Nanotechnology Now

Our NanoNews Digest Sponsors



Heifer International

Wikipedia Affiliate Button


android tablet pc

Home > Press > Penn Research May Help Drastically Reduce Cost of Powerful Microscope Technique

The same section of a mouse brain imaged with a femtosecond laser (above) and a much weaker laser but the new dye (below).
The same section of a mouse brain imaged with a femtosecond laser (above) and a much weaker laser but the new dye (below).

Abstract:
A dye-based imaging technique known as two-photon microscopy can produce pictures of active neural structures in much finer detail than functional magnetic resonance imaging, or fMRI, but it requires powerful and expensive lasers. Now, a research team at the University of Pennsylvania has developed a new kind of dye that could reduce the cost of the technique by several orders of magnitude.

Penn Research May Help Drastically Reduce Cost of Powerful Microscope Technique

Philadelphia, PA | Posted on April 22nd, 2013

The study was led by associate professor Sergei Vinogradov and postdoctoral researcher Tatiana Esipova, both of the Department of Biochemistry and Biophysics in Penn's Perelman School of Medicine, along with Christopher Murray, a professor in the departments of Chemistry in the School of Arts and Sciences and of Materials Science and Engineering in the School of Engineering and Applied Science.

It was published in the Proceedings of the National Academies of Science.

Two-photon microscopy involves using a powerful laser to rapidly shoot photons in a highly focused beam that can pass through living tissue. The combined energy of a pair of infrared photons that collide with a molecule of a marker dye causes it to fluoresce in the visible range. By scanning the focus of the beam over a three-dimensional space, the fluorescence of the dye can reveal even the tiniest 3D structures, such as blood capillaries in the brain and even individual cells. And by using dyes sensitive to the chemistry of specific biological processes, such as the movement of calcium ions that allows neurons to fire, the technique can even be used for functional imaging; it can sense changes in neural activity as a subject is thinking.

"It's practically the only way to look at individual cells or even sub-cellular structures in the brain at depth," Vinogradov said. "FMRI gives you only bigger regions; you don't see the details. And a lot of the things we're interested in probing are very close together."

The drawback to this technique is that currently available dyes require tremendous amounts of energy to produce usable images. Researchers must use femtosecond lasers, which can shoot a quadrillion photon pairs a second. These lasers are very expensive, however, limiting the applications of the microscopy technique.

One possible solution would be to use a dye that fluoresces more easily. To this end, nanoparticles made from the lanthanide elements have long been investigated as molecular probes.

"These nanoparticles have an excitability that is a million to 10 million times higher than existing molecular dyes," Vinogradov said. "That means in order to excite these nanoparticles, you could use a light source that costs closer to $200 rather than $200,000."

The challenge was then to get lanthanide nanoparticles into the kinds of tissues researchers wanted to study, such as the brain. Because these nanoparticles aren't soluble, they can't safely be injected into the bloodstream. Instead of flowing along with the blood, they would sit on the bottom of blood vessels, eventually forming a clot.

Other groups had tried increasing the nanoparticle's solubility by wrapping them in hydrophilic, or water-loving, polymers. These polymers are essentially strings with a tail that is attracted to water and a head that is attracted to the particle. In theory, the head would bind to the nanaoparticle surface and the tail would interact with the bloodstream, but, because the string would be attached to the particle by a single point of contact, it could easily fall off. Adding more particle-binding sites to the string solves one problem but creates another.

"This kind of string wraps up and glues to the particle, but none of its hydrophilic parts remains available to interact with the solvent," Vinogradov said. "It attaches to the nanoparticle but doesn't make it significantly more soluble."

Vinogradov and his colleagues took a different approach, fashioning dendritic polymers. These dendrimers have multiple branches attached to a core, giving them an overall spherical shape.

"Imagine you have a tennis ball, and you stick it to a Velcro-coated wall. Because it's a ball, there's still a significant fraction of its surface that's still exposed," Vinogradov said. "We take the lanthanide nanoparticles and cover their entire surface with these hydrophilic balls. It's a very simple geometric concept."

Attaching these dendrimers to nanoparticles was possible due to Christopher Murray's earlier research, which enabled a special procedure to "prime-coat" nanoparticle surfaces with a layer that facilitates their interaction with dendrimers.

The researchers tested the efficacy of this approach on a mouse model. They started by injecting a conventional marker dye and using a femtosecond laser to map the vasculature of a section of the mouse's brain. They then switched to a laser that was a million times weaker and mapped the same region again, predictably producing no fluorescence. Finally, they kept the same weak laser but injected the dendrimer-coated nanoparticles, which allowed the researchers to produce the same imagery as in the first trial.

"This means we did the same experiment as the femtosecond laser but with one that costs hundreds of thousands of dollars less," Vinogradov said.

This experiment was the first demonstration of use of lanthanide nanoparticles in neuromiaging as well as the first example of two-photon in vivo microscopy with simple, inexpensive lasers.

