Electrochemical detection of neurotransmitters at structurally small electrodes

Electroanalytical chemistry has been widely applied to the study of neurochemical systems. This feasibility stems from the ease of oxidative detection of many neurotransmitters, the small dimensions of electrodes and their inherent fast response time. Dopamine is a neurotransmitter that has long been of interest to both chemists and neuroscientists. For instance, a loss of dopamine-containing neurons or its transmission is related to a number of illnesses and conditions including Parkinson's disease and schizophrenia. It is therefore of interest to perform quantitative and qualitative determination of dopamine in the extracellular fluid in animals in order to gain an understanding of the neurotransmission processes. Such a study will also aid in correlating neurochemistry with behaviour. Among the electroanalytical techniques, fast-scan cyclic voltammetry is often used to detect dopamine in vivo. Detection of dopamine is further enhanced when fast-scan cyclic voltammetry is conducted at probes with a micrometer-dimension. A review of common materials and techniques for fabricating physically small electrodes is therefore presented in this chapter. Unfortunately, detecting dopamine at naked electrodes is challenging partly because of overlapping oxidation signals from interferents of high concentrations in the brain. Furthermore, electrode fouling caused by adsorption of biological molecules is another common problem encountered in detecting dopamine in vivo. In this chapter, a number of approaches including electrode surface modification and diamond electrodes used to minimize these shortcomings have also been reviewed.