Chemists Synthesize Artificial Cell Membrane

Neal Devaraj watches as undergraduate student Weilong Li works on a next step in their quest to create an entirely artificial cell. (Credit: Image courtesy of University of California - San Diego)

Chemists have taken an important step in making artificial life forms from scratch. Using a novel chemical reaction, they have created self-assembling cell membranes, the structural envelopes that contain and support the reactions required for life.

Neal Devaraj, assistant professor of chemistry at the University of California, San Diego, and Itay Budin, a graduate student at Harvard University, report their success in theJournal of the American Chemical Society.

"One of our long term, very ambitious goals is to try to make an artificial cell, a synthetic living unit from the bottom up -- to make a living organism from non-living molecules that have never been through or touched a living organism," Devaraj said. "Presumably this occurred at some point in the past. Otherwise life wouldn't exist."

By assembling an essential component of earthly life with no biological precursors, they hope to illuminate life's origins.

"We don't understand this really fundamental step in our existence, which is how non-living matter went to living matter," Devaraj said. "So this is a really ripe area to try to understand what knowledge we lack about how that transition might have occurred. That could teach us a lot -- even the basic chemical, biological principles that are necessary for life."

Molecules that make up cell membranes have heads that mix easily with water and tails that repel it. In water, they form a double layer with heads out and tails in, a barrier that sequesters the contents of the cell.

Devaraj and Budin created similar molecules with a novel reaction that joins two chains of lipids. Nature uses complex enzymes that are themselves embedded in membranes to accomplish this, making it hard to understand how the very first membranes came to be.

"In our system, we use a sort of primitive catalyst, a very simple metal ion," Devaraj said. "The reaction itself is completely artificial. There's no biological equivalent of this chemical reaction. This is how you could have a de novoformation of membranes."

They created the synthetic membranes from a watery emulsion of an oil and a detergent. Alone it's stable. Add copper ions and sturdy vesicles and tubules begin to bud off the oil droplets. After 24 hours, the oil droplets are gone, "consumed" by the self-assembling membranes.

Although other scientists recently announced the creation of a "synthetic cell," only its genome was artificial. The rest was a hijacked bacterial cell. Fully artificial life will require the union of both an information-carrying genome and a three-dimensional structure to house it.

The real value of this discovery might reside in its simplicity. From commercially available precursors, the scientists needed just one preparatory step to create each starting lipid chain.

"It's trivial and can be done in a day," Devaraj said. "New people who join the lab can make membranes from day one."

The National Institute of Biomedical Imaging and Bioengineering supported this work. UC San Diego has filed a patent application on this discovery.

Story Source:

The above story is reprinted from materials provided byUniversity of California - San Diego. The original article was written by Susan Brown.

Note: Materials may be edited for content and length. For further information, please contact the source cited above.

---

Journal Reference:

1. Itay Budin, Neal K. Devaraj. Membrane Assembly Driven by a Biomimetic Coupling Reaction. Journal of the American Chemical Society, 2012; 134 (2): 751 DOI:10.1021/ja2076873

With an Artificial Memory Chip, Rats Can Remember and Forget At the Touch of a Button

Dr. Theodore Berger PR NEWSWIRE

A new brain implant tested on rats restored lost memories at the flick of a switch, heralding a possible treatment method for patients with Alzheimer’s disease, stroke or amnesia. Such a “neural prosthesis” could someday be used to facilitate the memory-forming process and help patients remember.

The device can mimic the brain’s own neural signals, thereby serving as a surrogate for a piece of the brain associated with forming memories. If there is sufficient neural activity to trace, the device can restore memories after they have been lost. If it’s used with a normal, functioning hippocampus, the device can even enhance memory.

In the study, scientists at Wake Forest University and the University of Southern California trained rats to learn a task, pressing one lever after another to receive water. In a series of tests, the rats pressed one lever and were then distracted. They had to remember which one they’d already pressed and therefore which lever to press next, left or right, in order to receive their reward.

The team attached electrodes to the rats’ brains, connected to two areas in the hippocampus, called CA1 and CA3. Prior research has shown that the hippocampus converts short-term memory into long-term memory. The team recorded the signals between these regions as the rats performed their tasks, and then they drugged the rats so that the hippocampus regions could not communicate. The rats forgot which lever to press next, said Theodore Berger, a biomedical engineering professor at USC and lead author of the study, which is published in the Journal of Neural Engineering.

“The rats still showed that they knew ‘when you press left first, then press right next time, and vice-versa,’” Berger said. “And they still knew in general to press levers for water, but they could only remember whether they had pressed left or right for 5-10 seconds.”

