Electrodeposition of neurotransmitters onto carbon-fiber microelectrodes to enhance Cu2+ detection with fast-scan cyclic voltammetry

Neurological disorders affect millions of people globally despite the wide variety of medications developed to slow down progression. The lack of efficient drugs available highlights the need for a deeper understanding of the etiology of these diseases and the effect of environmental factors, such as heavy metals. Studies have shown that heavy metal exposure can initiate cell death, a known contributor to the onset of these disorders. Traditionally employed methods of metal ion detection analyze blood or urine samples, thus eliminating in vivo, real-time measurements. These diagnostic methods cannot be applied to living systems and therefore lack insight into the relationship between heavy metals and neurodegenerative diseases. In order to complete in vivo measurements, a low sensitivity system is required to detect physiological metal ion concentrations. Electrochemists have discovered several surface modifications protocols; however, an ideal strategy should be biocompatible and cheap. In this study, we fabricated a carbon-fiber microelectrode electrodeposited with neurotransmitters to enhance the detection of Cu2+. We characterized our sensor with dopamine, ascorbic acid, and Cu2+ with fast-scan cyclic voltammetry. To determine which neurotransmitter best improved the Cu2+ signal, we analyzed dopamine and ascorbic acid along with a mixture of both and proceeded with the best one. We then optimized the length of electrodeposition by comparing different deposition times and choosing the best one. We performed all our experiments in a buffer solution that mimics artificial cerebellum fluid; thus, we showcase the ability of our sensors for the in vivo detection of Cu2+ with high sensitivity and excellent biocompatibility.