Sunday, February 8, 2009

Nanoparticle system scans opaque objects

U.S. scientists say they've developed a nanoparticle system that allows microscopes to view the internal structure of nearly opaque biological materials.

University of Utah researchers said their new nanotechnology can scan materials such as bones and tumor cells and the method might be used for detecting fatigue in materials such as carbon-fiber plastics.

Associate Professor John Lupton and Assistant Professor of chemistry Michael Bartl said optical microscopes are limited in how much detail and contrast can be seen within a specimen. Electron microscopes are expensive, not always readily available and cannot be used on all types of samples.

Laser or fluorescence microscopy, in which a laser is used to make a specimen emit light, either because the specimen does so naturally or because it has been injected or "labeled" with fluorescent dye. The trouble is such dyes generate toxic chemicals that kill living cells.

"It would be much better to place the cell, without any labels, on top of metal nanoparticles and measure the transmission of light," Lupton said.

The new method involves using infrared lasers to excite clusters of silver nanoparticles placed below the sample being studied. The particles form "plasmonic hotspots," which act as beacons, shooting intensely focused white light upward through the overlying sample.

The study that included Debansu Chaudhuri, Jeremy Galusha, Manfred Walter and Nicholas Borys will be reported in the March issue of the journal Nano Letters.

Original here

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