Listening to cancer cells for drug discovery
WEST LAFAYETTE, Ind. – Researchers are making strides in the field of drug discovery, thanks
to holography and lasers. They are now able to detect motion inside three-dimensional
tumor spheroids that could show how various drug candidates affect intracellular
Researchers at Purdue University have developed holographic tissue
dynamics spectroscopy, a technique to measure the living motion inside a cell and
to determine the cell’s response to applied drugs. The technology was highlighted
in a letter in the Journal of Biomedical Optics.
The spectrogram shows how cells react to drugs; for instance, when they interact with a metabolic
drug (iodo-acetate) in comparison to an antimitosis drug (cytochalasin). Courtesy
of David D. Nolte, Purdue University.
The scientists were able to view a tumor’s tissues in three
dimensions using holography. Using the holographic technique with lasers allows
them to see the tumor’s interior as well as its surface. Like polarized sunglasses,
the approach cancels the effect of any light scattered by skin and tissues, uncovering
the image-bearing light that is already there. Images similar to voiceprints used
in voice recognition security software are left that can show changes taking place
within the cells.
Upon completion of the hologram, the researchers use fluctuation
spectroscopy to measure time-dependent changes within the hologram. They measure
the frequency of light fluctuations as a function of time after a drug has been
administered. The resulting spectrogram represents a voiceprint of the drug used
on the cells, enabling drug researchers and manufacturers to see how various drug
candidates affect organlike structures within a cell.
With its high throughput, the technology will soon allow manufacturers
to more quickly determine which drugs are most effective in battling tumors and
other tissue diseases.
- An interference pattern that is recorded on a high-resolution plate, the two interfering beams formed by a coherent beam from a laser and light scattered by an object. If after processing, the plate is viewed correctly by monochromatic light, a three-dimensional image of the object is seen.
- The optical recording of the object wave formed by the resulting interference pattern of two mutually coherent component light beams. In the holographic process, a coherent beam first is split into two component beams, one of which irradiates the object, the second of which irradiates a recording medium. The diffraction or scattering of the first wave by the object forms the object wave that proceeds to and interferes with the second coherent beam, or reference wave at the medium. The resulting...
- With respect to light radiation, the restriction of the vibrations of the magnetic or electric field vector to a single plane. In a beam of electromagnetic radiation, the polarization direction is the direction of the electric field vector (with no distinction between positive and negative as the field oscillates back and forth). The polarization vector is always in the plane at right angles to the beam direction. Near some given stationary point in space the polarization direction in the beam...
- A chart formed by a spectrograph; the record of the spectral range. See spectrograph.
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