Single-Cell Voltage Measurements with a Set of Nanoprobes

Abstract

Noninvasive single cell electrical measurements using carbon nanotubes as electrodes are reported here. The device consists of four nanotubes deposited in the corner of a 2 micron square. Using flow, single cells are places on top of the electrodes. Two of the probes are used to apply voltage pulses to the cell and the other two are used to measure the response as a function of time. As a control, measurements of water, cell medium, cells and biomolecules have been made with metallic plates, defined by 60nm holes in a 75nm insulating film. For proof of principle, yeast cells suspended in HEPES are measured. The results show that the nanotubes allow a contact with the ionic environment 100 times better than the metallic plates. The nanotubes also show a different response when the cell is nearby or touching a cell. Since the nanotubes are 1.2 nm in diameter, comparable in size with membrane proteins, we plan to use the nanotube array to perform some of the functions of patch clamps but with less perturbation to the cells due to the small dimension of carbon nanotubes.