Posts Tagged ‘Anne Trafton’

DNA tattoo patches

Friday, February 1st, 2013

Scientists seem fascinated with tattoos these days (my Dec. 4, 2012 posting, my Nov. 9, 2012 posting, March 20, 2012 posting amongst others). The latest work comes from the Massachusetts Institute of Technology (MIT) according to this Jan. 29, 2013 news item,

In a paper appearing in the Jan. 27 [2013] online issue of Nature Materials (“Polymer multilayer tattooing for enhanced DNA vaccination”), MIT researchers describe a new type of vaccine-delivery film that holds promise for improving the effectiveness of DNA vaccines. If such vaccines could be successfully delivered to humans, they could overcome not only the safety risks of using viruses to vaccinate against diseases such as HIV, but they would also be more stable, making it possible to ship and store them at room temperature.

The Jan. 29, 2013 MIT news release by Anne Trafton, which originated the news item, explains the interest in DNA vaccines and this proposed delivery system,

Vaccines usually consist of inactivated viruses that prompt the immune system to remember the invader and launch a strong defense if it later encounters the real thing. However, this approach can be too risky with certain viruses, including HIV.

In recent years, many scientists have been exploring DNA as a potential alternative vaccine. About 20 years ago, DNA coding for viral proteins was found to induce strong immune responses in rodents, but so far, tests in humans have failed to duplicate that success.

…

This type of vaccine delivery would also eliminate the need to inject vaccines by syringe, says Darrell Irvine, an MIT professor of biological engineering and materials science and engineering. “You just apply the patch for a few minutes, take it off and it leaves behind these thin polymer films embedded in the skin,” he says.

…

Scientists have had some recent success delivering DNA vaccines to human patients using a technique called electroporation. This method requires first injecting the DNA under the skin, then using electrodes to create an electric field that opens small pores in the membranes of cells in the skin, allowing DNA to get inside. However, the process can be painful and give varying results, Irvine says.

“It’s showing some promise but it’s certainly not ideal and it’s not something you could imagine in a global prophylactic vaccine setting, especially in resource-poor countries,” he says.

Irvine and Hammond took a different approach to delivering DNA to the skin, creating a patch made of many layers of polymers embedded with the DNA vaccine. These polymer films are implanted under the skin using microneedles that penetrate about half a millimeter into the skin — deep enough to deliver the DNA to immune cells in the epidermis, but not deep enough to cause pain in the nerve endings of the dermis.

Once under the skin, the films degrade as they come in contact with water, releasing the vaccine over days or weeks. As the film breaks apart, the DNA strands become tangled up with pieces of the polymer, which protect the DNA and help it get inside cells.

The researchers can control how much DNA gets delivered by tuning the number of polymer layers. They can also control the rate of delivery by altering how hydrophobic (water-fearing) the film is. DNA injected on its own is usually broken down very quickly, before the immune system can generate a memory response. When the DNA is released over time, the immune system has more time to interact with it, boosting the vaccine’s effectiveness.

The polymer film also includes an adjuvant — a molecule that helps to boost the immune response. In this case, the adjuvant consists of strands of RNA that resemble viral RNA, which provokes inflammation and recruits immune cells to the area.

The ability to provoke inflammation is one of the key advantages of the new delivery system, says Michele Kutzler, an assistant professor at Drexel University College of Medicine. Other benefits include targeting the wealth of immune cells in the skin, the use of a biodegradable delivery material, and the possibility of pain-free vaccine delivery, she says.

Here’s a citation and link to the paper,

Polymer multilayer tattooing for enhanced DNA vaccination by Peter C. DeMuth, Younjin Min, Bonnie Huang, Joshua A. Kramer, Andrew D. Miller, Dan H. Barouch, Paula T. Hammond, & Darrell J. Irvine. Nature Materials (2013) doi:10.1038/nmat3550 Published online 27 January 2013

The article is behind a paywall. And, for those who find images help to better understand,

Graphic: Christine Daniloff/MIT [downloaded from http://web.mit.edu/newsoffice/2013/vaccine-film-delivery-hiv-0127.html]

Graphic: Christine Daniloff/MIT [downloaded from http://web.mit.edu/newsoffice/2013/vaccine-film-delivery-hiv-0127.html]

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NBD Nano startup company and the Namib desert beetle

Monday, November 26th, 2012

In 2001, Andrew Parker and Chris Lawrence published an article in Nature magazine about work which has inspired a US startup company in 2012 to develop a water bottle that fills itself up with water by drawing moisture from the air. Parker’s and Lawrence’s article was titled Water capture by a desert beetle. Here’s the abstract (over 10 years later the article is still behind a paywall),

Some beetles in the Namib Desert collect drinking water from fog-laden wind on their backs1. We show here that these large droplets form by virtue of the insect’s bumpy surface, which consists of alternating hydrophobic, wax-coated and hydrophilic, non-waxy regions. The design of this fog-collecting structure can be reproduced cheaply on a commercial scale and may find application in water-trapping tent and building coverings, for example, or in water condensers and engines.

