In multicellular organisms, cells typically communicate by sending and receiving chemical signals. Chemical messengers involved in the exocytosis of neuroendocrine cells or neurons are generally assumed to only originate from the fusing of intracellular large dense core vesicles (LDCVs) or synaptic vesicles with the cellular membrane following stimulation. Accumulated evidence suggests that exosomes - one of the main extracellular vesicles (EVs) - carrying cell-dependent DNA, mRNA and proteins etc. play an essential role in cellular communication. Due to experimental limitations, it has been difficult to monitor the real-time release of individual exosomes, which impedes a comprehensive understanding of the basic molecular mechanisms and the functions of exosomes. We introduce amperometry with microelectrodes to capture the dynamic release of single exosomes from a single living cell, distinguish them from other EVs and identify between the molecules inside exosomes and those secreted from LDCVs. We show that similar to many LDCVs and synaptic vesicles, exosomes released by neuroendocrine cells also contain catecholamine transmitters. This finding reveals long-range chemical communication via exosome-encapsulated chemical messengers and a potential interconnection between the two release pathways, changing the canonical view of exocytosis of neuroendocrine cells and possibly neurons. This defines a new mechanism for chemical communication at the fundamental level and opens new avenues in the research of the molecular biology of exosomes in the neuroendocrine and central nervous systems. In addition, electrochemically renewable surface-enhanced Raman spectroscopy (SERS) microprobes enable real-time dynamic measurement of ROS released from single cells, which lays the foundation for the development of the integrated technology of electrochemistry and Raman.                                                                                                                                                                                                                                                              

References:
[1]K. Hu, K. L. V. Long, F. Wang, X. Zhang, C. Gu, N. Fang, N. T. N. Phan and A. G. Ewing, J. Am. Chem. Soc. 2023, 21, 11499.