Featured Research

from universities, journals, and other organizations

3-D Imaging Inside Living Organism, Using Quantum Dots Coursing Through Mouse's Body

Date:
June 2, 2003
Source:
Cornell University
Summary:
Tiny blood vessels, viewed beneath a mouse's skin with a newly developed application of multiphoton microscopy, appear so bright and vivid in high-resolution images that researchers can see the vessel walls ripple with each heartbeat -- 640 times a minute.

ITHACA, N.Y. -- Tiny blood vessels, viewed beneath a mouse's skin with a newly developed application of multiphoton microscopy, appear so bright and vivid in high-resolution images that researchers can see the vessel walls ripple with each heartbeat -- 640 times a minute.

Related Articles


The capillaries are illuminated in unprecedented detail using fluorescence imaging labels, which are molecule-size nanocrystals called quantum dots circulating through the bloodstream. Quantum dots are microscopic metal or semiconductor boxes (in this case cadmium selenide-zinc sulfide) that hold a certain number of electrons and, thus, have a wide number of potential applications in electronics and photonics. Writing in the latest issue of the journal Science (May 30, 2003), researchers at Cornell University and a nanocrystal manufacturer, Quantum Dot Corp., report that the nanocrystals are particularly useful for producing high-resolution, three-dimensional images inside living.

"We have demonstrated a new approach to using quantum dots for biological studies of living animals," says Watt W. Webb, Cornell's S.B. Eckert Professor of Engineering and professor of applied physics, co-inventor of multiphoton microscopy (with Winfried Denk) and leader of the experimental imaging team at Cornell.

"Of course, there are easier ways to take a mouse's pulse," says Webb's Cornell collaborator, senior research associate Warren R. Zipfel, "but this kind of resolution and high signal-to-noise illustrates how useful multiphoton microscopy with quantum dots can become, in a biological research context, for tracking cells and visualizing tissue structures deep inside living animals."

Zipfel cited the study of vascular changes in cancer tumors as one possible application, cautioning that the Cornell researchers are not ready to recommend human-medicine clinical applications for quantum dot imaging, in part because some of the best fluorescing nanocrystals have unknown toxicity. However, mice used in the Cornell study are still alive and apparently healthy, months later, and are being monitored for long-term effects of their treatments.The Cornell researchers used quantum dots for fluorescence imaging microscopy because when excited by light, they emit bright fluorescence in different colors, according to their size, reports biophysics graduate student Daniel Larson. The quantum dots were 6 to 10 nanometers in diameter. (A nanometer is one one-billionth of a meter. By comparison, a red blood cell, at 7 millionths of a meter, is a thousand times bigger). "Even with their water-soluble coating, which is something like being encased in a soap bubble, the quantum dots are only about 24 nanometers in diameter," Larson notes.

Webb explains that the laser scanning microscope used in multiphoton microscopy is particularly adept at producing high-resolution, three-dimensional images inside living tissue because it combines the energies of two photons, striking a molecule at the same time, with an additive effect. Under the conditions used, this only occurs at the focus of the laser, so only at that point is the molecule excited to a state that results in fluorescence emission. This excitation is the same as if it arose from the absorption of a single photon of higher energy, but it is three-dimensionally localized since it is only occurring at the beam focus. The scanning microscope moves the laser beam across the area being imaged at a precise depth. When repeated scans at different planes of focus are "stacked," the result is a brightly lit and vividly detailed three-dimensional image -- and video that takes a viewer inside a living organism.

Because of the special properties of the nanoparticles, multiphoton microscopy with quantum-dot imaging can be 1,000 times brighter in tissue than conventional organic fluorophores (the chemical labels that are temporarily added to samples), says Webb. "We looked to quantum dots for even brighter images at better resolution, and that's what we found."

Results presented in the Science report show highly detailed images of capillaries beneath the skin of a living mouse after quantum dots were injected through a vein in its tail, as well as capillaries through the adipose (fat) layer around the mouse's ovaries. The researchers were particularly surprised at the saw-toothed ripples in the walls of one capillary image -- until they made a calculation. Noting the time it took to scan that part of the tiny blood vessel and the animal's heart rate during the experiment, they determined that each ripple represented the undulation of the capillary wall from one heartbeat.

Besides demonstrating the feasibility of microscopic angiography with quantum-dot labeling through skin and adipose tissue -- two of the most challenging tissue types -- the researchers said they had resolved several fundamental questions, including the fact that sometimes as many as half the dots in a preparation are not fluorescent.

###

Other authors of the Science article are Marcel P. Bruchez, principal scientist at Quantum Dots; Rebecca M. Williams, a research associate with the National Institutes of Health (NIH)-funded Bioimaging Resource at Cornell; Frank Wise, professor of applied and engineering physics; and Stephen W. Clark, a graduate student in Wise's laboratory. Funding came from NIH, the Defense Advanced Research Projects Agency and the National Science Foundation.


Story Source:

The above story is based on materials provided by Cornell University. Note: Materials may be edited for content and length.


Cite This Page:

Cornell University. "3-D Imaging Inside Living Organism, Using Quantum Dots Coursing Through Mouse's Body." ScienceDaily. ScienceDaily, 2 June 2003. <www.sciencedaily.com/releases/2003/06/030602024837.htm>.
Cornell University. (2003, June 2). 3-D Imaging Inside Living Organism, Using Quantum Dots Coursing Through Mouse's Body. ScienceDaily. Retrieved December 22, 2014 from www.sciencedaily.com/releases/2003/06/030602024837.htm
Cornell University. "3-D Imaging Inside Living Organism, Using Quantum Dots Coursing Through Mouse's Body." ScienceDaily. www.sciencedaily.com/releases/2003/06/030602024837.htm (accessed December 22, 2014).

Share This


More From ScienceDaily



More Matter & Energy News

Monday, December 22, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Touch-Free Smart Phone Empowers Mobility-Impaired

Touch-Free Smart Phone Empowers Mobility-Impaired

Reuters - Innovations Video Online (Dec. 21, 2014) A touch-free phone developed in Israel enables the mobility-impaired to operate smart phones with just a movement of the head. Suzannah Butcher reports. Video provided by Reuters
Powered by NewsLook.com
Building Google Into Cars

Building Google Into Cars

Reuters - Business Video Online (Dec. 19, 2014) Google's next Android version could become the standard that'll power your vehicle's entertainment and navigation features, Reuters has learned. Fred Katayama reports. Video provided by Reuters
Powered by NewsLook.com
AP Review: Nikon D750 and GoPro Hero 4

AP Review: Nikon D750 and GoPro Hero 4

AP (Dec. 19, 2014) What to buy an experienced photographer or video shooter? There is some strong gear on the market from Nikon and GoPro. The AP's Ron Harris takes a closer look. (Dec. 19) Video provided by AP
Powered by NewsLook.com
Obama: Better Ways to Create Jobs Than Keystone Pipeline

Obama: Better Ways to Create Jobs Than Keystone Pipeline

AFP (Dec. 19, 2014) US President Barack Obama says that construction of the Keystone pipeline would have 'very little impact' on US gas prices and believes there are 'more direct ways' to create construction jobs. Duration: 00:47 Video provided by AFP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Space & Time

Matter & Energy

Computers & Math

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins