A DNA origami-based nanoscopic force clamp

Nanoclamp made of DNA strands. Illustration: Christoph Hohmann

Nanoclamp made of DNA strands. Illustration: Christoph Hohmann

An Oct. 21, 2016 news item on ScienceDaily announces a new nanotool,

Physicists at Ludwig-Maximilians-Universitat (LMU) in Munich have developed a novel nanotool that provides a facile means of characterizing the mechanical properties of biomolecules.

An Oct. 21, 2016 Ludwig-Maximilians-Universitat (LMU) press release (also on EurekAlert), which originated the news item, explains the work in more detail (Note: A link has been removed),

Faced with the thousands of proteins and genes found in virtually every cell in the body, biologists want to know how they all work exactly: How do they interact to carry out their specific functions and how do they respond and adapt to perturbations? One of the crucial factors in all of these processes is the question of how biomolecules react to the minuscule forces that operate at the molecular level. LMU physicists led by Professor Tim Liedl, in collaboration with researchers at the Technical University in Braunschweig and at Regensburg University, have come up with a method that allows them to exert a constant force on a single macromolecule with dimensions of a few nanometers, and to observe the molecule’s response. The researchers can this way test whether or not a protein or a gene is capable of functioning normally when its structure is deformed by forces of the magnitude expected in the interior of cells. This new method of force spectroscopy uses self-assembled nanoscopic power gauges, requires no macroscopic tools and can analyze large numbers of molecules in parallel, which speeds up the process of data acquisition enormously.

With their new approach, the researchers have overcome two fundamental limitations of the most commonly used force spectroscopy instruments. In the case of force microscopy and methodologies based on optical or magnetic tweezers, the molecules under investigation are always directly connected to a macroscopic transducer. They require precise control of the position of an object – a sphere or a sharp metal tip on the order of a micrometer in size – that exerts a force on molecules that are anchored to that object. This strategy is technically extremely demanding and the data obtained is often noisy. Furthermore, these procedures can only be used to probe molecules one at a time. The new method dispenses with all these restrictions. “The structures we use operate completely autonomously“, explains Philipp Nickels, a member of Tim Liedl’s research group. “And we can use them to study countless numbers of molecules simultaneously.”

A feather-light touch

The members of the Munich group, which is affiliated with the Cluster of Excellence NIM (Nanosystems Initiative Munich), are acknowledged masters of “DNA origami”. This methodology exploits the base-pairing properties of DNA for the construction of nanostructures from strands that fold up and pair locally in a manner determined by their nucleotide sequences. In the present case, the DNA sequences are programmed to interact with each other in such a way that the final structure is a molecular clamp that can be programmed to exert a defined force on a test molecule. To this end, a single-stranded DNA that contains a specific sequence capable of recruiting the molecule of interest spans from one arm of the clamp to the other. The applied force can then be tuned by changing the length of the single strand base by base. “That is equivalent to stretching a spring ever so-o-o slightly,” says Nickels. Indeed, by this means it is possible to apply extremely tiny forces between 1 and 15 pN (1 pN = one billionth of a Newton) – comparable in magnitude to those that act on proteins and genes in cells. “In principle, we can capture any type of biomolecule with these clamps and investigate its physical properties,” says Tim Liedl.

The effect of the applied force is read out by taking advantage of the phenomenon of Förster Resonant Energy Transfer (FRET). “FRET involves the transfer of energy between two fluorescent dyes and is strongly dependent on the distance between them.” explains Professor Philip Tinnefeld from TU Braunschweig. When the force applied to the test molecule is sufficient to deform it, the distance between the fluorescent markers changes and the magnitude of energy transfer serves as an exquisitely precise measure of the distortion of the test molecule on the nanometer scale.

Together with Dina Grohmann from Universität Regensburg, the team has used the new technique to investigate the properties of the so-called TATA Binding Protein, an important gene regulator which binds to a specific upstream nucleotide sequence in genes and helps to trigger their expression. They found that the TATA protein can no longer perform its normal function if its target sequence is subjected to a force of more than 6 pN. – The new technology has just made its debut. But since the clamps are minuscule and operate autonomously, it may well be possible in the future to use them to study molecular processes in living cells in real time.