Some five years later, there was a June 15, 2006 news item on phys.org about the development of a new material based on the Namib desert beetle,

When that fog rolls in, the Namib Desert beetle is ready with a moisture-collection system exquisitely adapted to its desert habitat. Inspired by this dime-sized beetle, MIT [Massachusetts Institute of Technology] researchers have produced a new material that can capture and control tiny amounts of water.

The material combines a superhydrophobic (water-repelling) surface with superhydrophilic (water-attracting) bumps that trap water droplets and control water flow. The work was published in the online version of Nano Letters on Tuesday, May 2 [2006] {behind a paywall}.

Potential applications for the new material include harvesting water, making a lab on a chip (for diagnostics and DNA screening) and creating microfluidic devices and cooling devices, according to lead researchers Robert Cohen, the St. Laurent Professor of Chemical Engineering, and Michael Rubner, the TDK Professor of Polymer Materials Science and Engineering.

The MIT June 14, 2006 news release by Anne Trafton, which originated the news item about the new material, indicates there was some military interest,

The U.S. military has also expressed interest in using the material as a self-decontaminating surface that could channel and collect harmful substances.

The researchers got their inspiration after reading a 2001 article in Nature describing the Namib Desert beetle’s moisture-collection strategy. Scientists had already learned to copy the water-repellent lotus leaf, and the desert beetle shell seemed like another good candidate for “bio-mimicry.”

…

When fog blows horizontally across the surface of the beetle’s back, tiny water droplets, 15 to 20 microns, or millionths of a meter, in diameter, start to accumulate on top of bumps on its back.

The bumps, which attract water, are surrounded by waxy water-repelling channels. “That allows small amounts of moisture in the air to start to collect on the tops of the hydrophilic bumps, and it grows into bigger and bigger droplets,” Rubner said. “When it gets large, it overcomes the pinning force that holds it and rolls down into the beetle’s mouth for a fresh drink of water.”

To create a material with the same abilities, the researchers manipulated two characteristics — roughness and nanoporosity (spongelike capability on a nanometer, or billionths of a meter, scale).

By repeatedly dipping glass or plastic substrates into solutions of charged polymer chains dissolved in water, the researchers can control the surface texture of the material. Each time the substrate is dipped into solution, another layer of charged polymer coats the surface, adding texture and making the material more porous. Silica nanoparticles are then added to create an even rougher texture that helps trap water droplets.

The material is then coated with a Teflon-like substance, making it superhydrophobic. Once that water-repellent layer is laid down, layers of charged polymers and nanoparticles can be added in certain areas, using a properly formulated water/alcohol solvent mixture, thereby creating a superhydrophilic pattern. The researchers can manipulate the technique to create any kind of pattern they want.

…

The research is funded by the Defense Advanced Research Projects Agency and the National Science Foundation.

I’m not sure what happened with the military interest or the group working out of MIT in 2006 but on Nov. 23, 2012, BBC News online featured an article about a US startup company, NBD Nano, which aims to bring a self-filling water bottle based on Namib desert beetle to market,

NBD Nano, which consists of four recent university graduates and was formed in May, looked at the Namib Desert beetle that lives in a region that gets about half an inch of rainfall per year.

Using a similar approach, the firm wants to cover the surface of a bottle with hydrophilic (water-attracting) and hydrophobic (water-repellent) materials.

The work is still in its early stages, but it is the latest example of researchers looking at nature to find inspiration for sustainable technology.

“It was important to apply [biomimicry] to our design and we have developed a proof of concept and [are] currently creating our first fully-functional prototype,” Miguel Galvez, a co-founder, told the BBC.

“We think our initial prototype will collect anywhere from half a litre of water to three litres per hour, depending on local environments.”

According to the Nov. 25, 2012 article by Nancy Owano for phys.org, the company is at the prototype stage now,

NBD Nano plans to enter the worldwide marketplace between 2014 and 2015.

