Tag Archives: Korea

A pumpkin-shaped molecule for the first real-time methamphetamine and amphetamine sensor

A Sept. 28,2017 news item on Nanowerk announces a portable, inexpensive sensor for drugs (Note: A link has been renewed),

Speed, uppers, chalk, glass, crystal, or whatever you prefer to call them, can be instantly detected from biological fluids with a new portable kit that costs as little as $50. Scientists at the Center for Self-Assembly and Complexity, within the Institute for Basic Science (IBS, South Korea), in collaboration with Pohang University of Science and Technology (POSTECH), have devised the first methamphetamine and amphetamine sensor that can detect minute concentrations of these drugs from a single drop of urine in real-time.

Published in the journal Chem (“Point-of-Use Detection of Amphetamine-Type Stimulants with Host-Molecule-Functionalized Organic Transistors”), this simple and flexible sensor, which can be attached to a wristband and connected to an Android app via Bluetooth, could move drug screening from the labs to the streets.

A Sept. 28 (?), 2017 IBS press release by Letizia Diamante (also on EurekAlert), which originated the news item, expands on the theme,

Easy to synthesize and cheaper than heroin or cocaine, amphetamine-based drugs are the most abused drugs in the world, after cannabis. Conventional drug detection methods require a long time, as the sample must be taken into a lab for the analysis. It also needs experts to run the expensive equipment. The technology reported in this study is instead small, portable, cheap, fast and easy to use.

The idea for this technology came from the IBS chemist HWANG Ilha: “I was watching a TV news report on the usage of illegal drugs, and I thought to check what the chemical structure of methamphetamine looks like.” Soon after, the scientist anticipated that the drug would form a tight complex with a family of hollow pumpkin-shaped molecules, called cucurbituril (CB) members. The team then discovered that cucurbit[7]uril (CB[7])’s empty cavity binds well with amphetamine-based drugs and can be used as the drug recognition unit of a sensor. Cucurbiturils’ hollow chamber has already been studied for various technological uses, but this is the first device application in amphetamine-based drug detection.


▲ Figure 1: Wireless sensor for amphetamine-based drug detection.The kit is made of an organic field-effect transistor (OFET) device, an electric circuit board with a rechargeable battery and an antenna. The OFET device surface is coated with CB[7], whose function is to bind amphetamine and methamphetamine drugs in solution. The binding event is instantly converted to current, whose magnitude is proportional to the concentration of the drug. The app on the smartphone shows a peak as soon as a drop of urine with the drug is applied to the device. Moreover the entire kit can fit in a handy wristband.


▲ Video 1: The detector in action.
[Click text not image]
As soon as a drop of water with 0.0001 ng/mL (1 pM) of amphetamine is applied to the kit, the app shows a peak in current proportional to the concentration of drug. When the liquid is removed, the current level goes back to baseline, and the sensor can be reused. (Modified from Jang et al, Chem 2017)

Combining a transistor coated with CB[7], flexible materials, rechargeable batteries and a Bluetooth antenna, the research team developed a detector wristband connected to an app. In the presence of the drug, the molecular recognition between CB[7] and the drug molecule triggers an electrical signal which appears as a peak on the smartphone screen.

Current drug detection based on immunoassay or liquid chromatography/mass spectrometry techniques has a detection limit of about 10 ng/mL. On the contrary, the sensitivity of this new sensor is about 0.0001 ng/mL in water and 0.1 ng/mL in urine. Therefore, it is expected that this method will allow the detection of drug molecules in biological fluids, like urine and sweat, for a longer time after drug consumption.


▲ Figure 2: Graphic representation of the drug detection platform.Binding of drug molecules to the hollow cucurbit[7]uril (CB[7])’s cavity changes the current signal flowing in the transistor and therefore can be used as a detection system. The molecular structure of amphetamine and methamphetamine bound to cucurbit[7]uril (CB[7]) was confirmed with X-ray crystallography. Each color indicates a different atom (blue: nitrogen, red: oxygen, gray: carbon, and white: hydrogen). CB[7]’s hydrogen atoms have been omitted for clarity.


▲ Figure 3: Humorous view of the pumpkin-shaped molecule, cucurbit[7]uril (CB[7]), able to bind and detect amphetamine and methamphetamine molecules.(Credits: Modified from Titusurya – Freepik.com)

“Real time detection of amphetamine drugs on location would bring a big change to society,” explains another corresponding author KIM Kimoon. “In the same way as police can use a breathalyzer to detect alcohol on the spot, we aim to achieve the same with this device.”

False positives cannot be excluded yet, as urine contains a rich mixture of proteins and other metabolites that could affect the reading. Therefore, before commercializing it, clinical trials with drug users’ biological fluids are necessary. The researchers have patented the technology and they will continue to do further research in the near future.s

“Combining basic science with the latest technology, we can expect that this research will also lead to other new sensors, useful for our daily life,” concludes the third corresponding author OH Joon Hak. Indeed, the team is also keen on developing sensors for other kinds of drugs, as well as kits for the detection of dangerous substances, environmental monitoring, healthcare and safety.

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

Point-of-Use Detection of Amphetamine-Type Stimulants with Host-Molecule-Functionalized Organic Transistors by Yoonjung Jang, Moonjeong Jang, Hyoeun Kim, Sang Jin Lee, Eunyeong Jin, Jin Young Koo, In-Chul Hwang, Yonghwi Kim, Young Ho Ko, Ilha Hwang., Joon Hak Oh, Kimoon Kim. Chem (2017). DOI: 10.1016/j.chempr.2017.08.015 Publication stage: In Press Corrected Proof

This paper appears to be behind a paywall.

Limitless energy and the International Thermonuclear Experimental Reactor (ITER)

Over 30 years in the dreaming, the International Thermonuclear Experimental Reactor (ITER) is now said to be 1/2 way to completing construction. A December 6, 2017 ITER press release (received via email) makes the joyful announcement,

WORLD’S MOST COMPLEX MACHINE IS 50 PERCENT COMPLETED
ITER is proving that fusion is the future source of clean, abundant, safe and economic energy_

The International Thermonuclear Experimental Reactor (ITER), a project to prove that fusion power can be produced on a commercial scale and is sustainable, is now 50 percent built to initial operation. Fusion is the same energy source from the Sun that gives the Earth its light and warmth.

ITER will use hydrogen fusion, controlled by superconducting magnets, to produce massive heat energy. In the commercial machines that will follow, this heat will drive turbines to produce electricity with these positive benefits:

* Fusion energy is carbon-free and environmentally sustainable, yet much more powerful than fossil fuels. A pineapple-sized amount of hydrogen offers as much fusion energy as 10,000 tons of coal.

