A nanotube composite microelectrode for monitoring dopamine levels using cyclic voltammetry and differential pulse voltammetry

Needle-type nanotube composite microelectrodes were fabricated by injecting a carbon nanotube epoxy solution into pulled-glass tubes. Electrochemical impedance spectroscopy was used to study the complex impedance of the electrode and showed that the electron transfer resistance of the electrode decreases with an increase in the percentage of nanotubes in the epoxy. Cyclic voltammetry was performed under reducing conditions in 6.0mM K₃Fe(CN)₆ to examine the surface properties of the microelectrodes. The results showed a steady-state response up to 0.5 V/s attributable to radial diffusion with a high steady-state current density. Cyclic voltammetry and differential pulse voltammetry were then used to detect dopamine. The results showed a linear response with a sensitivity of 100nA/mM. Based on the cyclic voltammetry and differential pulse voltammetry results, needle-type nanotube composite microelectrodes are promising sensors for detecting neurotransmitters.