You can find out more about NBD Nano here.

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Come, see my etchings … they detect poison gases

Tuesday, October 9th, 2012

Inviting someone over to come see your etchings is an old seduction line made laughable through endless repetition. Maybe this latest innovation, will bring the line back into vogue. Researchers at the Massachusetts Institute of Technology (MIT) have devised a gas sensor that you can create/etch with a simple mechanical pencil and paper imprinted with gold electrodes.

The Oct. 9, 2012 news item on Nanowerk provides details,

Carbon nanotubes offer a powerful new way to detect harmful gases in the environment. However, the methods typically used to build carbon nanotube sensors are hazardous and not suited for large-scale production.

A new fabrication method created by MIT chemists — as simple as drawing a line on a sheet of paper — may overcome that obstacle. MIT postdoc Katherine Mirica has designed a new type of pencil lead in which graphite is replaced with a compressed powder of carbon nanotubes. The lead, which can be used with a regular mechanical pencil, can inscribe sensors on any paper surface.

The sensor, described in the journal Angewandte Chemie (“Mechanical Drawing of Gas Sensors on Paper”), detects minute amounts of ammonia gas, an industrial hazard. Timothy Swager, the John D. MacArthur Professor of Chemistry and leader of the research team, says the sensors could be adapted to detect nearly any type of gas.

The Oct. 9, 2012 MIT news release by Anne Trafton, which originated the news item, describes how the scientists developed this new fabrication system,

Swager and Mirica set out to create a solvent-free fabrication method based on paper. Inspired by pencils on her desk, Mirica had the idea to compress carbon nanotubes into a graphite-like material that could substitute for pencil lead.

To create sensors using their pencil, the researchers draw a line of carbon nanotubes on a sheet of paper imprinted with small electrodes made of gold. They then apply an electrical current and measure the current as it flows through the carbon nanotube strip, which acts as a resistor. If the current is altered, it means gas has bound to the carbon nanotubes.

The researchers tested their device on several different types of paper, and found that the best response came with sensors drawn on smoother papers. They also found that the sensors give consistent results even when the marks aren’t uniform.

Two major advantages of the technique are that it is inexpensive and the “pencil lead” is extremely stable, Swager says. “You can’t imagine a more stable formulation. The molecules are immobilized,” he says.

The new sensor could prove useful for a variety of applications, says Zhenan Bao, an associate professor of chemical engineering at Stanford University. “I can already think of many ways this technique can be extended to build carbon nanotube devices,” says Bao, who was not part of the research team. “Compared to other typical techniques, such as spin coating, dip coating or inkjet printing, I am impressed with the good reproducibility of sensing response they were able to get.”

It’s interesting but where carbon nanotubes are concerned I would like to know if they’ve considered safety issues. Given their similarity to asbestos fibres, it would seem researchers might want to indicate it’s safe to use carbon nanotubes in this new fabrication process.

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Soldiers sniff overripe fruit

Tuesday, May 1st, 2012

Technically speaking the soldiers are not sniffing the fruit, it’s the sensing technology developed at the Massachusetts Institute of Technology’s Institute for Soldier Nanotechnologies which is doing the ‘sniffing’. From the April 30, 2012 news item on Nanowerk (I have removed some links),

Every year, U.S. supermarkets lose roughly 10 percent of their fruits and vegetables to spoilage, according to the Department of Agriculture. To help combat those losses, MIT chemistry professor Timothy Swager and his students have built a new sensor that could help grocers and food distributors better monitor their produce.

The new sensors, described in the journal Angewandte Chemie (“Selective Detection of Ethylene Gas Using Carbon Nanotube-based Devices: Utility in Determination of Fruit Ripeness”), can detect tiny amounts of ethylene, a gas that promotes ripening in plants. Swager envisions the inexpensive sensors attached to cardboard boxes of produce and scanned with a handheld device that would reveal the contents’ ripeness.

…

Detecting gases to monitor the food supply is a new area of interest for Swager, whose previous research has focused on sensors to detect explosives or chemical and biological warfare agents.

Here’s how the technology works (from the April 30, 2012 news release by Anne Trafton for MIT News),

Funded by the U.S. Army Office of Research through MIT’s Institute for Soldier Nanotechnologies, the MIT team built a sensor consisting of an array of tens of thousands of carbon nanotubes: sheets of carbon atoms rolled into cylinders that act as “superhighways” for electron flow.