* ITER uses two forms of hydrogen fuel: deuterium, which is easily extracted from seawater; and tritium, which is bred from lithium inside the fusion reactor. The supply of fusion fuel for industry and megacities is abundant, enough for millions of years.

* When the fusion reaction is disrupted, the reactor simply shuts down-safely and without external assistance. Tiny amounts of fuel are used, about 2-3 grams at a time; so there is no physical possibility of a meltdown accident.

* Building and operating a fusion power plant is targeted to be comparable to the cost of a fossil fuel or nuclear fission plant. But unlike today’s nuclear plants, a fusion plant will not have the costs of high-level radioactive waste disposal. And unlike fossil fuel plants,
fusion will not have the environmental cost of releasing CO2 and other pollutants.

ITER is the most complex science project in human history. The hydrogen plasma will be heated to 150 million degrees Celsius, ten times hotter than the core of the Sun, to enable the fusion reaction. The process happens in a donut-shaped reactor, called a tokamak(*), which is surrounded by giant magnets that confine and circulate the superheated, ionized plasma, away from the metal walls. The superconducting magnets must be cooled to minus 269°C, as cold as interstellar space.

The ITER facility is being built in Southern France by a scientific partnership of 35 countries. ITER’s specialized components, roughly 10 million parts in total, are being manufactured in industrial facilities all over the world. They are subsequently shipped to the ITER worksite, where they must be assembled, piece-by-piece, into the final machine.

Each of the seven ITER members-the European Union, China, India, Japan, Korea, Russia, and the United States-is fabricating a significant portion of the machine. This adds to ITER’s complexity.

In a message dispatched on December 1 [2017] to top-level officials in ITER member governments, the ITER project reported that it had completed 50 percent of the “total construction work scope through First Plasma” (**). First Plasma, scheduled for December 2025, will be the first stage of operation for ITER as a functional machine.

“The stakes are very high for ITER,” writes Bernard Bigot, Ph.D., Director-General of ITER. “When we prove that fusion is a viable energy source, it will eventually replace burning fossil fuels, which are non-renewable and non-sustainable. Fusion will be complementary with wind, solar, and other renewable energies.

“ITER’s success has demanded extraordinary project management, systems engineering, and almost perfect integration of our work.

“Our design has taken advantage of the best expertise of every member’s scientific and industrial base. No country could do this alone. We are all learning from each other, for the world’s mutual benefit.”

The ITER 50 percent milestone is getting significant attention.

“We are fortunate that ITER and fusion has had the support of world leaders, historically and currently,” says Director-General Bigot. “The concept of the ITER project was conceived at the 1985 Geneva Summit between Ronald Reagan and Mikhail Gorbachev. When the ITER Agreement was signed in 2006, it was strongly supported by leaders such as French President Jacques Chirac, U.S. President George W. Bush, and Indian Prime Minister Manmohan Singh.

“More recently, President Macron and U.S. President Donald Trump exchanged letters about ITER after their meeting this past July. One month earlier, President Xi Jinping of China hosted Russian President Vladimir Putin and other world leaders in a showcase featuring ITER and fusion power at the World EXPO in Astana, Kazakhstan.

“We know that other leaders have been similarly involved behind the scenes. It is clear that each ITER member understands the value and importance of this project.”

Why use this complex manufacturing arrangement?

More than 80 percent of the cost of ITER, about $22 billion or EUR18 billion, is contributed in the form of components manufactured by the partners. Many of these massive components of the ITER machine must be precisely fitted-for example, 17-meter-high magnets with less than a millimeter of tolerance. Each component must be ready on time to fit into the Master Schedule for machine assembly.

Members asked for this deal for three reasons. First, it means that most of the ITER costs paid by any member are actually paid to that member’s companies; the funding stays in-country. Second, the companies working on ITER build new industrial expertise in major fields-such as electromagnetics, cryogenics, robotics, and materials science. Third, this new expertise leads to innovation and spin-offs in other fields.

For example, expertise gained working on ITER’s superconducting magnets is now being used to map the human brain more precisely than ever before.

The European Union is paying 45 percent of the cost; China, India, Japan, Korea, Russia, and the United States each contribute 9 percent equally. All members share in ITER’s technology; they receive equal access to the intellectual property and innovation that comes from building ITER.

When will commercial fusion plants be ready?

ITER scientists predict that fusion plants will start to come on line as soon as 2040. The exact timing, according to fusion experts, will depend on the level of public urgency and political will that translates to financial investment.

How much power will they provide?

The ITER tokamak will produce 500 megawatts of thermal power. This size is suitable for studying a “burning” or largely self-heating plasma, a state of matter that has never been produced in a controlled environment on Earth. In a burning plasma, most of the plasma heating comes from the fusion reaction itself. Studying the fusion science and technology at ITER’s scale will enable optimization of the plants that follow.

A commercial fusion plant will be designed with a slightly larger plasma chamber, for 10-15 times more electrical power. A 2,000-megawatt fusion electricity plant, for example, would supply 2 million homes.

How much would a fusion plant cost and how many will be needed?

The initial capital cost of a 2,000-megawatt fusion plant will be in the range of $10 billion. These capital costs will be offset by extremely low operating costs, negligible fuel costs, and infrequent component replacement costs over the 60-year-plus life of the plant. Capital costs will decrease with large-scale deployment of fusion plants.

At current electricity usage rates, one fusion plant would be more than enough to power a city the size of Washington, D.C. The entire D.C. metropolitan area could be powered with four fusion plants, with zero carbon emissions.

“If fusion power becomes universal, the use of electricity could be expanded greatly, to reduce the greenhouse gas emissions from transportation, buildings and industry,” predicts Dr. Bigot. “Providing clean, abundant, safe, economic energy will be a miracle for our planet.”

*     *     *

FOOTNOTES:

* “Tokamak” is a word of Russian origin meaning a toroidal or donut-shaped magnetic chamber. Tokamaks have been built and operated for the past six decades. They are today’s most advanced fusion device design.

** “Total construction work scope,” as used in ITER’s project performance metrics, includes design, component manufacturing, building construction, shipping and delivery, assembly, and installation.

It is an extraordinary project on many levels as Henry Fountain notes in a March 27, 2017 article for the New York Times (Note: Links have been removed),

At a dusty construction site here amid the limestone ridges of Provence, workers scurry around immense slabs of concrete arranged in a ring like a modern-day Stonehenge.

