A Purdue physicist has created technology to detect motion inside three-dimensional tumor spheroids, which may enhance the pharmaceutical industry's early drug discovery capabilities.

David Nolte has developed Holographic Tissue Dynamics Spectroscopy, a technology that allows researchers to look inside cells using holography and lasers. The technology was highlighted in a letter in the peer-reviewed Journal of Biomedical Optics. The work is done in collaboration with John Turek, professor of basic medical sciences at Purdue.

"This technique measures living motion inside a cell," Nolte said. "We're picking up all the activity and seeing how the cell modifies its activities in response to applied drugs."

The first process used by Nolte's technology is holography, which shows tumor tissue in three dimensions.

"We make digital holograms of the tumor, which can grow up to one millimeter," Nolte said. "This holographic technique using lasers lets us see all the way through the tumor, not just the surface."

The tissue dynamics spectroscopy used in Nolte's technology creates an image that shows changes taking place inside cells.

"After making the hologram, we use spectroscopy to measure the time-dependent changes in the hologram," Nolte said. "Fluctuation spectroscopy breaks down the changes into different frequencies, and we can tell how a cell's membranes, mitochondria, nucleus and even cell division respond to drugs. We measure the frequency of light fluctuations as a function of time after a drug is applied."

The resulting colorful frequency-versus-time spectrogram represents a unique voice-print of the drug used on the cells.

"Individual drugs have different spectrograms, but with similarities within specific classes," Nolte said. "By looking at how cell motion responds to drugs, we can differentiate very fine mechanistic points between them."

Drug researchers and manufacturers may benefit from the technology by being able to more quickly determine which drug candidates are most effective in battling tumors and other tissue diseases.

"This technology, with its high-throughput aspect, allows manufacturers to place a different tumor into 384 plates, test 384 different drug compounds and create 384 spectrograms in six hours," Nolte said.

Purdue Research Foundation and Medical News Today