Then, the team made an artificial hippocampus, which could duplicate the normal neural signals between the CA1 and CA3 regions. They turned it on, and replayed the previously recorded signal from CA1 — like a recorded message from the brain. The rats remembered.

“Flip the switch on, and the rats remember. Flip it off, and the rats forget,” Berger said.

Although this is a long way from being tested in humans, the research shows that if there’s enough information about the neural coding of memories, the signal patterns can be recorded and duplicated, and restored later through a neural implant. This could be difficult to do in patients with severely limited memory, as the New York Times points out — there needs to be a memory trace that can be recorded and amplified. But for patients with dementia, enhancing the memory-formation process can be useful — remembering where you put the keys, for instance, or where the bathroom is located. Simple memories like those could keep people independent for longer periods.

The researchers want to test the device in monkeys next, according to USC.

View the original article here

Novel artificial material could facilitate wireless power

ScienceDaily (May 24, 2011) — Electrical engineers at Duke University have determined that unique artificial materials should theoretically make it possible to improve the power transfer to small devices, such as laptops or cell phones, or ultimately to larger ones, such as cars or elevators, without wires.

This advance is made possible by the recent ability to fabricate exotic composite materials known as metamaterials, which are not so much a single substance, but an entire human-made structure that can be engineered to exhibit properties not readily found in nature. In fact, the metamaterial used in earlier Duke studies, and which would likely be used in future wireless power transmission systems, resembles a miniature set of tan Venetian blinds.

Theoretically, this metamaterial can improve the efficiency of "recharging" devices without wires. As power passes from the transmitting device to the receiving device, most if not all of it scatters and dissipates unless the two devices are extremely close together. However, the metamaterial postulated by the Duke researchers, which would be situated between the energy source and the "recipient" device, greatly refocuses the energy transmitted and permits the energy to traverse the open space between with minimal loss of power.

"We currently have the ability to transmit small amounts of power over short distances, such as in radio frequency identification (RFID) devices," said Yaroslav Urzhumov, assistant research professor in electrical and computer engineering at Duke's Pratt School of Engineering. "However, larger amounts of energy, such as that seen in lasers or microwaves, would burn up anything in its path.

"Based on our calculations, it should be possible to use these novel metamaterials to increase the amount of power transmitted without the negative effects," Urzhumov said.

The results of the Duke research were published online in the journal Physical Review B. Urzhumov works in the laboratory of David R. Smith, William Bevan Professor of electrical and computer engineering at Pratt School of Engineering. Smith's team was the first demonstrate that similar metamaterials could act as a cloaking device in 2006.

Just as the metamaterial in the cloaking device appeared to make a volume of space "disappear," in the latest work, the metamaterial would make it seem as if there was no space between the transmitter and the recipient, Urzhumov said. Therefore, he said, the loss of power should be minimal.

Urzhumov's research is an offshoot of "superlens" research conducted in Smith's laboratory. Traditional lenses get their focusing power by controlling rays as they pass through the two outside surfaces of the lens. On the other hand, the superlens, which is in fact a metamaterial, directs waves within the bulk of the lens between the outside surfaces, giving researchers a much greater control over whatever passes through it.

The metamaterial used in wireless power transmission would likely be made of hundreds to thousands -- depending on the application -- of individual thin conducting loops arranged into an array. Each piece is made from the same copper-on-fiberglass substrate used in printed circuit boards, with excess copper etched away. These pieces can then be arranged in an almost infinite variety of configurations.

"The system would need to be tailored to the specific recipient device, in essence the source and target would need to be 'tuned' to each other," Urzhumov said. "This new understanding of how matematerials can be fabricated and arranged should help make the design of wireless power transmission systems more focused."

The analysis performed at Duke was inspired by recent studies at Mitsubishi Electric Research Labs (MERL), an industrial partner of the Duke Center for Metamaterials and Integrated Plasmonics. MERL is currently investigating metamaterials for wireless power transfer. The Duke researchers said that with these new insights into the effects of metamaterials, developing actual devices can be more targeted and efficient.

The Duke University research was supported by a Multidisciplinary University Research Initiative (MURI) grant through the Air Force Office of Scientific Research and the U.S. Army Research Office.

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by Duke University, via EurekAlert!, a service of AAAS.

Journal Reference:

Yaroslav Urzhumov, David Smith. Metamaterial-enhanced coupling between magnetic dipoles for efficient wireless power transfer. Physical Review B, 2011; 83 (20) DOI: 10.1103/PhysRevB.83.205114

Note: If no author is given, the source is cited instead.