The work was supported by the National Science Foundation, the National Institutes of Health, the Office of Naval Research, the American Heart Association, Penn's Nano/Bio Interface Center and the Penn Medicine Neuroscience Center. It was done in collaboration with researchers at Harvard Medical School, Massachusetts General Hospital and Intelligent Materials Solutions Inc.

Murray is a Penn Integrates Knowledge professor. The Penn Integrates Knowledge program is an initiative conceived by President Amy Gutmann to recruit scholars whose research and teaching exemplify the integration of knowledge. These scholars hold endowed professorships and joint appointments between Penn's schools.

####

For more information, please click here

Contacts:
Evan Lerner

215-573-6604

Copyright © University of Pennsylvania

If you have a comment, please Contact us.

Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.

Bookmark:
Delicious Digg Newsvine Google Yahoo Reddit Magnoliacom Furl Facebook

Related News Press

News and information

NREL Announces New Center Directors to lead R&D, Analysis Efforts September 30th, 2014

Yale University and Leica Microsystems Partner to Establish Microscopy Center of Excellence: Yale Welcomes Scientists to Participate in Core Facility Opening and Super- Resolution Workshops October 20 Through 31, 2014 September 30th, 2014

Speed at its limits September 30th, 2014

Research mimics brain cells to boost memory power September 30th, 2014

Imaging

Yale University and Leica Microsystems Partner to Establish Microscopy Center of Excellence: Yale Welcomes Scientists to Participate in Core Facility Opening and Super- Resolution Workshops October 20 Through 31, 2014 September 30th, 2014

Govt.-Legislation/Regulation/Funding/Policy

NREL Announces New Center Directors to lead R&D, Analysis Efforts September 30th, 2014

A Heartbeat Away? Hybrid "Patch" Could Replace Transplants: TAU researcher harnesses gold nanoparticles to engineer novel biocompatible cardiac patch September 30th, 2014

How things coil: Researchers discover that simulation technology designed for Hollywood can be used as a predictive tool for understanding fundamental engineering problems September 29th, 2014

UT Arlington researchers develop transparent nanoscintillators for radiation detection for medical safety and homeland security September 29th, 2014

Nanomedicine

Speed at its limits September 30th, 2014

Ad-REIC vaccine: A magic bullet for cancer treatment September 30th, 2014

New Topical Hemostatic Agent: Neutral Self-Assembling Peptide Hydrogel September 30th, 2014

A Heartbeat Away? Hybrid "Patch" Could Replace Transplants: TAU researcher harnesses gold nanoparticles to engineer novel biocompatible cardiac patch September 30th, 2014

Discoveries

Research mimics brain cells to boost memory power September 30th, 2014

Ad-REIC vaccine: A magic bullet for cancer treatment September 30th, 2014

New Topical Hemostatic Agent: Neutral Self-Assembling Peptide Hydrogel September 30th, 2014

Chemical interactions between silver nanoparticles and thiols: A comparison of mercaptohexanol again September 30th, 2014

Announcements

Park Systems Announces Outsourced Analytical Services Including AFM Surface Imaging, Data Analysis and Interpretation September 30th, 2014

Ad-REIC vaccine: A magic bullet for cancer treatment September 30th, 2014

New Topical Hemostatic Agent: Neutral Self-Assembling Peptide Hydrogel September 30th, 2014

Chemical interactions between silver nanoparticles and thiols: A comparison of mercaptohexanol again September 30th, 2014

Tools

Yale University and Leica Microsystems Partner to Establish Microscopy Center of Excellence: Yale Welcomes Scientists to Participate in Core Facility Opening and Super- Resolution Workshops October 20 Through 31, 2014 September 30th, 2014

Park Systems Announces Outsourced Analytical Services Including AFM Surface Imaging, Data Analysis and Interpretation September 30th, 2014

Iranian Scientists Determine Grain Size, Minimize Time of Nanocomposite Synthesis September 29th, 2014

Oxford Instruments launches 3rd annual Indian nanotechnology seminars in Kolkata and Delhi - sharing expertise with Nanotechnology researchers in India September 25th, 2014

Military

UT Arlington researchers develop transparent nanoscintillators for radiation detection for medical safety and homeland security September 29th, 2014

'Pixel' engineered electronics have growth potential: Rice, Oak Ridge, Vanderbilt, Penn scientists lead creation of atom-scale semiconducting composites September 29th, 2014

Nanotechnology leads to better, cheaper LEDs for phones and lighting September 24th, 2014

Engineered proteins stick like glue even in water: New adhesives based on mussel proteins could be useful for naval or medical applications September 22nd, 2014

NanoNews-Digest
The latest news from around the world, FREE



  Premium Products
NanoNews-Custom
Only the news you want to read!
 Learn More
NanoTech-Transfer
University Technology Transfer & Patents
 Learn More
NanoStrategies
Full-service, expert consulting
 Learn More














ASP
Nanotechnology Now Featured Books




NNN

The Hunger Project







© Copyright 1999-2014 7th Wave, Inc. All Rights Reserved PRIVACY POLICY :: CONTACT US :: STATS :: SITE MAP :: ADVERTISE