Nanomachines Deliver Tiny Payload to Cancerous
Tissue in Live Mice
|Quantum dots programmed to emit
red or green light were injected into live mice and delivered
to three different tissues. The qdot’s destination was
determined by its peptide coating which coded for either normal
lung tissue, the blood vessels feeding tumors, or the lymphatic
vessels draining tumor tissue.
Researchers at The Burnham Institute and the Jacobs School have developed
hybrid organic/ inorganic machines that home to cancerous tissues in live
mice. They programmed nanocrystalline semiconductor particles, called
quantum dots (qdots), and wrapped them with tiny pieces of protein that
home to specific addresses inside living tissue (“homing peptides”).
This is the first successful targeting of an inorganic nanomachine into
a cancerous tumor.
“We showed that qdots could be successfully used inside the body
without causing blood clotting, and that homing peptides directed the
qdots to a specific type of cancer, in this case, breast cancer,”
said Jacobs School Bioengineering Professor Sangeeta Bhatia. She and postdoctoral
fellow Warren Chan developed the qdots used in the study.
Researchers have been working for many years to find a way to use nanomachines
to deliver drugs, diagnose disease, or provide images of tissues in the
body. Bhatia finds qdots especially attractive candidates for such nanotechnology
because they glow, making it easy to see and track the miniscule particles.
It is possible to tune the qdot’s light frequency across the light
spectra by altering the crystal’s particle size or composition.
For targeting, much research has focused on the use of antibodies to
help locate and bind to specific tissues. Such antibodies may make the
nanodevices too large to travel freely to the tumor. The homing peptides
developed by Erkki Ruoslahti, Distinguished Professor at The Burnham Institute,
are much smaller. The smallest of the homing peptides used in this study
were comprised of nine amino acids; a whole protein such as an antibody
is huge by comparison. Two of the peptides used in this study home to
the nucleus of their target, tumor cells. The investigators hope eventually
to be able to direct a nanomachine all the way to the nucleus of a target