(365f) Double-Bore Carbon Fiber Microelectrodes for the Simultaneous Detection of Heavy Metals and Neurotransmitters Via Fast Scan Cyclic Voltammetry

The prevalence of neurodegenerative diseases (NDDs) is on the rise with more than 600 different conditions affecting over 50 million Americans each year. Due to the complex multifactorial etiology of these diseases, the development of therapeutics capable of slowing down or preventing further progression has proven challenging. Although the mechanism of these diseases is not well understood, the identification of abnormal levels of neurotransmitters has been linked to patients suffering with these disorders. These abnormal levels are correlated to the loss of motor functions, dementia, and overall cognitive incline that is associated with these diseases since neurotransmitters are responsible for neural communications. Additionally, the presence of redox active metal ions, such as copper, has been linked to increased neuronal cell death, a known hallmark of these diseases. Electrochemists have extensively used carbon-fiber microelectrodes (CFMs) to reveal significant findings related to NDDs over the last few decades. However, most studies analyze one neurotransmitter or metal at a time with a single CFM, thus, limiting the real-time information about interactions between neurotransmitters and other factors. In contrast, a multi-bore microelectrode with multiple carbon fibers (CF) can provide information about the heterogeneity of an evoked neurotransmitter and interactions between neurotransmitters at a specific location. However, engineering a microelectrode with multiple sensors has been challenging due to the lengthy processing time and cost associated with conventional fabrication and analysis methods. In this study, we fabricated a simple double-bore CFM with two sensing components. Each bore contains a single CF that acts as a single electrode capable of detecting a specific analyte using a unique waveform. We characterized our sensor with dopamine, serotonin, ascorbic acid, and Cu(II) with fast-scan cyclic voltammetry (FSCV). We acquired FSCV signals simultaneously in analyte mixtures prepared with two analytes in tris buffer. We constructed calibration curves showing that our double electrodes are not interfering with each other at nm-wide separation while cycling the potential at ultra-fast scan rates. We also found some exciting interactions between ascorbic acid and Cu(II). To the best of our knowledge, this is the first study reporting use of double-bore CFM to detect two analytes simultaneously without altering any electrochemical parameters at the temporal resolution of 100 ms; thus, showcasing an excellent possibility to use this sensor in vivo for real-time detection of multiple neurotransmitters and other toxic metal ions.