It looks like the beginnings of a large commercial power plant, but it is not. The project, called ITER, is an enormous, and enormously complex and costly, physics experiment. But if it succeeds, it could determine the power plants of the future and make an invaluable contribution to reducing planet-warming emissions.

ITER, short for International Thermonuclear Experimental Reactor (and pronounced EAT-er), is being built to test a long-held dream: that nuclear fusion, the atomic reaction that takes place in the sun and in hydrogen bombs, can be controlled to generate power.

ITER will produce heat, not electricity. But if it works — if it produces more energy than it consumes, which smaller fusion experiments so far have not been able to do — it could lead to plants that generate electricity without the climate-affecting carbon emissions of fossil-fuel plants or most of the hazards of existing nuclear reactors that split atoms rather than join them.

Success, however, has always seemed just a few decades away for ITER. The project has progressed in fits and starts for years, plagued by design and management problems that have led to long delays and ballooning costs.

ITER is moving ahead now, with a director-general, Bernard Bigot, who took over two years ago after an independent analysis that was highly critical of the project. Dr. Bigot, who previously ran France’s atomic energy agency, has earned high marks for resolving management problems and developing a realistic schedule based more on physics and engineering and less on politics.

The site here is now studded with tower cranes as crews work on the concrete structures that will support and surround the heart of the experiment, a doughnut-shaped chamber called a tokamak. This is where the fusion reactions will take place, within a plasma, a roiling cloud of ionized atoms so hot that it can be contained only by extremely strong magnetic fields.

Here’s a rendering of the proposed reactor,

Source: ITER Organization

It seems the folks at the New York Times decided to remove the notes which help make sense of this image. However, it does get the idea across.

If I read the article rightly, the official cost in March 2017 was around 22 B Euros and more will likely be needed. You can read Fountain’s article for more information about fusion and ITER or go to the ITER website.

I could have sworn a local (Vancouver area) company called General Fusion was involved in the ITER project but I can’t track down any sources for confirmation. The sole connection I could find is in a documentary about fusion technology,

Here’s a little context for the film from a July 4, 2017 General Fusion news release (Note: A link has been removed),

A new documentary featuring General Fusion has captured the exciting progress in fusion across the public and private sectors.

Let There Be Light made its international premiere at the South By Southwest (SXSW) music and film festival in March [2017] to critical acclaim. The film was quickly purchased by Amazon Video, where it will be available for more than 70 million users to stream.

Let There Be Light follows scientists at General Fusion, ITER and Lawrenceville Plasma Physics in their pursuit of a clean, safe and abundant source of energy to power the world.

The feature length documentary has screened internationally across Europe and North America. Most recently it was shown at the Hot Docs film festival in Toronto, where General Fusion founder and Chief Scientist Dr. Michel Laberge joined fellow fusion physicist Dr. Mark Henderson from ITER at a series of Q&A panels with the filmmakers.

Laberge and Henderson were also interviewed by the popular CBC radio science show Quirks and Quarks, discussing different approaches to fusion, its potential benefits, and the challenges it faces.

It is yet to be confirmed when the film will be release for streaming, check Amazon Video for details.

You can find out more about General Fusion here.

Brief final comment

ITER is a breathtaking effort but if you’ve read about other large scale projects such as building a railway across the Canadian Rocky Mountains, establishing telecommunications in an  astonishing number of countries around the world, getting someone to the moon, eliminating small pox, building the pyramids, etc., it seems standard operating procedure both for the successes I’ve described and for the failures we’ve forgotten. Where ITER will finally rest on the continuum between success and failure is yet to be determined but the problems experienced so far are not necessarily a predictor.

I wish the engineers, scientists, visionaries, and others great success with finding better ways to produce energy.

Korean researchers extend food shelf *life* with nanomicrobial coating

These Korean scientists have applied their new coating to food and to shoe insoles as they test various uses for their technology. From an Aug. 11, 2017 news item on Nanowerk,

The edible coating on produce has drawn a great deal of attention in the food and agricultural industry. It could not only prolong postharvest shelf life of produce against external changes in the environment but also provide additional nutrients to be useful for human health. However, most versions of the coating have had intrinsic limitations in their practical application.

First, highly specific interactions between coating materials and target surfaces are required for a stable and durable coating. Even further, the coating of bulk substrates, such as fruits, is time consuming or is not achievable in the conventional solution-based coating. In this respect, material-independent and rapid coating strategies are highly demanded.

The research team led by Professor Insung Choi of the Department of Chemistry developed a sprayable nanocoating technique using plant-derived polyphenol that can be applied to any surface.

An Aug. 10, 2017 KAIST (Korea Advanced Institute of Science and Technology) press release, which originated the news item, expands on the theme,

Polyphenols, a metabolite of photosynthesis, possess several hydroxyl groups and are found in a large number of plants showing excellent antioxidant properties. They have been widely used as a nontoxic food additive and are known to exhibit antibacterial, as well as potential anti-carcinogenic capabilities. Polyphenols can also be used with iron ions, which are naturally found in the body, to form an adhesive complex, which has been used in leather tanning, ink, etc.

The research team combined these chemical properties of polyphenol-iron complexes with spray techniques to develop their nanocoating technology. Compared to conventional immersion coating methods, which dip substrates in specialized coating solutions, this spray technique can coat the select areas more quickly. The spray also prevents cross contamination, which is a big concern for immersion methods. The research team has showcased the spray’s ability to coat a variety of different materials, including metals, plastics, glass, as well as textile fabrics. The polyphenol complex has been used to form antifogging films on corrective lenses, as well as antifungal treatments for shoe soles, demonstrating the versatility of their technique.

Furthermore, the spray has been used to coat produce with a naturally antibacterial, edible film. The coatings significantly improved the shelf life of tangerines and strawberries, preserving freshness beyond 28 days and 58 hours, respectively. (Uncoated fruit decomposed and became moldy under the same conditions). See the image below.

 

a –I, II: Uncoated and coated tangerines incubated for 14 and 28 days in daily-life settings

b –I: Uncoated and coated strawberries incubated for 58 hours in daily-life settings

b –II: Statistical investigation of the resulting edibility.

Professor Choi said, “Nanocoating technologies are still in their infancy, but they have untapped potential for exciting applications. As we have shown, nanocoatings can be easily adapted for several different uses, and the creative combination of existing nanomaterials and coating methods can synergize to unlock this potential.”

