In flow cytometry, cells are bombarded with laser light as they pass through a scanning chamber. The cells can then be analyzed and based on their characteristics, sorted and routed to different destinations within the cytometer.

The new high-tech dye-containing particles used by the Stanford team go a step further, Shachaf said. They give off not just single-wavelength fluorescent echoes but also more-complex fingerprints comprising wavelengths slightly different from the single-color beams that lasers emit. These patterns, or Raman signals, occur when energy levels of electrons are just barely modified by weak interactions among the constituent atoms in the molecule being inspected.


Intel Nanoparticles

Raman signals are emitted all the time by various molecules, but they're ordinarily too weak to detect. To beef up their strength, the Stanford team employed specialized nanoparticles produced by Intel Corp., each with its own distinctive signature.

Intel has designed more than 100 different so-called COINs, or composite organic-inorganic nanoparticles: these are essentially sandwiches of dye molecules and atoms of metals such as silver, gold or copper whose reflective properties amplify a dye molecule's Raman signals while filtering out its inherent fluorescent response. The signals are collected and quantified by a customized, automated microscope.

Shachaf anticipates being able to demonstrate simultaneous visualization of nine or 10 COIN-tagged cellular features in the near future and hopes to bring that number to 20 or 30, a new high, before long. "The technology's capacity may ultimately far exceed that number," Shachaf said. "Some day it could be used for more than 100 features."

Source: Stanford University School of Medicine

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