Nano-sized particles embedded with bright, light-emitting molecules have enabled researchers to visualize a tumor more than one centimeter below the skin surface using only infrared light. An interdisciplinary team from the Universities of Pennsylvania and Minnesota have imaged tumors within living rats by embedding fluorescent materials into cell-like vesicles called polymersomes, which are composed of two layers of self-assembling copolymers. According to the researchers, this imaging process has the potential to go even deeper. And "it should also be possible to use an emissive polymersome vesicle to transport therapeutics directly to a tumor, enabling us to actually see if chemotherapy is really going to its intended target." Read more.
"We have shown that the dispersion of thousands of brightly emissive multi-porphyrin fluorophores within the polymersome membrane can be used to optically image tissue structures deep below the skin -- with the potential to go even deeper," said Michael J. Therien, a professor of chemistry at Penn. "It should also be possible to use an emissive polymersome vesicle to transport therapeutics directly to a tumor, enabling us to actually see if chemotherapy is really going to its intended target."
Here is a picture showing how these nanoparticles are used to image a tumor beneath the skin of a rat (Credit: Michael Therien). This photograph comes from a brief article published by Betterhumans, "Nanoparticles Set Cancer Aglow."
"These polymers are also larger than phospholipids, so that there is enough space for the fluorophores, which are larger than the average molecule that is found inside cell membranes," said Daniel Hammer, professor and chair of the Department of Bioengineering at Penn's School of Engineering and Applied Sciences. "Another feature that makes emissive polymersomes so useful is that they self-assemble. Simply mixing together all component parts gives rise to these functional nanometer-sized, cell-like vesicles."
Now, what's next?
According to Therien, there is keen interest in developing new technology that will enable optical imaging of cancer tissue, as such technology will be less costly and more accessible than MRI-based methods and free of the harmful side effects associated with radioactivity. In this imaging system, the fluorophores can also be tuned to respond to different wavelengths of near-infrared light. This sets the stage for using emissive polymersomes to target multiple cancer cell-surface markers in the body simultaneously.
This is the patent age of new inventions
For killing bodies, and for saving souls,
All propagated with the best intentions.
—George Gordon Noel Byron (1788–1824)
The research work will be published by the Proceedings of the National Academy of Sciences in its online Early Edition. As I'm typing this, the article is not yet online. Be sure to visit the site in a couple of days.
A patent application was filed in February 2004 for this invention named "Polymersomes incorporating highly emissive probes." You can find technical details on this patent by visiting the United States Patent and Trademark Office and search for it. As the patent is not yet approved, click on the left side of the screen on the "Status & IFW" link. On the next window, enter 10/777,552 as the application number. And in the next window, click on the "Published documents" tab.
Here is a direct link to the patent, but I can't guarantee it always will work. So use the above method if this direct link leads you to an error. In the mean time, here is the abstract.
The instant invention concerns compositions comprising polymersomes, visible or near infrared emissive agents, and optionally a targeting moiety associated with a surface of the polymersome. The invention also relates to use of these compositions in the treatment of disease and in imaging methodology.
The "Images" section of the patent description contains 16 pages of drawings and pictures, including a black and white version of the photograph shown above.
Sources: University of Pennsylvania news release, via EurekAlert!, and various websites
The journalists think that they cannot say too much in favor of such “improvements” in husbandry; it is a safe theme, like piety; but as for the beauty of one of these “model farms,” I would as lief see a patent churn and a man turning it. They are, commonly, places merely where somebody is making money, it may be counterfeiting.
—Henry David Thoreau (1817–1862)
Related stories can be found in the following categories.
Biotechnology
Chemistry
Medicine
Nanotechnology.