To modify the tubes to detect ethylene gas, the researchers added copper atoms, which serve as “speed bumps” to slow the flowing electrons. “Anytime you put something on these nanotubes, you’re making speed bumps, because you’re taking this perfect, pristine system and you’re putting something on it,” Swager says.

Copper atoms slow the electrons a little bit, but when ethylene is present, it binds to the copper atoms and slows the electrons even more. By measuring how much the electrons slow down — a property also known as resistance — the researchers can determine how much ethylene is present.

To make the device even more sensitive, the researchers added tiny beads of polystyrene, which absorbs ethylene and concentrates it near the carbon nanotubes. With their latest version, the researchers can detect concentrations of ethylene as low as 0.5 parts per million. The concentration required for fruit ripening is usually between 0.1 and one part per million.

The researchers tested their sensors on several types of fruit — banana, avocado, apple, pear and orange — and were able to accurately measure their ripeness by detecting how much ethylene the fruits secreted.

It looks like the technology will be commercialized in the not too distant future (from the Trafton news release) here’s why,

John Saffell, the technical director at Alphasense, a company that develops sensors, describes the MIT team’s approach as rigorous and focused. “This sensor, if designed and implemented correctly, could significantly reduce the level of fruit spoilage during shipping,” he says.

“At any given time, there are thousands of cargo containers on the seas, transporting fruit and hoping that they arrive at their destination with the correct degree of ripeness,” adds Saffell, who was not involved in this research. “Expensive analytical systems can monitor ethylene generation, but in the cost-sensitive shipping business, they are not economically viable for most of shipped fruit.”

Swager has filed for a patent on the technology and hopes to start a company to commercialize the sensors. In future work, he plans to add a radio-frequency identification (RFID) chip to the sensor so it can communicate wirelessly with a handheld device that would display ethylene levels. The system would be extremely cheap — about 25 cents for the carbon nanotube sensor plus another 75 cents for the RFID chip, Swager estimates.

“This could be done with absolutely dirt-cheap electronics, with almost no power,” he says.

I should mention that a couple of students were part of the MIT research team with Birgit Esser being the lead author and Jan Schnorr also contributing to the paper in Angewandte Chemie.

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Never bleed again? New nanoscale bio coating stops bleeding in seconds

Thursday, January 12th, 2012

It’s not quite instantaneous but the new nanoscale biological coating devised by MIT (Massachusetts Institute of Technology) engineers at their Institute of Soldier Nanotechnologies cuts bleeding time to less than 1/2 of what it was (from 150 seconds to 60 seconds) in animal tests. The Jan. 10, 2012 news item on Nanowerk provides more detail,

MIT engineers have developed a nanoscale biological coating that can halt bleeding nearly instantaneously, an advance that could dramatically improve survival rates for soldiers injured in battle.

The researchers, led by Paula Hammond and funded by MIT’s Institute of Soldier Nanotechnologies and a Denmark-based company, Ferrosan Medical Devices A/S, created a spray coating that includes thrombin, a clotting agent found in blood. Sponges coated with this material can be stored stably and easily carried by soldiers or medical personnel.

The Jan. 10, 2012 news release by Anne Trafton for MIT notes,

Uncontrolled bleeding is the leading cause of trauma death on the battlefield. Traditional methods to halt bleeding, such as tourniquets, are not suitable for the neck and many other parts of the body. In recent years, researchers have tried alternative approaches, all of which have some disadvantages. Fibrin dressings and glues have a short shelf life and can cause an adverse immune response, and zeolite powders are difficult to apply under windy conditions and can cause severe burns. Another option is bandages made of chitosan, a derivative of the primary structural material of shellfish exoskeletons. Those bandages have had some success but can be difficult to mold to fit complex wounds.

Many civilian hospitals use a highly absorbent gelatin sponge produced by Ferrosan to stop bleeding. However, those sponges need to be soaked in liquid thrombin just before application to the wound, making them impractical for battlefield use. Hammond’s team came up with the idea to coat the sponges with a blood-clotting agent in advance, so they would be ready when needed, for either military or civilian use.

To do that, the researchers developed a nanoscale biological coating that consists of two alternating layers sprayed onto a material, such as the sponges used in this study. The researchers discovered that layers of thrombin, a natural clotting protein, and tannic acid, a small molecule found naturally in tea, yield a film containing large amounts of functional thrombin. Both materials are already approved by the U.S. Food and Drug Administration, which could help with the approval process for a commercialized version of the sponges, Shukla [Anita Shukla PhD ’11] says.

