UCSD Jacobs School of Engineering University of California San Diego
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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 cell.