Sometimes reading these news releases, my mind is boggled. What an extraordinary time to live.

Here’s a link to and a citation for the paper,

Molecular force spectroscopy with a DNA origami–based nanoscopic force clamp by Philipp C. Nickels, Bettina Wünsch, Phil Holzmeister, Wooli Bae, Luisa M. Kneer, Dina Grohmann, Philip Tinnefeld, Tim Lied. Science  21 Oct 2016: Vol. 354, Issue 6310, pp. 305-307 DOI: 10.1126/science.aah5974

This paper is behind a paywall.

Repelling liquid with superomniphobic tape

The Kota lab at Colorado State University has created a superomniphobic tape that adheres to any surface and imparts liquid-repellant properties. Credit: Kota lab/Colorado State University

The Kota lab at Colorado State University has created a superomniphobic tape that adheres to any surface and imparts liquid-repellant properties. Credit: Kota lab/Colorado State University

An Oct. 20, 2016 news item on ScienceDaily celebrates the creation of a liquid-repelling superomniphobic tape,

Arun Kota, assistant professor of mechanical engineering at Colorado State University, has made a superomniphobic tape that, when adhered to any surface, gives the surface liquid-repelling properties. This recent breakthrough has been published by the American Chemical Society.

An Oct. 20, 2016 Colorado State University news release on EurekAlert, which originated the news item, provides more description,

Superomniphobic surfaces are extremely repellent to all liquids, made possible by an air cushion that lies between a liquid and a solid surface. With more than 10 years of research in this area, Kota has made many breakthroughs in super-repellent coatings. This latest product is similar in flexibility to Scotch Tape, but has the additional functionality of being extremely liquid-repellant.

Kota, doctoral student Hamed Vahabi, and postdoctoral fellow Wei Wang, developed the unusual tape. Though simple at first glance, the technology’s potential impact is extraordinary, the researchers say.

The concept of superomniphobic surfaces isn’t new. Researchers have been studying superomniphobic coatings since about 2007, and currently superomniphobic coatings can be sprayed, deposited or etched onto any surface for a similar effect; however, it requires costly equipment, complex techniques, and must be done by an experienced professional.

By contrast, the Kota group’s superomniphobic tape can be used by anyone, making it a practical solution in a variety of civilian, commercial, and military applications including corrosion resistance, self cleaning, drag reduction, liquid waste minimization, and more.

The researchers feel that future challenges in this field are exciting ­- yet puzzling. While many applications of superomniphobic coatings have already been outlined, coming up with a superomniphobic coating that is mechanically durable remains a major challenge.

Kota has filed a patent and sees tape and adhesive manufacturers as well as the packing industry having a strong interest in the product. He and his group will continue to research the mechanical durability of their product.

Here’s a link to and a citation for the paper,

Free-Standing, Flexible, Superomniphobic Films by Hamed Vahabi, Wei Wang, Sanli Movafaghi, and Arun K. Kota. ACS Appl. Mater. Interfaces, 2016, 8 (34), pp 21962–21967 DOI: 10.1021/acsami.6b06333 Publication Date (Web): August 19, 2016

Copyright © 2016 American Chemical Society

This paper is behind a paywall.

The volatile lithium-ion battery

On the heels of Samsung’s Galaxy Note 7 recall due to fires (see Alex Fitzpatrick’s Sept. 9, 2016 article for Time magazine for a good description of lithium-ion batteries and why they catch fire; see my May 29, 2013 posting on lithium-ion batteries, fires [including the airplane fires], and nanotechnology risk assessments), there’s new research on lithium-ion batteries and fires from China. From an Oct. 21, 2016 news item on Nanotechnology Now,

Dozens of dangerous gases are produced by the batteries found in billions of consumer devices, like smartphones and tablets, according to a new study. The research, published in Nano Energy, identified more than 100 toxic gases released by lithium batteries, including carbon monoxide.