Disclaimer: Views expressed in this article do not necessarily reflect those of ScienceDaily or its staff.

View the original article here

Novel artificial material could facilitate wireless power

ScienceDaily (May 24, 2011) — Electrical engineers at Duke University have determined that unique artificial materials should theoretically make it possible to improve the power transfer to small devices, such as laptops or cell phones, or ultimately to larger ones, such as cars or elevators, without wires.

This advance is made possible by the recent ability to fabricate exotic composite materials known as metamaterials, which are not so much a single substance, but an entire human-made structure that can be engineered to exhibit properties not readily found in nature. In fact, the metamaterial used in earlier Duke studies, and which would likely be used in future wireless power transmission systems, resembles a miniature set of tan Venetian blinds.

Theoretically, this metamaterial can improve the efficiency of "recharging" devices without wires. As power passes from the transmitting device to the receiving device, most if not all of it scatters and dissipates unless the two devices are extremely close together. However, the metamaterial postulated by the Duke researchers, which would be situated between the energy source and the "recipient" device, greatly refocuses the energy transmitted and permits the energy to traverse the open space between with minimal loss of power.

"We currently have the ability to transmit small amounts of power over short distances, such as in radio frequency identification (RFID) devices," said Yaroslav Urzhumov, assistant research professor in electrical and computer engineering at Duke's Pratt School of Engineering. "However, larger amounts of energy, such as that seen in lasers or microwaves, would burn up anything in its path.

"Based on our calculations, it should be possible to use these novel metamaterials to increase the amount of power transmitted without the negative effects," Urzhumov said.

The results of the Duke research were published online in the journal Physical Review B. Urzhumov works in the laboratory of David R. Smith, William Bevan Professor of electrical and computer engineering at Pratt School of Engineering. Smith's team was the first demonstrate that similar metamaterials could act as a cloaking device in 2006.

Just as the metamaterial in the cloaking device appeared to make a volume of space "disappear," in the latest work, the metamaterial would make it seem as if there was no space between the transmitter and the recipient, Urzhumov said. Therefore, he said, the loss of power should be minimal.

Urzhumov's research is an offshoot of "superlens" research conducted in Smith's laboratory. Traditional lenses get their focusing power by controlling rays as they pass through the two outside surfaces of the lens. On the other hand, the superlens, which is in fact a metamaterial, directs waves within the bulk of the lens between the outside surfaces, giving researchers a much greater control over whatever passes through it.

The metamaterial used in wireless power transmission would likely be made of hundreds to thousands -- depending on the application -- of individual thin conducting loops arranged into an array. Each piece is made from the same copper-on-fiberglass substrate used in printed circuit boards, with excess copper etched away. These pieces can then be arranged in an almost infinite variety of configurations.

"The system would need to be tailored to the specific recipient device, in essence the source and target would need to be 'tuned' to each other," Urzhumov said. "This new understanding of how matematerials can be fabricated and arranged should help make the design of wireless power transmission systems more focused."

The analysis performed at Duke was inspired by recent studies at Mitsubishi Electric Research Labs (MERL), an industrial partner of the Duke Center for Metamaterials and Integrated Plasmonics. MERL is currently investigating metamaterials for wireless power transfer. The Duke researchers said that with these new insights into the effects of metamaterials, developing actual devices can be more targeted and efficient.

The Duke University research was supported by a Multidisciplinary University Research Initiative (MURI) grant through the Air Force Office of Scientific Research and the U.S. Army Research Office.

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by Duke University, via EurekAlert!, a service of AAAS.

Journal Reference:

Yaroslav Urzhumov, David Smith. Metamaterial-enhanced coupling between magnetic dipoles for efficient wireless power transfer. Physical Review B, 2011; 83 (20) DOI: 10.1103/PhysRevB.83.205114

Note: If no author is given, the source is cited instead.

Disclaimer: Views expressed in this article do not necessarily reflect those of ScienceDaily or its staff.

View the original article here

Harnessing the energy of the Sun: New technique improves artificial photosynthesis

ScienceDaily (May 11, 2011) — Transforming solar energy into a usable form is a real challenge. One technique is to use semiconductors to store the energy as hydrogen. Unfortunately, the most efficient semiconductors are not the most stable. An EPFL team has just discovered that it is possible to protect the semiconductor with a uniform layer just a few nanometers thick.