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

Antimicrobial spray nanocoating of supramolecular Fe(III)-tannic acid metal-organic coordination complex: applications to shoe insoles and fruits by Ji Park, Sohee Choi, Hee Moon, Hyelin Seo, Ji Kim, Seok-Pyo Hong, Bong Lee, Eunhye Kang, Jinho Lee, Dong Ryu, & Insung S. Choi. Scientific Reports 7, Article number: 6980 (2017) doi:10.1038/s41598-017-07257-x Published online: 01 August 2017

This paper is open access.

*’life’ added to correct headline on Sept. 4, 2017.

Ceria-zirconia nanoparticles for sepsis treatment

South Korean researchers are looking at a new way of dealing with infections (sepsis) according to a July 6, 2017 news item on phys.org,

During sepsis, cells are swamped with reactive oxygen species generated in an aberrant response of the immune system to a local infection. If this fatal inflammatory path could be interfered, new treatment schemes could be developed. Now, Korean scientists report in the journal Angewandte Chemie that zirconia-doped ceria nanoparticles act as effective scavengers of these oxygen radicals, promoting a greatly enhanced surviving rate in sepsis model organisms.

A July 6, 2017 Wiley (Publishers) press release, which originated the news item, provides more detail,

Sepsis proceeds as a vicious cycle of inflammatory reactions of the immune system to a local infection. Fatal consequences can be falling blood pressure and the collapse of organ function. As resistance against antibiotics is growing, scientists turn to the inflammatory pathway as an alternative target for new treatment strategies. Taeghwan Heyon from Seoul National University, Seung-Hoon Lee at Seoul National University Hospital, South Korea, and collaborators explore ceria nanoparticles for their ability to scavenge reactive oxygen species, which play a key role in the inflammatory process. By quickly converting between two oxidation states, the cerium ion can quench typical oxygen radical species like the superoxide anion, the hydroxyl radical anion, or even hydrogen peroxide. But in the living cell, this can only happen if two conditions are met.

The first condition is the size and nature of the particles. Small, two-nanometer-sized particles were coated by a hydrophilic shell of poly(ethylene glycol)-connected phospholipids to make them soluble so that they can enter the cell and remain there. Second, the cerium ion responsible for the quenching (Ce3+) should be accessible on the surface of the nanoparticles, and it must be regenerated after the reactions. Here, the scientists found out that a certain amount of zirconium ions in the structure helped, because “the Zr4+ ions control the Ce3+-to-Ce4+ ratio as well as the rate of conversion between the two oxidation states,” they argued.

The prepared nanoparticles were then tested for their ability to detoxify reactive oxygen species, not only in the test tube, but also in live animal models. The results were clear, as the authors stated: “A single dose of ceria-zirconia nanoparticles successfully attenuated the vicious cycle of inflammatory responses in two sepsis models.” The nanoparticles accumulated in organs where severe immune responses occurred, and they were successful in the eradication of reactive oxygen species, as evidenced with fluorescence microscopy and several other techniques. And importantly, the treated mice and rats had a far higher survival rate.

This work demonstrates that other approaches in sepsis treatment than killing bacteria with antibiotics are possible. Targeting the inflammatory signal pathways in macrophages is a very promising option, and the authors have shown that effective scavenging of reactive oxygen species and stopping inflammation is possible with a suitably designed chemical system like this cerium ion redox system provided by nanoparticles.

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

Ceria–Zirconia Nanoparticles as an Enhanced Multi-Antioxidant for Sepsis Treatment by Min Soh, Dr. Dong-Wan Kang, Dr. Han-Gil Jeong, Dr. Dokyoon Kim, Dr. Do Yeon Kim, Dr. Wookjin Yang, Changyeong Song, Seungmin Baik, In-Young Choi, Seul-Ki Ki, Hyek Jin Kwon, Dr. Taeho Kim, Prof. Dr. Chi Kyung Kim, Prof. Dr. Seung-Hoon Lee, and Prof. Dr. Taeghwan Hyeon. Angewandte Chemie DOI: 10.1002/anie.201704904 Version of Record online: 5 JUL 2017

© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

This paper is behind a paywall.

Graphene-based neural probes

I have two news bits (dated almost one month apart) about the use of graphene in neural probes, one from the European Union and the other from Korea.

European Union (EU)

This work is being announced by the European Commission’s (a subset of the EU) Graphene Flagship (one of two mega-funding projects announced in 2013; 1B Euros each over ten years for the Graphene Flagship and the Human Brain Project).

According to a March 27, 2017 news item on ScienceDaily, researchers have developed a graphene-based neural probe that has been tested on rats,

Measuring brain activity with precision is essential to developing further understanding of diseases such as epilepsy and disorders that affect brain function and motor control. Neural probes with high spatial resolution are needed for both recording and stimulating specific functional areas of the brain. Now, researchers from the Graphene Flagship have developed a new device for recording brain activity in high resolution while maintaining excellent signal to noise ratio (SNR). Based on graphene field-effect transistors, the flexible devices open up new possibilities for the development of functional implants and interfaces.

The research, published in 2D Materials, was a collaborative effort involving Flagship partners Technical University of Munich (TU Munich; Germany), Institut d’Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS; Spain), Spanish National Research Council (CSIC; Spain), The Biomedical Research Networking Center in Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN; Spain) and the Catalan Institute of Nanoscience and Nanotechnology (ICN2; Spain).

Caption: Graphene transistors integrated in a flexible neural probe enables electrical signals from neurons to be measured with high accuracy and density. Inset: The tip of the probe contains 16 flexible graphene transistors. Credit: ICN2

A March 27, 2017 Graphene Flagship press release on EurekAlert, which originated the news item, describes the work,  in more detail,

The devices were used to record the large signals generated by pre-epileptic activity in rats, as well as the smaller levels of brain activity during sleep and in response to visual light stimulation. These types of activities lead to much smaller electrical signals, and are at the level of typical brain activity. Neural activity is detected through the highly localised electric fields generated when neurons fire, so densely packed, ultra-small measuring devices is important for accurate brain readings.

The neural probes are placed directly on the surface of the brain, so safety is of paramount importance for the development of graphene-based neural implant devices. Importantly, the researchers determined that the graphene-based probes are non-toxic, and did not induce any significant inflammation.

Devices implanted in the brain as neural prosthesis for therapeutic brain stimulation technologies and interfaces for sensory and motor devices, such as artificial limbs, are an important goal for improving quality of life for patients. This work represents a first step towards the use of graphene in research as well as clinical neural devices, showing that graphene-based technologies can deliver the high resolution and high SNR needed for these applications.

