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Tiny nanocubes help scientists tell left from right

Posted on June 28, 2013
Electron microscopy "maps" of octahedral gold nanoparticles surrounded by cubic silver shells. Attaching a biomolecule (e.g., DNA) to these nanoparticles strengthens a signal representing a difference between left- and right-handed molecules' response to light by 100 times, and pushes it toward the visible range of the electromagnetic spectrum.

Electron microscopy “maps” of octahedral gold nanoparticles surrounded by cubic silver shells. Attaching a biomolecule (e.g., DNA) to these nanoparticles strengthens a signal representing a difference between left- and right-handed molecules’ response to light by 100 times, and pushes it toward the visible range of the electromagnetic spectrum.

In chemical reactions, left and right can make a big difference. A “left-handed” molecule of a particular chemical composition could be an effective drug, while its mirror-image “right-handed” counterpart could be completely inactive. That’s because, in biology, “left” and “right” molecular designs are crucial: Living organisms are made only from left-handed amino acids. So telling the two apart is important—but difficult.

Now, a team of scientists at the U.S. Department of Energy’s Brookhaven National Laboratory and Ohio University has developed a new, simpler way to discern molecular handedness, known as chirality. They used gold-and-silver cubic nanoparticles to amplify the difference in left- and right-handed molecules’ response to a particular kind of light. The study, described in the journal NanoLetters, provides the basis for a new way to probe the effects of handedness in molecular interactions with unprecedented sensitivity.

“Our discovery and methods based on this research could be extremely useful for the characterization of biomolecular interactions with drugs, probing protein folding, and in other applications where stereometric properties are important,” said Oleg Gang, a researcher at Brookhaven’s Center for Functional Nanomaterials and lead author on the paper. “We could use this same approach to monitor conformational changes inbiomolecules under varying environmental conditions, such as temperature—and also to fabricate nano-objects that exhibit a chiral response to light, which could then be used as new kinds of nanoscale sensors.”

Read more at: Phys.org

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