An Oct. 20, 2016 Elsevier Publishing press release (also on EurekAlert), which originated the news item, expands on the theme,

The gases are potentially fatal, they can cause strong irritations to the skin, eyes and nasal passages, and harm the wider environment. The researchers behind the study, from the Institute of NBC Defence and Tsinghua University in China, say many people may be unaware of the dangers of overheating, damaging or using a disreputable charger for their rechargeable devices.

In the new study, the researchers investigated a type of rechargeable battery, known as a “lithium-ion” battery, which is placed in two billion consumer devices every year.

“Nowadays, lithium-ion batteries are being actively promoted by many governments all over the world as a viable energy solution to power everything from electric vehicles to mobile devices. The lithium-ion battery is used by millions of families, so it is imperative that the general public understand the risks behind this energy source,” explained Dr. Jie Sun, lead author and professor at the Institute of NBC Defence.

The dangers of exploding batteries have led manufacturers to recall millions of devices: Dell recalled four million laptops in 2006 and millions of Samsung Galaxy Note 7 devices were recalled this month after reports of battery fires. But the threats posed by toxic gas emissions and the source of these emissions are not well understood.

Dr. Sun and her colleagues identified several factors that can cause an increase in the concentration of the toxic gases emitted. A fully charged battery will release more toxic gases than a battery with 50 percent charge, for example. The chemicals contained in the batteries and their capacity to release charge also affected the concentrations and types of toxic gases released.

Identifying the gases produced and the reasons for their emission gives manufacturers a better understanding of how to reduce toxic emissions and protect the wider public, as lithium-ion batteries are used in a wide range of environments.

“Such dangerous substances, in particular carbon monoxide, have the potential to cause serious harm within a short period of time if they leak inside a small, sealed environment, such as the interior of a car or an airplane compartment,” Dr. Sun said.

Almost 20,000 lithium-ion batteries were heated to the point of combustion in the study, causing most devices to explode and all to emit a range of toxic gases. Batteries can be exposed to such temperature extremes in the real world, for example, if the battery overheats or is damaged in some way.

The researchers now plan to develop this detection technique to improve the safety of lithium-ion batteries so they can be used to power the electric vehicles of the future safely.

“We hope this research will allow the lithium-ion battery industry and electric vehicle sector to continue to expand and develop with a greater understanding of the potential hazards and ways to combat these issues,” Sun concluded.

Here’s a link to and a citation for the paper,

Toxicity, a serious concern of thermal runaway from commercial Li-ion battery by Jie Sun, Jigang Li, Tian Zhou, Kai Yang, Shouping Wei, Na Tang, Nannan Dang, Hong Li, Xinping Qiu, Liquan Chend. Nano Energy Volume 27, September 2016, Pages 313–319  http://dx.doi.org/10.1016/j.nanoen.2016.06.031

This paper appears to be open access.

Self-healing lithium-ion batteries for textiles

It’s easy to forget how hard we are on our textiles. We rip them, step on them, agitate them in water, splatter them with mud, and more. So, what happens when we integrate batteries and electronics into them? An Oct. 20, 2016 news item on phys.org describes one of the latest ‘textile batter technologies’,

Electronics that can be embedded in clothing are a growing trend. However, power sources remain a problem. In the journal Angewandte Chemie, scientists have now introduced thin, flexible, lithium ion batteries with self-healing properties that can be safely worn on the body. Even after completely breaking apart, the battery can grow back together without significant impact on its electrochemical properties.

wiley_selfhealinglithiumionbattery

© Wiley-VCH

An Oct. 20, 2016 Wiley Angewandte Chemie International Edition press release (also on EurekAlert), which originated the news item, describes some of the problems associated with lithium-ion batteries and this new technology designed to address them,

Existing lithium ion batteries for wearable electronics can be bent and rolled up without any problems, but can break when they are twisted too far or accidentally stepped on—which can happen often when being worn. This damage not only causes the battery to fail, it can also cause a safety problem: Flammable, toxic, or corrosive gases or liquids may leak out.

