Transistors tune in: The chromogranin A (CgA) released from the synaptic terminal of cortical neurons can be detected in situ by immobilization of an antibody against CgA on a single‐walled carbon‐nanotube field‐effect transistor (see picture), to give a device with high selectivity, sensitivity, and real‐time detection capability. This biosensory technique can be used to study the activity of individual living neurons.

Exocytosis of a single bovine adrenal chromaffin cell, triggered by histamine stimulation, was investigated via the electric responses detected with single-walled carbon-nanotube field-effect transistors (SWCNT-FET) and the morphological changes acquired by atomic force microscopy (AFM). Secretion of chromogranin A (CgA), stored in the vesicles of a single chromaffin cell, can be monitored in situ by the antibody against CgA (CgA-antibody) functionalized on the SWCNT-FET devices. The SWCNT-FET can further discriminate the amount of released CgA with different levels of histamine stimulations. The AFM morphological studies on a chromaffin cell indicate that the depression structures on the cell surface, caused by the histamine-evoked exocytotic fusion pores, appeared much more frequently than those without histamine stimulation or with the pretreatment of mepyramine before histamine stimulation. The vesicle diameters are about 50 nm calculated from the obtained three-dimensional AFM images. In comparison, the fusion pores of chromaffin cells stimulated by high-K (+) buffer solution were also investigated to have a wider-ranging distribution of vesicle diameters of 60-260 nm. This work demonstrates that the combination of novel techniques, SWCNT-FET and AFM, can provide further insights into the fundamental properties of exocytosis in neuroendocrine cells.