Characterization of the electrode used for intracellular vesicle electrochemical cytometry, a) global view (scanning electron microscopy) of a nano-tip conical carbon fiber microelectrode showing its shape, scale bar, 5 μm; b) an amplified view of the tip of another nano-tip conical carbon fiber microelectrode, scale bar, 400 nm; c) representative cyclic voltammogram (CV) of 0.10 mM dopamine at a nano-tip conical carbon fiber microelectrode, scan rate, 0.10 V s−1.