award © CNRS Photothèque / Cyril Frésillon MART IN KARPLUS RECEIVES THE 2013 NOBEL PRIZE IN CHEMISTRY Associate Professor at the University of Strasbourg (France) and Professor at Harvard University (US), Martin Karplus was awarded the Nobel Prize in Chemistry 2013, together with Michael Levitt and Arieh Warshel, for their work on modeling chemical reactions. A theoretical chemist, Karplus is the director of the Biophysical Chemistry Laboratory at the Institute for Supramolecular Science and Engineering (CNRS/Université de Strasbourg). OPTICS TO SEE A SINGLE MOLECULE PUT IT IN A BOX Improving existing knowledge of cell and molecular biology involves understanding how biomolecules interact with one another. Thanks to the molecular detection method devised by an international team1, an important step has been taken toward the development of ultrasensitive biochemical analysis techniques. Dubbed “antenna-in-box”, the device makes it possible to observe a single molecule through an optical microscope. It relies on the ability of certain molecules to absorb light and subsequently re-emit it as radiation of longer wavelength. “The tiny amount of light emitted by a single molecule makes it difficult to observe it through an optical microscope,” points out Jérôme Wenger of the Fresnel Institute. To get around the problem, the researcher and his team designed a kind of nanometer-scale brightness enhancer. This optical antenna, made up of two gold hemispheres with a diameter of 80 nanometers, confines the light into the ten or so nanometer gap between them, which is roughly the size of a molecule. To test the efficiency of the device, which increases the intensity of the molecular radiation tenfold, the researchers placed tiny samples containing tens of millions of molecules inside it. By inserting their detection system into a nanometer-sized protective chamber, they isolated it from the ambient light emitted by the surrounding molecules. Thus protected, the nano-antenna fully reveals the light signal from a molecule that binds to it. “For the smallest molecules tested, we managed to increase brightness a thousand-fold for samples with a volume smaller than that of a cell,” says Wenger. Encouraged by these results, which demonstrate the efficiency of their device, the scientists now aim to place a cell membrane on an “antenna-in-box” to study the interaction between molecules and perhaps observe cascades of enzyme reactions for the first time. 1 Institut Fresnel de Marseille (CNRS/Aix-Marseille Université/École centrale Marseille); Institute of Photonic Sciences, Barcelona. Nature Nanotechnology July 2013 © ICFO - The Institute of Photonic Sciences This optical nano-antenna inserted in a box can analyze a single molecule in a highly concentrated solution. 15 BEST OF SCIENCE
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