Real‐time Monitoring of Exocytotic Glutamate Release from Single Neuron by Amperometry at an Enzymatic Biosensor

Abstract Glutamate (Glu) is recognized as a vital neurotransmitter released via vesicular exocytosis and plays important roles in many physiological processes. Microelectrode amperometry has become a powerful method to study the secreted electroactive biochemicals via exocytosis, however, there was no means for direct monitoring of exocytosis of the non‐electroactive Glu so far. Herein, we developed an enzymatic micro‐biosensor by co‐modification of glutamate oxidase (GluOx) and Pt nanoparticles (Pt NPs) on the surface of a carbon fiber microelectrode. The Glu was enzymatically transformed by GluOx to an electroactive product, H 2 O 2 , which was then electrochemically detected by the Pt NPs. The prominent catalytic activity of enzyme and micrometer scale of microelectrode endow the sensor with high sensitivity and spatio‐temporal resolution, allowing real‐time monitoring Glu exocytosis from single hippocampal varicosities. The results demonstrate the capability of this biosensor in monitoring and quantification of the quantal release of neurotransmitter Glu, indicating its great potential in exploring the cellular mechanism of neuron communication and synaptic plasticity.