‘ORGAN PIPE’ NANORODS
No such beacons existed for OCT, though researchers knew that tiny particles called gold nanorods had some of the properties he was looking for. The problem was that the commercially available nanorods didn’t produce nearly enough signal to be detected in a tissue.
What the team needed were nanorods, but big ones. Nanorods are analogous to organ pipes, says graduate student Elliott SoRelle, because longer pipes vibrate at lower frequencies, creating a deep, low sound. Likewise, longer nanorods vibrate at lower frequencies, or wavelengths, of light. Those vibrations scatter the light, which the microscope detects.
If all the other tissues are vibrating in a white noise of higher frequencies, longer nanorods would stand out like low organ notes amidst a room of babble.
SoRelle’s challenge was to manufacture longer nanorods that were nontoxic, stable, and very bright, which turned out to be a lot to ask. “My background was biochemistry, and this turned out to be a problem of materials science and surface chemistry,” he says. He can now make nontoxic nanorods in various sizes that all vibrate at unique and identifiable frequencies.
The next challenge was filtering out the nanorods’ frequency from the surrounding tissue.
To do that, electrical engineering graduate student and Orly Liba developed computer algorithms that could separate out the frequencies of light scattered by nanorods of various lengths and differentiate those from surrounding tissue.
With the large nanorods and the sensitive algorithms, de la Zerda solved the initial problem of detecting specific structures in three-dimensional images of living tissues. The resulting three-dimensional, high-resolution images were so big—on the order of gigapixels—that the team needed to develop additional algorithms for analyzing and storing such large images.
The team tested their technology in the ear of a living mouse, where they were able to watch as the nanorods were taken up into the lymph system and transported through a network of valves. They were able to distinguish between two different size nanorods that resonated at different wavelengths in separate lymph vessels, and they could distinguish between those two nanorods in the lymph system and the blood vessels. In one study, they could watch individual valves within the lymph vessels open and close to control the flow of fluid in a single direction.
“Nobody has shown that level of detail before,” Liba says.
Having shown that the gold nanorods can be seen in living tissue, the next step is to show that those nanorods can bind to specific kinds of cells, like skin cancer or abnormal vessels in early stage macular degeneration. Then, the technique could be used to learn more about how those diseases progress at the molecular level and also evaluate treatments in individual patients, something that previously hadn’t been possible.
The US Air Force, the National Institutes of Health Directors Office, the National Science Foundation, the Damon Runyon Cancer Research Foundation, the Susan G. Komen Breast Cancer Foundation, the Mary Kay Foundation, the Donald E. and Delia B. Baxter Foundation, the Center for Cancer Nanotechnology Excellence and Translation, the Arnold and Mabel Beckman Initiative for Macular Research, the Pew Charitable Trusts and the Alexander and Margaret Stewart Trust, the Skippy Frank Foundation, the Claire Giannini Fund and Stanford Bio-X funded the work. The study is published in Scientific Reports.
Source: Republished from Futurity.org as a derivative work under the Attribution 4.0 International license. Original article posted to Futurity by Amy Adams-Stanford.
Featured Image Credit: De la Zerda Lab
Now, Check Out:
- Scans and DNA tests reveal the secrets of a rare African mummy
- Pen-sized Microscope Will Simplify Cancer Detection [Video]
- Fat-burning fat exists, but might not be the key to weight loss
- Here’s a Wacky Idea: Use Xbox to Improve the Safety of X-rays
- 3D Printing of Blood Vessels May Keep Transplanted Lab-Grown Organs Alive