First author Benno Blaschke (TU Munich) said “Graphene is one of the few materials that allows recording in a transistor configuration and simultaneously complies with all other requirements for neural probes such as flexibility, biocompability and chemical stability. Although graphene is ideally suited for flexible electronics, it was a great challenge to transfer our fabrication process from rigid substrates to flexible ones. The next step is to optimize the wafer-scale fabrication process and improve device flexibility and stability.”

Jose Antonio Garrido (ICN2), led the research. He said “Mechanical compliance is an important requirement for safe neural probes and interfaces. Currently, the focus is on ultra-soft materials that can adapt conformally to the brain surface. Graphene neural interfaces have shown already great potential, but we have to improve on the yield and homogeneity of the device production in order to advance towards a real technology. Once we have demonstrated the proof of concept in animal studies, the next goal will be to work towards the first human clinical trial with graphene devices during intraoperative mapping of the brain. This means addressing all regulatory issues associated to medical devices such as safety, biocompatibility, etc.”

Caption: The graphene-based neural probes were used to detect rats’ responses to visual stimulation, as well as neural signals during sleep. Both types of signals are small, and typically difficult to measure. Credit: ICN2

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

Mapping brain activity with flexible graphene micro-transistors by Benno M Blaschke, Núria Tort-Colet, Anton Guimerà-Brunet, Julia Weinert, Lionel Rousseau, Axel Heimann, Simon Drieschner, Oliver Kempski, Rosa Villa, Maria V Sanchez-Vives. 2D Materials, Volume 4, Number 2 DOI https://doi.org/10.1088/2053-1583/aa5eff Published 24 February 2017

© 2017 IOP Publishing Ltd

This paper is behind a paywall.

Korea

While this research from Korea was published more recently, the probe itself has not been subjected to in vivo (animal testing). From an April 19, 2017 news item on ScienceDaily,

Electrodes placed in the brain record neural activity, and can help treat neural diseases like Parkinson’s and epilepsy. Interest is also growing in developing better brain-machine interfaces, in which electrodes can help control prosthetic limbs. Progress in these fields is hindered by limitations in electrodes, which are relatively stiff and can damage soft brain tissue.

Designing smaller, gentler electrodes that still pick up brain signals is a challenge because brain signals are so weak. Typically, the smaller the electrode, the harder it is to detect a signal. However, a team from the Daegu Gyeongbuk Institute of Science & Technology [DGIST} in Korea developed new probes that are small, flexible and read brain signals clearly.

This is a pretty interesting way to illustrate the research,

Caption: Graphene and gold make a better brain probe. Credit: DGIST

An April 19, 2017 DGIST press release (also on EurekAlert), which originated the news item, expands on the theme (Note: A link has been removed),

The probe consists of an electrode, which records the brain signal. The signal travels down an interconnection line to a connector, which transfers the signal to machines measuring and analysing the signals.

The electrode starts with a thin gold base. Attached to the base are tiny zinc oxide nanowires, which are coated in a thin layer of gold, and then a layer of conducting polymer called PEDOT. These combined materials increase the probe’s effective surface area, conducting properties, and strength of the electrode, while still maintaining flexibility and compatibility with soft tissue.

Packing several long, thin nanowires together onto one probe enables the scientists to make a smaller electrode that retains the same effective surface area of a larger, flat electrode. This means the electrode can shrink, but not reduce signal detection. The interconnection line is made of a mix of graphene and gold. Graphene is flexible and gold is an excellent conductor. The researchers tested the probe and found it read rat brain signals very clearly, much better than a standard flat, gold electrode.

“Our graphene and nanowires-based flexible electrode array can be useful for monitoring and recording the functions of the nervous system, or to deliver electrical signals to the brain,” the researchers conclude in their paper recently published in the journal ACS Applied Materials and Interfaces.

The probe requires further clinical tests before widespread commercialization. The researchers are also interested in developing a wireless version to make it more convenient for a variety of applications.

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

Enhancement of Interface Characteristics of Neural Probe Based on Graphene, ZnO Nanowires, and Conducting Polymer PEDOT by Mingyu Ryu, Jae Hoon Yang, Yumi Ahn, Minkyung Sim, Kyung Hwa Lee, Kyungsoo Kim, Taeju Lee, Seung-Jun Yoo, So Yeun Kim, Cheil Moon, Minkyu Je, Ji-Woong Choi, Youngu Lee, and Jae Eun Jang. ACS Appl. Mater. Interfaces, 2017, 9 (12), pp 10577–10586 DOI: 10.1021/acsami.7b02975 Publication Date (Web): March 7, 2017

Copyright © 2017 American Chemical Society

This paper is behind a paywall.

Nanozymes as an antidote for pesticides

Should you have concerns about exposure to pesticides or chemical warfare agents (timely given events in Syria as per this April 4, 2017 news item on CBC [Canadian Broadcasting News Corporation] online) , scientists at the Lomonosov Moscow State University have developed a possible antidote according to a March 8,, 2017 news item on phys.org,

Members of the Faculty of Chemistry of the Lomonosov Moscow State University have developed novel nanosized agents that could be used as efficient protective and antidote modalities against the impact of neurotoxic organophosphorus compounds such as pesticides and chemical warfare agents. …

A March 7, 2017 Lomonosov Moscow State University press release on EurekAlert, which originated the news item, describes the work in detail,

A group of scientists from the Faculty of Chemistry under the leadership of Prof. Alexander Kabanov has focused their research supported by a “megagrant” on the nanoparticle-based delivery to an organism of enzymes, capable of destroying toxic organophosphorous compounds. Development of first nanosized drugs has started more than 30 years ago and already in the 90-s first nanomedicines for cancer treatment entered the market. First such medicines were based on liposomes – spherical vesicles made of lipid bilayers. The new technology, developed by Kabanov and his colleagues, uses an enzyme, synthesized at the Lomonosov Moscow State University, encapsulated into a biodegradable polymer coat, based on an amino acid (glutamic acid).

Alexander Kabanov, Doctor of Chemistry, Professor at the Eshelman School of Pharmacy of the University of North Carolina (USA) and the Faculty of Chemistry, M. V. Lomonosov Moscow State University, one of the authors of the article explains: “At the end of the 80-s my team (at that time in Moscow) and independently Japanese colleagues led by Prof. Kazunori Kataoka from Tokyo began using polymer micelles for small molecules delivery. Soon the nanomedicine field has “exploded”. Currently hundreds of laboratories across the globe work in this area, applying a wide variety of approaches to creation of such nanosized agents. A medicine on the basis of polymeric micelles, developed by a Korean company Samyang Biopharm, was approved for human use in 2006.”