A team led by Yonggang Wang and Huisheng Peng has now developed a new family of lithium ion batteries that can overcome such accidents thanks to their amazing self-healing powers. In order for a complicated object like a battery to be made self-healing, all of its individual components must also be self-healing. The scientists from Fudan University (Shanghai, China), the Samsung Advanced Institute of Technology (South Korea), and the Samsung R&D Institute China, have now been able to accomplish this.

The electrodes in these batteries consist of layers of parallel carbon nanotubes. Between the layers, the scientists embedded the necessary lithium compounds in nanoparticle form (LiMn2O4 for one electrode, LiTi2(PO4)3 for the other). In contrast to conventional lithium ion batteries, the lithium compounds cannot leak out of the electrodes, either while in use or after a break. The thin layer electrodes are each fixed on a substrate of self-healing polymer. Between the electrodes is a novel, solvent-free electrolyte made from a cellulose-based gel with an aqueous lithium sulfate solution embedded in it. This gel electrolyte also serves as a separation layer between the electrodes.

After a break, it is only necessary to press the broken ends together for a few seconds for them to grow back together. Both the self-healing polymer and the carbon nanotubes “stick” back together perfectly. The parallel arrangement of the nanotubes allows them to come together much better than layers of disordered carbon nanotubes. The electrolyte also poses no problems. Whereas conventional electrolytes decompose immediately upon exposure to air, the new gel is stable. Free of organic solvents, it is neither flammable nor toxic, making it safe for this application.

The capacity and charging/discharging properties of a battery “armband” placed around a doll’s elbow were maintained, even after repeated break/self-healing cycles.

Here’s a link to and a citation for the paper,

A Self-Healing Aqueous Lithium-Ion Battery by Yang Zhao, Ye Zhang, Hao Sun, Xiaoli Dong, Jingyu Cao, Lie Wang, Yifan Xu, Jing Ren, Yunil Hwang, Dr. In Hyuk Son, Dr. Xianliang Huang, Prof. Yonggang Wang, and Prof. Huisheng Peng. Angewandte Chemie International Edition DOI: 10.1002/anie.201607951 Version of Record online: 12 OCT 2016

© 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

This paper is behind a paywall.

US nanotechnology resource map

I have two links to the US National Nanotechnology Inititative’s (NNI) Nanotechnology Resource Map. Here’s the more confusing one: US Nanotechnology Resource Map: Higher Ed Programs and NNI Centers and User Facilities (from the homepage),

This interactive map shows the currently funded NNI Centers and User Facilities, as well as the nation’s higher education nanotechnology degrees– from community college through PhD programs.

Here’s the less confusing version: NNI’s Interactive
Nanotechnology Resource Map (from the About the map webpage),

With this interactive map tool, you can search for nanotechnology-related higher education and training programs, NNI Centers and User Facilities, as well as regional, state, and local initiatives in nanotechnology located throughout the country. In addition, the map provides the location of the facility, as well as a street view, directions to the site, and a link to the facility’s website.

This map is searchable by state, facility-type, or keyword. Hovering the mouse over a state creates a small pop up window that provides the statewide totals for the following figures:

  • Schools offering Bachelor Degree programs in nanotechnology
  • Schools offering Masters Degree programs in nanotechnology
  • Schools offering Ph.D. programs in nanotechnology
  • Community Colleges and Training Programs with nanotechnology courses and degree programs
  • National Nanotechnology Initiative Centers and User Facilities (laboratories)
  • Regional, state, & local initiatives in nanotechnology

….

  • You can narrow your search results by using the filter criteria and limit your search to your areas of interest, e.g., checking or unchecking the boxes or choosing a state from the drop down menu.
  • Alternatively, you can search by keyword or phrase and the results will be populated in tabular format under the map. Type “all” and all results will be displayed.
  • Clicking on a state will open a new window that displays the map of that state and the statewide results under the map as defined in the search criteria.
  • Clicking on a point on the map or a row in the table, will display more information about that particular institution.
  • From the main map, you can toggle the view at anytime between the state totals map and the cluster map that shows nationwide results.

Good luck!

