(360d) Four-Bore Carbon Fiber Microelectrodes for the Simultaneous Detection of Heavy Metals and Neurotransmitters Via Fast Scan Cyclic Voltammetry

Neurodegenerative diseases (NDDs) pose an increasing burden on global health, with conditions such as Alzheimer's disease, Parkinson's disease, and amyotrophic lateral sclerosis affecting more than 50 million people globally. The etiology of these conditions is complex and multifactorial making the development of efficient therapeutics to slow down or stop progression 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, epidemiological studies have implicated heavy metals in increased NDD risk, with chronic exposure posing a significant threat to neurological health. Understanding the intricate network of factors driving NDDs is critical for the development of effective therapeutics. Electrochemists have extensively used carbon-fiber microelectrodes (CFMs) to better understand the pathology of 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. Recently, double-bore CFMs have been reported to study the interaction of two analytes, revealing more crucial information on NDDs; however, it would be beneficial to have an electrode with even more sensing components. In this study, we fabricated a four-bore CFM with four separate sensing components to analyze four analytes using their analyte-specific waveforms. We characterized our sensor with dopamine, serotonin, ascorbic acid, Cu²⁺, Cd²⁺, As³⁺, and Cr³⁺ via fast-scan cyclic voltammetry (FSCV). We acquired FSCV signals simultaneously in analyte mixtures prepared with four analytes in tris buffer. We constructed calibration curves showcasing the stability of our multi-bore electrode and ultra-fast scan rates. To the best of our knowledge, this is the first study reporting use of four-bore CFM to detect four 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.