November 9, 2005

Purdue, Vanderbilt scientists develop new cancer detection technique

WEST LAFAYETTE, Ind. – Purdue scientists who recently streamlined a common chemistry lab tool have joined forces with a biomedical group at Vanderbilt University to make the invention potentially valuable in hospital operating rooms.

By custom-modifying a device called a mass spectrometer with a novel sample introduction device, a team including R. Graham Cooks, has found that the wand-like sample probe can be used to accurately identify liver cancers. The technique can tell the difference between diseased and non-diseased regions of tissue samples within a few seconds. Cooks said that the devices might one day prove useful in helping doctors ensure that a tumor is fully removed before a patient leaves the operating table.

"A host of medical issues could be confronted with this tool, which has a very wide range of applications," said Cooks, who is the Henry Bohn Hass Distinguished Professor of Analytical Chemistry in Purdue's College of Science. "For example, in previous studies, it has been found to be useful in detecting the residues of explosives found on luggage."

The team's paper appears on the cover of the current issue of Angewandte Chemie, a leading European scientific journal. Members of the team include Purdue's Justin M. Wiseman and Zoltán Takáts, as well as Vanderbilt University's Satu M. Puolitaival and Richard M. Caprioli.

The wand-like probes are one of the improvements the team has made to the mass spectrometer, an analytical device that in its conventional form has been long established in modern laboratories. But while ordinary mass spectrometry is both time- and labor-intensive, the Cooks team has modified the devices so that not only are they portable enough to be carried in backpacks, but they can also determine the chemical composition of an unprepared sample within five seconds.

Their modified spectrometric technique, which the team has dubbed desorption electrospray ionization (DESI, pronounced "daisy"), involves aiming a fine water mist at a surface with a pencil-sized tube that also sucks up the fluid after the droplets have mixed with the material in the sample.

"This paper shows specifically that DESI can detect cancer in liver tissue, but its medical applications can go beyond that," said Takáts, who is a postdoctoral assistant in Cooks' lab. "We see DESI as a microscope that can 'see' chemicals instead of light. As we move the 'wand' across tissue, it can reveal what chemicals are where, and these chemical signatures are clues to what's happening in the body."

Takáts said, for example, that DESI could help doctors determine how well a drug is working in different parts of a bodily organ. By analyzing different regions in a tissue sample, doctors could better evaluate the mechanism of its action, thus revealing its effectiveness.

"One advantage of DESI for these types of problems is its potential for analyzing tissue in live patients in real time, right on the operating table," Takáts said. "While we are not qu