Professor Kabanov’s team after moving to the USA in 1994 focused on development of polymer micelles, which could include biopolymers due to electrostatic interactions. Initially chemists were interested in usage of micelles for RNA and DNA delivery but later on scientists started actively utilizing this approach for delivery of proteins and, namely, enzymes, to the brain and other organs.

Alexander Kabanov says: “At the time I worked at the University of Nebraska Medical Center, in Omaha (USA) and by 2010 we had a lot of results in this area. That’s why when my colleague from the Chemical Enzymology Department of the Lomonosov Moscow State University, Prof. Natalia Klyachko offered me to apply for a megagrant the research theme of the new laboratory was quite obvious. Specifically, to use our delivery approach, which we’ve called a “nanozyme”, for “improvement” of enzymes, developed by colleagues at the Lomonosov Moscow State University for its further medical application.”

Scientists together with the group of enzymologists from the Lomonosov Moscow State University under the leadership of Elena Efremenko, Doctor of Biological Sciences, have chosen organophosphorus hydrolase as a one of the delivered enzymes. Organophosphorus hydrolase is capable of degrading toxic pesticides and chemical warfare agents with very high rate. However, it has disadvantages: because of its bacterial origin, an immune response is observed as a result of its delivery to an organism of mammals. Moreover, organophosphorus hydrolase is quickly removed from the body. Chemists have solved this problem with the help of a “self-assembly” approach: as a result of inclusion of organophosphorus hydrolase enzyme in a nanozyme particles the immune response becomes weaker and, on the contrary, both the storage stability of the enzyme and its lifetime after delivery to an organism considerably increase. Rat experiments have proved that such nanozyme efficiently protects organisms against lethal doses of highly toxic pesticides and even chemical warfare agents, such as VX nerve gas.

Alexander Kabanov summarizes: “The simplicity of our approach is very important. You could get an organophosphorus hydrolase nanozyme by simple mixing of aqueous solutions of anenzyme and safe biocompatible polymer. This nanozyme is self-assembled due to electrostatic interaction between a protein (enzyme) and polymer”.

According to the scientist’s words the simplicity and technological effectiveness of the approach along with the obtained promising results of animal experiments bring hope that this modality could be successful and in clinical use.

Members of the Faculty of Chemistry of the Lomonosov Moscow State University, along with scientists from the 27th Central Research Institute of the Ministry of Defense of the Russian Federation, the Eshelman School of Pharmacy of the University of North Carolina at Chapel Hill (USA) and the University of Nebraska Medical Center (UNC) have taken part in the Project.

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

A simple and highly effective catalytic nanozyme scavenger for organophosphorus neurotoxins by Elena N. Efremenko, Ilya V. Lyagin, Natalia L. Klyachko, Tatiana Bronich, Natalia V. Zavyalova, Yuhang Jiang, Alexander V. Kabanov. Journal of Controlled Release Volume 247, 10 February 2017, Pages 175–181  http://dx.doi.org/10.1016/j.jconrel.2016.12.037

This paper is behind a paywall.

Nanotechnology-enabled acupuncture needles

An Oct. 17, 2016 news item on phys.org makes an announcement about nanotechnology-enabled acupuncture needles (Note: The writing style is a little unusual for this kind of announcement),

A Daegu Gyeongbuk Institute of Science and Technology [Korea] research team led by Professor Su-Il In, who developed acupuncture needles combined with nanotechnology, was recognized as the world’s first application of this technology. This development is expected to open new directions in the oriental medicine research field.

Professor Su-Il In’s research team from the Department of Energy Systems Engineering succeeded in developing porous acupuncture needles (hereafter PANs) that offer enhanced therapeutic properties by applying nanotechnology on the acupuncture needles for the first time in the world.

The findings of this experiment, which was conducted in collaboration with DGIST’s research team and the Addiction Control Research Center at Daegu Haany University, have attracted the attention of the relevant academic field in light of the fact that the experiment combined nanotechnology with acupuncture needles.

An Oct. 17, 2016 DGIST press release on EurekAlert, which originated the news item, provides more technical detail,

Professor In’s research team developed PANs with fine pores ranging in sizes from nanometers (nm= one billionth of a meter) to micrometers (? = one millionth of a meter) on the surface of the needles using a nano-electrochemical method.

PANs are formed by anodization, and are characterized by a widened surface of the needles through the following process: anion (F-) contained in the electrolyte bored into the surface of the metal needles (positive) and created fine and uniform pores.

PANs are expected to be as effective as conventional large and long needles by minimizing the sense of pain during acupuncture treatment while expanding the surface area of the needle 20 times greater than conventional acupuncture ones.

Through electrophysiological experiments with rats, In’s research team proved that PANs excel in transferring signals from a spinal dorsal horn by the in vivo stimulation of Shenmen (HT7) points, and in particular, demonstrated that the efficacy of PANs is superior to conventional acupuncture needles in treating alcohol and cocaine addiction in animal experiments.

Applications for international patents for the fabrication technology of PANs developed by DGIST have already been submitted in countries such as the US, China, and Europe. In addition, in the domestic oriental medicine field, the fact that the efficacy of acupuncture needles has been improved through their structural transformation by applying nanotechnology has been recognized and evaluated as the first such instance in the thousand-year history of eastern medicine.

Professor Su-Il In from DGIST’s Department of Energy Systems Engineering said, “The development of nanotechnology has taken science and technology to the next level in various fields such as solar cells, quantum computers, display development, and the like. Based on this experiment’s achievement of combining nanotechnology and oriental medicine, I will continue to conduct research in order to be at the forefront of the scientific population of oriental medicine.”

Director Jae-ha Yang from Daegu Haany University said, “In western medicine, nanotechnology is widely used from diagnosis to treatment; but in eastern medicine, particularly in acupuncture therapy, it is rare to utilize nano science. The findings of this study are expected to open new directions in the field of eastern medicine where nano science is rarely explored and utilized.”

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

Hierarchical Micro/Nano-Porous Acupuncture Needles Offering Enhanced Therapeutic Properties by Su-ll In, Young S. Gwak, Hye Rim Kim, Abdul Razzaq, Kyeong-Seok Lee, Hee Young Kim, SuChan Chang, Bong Hyo Lee, Craig A. Grimes, & Chae Ha Yang. Scientific Reports 6, Article number: 34061 (2016) doi:10.1038/srep34061 Published online: 07 October 2016

This paper is open access.

Glucose-sensing contact lens invented by US and Korean researchers

Blood tests for glucose levels may one day be a feature of the past according to an Oct. 3, 2016 news item on ScienceDaily,

Blood testing is the standard option for checking glucose levels, but a new technology could allow non-invasive testing via a contact lens that samples glucose levels in tears.