Science literacy and illiteracy according to the US National Academy of Sciences

Phys.org is hosting a commentary by Mike Klymkowsky on the recent report (Science Literacy: Concepts, Contexts, and Consequences) published the US National Academy of Sciences in an Oct. 18, 2016 news item,

Scientific literacy – what it is, how to recognize it, and how to help people achieve it through educational efforts, remains a difficult topic. The latest attempt to inform the conversation is a recent National Academy report “Science Literacy: concepts, contexts, and consequences.”

While there is lots of substance to take away from the report, three quotes seem particularly telling to me. The first is from Roberts [D. A. Roberts] that points out that scientific literacy has “become an umbrella concept with a sufficiently broad, composite meaning that it meant both everything, and nothing specific, about science education and the competency it sought to describe.” The second quote, from the report’s authors, is that “In the field of education, at least, the lack of consensus surrounding science literacy has not stopped it from occupying a prominent place in policy discourse” (p. 2.6). And finally, “the data suggested almost no relationship between general science knowledge and attitudes about genetically modified food, a potentially negative relationship between biology-specific knowledge and attitudes about genetically modified food, and a small, but negative relationship between that same general science knowledge measure and attitudes toward environmental science.”

"Flat Earth” The Flammarion engraving (1888) Wikipedia [downloaded from http://blogs.plos.org/scied/2016/10/16/recognizing-scientific-literacy-illiteracy/]

“Flat Earth” The Flammarion engraving (1888) Wikipedia [downloaded from http://blogs.plos.org/scied/2016/10/16/recognizing-scientific-literacy-illiteracy/]

The commentary was originally published on Klymkowsky’s Oct. 16, 2016 posting on Sci-Ed, a Public Library of Science (PLOS) blog where you find a list of references including one for D. A. Roberts at the end of the post,

… what is added when we move to scientific in contrast to standard literacy, what is missing from the illiterate response.  At the simplest level we are looking for mistakes, irrelevancies, failures in logic, or in recognizing contradictions within the answer, explanation or critique. The presence of unnecessary language suggests, at the very least, a confused understanding of the situation.[3]  A second feature of a scientifically illiterate response is a failure to recognize the limits of scientific knowledge; this includes an explicit recognition of the tentative nature of science, combined with the fact that some things are, theoretically, unknowable scientifically.  For example, is “dark matter” real or might an alternative model of gravity remove its raison d’être?[4]

For me, one of the more intriguing ideas Klymkowsky explores is scientific illiteracy in the scientific community (from the Oct. 16, 2016 PLOS posting),

There are also suggestions of scientific illiteracy (or perhaps better put, sloppy and/or self-serving thinking) in much of the current “click-bait” approach to the public dissemination of scientific ideas and observations.  All too often, scientific practitioners, who we might expect to be as scientifically literate as possible, abandon the discipline of science to make claims that are over-arching and often self-serving (this is, after all, why peer-review is necessary).

A common example [of scientific illiteracy practiced by scientists and science communicators] is provided by studies of human disease in “model” organisms, ranging from yeasts to non-human primates. While there is no doubt that such studies have been, and continue to be critical to understanding how organisms work (and certainly deserving of public and private support) – their limitations need to be made explicit, while a mouse that displays behavioral defects (for a mouse) might well provide useful insights into the mechanisms involved in human autism, an autistic mouse may well be a scientific oxymoron.

Discouraging scientific illiteracy within the scientific community is challenging, particularly in the highly competitive, litigious,[5] and high stakes environment we currently find ourselves in.[6]  How to best help our students, both within and without scientific disciplines, avoid scientific illiteracy remains unclear, but is likely to involve establishing a culture of Socratic discourse (as opposed to posturing). ….

I recommend reading the commentary in its entirety. You might also want to check out Klymkowsky’s website here.

Finally, the US National Academy of Sciences report, Science Literacy: Concepts, Contexts, and Consequences is available as a free download.

