Tiny turnstile counts nanoparticles

UC SANTA BARBARA (US) — A new device can detect nanoparticles, suspended in fluid, as they flow one by one at estimated rates as high as half a million particles per second.

Precisely measuring nanoparticles—with diameters as small as a few tens of nanometers—has proven challenging.

Jean-Luc Fraikin, a postdoctoral associate at the University of California, Santa Barbara, compares the device to a nanoscale turnstile that can count—and measure—particles as they pass individually through the electronic “eye” of the instrument.


Scanning electron microscope image of polystyrene nanoparticles. These particles are roughly 100 nanometers in diameter, and are readily detected with the analyzer. The uniform size distribution is used to calibrate the instrument. (Credit: J.L. Fraikin and A.N. Cleland, UCSB)

“This device opens up a wide range of potential applications in nanoparticle analysis,” says Fraikin, lead author of a study detailing the work in the journal Nature Nanotechnology.

“Applications in water analysis, pharmaceutical development, and other biomedical areas are likely to be developed using this new technology.”

The instrument measures the volume of each nanoparticle, allowing for very rapid and precise size analysis of complex mixtures. Additionally, Fraikin and colleagues showed that the instrument could detect bacterial virus particles, both in saline solution as well as in mouse blood plasma.

They also discovered a surprisingly high concentration of nanoparticles present in the native blood plasma. These particles exhibited an intriguing size distribution, with particle concentration increasing as the diameter fell to an order of 30 to 40 nanometers, an as-yet unexplained results.

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