Wed, 18 Nov 2009 15:54:1
Ayinde O. Chase - AHN Editor
British Columbia, Canada (AHN) - Reminiscent of Star Trek phasers and ray guns seen in Sci-fi movies and comic books, Canadian scientists are reporting development of an internal on-off "switch" that paralyzes animals when exposed to a beam of ultraviolet light.
According to the researchers from Simon Fraser University the test subjects remain paralyzed even when the light is turned off. However, when exposed to ordinary or natural light the paralysis wears off and the animals regain consciousness.
Neil Branda who headed the study along with his colleagues detail in the Journal of the American Chemical Society that similar "photoswitches" -- light-sensitive materials that undergo photoreactions -- have been available for years. Researchers use them in their studies and even doctors use light-sensitive materials and photoreactions in medicine in photodynamic therapy to treat certain forms of cancer.
However, what makes this study novel is that typically those light-sensitive materials, however, do not have the reversibility that exists in photoswitching.
The JACS report describes development and successful testing of a photoswitch composed of the light-sensitive material, dithienylethene. The scientists grew transparent, pinhead-sized worms and fed them a dithienylethene. When exposed to ultraviolet light, the worms turned blue and became paralyzed. When exposed to visible light, the dithienylethene became colorless again and the worms' paralysis ended.
Scientists are not completely sure how the switch causes paralysis. However, the study demonstrates that photoswitches may have the ability to yield future successes in turning photodynamic therapy on and off, and for other applications in medicine and research.
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