Researchers optimize photoluminescent probes to study DNA and more

September 6, 2012 in Chemistry / Analytical Chemistry
Researchers at Rice are working to optimize results from photoluminescent probes essential to the study of microscopic structures like cells, proteins and DNA. The technique doubled the efficiency of a hairpin-shaped probe called a molecular beacon (at left) to find a specific DNA sequence by maximizing the amount of signal pulled from the background noise. (Credit: Marti Group/Rice University)


A new paper by the Rice lab of Angel Martí, an assistant professor of chemistry and bioengineering, offers a methodology to optimize the sensitivity of photoluminescent probes using time-resolved spectroscopy. Martí and co-author Kewei Huang, a graduate student in his group, found their technique gave results nearly twice as good as standard fluorescence spectroscopy does when they probed for specific DNA sequences.


In spectroscopy, chemicals and materials from proteins to nanotubes can be identified and tracked by their fluorescence—the light they return when excited by an input of energy, usually from a laser. In the kind of targeted spectroscopy practiced by Martí and his colleagues, a luminescent probe called a molecular beacon is designed to attach to a target like a DNA sequence and then light up.









To prove their method, Martí and Huang tested ruthenium- and iridium-based light-switching probes under standard fluorescent and time-resolved spectroscopy. The hairpin-shaped probes' middles are designed to attach to a specific DNA sequence, while the ends are of opposite natures. One carries the fluorophore (iridium or ruthenium), the other a chemical quencher that keeps the fluorescence in check until the probe latches onto the . When that happens, the fluorophore and the quencher are pulled apart and the probe lights up.

The individual signal is a flash too tiny and quick for the naked eye to see. "But our instruments can," Martí said. "We're trying to show that you can use time-resolved for many applications, but to use it in the right way, you have to do some analysis first," he said. "If you do it in the correct way, then it's a very powerful technique."

More information: pubs.acs.org/doi/abs/10.1021/ac3019894

Provided by Rice University

"Researchers optimize photoluminescent probes to study DNA and more" September 6, 2012 http://phys.org/news/2012-09-optimize-photoluminescent-probes-dna.html