This discovery will make it possible to improve photoelectrochemical cells. In the same way that plants use photosynthesis to transform sunlight into energy, these cells use sunlight to drive chemical reactions that ultimately produce hydrogen from water. The process involves using a light-sensitive semi-conducting material such as cuprous oxide to provide the current needed to fuel the reaction. Although it is not expensive, the oxide is unstable if exposed to light in water. Research by

Adriana Paracchino and Elijah Thimsen, published May 8, 2011 in the journal Nature Materials, demonstrates that this problem can be overcome by covering the semiconductor with a thin film of atoms using the atomic layer deposition (ALD) technique.

Under the supervision of Professor Michael Grätzel in EPFL's Laboratory of Photonics and Interfaces, the two scientists achieved this remarkable feat by combining techniques used at the industrial scale, and then applying them to the problem of producing hydrogen. With their process, cuprous oxide can be simply and effectively protected from contact with water, making it possible to use it as a semiconductor. The advantages are numerous: cuprous oxide is abundantly available and inexpensive; the protective layer is completely impermeable, regardless of the roughness of the surface; and the process can easily be scaled up for industrial fabrication.

A promising technique

The research team developed the technique by "growing" layers of zinc oxide and titanium oxide, one atom-thick layer at a time, on the cuprous oxide surface. By using the ALD technique, they were able to control the thickness of the protective layer down to the precision of a single atom over the entire surface. This level of precision guarantees the stability of the semiconductor while preserving all of its hydrogen-producing efficiency. The next step in the research will be to improve the electrical properties of the protective layer.

Using widely available materials and techniques that can be easily scaled up will help the "green" photoelectrochemical production of hydrogen meet the needs of industry.

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by Ecole Polytechnique Fédérale de Lausanne, via EurekAlert!, a service of AAAS.

Journal Reference:

Adriana Paracchino, Vincent Laporte, Kevin Sivula, Michael Grätzel, Elijah Thimsen. Highly active oxide photocathode for photoelectrochemical water reduction. Nature Materials, 2011; DOI: 10.1038/NMAT3017

Note: If no author is given, the source is cited instead.

Disclaimer: Views expressed in this article do not necessarily reflect those of ScienceDaily or its staff.

View the original article here

Harnessing the energy of the Sun: New technique improves artificial photosynthesis

ScienceDaily (May 11, 2011) — Transforming solar energy into a usable form is a real challenge. One technique is to use semiconductors to store the energy as hydrogen. Unfortunately, the most efficient semiconductors are not the most stable. An EPFL team has just discovered that it is possible to protect the semiconductor with a uniform layer just a few nanometers thick.

This discovery will make it possible to improve photoelectrochemical cells. In the same way that plants use photosynthesis to transform sunlight into energy, these cells use sunlight to drive chemical reactions that ultimately produce hydrogen from water. The process involves using a light-sensitive semi-conducting material such as cuprous oxide to provide the current needed to fuel the reaction. Although it is not expensive, the oxide is unstable if exposed to light in water. Research by

Adriana Paracchino and Elijah Thimsen, published May 8, 2011 in the journal Nature Materials, demonstrates that this problem can be overcome by covering the semiconductor with a thin film of atoms using the atomic layer deposition (ALD) technique.

Under the supervision of Professor Michael Grätzel in EPFL's Laboratory of Photonics and Interfaces, the two scientists achieved this remarkable feat by combining techniques used at the industrial scale, and then applying them to the problem of producing hydrogen. With their process, cuprous oxide can be simply and effectively protected from contact with water, making it possible to use it as a semiconductor. The advantages are numerous: cuprous oxide is abundantly available and inexpensive; the protective layer is completely impermeable, regardless of the roughness of the surface; and the process can easily be scaled up for industrial fabrication.

A promising technique

The research team developed the technique by "growing" layers of zinc oxide and titanium oxide, one atom-thick layer at a time, on the cuprous oxide surface. By using the ALD technique, they were able to control the thickness of the protective layer down to the precision of a single atom over the entire surface. This level of precision guarantees the stability of the semiconductor while preserving all of its hydrogen-producing efficiency. The next step in the research will be to improve the electrical properties of the protective layer.

Using widely available materials and techniques that can be easily scaled up will help the "green" photoelectrochemical production of hydrogen meet the needs of industry.

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by Ecole Polytechnique Fédérale de Lausanne, via EurekAlert!, a service of AAAS.

Journal Reference:

Adriana Paracchino, Vincent Laporte, Kevin Sivula, Michael Grätzel, Elijah Thimsen. Highly active oxide photocathode for photoelectrochemical water reduction. Nature Materials, 2011; DOI: 10.1038/NMAT3017

Note: If no author is given, the source is cited instead.

Disclaimer: Views expressed in this article do not necessarily reflect those of ScienceDaily or its staff.

View the original article here