News Release

Measurement Technique Provides Snapshot Of Cell Physiology

Peer-Reviewed Publication

University of Illinois at Urbana-Champaign, News Bureau

CHAMPAIGN, Ill. -- A new measurement technique that simultaneously can identify and measure more than 30 compounds found in a single cell has been developed by a team of chemists and physiologists at the University of Illinois. The method -- which uses nanoliter sampling, capillary electrophoresis and fluorescence spectroscopy -- is direct, convenient and highly sensitive.

"By combining a nanoliter-volume separation technique with an information-rich spectroscopic detection scheme, we can obtain both qualitative and quantitative chemical information about the target species," said Jonathan Sweedler, a professor of chemistry and a researcher at the university's Beckman Institute for Advanced Science and Technology. "We can therefore more completely identify and measure biologically important compounds in individual cells without performing any chemical reactions to make the compounds detectable."

The measurement technique was developed by Sweedler, graduate research assistant Robert Fuller, physiology professor Rhanor Gillette and visiting scholar Leonid Moroz. The researchers describe the technique in the February issue of the journal Neuron.

"We begin by placing a freshly isolated cell in a microvial where it is homogenized and then drawn into a capillary tube," Fuller said. "The chemicals then separate in the capillary by electrophoresis and move into a flow cell where they are stimulated by a laser. The laser-induced fluorescence is then collected by a CCD/spectrograph and analyzed by a computer.

"We can identify compounds not only by the separation time, but also by the spectral fingerprints in the fluorescence emission," Fuller said. "This means we are able to distinguish between compounds that migrate at the same time, thereby avoiding potential misidentification."

In addition, because the detection scheme is based upon the native fluorescence of individual molecules, the researchers need not perform any additional chemistry in order to identify or quantify compounds. "Since we are not relying on any chemical reactions, we are able to measure the true amount of chemicals that are contained in the cell," Fuller said.

While most measurement techniques can identify or measure only a few compounds at the same time, the new technique can handle up to 30 compounds.

"By looking at so many compounds simultaneously, we really get a nice snapshot of the cell's physiology," Fuller said. "The concentrations of the various chemicals can indicate both the general health and the metabolic state of the cell. Such measurements also can aid in the identification of neurotransmitters and the mechanisms of their regulation."

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