Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Penn molecular scientists develop color-changing stress sensor

19.08.2011
It is helpful — even life-saving — to have a warning sign before a structural system fails, but, when the system is only a few nanometers in size, having a sign that's easy to read is a challenge.

Now, thanks to a clever bit of molecular design by University of Pennsylvania and Duke University bioengineers and chemists, such warning can come in the form of a simple color change.


This is an enhanced image of a polymersome changing color under stress. Credit: Neha Kamat, University of Pennsylvania

The study was conducted by professor Daniel Hammer and graduate students Neha Kamat and Laurel Moses of the Department of Bioengineering in Penn's School of Engineering and Applied Science. They collaborated with associate professor Ivan Dmochowski and graduate student Zhengzheng Liao of the Department of Chemistry in Penn's School of Arts and Sciences, as well as professor Michael Therien and graduate student Jeff Rawson of Duke.

Their work was published in the journal Proceedings of the National Academy of Sciences.

The researchers' work involves two molecules: porphyrins, a class of naturally occurring pigments, and polymersomes, artificially engineered capsules that can carry a molecular payload in their hollow interiors. In this case, Kamat and Liao hypothesized that polymersomes could be used as stress sensors if their membranes were embedded with a certain type of light-emitting porphyrins.

The Penn researchers collaborated with the Therien lab, where the porphyrins were originally developed, to design polymersomes that were studded with the light-emitting molecules. When light is shined on these labeled polymersomes, the porphyrins absorb the light and then release it at a specific wavelength, or color. The Therien lab's porphyrins play a critical role in using the polymersomes as stress sensors, because their configuration and concentration controls the release of light.

"When you package these porphyrins in a confined environment, such as a polymersome membrane, you can modulate the light emission from the molecules," Hammer said. "If you put a stress on the confined environment, you change the porphyrin's configuration, and, because their optical release is tied to their configuration, you can use the optical release as a direct measure of the stress in the environment."

For example, the labeled polymersomes could be injected into the blood stream and serve as a proxy for neighboring red blood cells. As both the cells and polymersomes travel through an arterial blockage, for example, scientists would be able to better understand what happens to the blood cell membranes by making inferences from the stress label measurements.

The researchers calibrated the polymersomes by subjecting them to several kinds of controlled stresses — tension and heat, among others — and measuring their color changes. The changes are gradations of the near infrared spectrum, so measurements must be made by computers, rather than the naked eye. Rapidly advancing body-scanning technology, which uses light rather than magnetism or radiation, is well suited to this approach.

Other advances in medicine could benefit, as well. As cutting-edge pharmaceutical approaches already use similar molecular technology, the researchers' porphyrin labeling system could be integrated into medicine-carrying polymersomes.

"These kinds of tools could be used to monitor drug delivery, for example," Kamat said. "If we have a way to see how stressed the container is over time, we know how much of the drug has come out."

And, though the researchers chose the engineered polymersomes due to the wide range of stress they can endure, the same stress-labeling technique could soon be applied directly to naturally occurring tissues.

"One future application for this is to use dyes like these porphyrins but include them directly in a cellular membranes," Kamat said. "No one has taken a look at the intrinsic stress inside a membrane so these molecules would be perfect for the job."

The work was supported by the National Institutes of Health, the National Science Foundation and its Materials Research Science and Engineering Center program and the National Center for Research Resources.

Kamat is an NSF Graduate Fellow.

Evan Lerner | EurekAlert!
Further information:
http://www.upenn.edu

More articles from Studies and Analyses:

nachricht Multi-year study finds 'hotspots' of ammonia over world's major agricultural areas
17.03.2017 | University of Maryland

nachricht Diabetes Drug May Improve Bone Fat-induced Defects of Fracture Healing
17.03.2017 | Deutsches Institut für Ernährungsforschung Potsdam-Rehbrücke

All articles from Studies and Analyses >>>

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

Northern oceans pumped CO2 into the atmosphere

27.03.2017 | Earth Sciences

Fingerprint' technique spots frog populations at risk from pollution

27.03.2017 | Life Sciences

Big data approach to predict protein structure

27.03.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>