“There’s no noninvasive method to do this,” said Wei-Chuan Shih, a researcher with the University of Houston [UH] who worked with colleagues at UH and in Korea to develop the project, described in the high-impact journal Advanced Materials. “It always requires a blood draw. This is unfortunately the state of the art.”

A Sept. 27, 2016 UH news release (also on EurekAlert) by Jeannie Kever, which originated the news item, describes the proposed technology,

… glucose is a good target for optical sensing, and especially for what is known as surface-enhanced Raman scattering spectroscopy [also known as surface-enhanced Raman scattering or surface-enhanced Raman spectroscopy, and SERS], said Shih, an associate professor of electrical and computer engineering whose lab, the NanoBioPhotonics Group, works on optical biosensing enabled by nanoplasmonics.

This is an alternative approach, in contrast to a Raman spectroscopy-based noninvasive glucose sensor Shih developed as a Ph.D. student at the Massachusetts Institute of Technology. He holds two patents for technologies related to directly probing skin tissue using laser light to extract information about glucose concentrations.

The paper describes the development of a tiny device, built from multiple layers of gold nanowires stacked on top of a gold film and produced using solvent-assisted nanotransfer printing, which optimized the use of surface-enhanced Raman scattering to take advantage of the technique’s ability to detect small molecular samples.

Surface-enhanced Raman scattering – named for Indian physicist C.V. Raman [Raman scattering; SERS history begins in 1973 according to its Wikipedia entry], who discovered the effect in 1928 – uses information about how light interacts with a material to determine properties of the molecules that make up the material.

The device enhances the sensing properties of the technique by creating “hot spots,” or narrow gaps within the nanostructure which intensified the Raman signal, the researchers said.

Researchers created the glucose sensing contact lens to demonstrate the versatility of the technology. The contact lens concept isn’t unheard of – Google has submitted a patent for a multi-sensor contact lens, which the company says can also detect glucose levels in tears – but the researchers say this technology would also have a number of other applications.

“It should be noted that glucose is present not only in the blood but also in tears, and thus accurate monitoring of the glucose level in human tears by employing a contact-lens-type sensor can be an alternative approach for noninvasive glucose monitoring,” the researchers wrote.

“Everyone knows tears have a lot to mine,” Shih said. “The question is, whether you have a detector that is capable of mining it, and how significant is it for real diagnostics.”

In addition to Shih, authors on the paper include Yeon Sik Jung, Jae Won Jeong and Kwang-Min Baek, all with the Korea Advanced Institute of Science and Technology; Seung Yong Lee of the Korea Institute of Science and Technology, and Md Masud Parvez Arnob of UH.

Although non-invasive glucose sensing is just one potential application of the technology, Shih said it provided a good way to prove the technology. “It’s one of the grand challenges to be solved,” he said. “It’s a needle in a haystack challenge.”

Scientists know that glucose is present in tears, but Shih said how tear glucose levels correlate with blood glucose levels hasn’t been established. The more important finding, he said, is that the structure is an effective mechanism for using surface-enhanced Raman scattering spectroscopy.

Although traditional nanofabrication techniques rely on a hard substrate – usually glass or a silicon wafer – Shih said researchers wanted a flexible nanostructure, which would be more suited to wearable electronics. The layered nanoarray was produced on a hard substrate but lifted off and printed onto a soft contact, he said.

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

Wafer Scale Phase-Engineered 1T- and 2H-MoSe2/Mo Core–Shell 3D-Hierarchical Nanostructures toward Efficient Electrocatalytic Hydrogen Evolution Reaction by Yindong Qu, Henry Medina, Sheng-Wen Wang, Yi-Chung Wang, Chia-Wei Chen, Teng-Yu Su, Arumugam Manikandan, Kuangye Wang, Yu-Chuan Shih, Je-Wei Chang, Hao-Chung Kuo, Chi-Yung Lee, Shih-Yuan Lu, Guozhen Shen, Zhiming M. Wang, and Yu-Lun Chueh. Advanced Materials DOI: 10.1002/adma.201602697 Version of Record online: 26 SEP 2016

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

This paper is behind a paywall.

Placenta-on-a-chip for research into causes for preterm birth

Preterm birth (premature baby) research has received a boost with this latest work from the University of Pennsylvania. A July 21, 2016 news item on phys.org tells us more,

Researchers at the University of Pennsylvania have developed the first placenta-on-a-chip that can fully model the transport of nutrients across the placental barrier.

A July 21, 2016 University of Pennsylvania news release, which originated the news item, provides more detail about the chip and the research (Note: Links have been removed),

The flash-drive-sized device contains two layers of human cells that model the interface between mother and fetus. Microfluidic channels on either side of those layers allow researchers to study how molecules are transported through, or are blocked by, that interface.

Like other organs-on-chips, such as ones developed to simulate lungs, intestines and eyes, the placenta-on-a-chip provides a unique capability to mimic and study the function of that human organ in ways that have not been possible using traditional tools.

Research on the team’s placenta-on-a-chip is part of a nationwide effort sponsored by the March of Dimes to identify causes of preterm birth and ways to prevent it. Prematurely born babies may experience lifelong, debilitating consequences, but the underlying mechanisms of this condition are not well understood due in part to the difficulties of experimenting with intact, living human placentae.

The research was led by Dan Huh, the Wilf Family Term Assistant Professor of Bioengineering in Penn’s School of Engineering and Applied Science, and Cassidy Blundell, a graduate student in the Huh lab. They collaborated with Samuel Parry, the Franklin Payne Professor of Obstetrics and Gynecology; Christos Coutifaris, the Nancy and Richard Wolfson Professor of Obstetrics and Gynecology in Penn’s Perelman School of Medicine; and Emily Su, assistant professor of obstetrics and gynecology in the Anschutz Medical School of the University of Colorado Denver.

The researchers’ placenta-on-a-chip is a clear silicone device with two parallel microfluidic channels separated by a porous membrane. On one side of those pores, trophoblast cells, which are found at the placental interface with maternal blood, are grown. On the other side are endothelial cells, found on the interior of fetal blood vessels. The layers of those two cell types mimic the placental barrier, the gatekeeper between the maternal and fetal circulatory systems.

“That barrier,” Blundell said, “mediates all transport between mother and fetus during pregnancy. Nutrients, but also foreign agents like viruses, need to be either transported by that barrier or stopped.”

“One of the most important function of the placental barrier is transport,” Huh said, “so it’s essential for us to mimic that functionality.”

