Two recently published papers by a University of Oregon biophysicist and colleagues suggest that putting lipids and other cell membrane components on manufactured surfaces could lead to new classes of self-assembling materials for use in precision optics, nanotechnology, electronics and pharmaceuticals.
Though the findings are basic, they provide new directions for research to help understand nature at nanotechnological scales where the orientation of minuscule proteins is crucial, said Raghuveer Parthasarathy, who is a member of the UO's Material Science Institute, the Institute of Molecular Biology and the Oregon Nanoscience and Microtechnologies Institute (ONAMI).
(Parthasarathy discusses his research at http://www.youtube.com/watch?v=XGOmp_fNVXQ, and he summarizes the studies described below at: http://www.youtube.com/watch?v=rvd7f6qYYro.)
œControlling interactions between colloidal materials
In the May issue of Soft Matter, a journal of the Royal Society of Chemistry, UO doctoral student Yupeng Kong and Parthasarathy applied biological material -- a thin layer of membrane lipids -- onto to tiny glass spheres about one-millionth of a meter in diameter to closely study colloidal interaction.
Colloids are tiny particles found dispersed in liquids: in milk, paints, many food stuffs, cosmetics and pharmaceuticals. Compared to atoms and molecules colloids are big, and creating artificial colloids with directed properties is a goal in many technologies, especially optics at nanoscales.
Before applying the biomembrane, the identical negatively charged spheres repelled each other. With the membrane attached, conditions changed dramatically. Suddenly, the like-charged spheres were attracted to each other.
"This was weird," Parthasarathy said. "Like-charged objects aren't supposed to attract each other. People have seen like-charge attraction in a few other colloidal systems in the last 10 or 15 years, but still no one understands it. Here, we've got the first system in which like-charge attraction can be controlled, simply by the incorporation of molecules from biological membranes. We can tune attraction or repulsion over the entire spectrum simply by changing the composition of the membrane. This is useful both for technological applications, and for illuminating the fundamental mechanisms behind colloidal interactions.h
The observations were made using an inverted microscopy technique in which the glass spheres were placed in a 655-nanometer diode laser beam, an approach developed in Parthasarathy's lab by former undergraduate biophysics student Greg Tietjen, now a doctoral student at the University of Chicago.
The findings of the National Science Foundation-funded research, he said, suggest that specially tweaked biological membranes applied to artificially produced materials may serve as specialty control knobs that direct materials to do very specific things.
œControlling molecular orientation from cell membranes:
In a paper appearing online in the Journal of the American Chemical Society (JACS) in early July, Parthasarathy teamed with organic chemists at the University of California, Berkeley, to study how molecules are oriented on their cell membranes to allow for cell-to-cell interactions.
The six-member research team built tiny artificial molecules that mimic brush-like membrane proteins and contain tiny fluorescent probes at the outer end. These miniscule polymers were incorporated into artificial membranes placed on a silicon wafer that acts like a mirror, allowing precise optical measurements of the orientation of the molecule.
Electron microscopy revealed the presence of rigid, rod-like brushy glycoprotein (sugar-containing compounds) -- 30 billionths of a meter long -- similar to natural cell-surface proteins. Interaction between cells occurs when these rods stand up from the membranes, a property whose control remains poorly understood.
The surprise, Parthasarathy said, was that the sugar-laden rods stood up like trees rising in a forest only for particular fluorescent probes, which represented just 2 percent of the molecule's weight.
The big issue that surfaced from the project -- funded by the U.S. Department of Energy, National Science Foundation and the Alfred P. Sloan Foundation -- was that the slightest trepidation of a molecule's structure affects its orientation, he said.
The goal, Parthasarathy said, may be to determine how to control the orientation of the brush-like forest through either chemical or optical measures to, in turn, control cell interaction. Such control of artificially produced molecules, he added, could have huge potential applications in the electronics industry.
Parthasarathy's UO team is now looking at DNA anchored to membranes to compare the findings and see if such on-off switching of the orientation of molecules may be possible.
"There are brush-like proteins at cell surfaces that are really important for such things as cellular interactions within the immune system," Parthasarathy said. "At the surface of every cell is a forest of molecules to induce interactions. These proteins need to rise from the forest. What allows them to stick up or lie down? We've really had a poor idea of what's going on. Knowing the genome and what proteins are there is crucially important, but that information in itself does not tell you anything about the answer to the question."
Co-authors of the JACS study with Parthasarathy are Kamil Godula, David Rabuka, Zsofia Botyanszki and Carolyn R. Bertozzi, all of UC-Berkeley, and Marissa L. Umbel, then an undergraduate student from Indiana University of Pennsylvania who worked in Parthasarathy's UO lab in summer 2008 as part of the UO's National Science Foundation-funded Research Experiences for Undergraduates. Umbel now is studying medical physics at Ohio State University.About the University of Oregon
Source: Raghu Parthasarathy, associate professor, department of physics, 541-346-2933, email@example.comLinks: Parthasarathy faculty page; http://physics.uoregon.edu/physics/faculty/raghu.html
Jim Barlow | Newswise Science News
Multi-institutional collaboration uncovers how molecular machines assemble
02.12.2016 | Salk Institute
Fertilized egg cells trigger and monitor loss of sperm’s epigenetic memory
02.12.2016 | IMBA - Institut für Molekulare Biotechnologie der Österreichischen Akademie der Wissenschaften GmbH
A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.
Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...
In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.
“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...
The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.
The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...
Broadband rotational spectroscopy unravels structural reshaping of isolated molecules in the gas phase to accommodate water
In two recent publications in the Journal of Chemical Physics and in the Journal of Physical Chemistry Letters, researchers around Melanie Schnell from the Max...
The efficiency of power electronic systems is not solely dependent on electrical efficiency but also on weight, for example, in mobile systems. When the weight of relevant components and devices in airplanes, for instance, is reduced, fuel savings can be achieved and correspondingly greenhouse gas emissions decreased. New materials and components based on gallium nitride (GaN) can help to reduce weight and increase the efficiency. With these new materials, power electronic switches can be operated at higher switching frequency, resulting in higher power density and lower material costs.
Researchers at the Fraunhofer Institute for Solar Energy Systems ISE together with partners have investigated how these materials can be used to make power...
16.11.2016 | Event News
01.11.2016 | Event News
14.10.2016 | Event News
02.12.2016 | Medical Engineering
02.12.2016 | Agricultural and Forestry Science
02.12.2016 | Physics and Astronomy