ANN ARBOR, Mich.---A wireless, nano-scale voltmeter developed at the University of Michigan is overturning conventional wisdom about the physical environment inside cells. It may someday help researchers tackle such tricky medical issues as why cancer cells grow out of control and how damaged nerves might be mended.
U-M professor Raoul Kopelman will discuss the device Saturday during a special session, "Creating Next Generation Nano Tools for Cell Biology," at the annual meeting of the American Society for Cell Biology in Washington, D.C.
"The basic idea behind this field of research is to follow cellular processes---both normal and abnormal---by monitoring physical properties inside the cell. There's a long history of research on the chemistry happening inside the cell, but now we're getting interested in measuring the physical properties, because physical and chemical processes are related," said Kopelman, who is the Richard Smalley Distinguished University Professor of Chemistry, Physics and Applied Physics.
With a diameter of about 30 nanometers, the spherical device is 1,000-fold smaller than existing voltmeters, Kopelman said. It is a photonic instrument, meaning that it uses light to do its work, rather than the electrons that electronic devices employ.
Kopelman's former postdoctoral fellow Katherine Tyner, now at the U.S. Food and Drug Administration, used the nano-voltmeter to measure electric fields deep inside a cell---a feat that until now was impossible. Scientists have measured electric fields in the membranes that surround cells, but not in the interior, Kopelman said.
With the new approach, the researchers don't simply insert a single voltmeter; they're able to deploy thousands of voltmeters at once, spread throughout the cell. Each unit is a single nano-particle that contains voltage-sensitive dyes. When stimulated with blue light, the dyes emit red and green light, and the ratio of red to green c
|Contact: Nancy Ross-Flanigan|
University of Michigan