Credit: © 2009 Wiley

Most biological processes that occur in or around a living cell are electrostatic or electrochemical in nature, and so sensors and field-effect transistors that use single-walled carbon nanotubes (SWNTs) can be used as sensitive probes for various cell studies. Researchers at the Kavli Institute of Nanoscience in The Netherlands now show that SWNT sensors can electrically interrogate the cellular activity of macrophages — a type of cell that scavenges and degrades foreign materials1.

Cees Dekker and colleagues fabricated a conventional SWNT field-effect transistor and coated the device with antibodies. Macrophages were allowed to attach to the SWNT segment in the device, and as the cell engulfed the nanotube the change in conductance of the transistor was measured. An increase in conductance was correlated with the presence of the cell on the device, but the changes could not be directly attributed to any cellular activity. Electrochemical measurements using platinum-coated nanotubes indicate that reactive oxygen and nitrogen species may be generated during uptake of the nanotube.

Although macrophage activity can be detected using the transistor, more detailed studies are required before any useful information about cellular activity can be derived from the measurements.