Testing ‘smart’ antibacterial surfaces and eating haute cuisine in space

Housekeeping in space, eh? This seems to be a French initiative. From a Nov. 15, 2016 news item on Nanowerk,

Leti [Laboratoire d’électronique des technologies de l’information (LETI)], an institute of CEA [French Alternative Energies and Atomic Energy Commission or Commissariat a l’Energie Atomique (CEA)] Tech, and three French partners are collaborating in a “house-cleaning” project aboard the International Space Station that will investigate antibacterial properties of new materials in a zero-gravity environment to see if they can improve and simplify cleaning inside spacecraft.

The Matiss experiment, as part of the Proxima Mission sponsored by France’s CNES space agency [Centre national d’études spatiales (CNES); National Centre for Space Studies (CNES)], is based on four identical plaques that European Space Agency (ESA) astronaut Thomas Pesquet, the 10th French citizen to go into space, will take with him and install when he joins the space station in November for a six-month mission. The plaques will be in the European Columbus laboratory in the space station for at least three months, and Pesquet will bring them back to earth for analysis at the conclusion of his mission.

A November 15, 2016 CEA-LETI press release on Business Wire (you may also download it from here), which originated the news item, describes the proposed experiments in more detail,

Leti, in collaboration with the ENS de Lyon, CNRS, the French company Saint Gobain and CNES, selected five advanced materials that could stop bacteria from settling and growing on “smart” surfaces. A sixth material, made of glass, will be used as control material.

The experiment will test the new smart surfaces in a gravity-free, enclosed environment. These surfaces are called “smart” because of their ability to provide an appropriate response to a given stimulus. For example, they may repel bacteria, prevent them from growing on the surface, or create their own biofilms that protect them from the bacteria.

The materials are a mix of advanced technology – from self-assembly monolayers and green polymers to ceramic polymers and water-repellent hybrid silica. By responding protectively to air-borne bacteria they become easier to clean and more hygienic. The experiment will determine which one is most effective and could lead to antibacterial surfaces on elevator buttons and bars in mass-transit cars, for example.

“Leveraging its unique chemistry platform, Leti has been developing gas, liquid and supercritical-phase-collective processes of surface functionalization for more than 10 years,” said Guillaume Nonglaton, Leti’s project manager for surface chemistry for biology and health-care applications. “Three Leti-developed surfaces will be part of the space-station experiment: a fluorinated thin layer, an organic silica and a biocompatible polymer. They were chosen for their hydrophobicity, or lack of attraction properties, their level of reproducibility and their rapid integration within Pesquet’s six-month mission.”

Now, for Haute Cusine

Pesquet is bringing meals from top French chefs Alain Ducasse and Thierry Marx for delectation. The menu includes beef tongue with truffled foie gras and duck breast confit. Here’s more from a Nov. 17, 2016 article by Thibault Marchand (Agence France Presse) ong phys.org,

“We will have food prepared by a Michelin-starred chef at the station. We have food for the big feasts: for Christmas, New Year’s and birthdays. We’ll have two birthdays, mine and Peggy’s,” said the Frenchman, who is also taking a saxophone up with him.

French space rookie Thomas Pesquet, 38, will lift off from the Baikonur cosmodrome in Kazakhstan with veteran US and Russian colleagues Peggy Whitson and Oleg Novitsky, for a six-month mission to the ISS.

Bon appétit! By the way, this is not the first time astronauts have been treated to haute cuisine (see a Dec. 2, 2006 article on the BBC [British Broadcasting Corporation] website.)

The launch

Mark Garcia’s Nov. 17, 2016 posting on one of the NASA (US National Aeronautics and Space Administration) blogs describes this latest launch into space,

The Soyuz MS-03 launched from the Baikonur Cosmodrome in Kazakhstan to the International Space Station at 3:20 p.m. EST Thursday, Nov. 17 (2:20 a.m. Baikonur time, Nov. 18). At the time of launch, the space station was flying about 250 miles over the south Atlantic east of Argentina. NASA astronaut Peggy Whitson, Oleg Novitskiy of Roscosmos and Thomas Pesquet of ESA (European Space Agency) are now safely in orbit.

Over the next two days, the trio will orbit the Earth for approximately two days before docking to the space station’s Rassvet module, at 5:01 p.m. on Saturday, Nov. 19. NASA TV coverage of the docking will begin at 4:15 p.m. Saturday.