A key advantage of the spray method is that it allows a large amount of thrombin to be packed into the sponges, coating even the interior fibers, says David King, a trauma surgeon and instructor in surgery at Massachusetts General Hospital who was not involved in this research.

“All of the existing hemostatic materials suffer from the same limitation, which is being able to deliver a dense enough package of hemostatic material to the bleeding site. That’s why this new material is exciting,” says King, also an Army reservist who has served in Afghanistan as chief of trauma surgery.

Very exciting stuff but no word as to when it might reach the marketplace. A patent application has been filed but it doesn’t seem that any human clinical trials have been held yet. As best I can determine, all of the testing done (at Ferrosan) so far has been on animals.

I did check out the Ferrosan website and found this on their About page,

Ferrosan is an international consumer health company with strong market positions and a solid financial performance.

We strive for optimal development by selectively aiming for position as a leader through organic as well as M&A-driven growth.

In order to accomplish our objectives each employee must deliver upon Ferrosan’s values:

  • Get things done
  • Exceed expectations
  • Appreciate individual differences
  • Enjoy and have fun

The foundation of our future success is based on each employee’s ability to make a difference.

Ferrosan is a well established pharmaceutical company with a great heritage. In 2010, we celebrated the company’s 90th anniversary.

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A nanocrystalline solar cell; nano haiku; and more courtesy of the NISE Net

Wednesday, June 15th, 2011

June’s Nanoscale Informal Science Education (NISE) Network newsletter features a 2009 video, Nanotechnology brings us Delicious Nanocrystalline solar cells,  which was entered for the American Chemical Society’s 2009 Nanotation Nanotube contest.Who knew you could use donuts and tea to make a solar cell?

ETA June 20, 2011: Dexter Johnson in a June 17, 2011 posting on his Nanoclast blog points out that the science in this video is not of the best calibre.

On another note entirely, an April 22, 2010 posting from Clark Miller on the NISE Net blog focuses on bio-non-bio interfaces. Excerpted from Miller’s posting,

What would it mean if biological and non-biological systems were not just fully connectable but fully interchangeable? That’s one of the questions that nanotechnology poses for us. More than any other field of scientific inquiry, nanotechnology operates at the basic scales of biology. DNA, for example, has a rough width of 2.5 nm. Viruses are roughly 20 to 250 nm. A bacteria is roughly 1000 nm. So, nanotechnology spans from the scale of individual biological molecules through the scale of simple biological systems to the scale of living cells.

Miller certainly poses an interesting question especially in light of work which could conceivably lead (or perhaps already has led) to interchangeable biological and nonbiological systems,

For example, researchers at the University of Wisconsin-Madison have developed a new sensor for viruses that works through a combination of nanotechnology elements. The base of the sensor is a flat basin filled with liquid crystals (these are crystal molecules that behave like a liquid and form the core materials used in computer and flat-screen TVs). Within the basin are a series of parallel ridges approximately 5 nm on each side. These ridges help orient the liquid crystals so that they line up in parallel to the ridges and therefore exhibit a constant color across the entire basin. Finally, set into the ridges are a series of antibody particles for a specific virus. Once built, the sensor is exposed to material that might contain the virus in question. If the virus is present, it will bind to the antibody and, when it does, disturb the arrangement of the liquid crystals. When the liquid crystals are disturbed, the sensor changes color, signaling a positive match.

I haven’t seen any public engagement exercises that raise the issue in quite that way. At this point, it seems to be the province of science fiction.

Before I finish this posting with the June 2011 Nano Haiku, I’ll give you a little information about the article by Anne Trafton that inspired it, Finding a needle in a haystack: New sensor developed by MIT chemical engineers can detect tiny traces of explosives,

MIT [Massachusetts Institute of Technology] researchers have created a new detector so sensitive it can pick up a single molecule of an explosive such as TNT.

To create the sensors, chemical engineers led by Michael Strano coated carbon nanotubes — hollow, one-atom-thick cylinders made of pure carbon — with protein fragments normally found in bee venom. This is the first time those proteins have been shown to react to explosives, specifically a class known as nitro-aromatic compounds that includes TNT.

And now the Nano Haiku,

Bee venom and nanotubes
Raise nano red flags
For super small explosives

by Vrylena Olney of the Museum of Science, Boston.

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