Electrochemical Characterization of Carbon Nanopipette Electrodes for Rapid Dopamine Detection

Dopamine is a neurotransmitter involved in motor, reward, and cognitive functions. Model systems are useful for studies of dopamine-related diseases, such as Parkinson’s and schizophrenia. Drosophila melanogaster is a convenient model organism because it has homologous neurotransmitters with mammals and is easy and fast for genetic manipulation. However, the central nervous system is extremely small, making real-time measurements of dopamine difficult. In the past, carbon fiber microelectrodes and fast-scan cyclic voltammetry (FSCV) have been used to detect dopamine release in the Drosophila ventral nerve cord. In order to measure dopamine in specific brain regions of the fly, a smaller, robust electrode is needed.

Carbon nanopipette electrodes (CNPEs) have been made with hollow tips for concurrent electrophysiological measurement and injection. The CNPEs used in this work are specifically designed to have solid tips 50-400 nm in diameter. This thesis introduces the use of CNPEs for detecting changes in concentrations of dopamine using FSCV. Chapter 1 describes CNPEs, gives a brief overview of neurotransmission and electrochemistry, and explains FSCV. Chapter 2 explores the characterization of the electrochemical properties of CNPEs using FSCV. We verified these electrodes were suitable for in vivo studies by measuring exogenous and endogenous dopamine in Drosophila larvae. Chapter 3 describes future studies that can be done with CNPEs. Ultimately, we envision using CNPEs in the adult Drosophila to study specific regions of the fully developed central nervous system.