Garcia’s post gives you details about how to access more information about the mission. The European Space Agency also offers more information as does Thomas Pesquet on his website.

Growing and sharpening gold

An Oct. 19, 2016 news item on phys.org compares nanogold to a snowflake,

Grown like a snowflake and sharpened with a sewing machine, a novel device by Kansas State University researchers may benefit biomedical professionals and the patients they serve during electrode and organ transplant procedures.

The device uses gold nanowires and was developed by Bret Flanders, associate professor of physics, and Govind Paneru, former graduate research assistant in physics, to manipulate and sense characteristics of individual cells in medical procedures. The gold nanowires are 1,000 times smaller than a human hair.

An Oct. 19, 2016 Kansas State University news release (also on EurekAlert) by Tiffany Roney, which originated the news item, expands on the theme,

“Conventional surgical tools, including electrodes that are implanted in people’s tissue, are unfavorably large on the cellular level,” Flanders said. “Working at the individual cellular level is of increasing importance in areas such as neurosurgery. Potentially, this sleek device, made from gold nanowires, could get in close and do the job.”

Flanders said the size of the nanowires is what makes their device so unique.

Each wire is less than 100 nanometers in diameter. Cells in skin and hair are about 10-20 micrometers in diameter, while red blood cells measure about 7 micrometers. Because the wire is so small, it can pierce a biological cell to stimulate the cell membrane and investigate its interior.

The nanowires are electrochemically grown, meaning they do not grow by a lengthening or enlarging an existing wire, but rather by accumulating particles from solution into a new wire.

In heavily zoomed video footage the nanowire appears to grow out of the micrometer-thick electrode. Actually, the nanowire forms similarly to how a snowflake is assembled in the sky when water vapor molecules in the air condense onto the surface of pollen or dust and grow non-uniformly until they become a recognizable snowflake.

“We start with a sharp microelectrode on a microscope stage,” Flanders said. “Similar to snowflake formation, the gold atoms condense onto its sharp tip. Like the water condensing onto the snowflake seed, the golden solution condenses onto the gold ‘seed,’ or the microelectrode.”

The researchers developed sharp electrodes with an unconventional tool not found in many laboratories: a sewing machine.

“It’s like putting the wire in a pencil sharpener, where you turn the crank to sharpen it, except we don’t do it mechanically with a pencil sharpener — we do it with a common salt solution and a sewing machine,” Flanders said. “This turned out to be the approach that worked the best, and the sewing machine cost only $10 at the Salvation Army.”

The sewing machine oscillates the microelectrode up and down in a beaker of potassium chloride solution. Application of a voltage dissolves the tip of the microelectrode.

“The process sharpens the electrode because the tip is in the solution longer than any other point,” Flanders said. “If we did not oscillate the wire, the whole wire would dissolve. Instead, dipping the tip in and out causes the tip to dissolve the most, thereby sharpening it.”

The sharpened electrode allows the nanowire to grow. The researchers then dismount the nanowire from the electrode and ship it to collaborators across the country, including a nanofabrication company that may incorporate the invention into a pre-existing device to provide it with greater power.

There are two published pieces associated with the research but they are older. Here’s a link to and a citation for each,

Single-step growth and low resistance interconnecting of gold nanowires by Birol Ozturk, Bret N Flanders, Daniel R Grischkowsky, and Tetsuya D Mishima. Nanotechnology, Volume 18, Number 17 doi:10.1088/0957-4484/18/17/175707 Published 2 April 2007
Directed growth of single-crystal indium wires by Ishan Talukdar, Birol Ozturk, Bret N. Flanders, and Tetsuya D. Mishima. Appl. Phys. Lett. 88, 221907 (2006); http://dx.doi.org/10.1063/1.2208431 Published online 31 May 2006

Both papers are behind paywalls.

Ocean-inspired coatings for organic electronics

An Oct. 19, 2016 news item on phys.org describes the advantages a new coating offers and the specific source of inspiration,

In a development beneficial for both industry and environment, UC Santa Barbara [University of California at Santa Barbara] researchers have created a high-quality coating for organic electronics that promises to decrease processing time as well as energy requirements.

