Electrochemical Sensor for the Quantification of Dopamine Using Glassy Carbon Electrodes Modified with Single-Wall Carbon Nanotubes Covalently Functionalized with Polylysine

We report a dopamine electrochemical sensor based on the modification of glassy carbon electrodes (GCE) with polylysine-functionalized single-wall carbon nanotubes (SWCNT-PLys). The resulting electrodes (GCE/SWCNT-PLys) showed a significant improvement in the electrooxidation of dopamine with drastic decrease in the peak potentials separation and important enhancement in the associated currents. Dopamine was detected by differential pulse voltammetry-adsorptive stripping with medium exchange at nanomolar levels even in the presence of high excess of ascorbic and uric acids. The sensor was successfully used for the quantification of dopamine in urine samples enriched with the neurotransmitter.