High-Tech Probes Sneak Inside Your Cells
By Bjorn Carey - LiveScience.com - 17 April 2005
The newest generation of nano-sized probes should give scientists
a look into the secret lives of nuclei within your body, researchers
say.
The tiny probes, called quantum dots, are a melding of biology and
technology. The crystalline semiconductors with a biological protein
coating are no larger than a few hundred atoms. Importantly, they
shine brilliantly when hit with a laser.
Quantum dots are leaps and bounds better than current fluorescent
probes, according to developers Fanqing Chen of Lawrence Berkeley
National Laboratory and Daniele Gerion of Lawrence Livermore National
Laboratory. Not only are the dots non-toxic to the cell, but they
don't fade when exposed to light.
"The advantage is that they don't photo-bleach like conventional
fluorescent dyes," Chen told LiveScience. The dots can stay
in cells for weeks, Chen said, adding that "it looks like the
protective coating we put on there is quite good."
The tricky part was to get the dots through a nuclear membrane.
Part of the solution is just a matter of making them tiny. But nuclear
membranes have gate-keeping mechanisms to keep foreign objects out.
To get past this barrier, Chen borrowed a page from a virus' playbook.
The virus SV40 coats itself with a special protein that allows it
to sneak into the nucleus. By attaching this protein to the quantum
dot, the part biological, part nano-sized semiconductor slips through
the membrane.
Scientists attach probes to cellular molecules, such as DNA and
proteins, to monitor their travels through a cell. Similarly, the
probes could be attached to disease-fighting drugs and scientists
could track how they go to work, Chen said. This type of information
could help doctors in prescribing medications.
The work was announced last month and detailed earlier in the journal
Nanoletters.
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