Electrochemical Assessment of Carbon Nanomaterial-Enabled Microelectrodes for Dopamine Sensing

Chronic neurochemical monitoring is critical for identifying the neural basis of human behavior and treating brain disorders. Studies have already shown that any abnormal neurochemical signaling cause brain disorders such as epilepsy, Parkinson's disease, traumatic brain injury and drug addiction. To treat such disorders, it is important to understand neurochemical dynamics over long-term, preferably in all areas of the brain. Currently, the preferred detection method is fast-scan cyclic voltammetry (FSCV) and the preferred electrode material is carbon fiber microelectrode (CFM). Unfortunately, CFM's increased sensitivity (sub-micromolar levels) is at the expense of increased surface fouling and chemical etching, which limits electrode lifetime to few days. Emerging carbon nanomaterials have spurred renewed interest in investigating new electrode material technology. We report the use of boron-doped ultrananocrystalline diamond (UNCD) and carbon nanotubes (CNTs) as advanced electrode materials for reliably detecting dopamine, a model neurochemical that plays a crucial role in various brain disorders. We present the electrochemical behavior and performance of these emerging materials in detecting dopamine long-term in standard buffer solutions and in biological fluids. Custom microfluidics was developed to study the electrode fouling behavior and the subsequent effect of in situ cleaning methods developed in our laboratory. Finally, development of electrochemical models to explain the progression of surface fouling using impedance techniques will be presented.