“It’s faster, and it’s nontoxic,” said Kollbe Ahn, a research faculty member at UCSB’s Marine Science Institute and corresponding author of a paper published in Nano Letters.

In the manufacture of polymer (also known as “organic”) electronics—the technology behind flexible displays and solar cells—the material used to direct and move current is of supreme importance. Since defects reduce efficiency and functionality, special attention must be paid to quality, even down to the molecular level.

Often that can mean long processing times, or relatively inefficient processes. It can also mean the use of toxic substances. Alternatively, manufacturers can choose to speed up the process, which could cost energy or quality.

Fortunately, as it turns out, efficiency, performance and sustainability don’t always have to be traded against each other in the manufacture of these electronics. Looking no further than the campus beach, the UCSB researchers have found inspiration in the mollusks that live there. Mussels, which have perfected the art of clinging to virtually any surface in the intertidal zone, serve as the model for a molecularly smooth, self-assembled monolayer for high-mobility polymer field-effect transistors—in essence, a surface coating that can be used in the manufacture and processing of the conductive polymer that maintains its efficiency.

An Oct. 18, 2016 UCSB news release by Sonia Fernandez, which originated the news item, provides greater technical detail,

More specifically, according to Ahn, it was the mussel’s adhesion mechanism that stirred the researchers’ interest. “We’re inspired by the proteins at the interface between the plaque and substrate,” he said.

Before mussels attach themselves to the surfaces of rocks, pilings or other structures found in the inhospitable intertidal zone, they secrete proteins through the ventral grove of their feet, in an incremental fashion. In a step that enhances bonding performance, a thin priming layer of protein molecules is first generated as a bridge between the substrate and other adhesive proteins in the plaques that tip the byssus threads of their feet to overcome the barrier of water and other impurities.

That type of zwitterionic molecule — with both positive and negative charges — inspired by the mussel’s native proteins (polyampholytes), can self-assemble and form a sub-nano thin layer in water at ambient temperature in a few seconds. The defect-free monolayer provides a platform for conductive polymers in the appropriate direction on various dielectric surfaces.

Current methods to treat silicon surfaces (the most common dielectric surface), for the production of organic field-effect transistors, requires a batch processing method that is relatively impractical, said Ahn. Although heat can hasten this step, it involves the use of energy and increases the risk of defects.

With this bio-inspired coating mechanism, a continuous roll-to-roll dip coating method of producing organic electronic devices is possible, according to the researchers. It also avoids the use of toxic chemicals and their disposal, by replacing them with water.

“The environmental significance of this work is that these new bio-inspired primers allow for nanofabrication on silicone dioxide surfaces in the absence of organic solvents, high reaction temperatures and toxic reagents,” said co-author Roscoe Lindstadt, a graduate student researcher in UCSB chemistry professor Bruce Lipshutz’s lab. “In order for practitioners to switch to newer, more environmentally benign protocols, they need to be competitive with existing ones, and thankfully device performance is improved by using this ‘greener’ method.”

Here’s a link to and a citation for the research paper,

Molecularly Smooth Self-Assembled Monolayer for High-Mobility Organic Field-Effect Transistors by Saurabh Das, Byoung Hoon Lee, Roscoe T. H. Linstadt, Keila Cunha, Youli Li, Yair Kaufman, Zachary A. Levine, Bruce H. Lipshutz, Roberto D. Lins, Joan-Emma Shea, Alan J. Heeger, and B. Kollbe Ahn. Nano Lett., 2016, 16 (10), pp 6709–6715
DOI: 10.1021/acs.nanolett.6b03860 Publication Date (Web): September 27, 2016

Copyright © 2016 American Chemical Society

This paper is behind a paywall but the scientists have made an illustration available,

An artist's concept of a zwitterionic molecule of the type secreted by mussels to prime surfaces for adhesion Photo Credit: Peter Allen

An artist’s concept of a zwitterionic molecule of the type secreted by mussels to prime surfaces for adhesion Photo Credit: Peter Allen