dopamine to better understand the neurochemical changes that occur during the onset of neurodegenerative diseases. However, further research is needed to devise a method to more accurately detect Dopamine. Future experiments will be conducted using gold nanoparticles to determine the effect of gold on detecting various dopamine levels in biological fluids such as sweat and blood using biosensor devices. These experiments will be conducted via cyclic voltammetry at various concentrations to see what can most effectively detect dopamine.