CHANNELS, RECEPTORS, AND ELECTRICAL SIGNALING |
"Nano-sized voltmeter" enables cellular-wide electric field mapping
Katherine M Tyner 1, Raoul Kopelman 1* and Martin A Philbert 1
1 University of Michigan
* To whom correspondence should be addressed. E-mail: kopelman{at}umich.edu.
Submitted on June 28, 2006
Revised on July 28, 2006
Accepted on 23 March 2007
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Abstract |
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Previously, all biological measurements of intracellular electric fields, using voltage dyes or patch/voltage clamps, were confined to cellular membranes, which account for less than 0.1% of the total cellular volume. These membrane-dependent techniques also frequently require lengthy calibration steps for each cell or cell type measured. A new 30 nm "photonic voltmeter", one thousand-fold smaller than existing voltmeters, enables, for the first time, complete 3-dimensional electric field profiling throughout the entire volume of living cells. These nano-devices are calibrated externally and then applied for E field determinations inside any live cell or cellular compartment, with no further calibration steps. The results indicate that the E fields from the mitochondrial membranes penetrate much deeper into the cytosol than previously estimated, indicating that, electrically, the cytoplasm cannot be described as a simple homogeneous solution, as often approximated, but should rather be thought of as a complex, heterogeneous hydrogel, with distinct microdomains.
Key Words:
E-field, Sensors, nanoparticles, voltage sensitive dyes, voltmeter
