Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Navy researchers recruit luminescent nanoparticles to image brain function

18.11.2015

Research biologists, chemists and theoreticians at the U.S. Naval Research Laboratory (NRL), are on pace to develop the next generation of functional materials that could enable the mapping of the complex neural connections in the brain. The ultimate goal is to better understand how the billions of neurons in the brain communicate with one another during normal brain function, or dysfunction, as result of injury or disease.

"There is tremendous interest in mapping all the neuron connections in the human brain," said Dr. James Delehanty, research biologist, Center for Biomolecular Science and Engineering.


Recruiting luminescent nanoparticles to image brain function, scientists at the US Naval Research Laboratory (NRL) are on pace to develop the next generation of functional materials that could enable the mapping of the complex neural connections in the brain. The intrinsic properties of quantum dots (QDs) and the growing ability to interface them controllably with living cells has far-reaching potential applications in probing cellular processes such as membrane action potential. The ultimate goal is to better understand how the billions of neurons in the brain communicate with one another during normal brain function or dysfunction as result of injury or disease.

Credit: Reprinted Courtesy the American Chemical Society - 2015

"To do that we need new tools or materials that allow us to see how large groups of neurons communicate with one another while, at the same time, being able to focus in on a single neuron's activity. Our most recent work potentially opens the integration of voltage-sensitive nanomaterials into live cells and tissues in a variety of configurations to achieve real-time imaging capabilities not currently possible."

The basis of neuron communication is the time-dependent modulation of the strength of the electric field that is maintained across the cell's plasma membrane. This is called an action potential. Among the nanomaterials under consideration for application in neuronal action potential imaging are quantum dots (QDs) -- crystalline semiconductor nanomaterials possessing a number of advantageous photophysical attributes.

"QDs are very bright and photostable so you can look at them for long times and they allow for tissue imaging configurations that are not compatible with current materials, for example, organic dyes," Delehanty added.

"Equally important, we've shown here that QD brightness tracks, with very high fidelity, the time-resolved electric field strength changes that occur when a neuron undergoes an action potential. Their nanoscale size make them ideal nanoscale voltage sensing materials for interfacing with neurons and other electrically active cells for voltage sensing."

QDs are small, bright, photo-stable materials that possess nanosecond fluorescence lifetimes. They can be localized within or on cellular plasma membranes and have low cytotoxicity when interfaced with experimental brain systems.

Additionally, QDs possess two-photon action cross-section orders of magnitude larger than organic dyes or fluorescent proteins. Two-photon imaging is the preferred imaging modality for imaging deep (millimeters) into the brain and other tissues of the body.

In their most recent work, the NRL researchers showed that an electric field typical of those found in neuronal membranes results in suppression of the QD photoluminescence (PL) and, for the first time, that QD PL is able to track the action potential profile of a firing neuron with millisecond time resolution.

This effect is shown to be connected with electric-field-driven QD ionization and consequent QD PL quenching, in contradiction with conventional wisdom that suppression of the QD PL is attributable to the quantum confined Stark effect -- the shifting and splitting of spectral lines of atoms and molecules due to presence of an external electric field.

"The inherent superior photostability properties of QDs coupled with their voltage sensitivity could prove advantageous to long-term imaging capabilities that are not currently attainable using traditional organic voltage sensitive dyes," Delehanty said. "We anticipate that continued research will facilitate the rational design and synthesis of voltage-sensitive QD probes that can be integrated in a variety of imaging configurations for the robust functional imaging and sensing of electrically active cells."

###

Additional contributors to this study included the Optical Sciences Division, and the Materials Science and Technology Division at NRL, Washington, D.C. A full report of the team's findings, entitled "Electric Field Modulation of Semiconductor Quantum Dot Photoluminescence: Insights Into the Design of Robust Voltage-Sensitive Cellular Imaging Probes", was published September 28, 2015 in the American Chemical Society publication, NANO Letters. This groundbreaking work was funded by the NRL Nanoscience Institute.

Media Contact

Daniel Parry
daniel.parry@nrl.navy.mil
202-767-2326

 @USNRL

http://www.nrl.navy.mil 

Daniel Parry | EurekAlert!

More articles from Life Sciences:

nachricht Cryo-electron microscopy achieves unprecedented resolution using new computational methods
24.03.2017 | DOE/Lawrence Berkeley National Laboratory

nachricht How cheetahs stay fit and healthy
24.03.2017 | Forschungsverbund Berlin e.V.

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Giant Magnetic Fields in the Universe

Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.

The results will be published on March 22 in the journal „Astronomy & Astrophysics“.

Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...

Im Focus: Tracing down linear ubiquitination

Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.

Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...

Im Focus: Perovskite edges can be tuned for optoelectronic performance

Layered 2D material improves efficiency for solar cells and LEDs

In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...

Im Focus: Polymer-coated silicon nanosheets as alternative to graphene: A perfect team for nanoelectronics

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...

Im Focus: Researchers Imitate Molecular Crowding in Cells

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to simulate these confined natural conditions in artificial vesicles for the first time. As reported in the academic journal Small, the results are offering better insight into the development of nanoreactors and artificial organelles.

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

International Land Use Symposium ILUS 2017: Call for Abstracts and Registration open

20.03.2017 | Event News

CONNECT 2017: International congress on connective tissue

14.03.2017 | Event News

ICTM Conference: Turbine Construction between Big Data and Additive Manufacturing

07.03.2017 | Event News

 
Latest News

Argon is not the 'dope' for metallic hydrogen

24.03.2017 | Materials Sciences

Astronomers find unexpected, dust-obscured star formation in distant galaxy

24.03.2017 | Physics and Astronomy

Gravitational wave kicks monster black hole out of galactic core

24.03.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>