In 2013, Huh and his collaborators at Seoul National University conducted a preliminary study to create a microfluidic device for culturing trophoblast cells and fetal endothelial cells. This model, however, lacked the ability to form physiological placental tissue and accurately simulate transport function of the placental barrier.

In their new study, the Penn researchers have demonstrated that the two layers of cells continue to grow and develop while inside the chip, undergoing a process known as “syncytialization.”

“The placental cells change over the course of pregnancy,” Huh said. “During pregnancy, the placental trophoblast cells actually fuse with one another to form an interesting tissue called syncytium. The barrier also becomes thinner as the pregnancy progresses, and with our new model we’re able to reproduce this change.

“This process is very important because it affects placental transport and was a critical aspect not represented in our previous model.”

The Penn team validated the new model by showing glucose transfer rates across this syncytialized barrier matched those measured in perfusion studies of donated human placentae.

While useful in providing this type of baseline, donated placental tissue can be problematic for doing many of the types of studies necessary for fully understanding the structure and function of the placenta, especially as it pertains to diseases and disorders.

“The placenta is arguably the least understood organ in the human body,” Huh said, “and much remains to be learned about how transport between mother and fetus works at the tissue, cellular and molecular levels. An isolated whole organ is an not ideal platform for these types of mechanistic studies.”

“Beyond the scarcity of samples,” Blundell said, “there’s a limited lifespan of how long the tissue remains viable, for only a few hours after delivery, and the system that is used to perfuse the tissue and perform transport studies is complex.”

While the placenta-on-a-chip is still in the early stages of testing, researchers at Penn and beyond are already planning to use it in studies on preterm birth.

“This effort,” Parry said, “was part of the much larger Prematurity Research Center here at Penn, one of five centers around the country funded by the March of Dimes to study the causes of preterm birth. The rate of preterm birth is about 10 to 11 percent of all pregnancies. That rate has not been decreasing, and interventions to prevent preterm birth have been largely unsuccessful.”

As part of a $10 million grant from the March of Dimes that established the Center, Parry and his colleagues research metabolic changes that may be associated with preterm birth using in vitro placental cell lines and ex vivo placental tissue. The grant also supported their work with the Huh lab to develop new tools that could model preterm birth-associated placental dysfunction and inform such research efforts.

“Since publishing this paper,” Samuel Parry said, “we’ve reached out to the principal investigators at the other four March of Dimes sites and offered to provide them this model to use in their experiments.”

“Eventually,” Huh said, “we hope to leverage the unique capabilities of our model to demonstrate the potential of organ-on-a-chip technology as a new strategy to innovate basic and translational research in reproductive biology and medicine.”

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

A microphysiological model of the human placental barrier by Cassidy Blundell, Emily R. Tess, Ariana S. R. Schanzer, Christos Coutifaris, Emily J. Su, Samuel Parry. and Dongeun Huh. Lab Chip, 2016, Advance Article DOI: 10.1039/C6LC00259E First published online 20 May 2016

I believe this paper is behind a paywall.

One final note, I thought this was a really well written news release.

Not exactly ‘Prey’: self-organizing materials that can mimic swarm behaviour

Prey, a 2002 novel by Michael Crichton, focused on nanotechnology and other emerging technologies and how their development could lead to unleashing swarms of nanobots with agendas of their own. Crichton’s swarms had collective artificial intelligence, and could massive themselves together to take on different macroscale shapes to achieve their own ends. This latest development has nowhere near that potential—not yet and probably never. From a July 21, 2016 news item on ScienceDaily,

A new study by an international team of researchers, affiliated with Ulsan National Institute of Science and Technology (UNIST) [Korea] has announced that they have succeeded in demonstarting control over the interactions occurring among microscopic spheres, which cause them to self-propel into swarms, chains, and clusters.

The research published in the current online edition of Nature Materials takes lessons from cooperation in nature, including that observed in honey bee swarms and bacterial clusters. In the study, the team has successfully demonstrated the self-organizing pattern formation in active materials at microscale by modifying only one parameter.

A July 21, 2016 UNIST press release, which originated the news item, expands on the theme,

This breakthrough comes from a research, conducted by Dr. Steve Granick (School of Natural Science, UNIST) of IBS Center for Soft and Living Matter in collaboration with Dr. Erik Luijten from Northwestern University. Ming Han, a PhD student in Luijten’s laboratory, and Jing Yan, a former graduate student at the University of Illinois, served as co-first authors of the paper.

Researchers expect that such active particles could open a new class of technologies with applications in medicine, chemistry, and engineering as well as advance scientists’ fundamental understanding of collective, dynamic behavior in systems.

According to the research team, the significance of team work was stressed by both Dr. Luijten and Dr. Granick as this current breakthrough is part of a longtime partnership using a new class of soft-matter particles known as Janus colloids, which Dr. Granick had earlier created in his laboratory. The theoretical computer simulations were completed by the team, led by Dr. Luijten and Dr. Granick used these colloids to experimentally test the collective, dynamic behavior in the laboratory.

The micron-sized spheres, typically suspended in solution, were named after the Roman god with two faces as they have attractive interactions on one side and negative charges on the other side.

The electrostatic interactions between the two sides of the self-propelled spheres could be manipulated by subjecting the colloids to an electric field. Some experienced stronger repulsions between their forward-facing sides, while others went through the opposite. Along with them, another set remained completely neutral. This imbalance caused the self-propelled particles to swim and self-organize into one of the following patterns, which are swarms, chains, clusters and isotropic gases.

To avoid head-to-head collisions, head-repulsive particles swam side-by-side, forming into swarms. Depending on the electric-field frequency, tail-repulsive particles positioned their tails apart, thus encouraging them to face each other to form jammed clusters of high local density. Also, swimmers with equal-and-opposite charges attracted one another into connected chains.

Dr. Granick states, “This truly is a joint work of the technological know-how by the Korean IBS and the University of Illinois, as well as the computer simulations technology by Northwestern University.” He expects that this breakthrough has probable application in sensing, drug delivery, or even microrobotics.

With this discovery, a drug could be placed within particles, for instance, that cluster into the delivery spot. Moreover, alterations in the environment could be perceived if the system unexpectedly switches from swarming to forming chains.

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

Reconfiguring active particles by electrostatic imbalance by Jing Yan, Ming Han, Jie Zhang, Cong Xu, Erik Luijten, & Steve Granick. Nature Materials (2016)  doi:10.1038/nmat4696 Published online 11 July 2016

This paper is behind a paywall.