Published: February 25, 2016
Scientists at Hong Kong University of Science and Technology have discovered molecules that fluoresce when grouped together, The New York Times reports. The technology bears important implications in the medical field.
Ben Zhong Tang, Ph.D., a scientist at Hong Kong University of Science and Technology observed molecules that glowed green as a solid, but did not glow when dissolved. His curiosity about this phenomenon led to a remarkable discovery: unlike most fluorescent molecules, some fluorescent molecules will glow when coalesced.
Fluorescent molecules glow after absorbing Ultraviolet light. The light’s energy excites the molecules so that they release energy in the form of light, causing the molecule to glow a certain color. Many fluorescent molecules fail to glow when they are grouped because they stack on top of each other and prevent light from being released. This process of failing to exhibit the same amount of light as usual is called quenching.
Scientists and researchers have been trying to utilize the technology of fluorescent molecules in the medical industry. Medical researchers hope to use fluorescent molecules to track or locate tumors in the body. For scientists trying to use the grouping of these molecules to locate tumors, the process of quenching is not ideal because the aggregation of these molecules in a tumor will not be able to reveal the location of that tumor.
Tang realized that the molecules he observed were not stacked on top of each other because they were shaped like five-bladed propellers and thus could not create a stack. He then hypothesized that normal molecules move around and release a lot of energy as heat. However, if the molecules are locked into place and cannot move, then they release the energy as light, which he termed “aggression-induced emission (AIE).”
Tang worked with a postdoctoral fellow named Junwu Chang, Ph.D., to study his hypothesis.
After freezing the molecules in place and showing that they glow brighter than other molecules that are not frozen into place, Tang and Chang worked to find other molecules that also exhibited AIE. One such molecule is known as tetraphenylethylene, or TPE. TPE is versatile. Scientists can tweak it to exhibit different colors or shine brighter in order to fit their particular needs.
Tang also discovered that AIE molecules will still glow when attached to biological structures, such as DNA fragments or proteins. The AIE molecules stay bright for longer and are less dangerous to humans than current fluorescent technologies because they do not contain metals. Scientists currently use AIE molecules to locate and track the movement of cancer cells. AIE molecules are an exciting area of future research, and hopefully this research will shed light on new medical technologies.
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