Tag Archives: bottom-up engineering

Making better concrete by looking to nature for inspiration

Researchers from the Masssachusetts Institute of Technology (MIT) are working on a new formula for concrete based on bones, shells, and other such natural materials. From a May 25, 2016 news item on Nanowerk (Note: A link has been removed),

Researchers at MIT are seeking to redesign concrete — the most widely used human-made material in the world — by following nature’s blueprints.

In a paper published online in the journal Construction and Building Materials (“Roadmap across the mesoscale for durable and sustainable cement paste – A bioinspired approach”), the team contrasts cement paste — concrete’s binding ingredient — with the structure and properties of natural materials such as bones, shells, and deep-sea sponges. As the researchers observed, these biological materials are exceptionally strong and durable, thanks in part to their precise assembly of structures at multiple length scales, from the molecular to the macro, or visible, level.

A May 26, 2016 MIT news release (also on EurekAlert), which originated the news item, provides more detail,

From their observations, the team, led by Oral Buyukozturk, a professor in MIT’s Department of Civil and Environmental Engineering (CEE), proposed a new bioinspired, “bottom-up” approach for designing cement paste.

“These materials are assembled in a fascinating fashion, with simple constituents arranging in complex geometric configurations that are beautiful to observe,” Buyukozturk says. “We want to see what kinds of micromechanisms exist within them that provide such superior properties, and how we can adopt a similar building-block-based approach for concrete.”

Ultimately, the team hopes to identify materials in nature that may be used as sustainable and longer-lasting alternatives to Portland cement, which requires a huge amount of energy to manufacture.

“If we can replace cement, partially or totally, with some other materials that may be readily and amply available in nature, we can meet our objectives for sustainability,” Buyukozturk says.

“The merger of theory, computation, new synthesis, and characterization methods have enabled a paradigm shift that will likely change the way we produce this ubiquitous material, forever,” Buehler says. “It could lead to more durable roads, bridges, structures, reduce the carbon and energy footprint, and even enable us to sequester carbon dioxide as the material is made. Implementing nanotechnology in concrete is one powerful example [of how] to scale up the power of nanoscience to solve grand engineering challenges.”

From molecules to bridges

Today’s concrete is a random assemblage of crushed rocks and stones, bound together by a cement paste. Concrete’s strength and durability depends partly on its internal structure and configuration of pores. For example, the more porous the material, the more vulnerable it is to cracking. However, there are no techniques available to precisely control concrete’s internal structure and overall properties.

“It’s mostly guesswork,” Buyukozturk says. “We want to change the culture and start controlling the material at the mesoscale.”

As Buyukozturk describes it, the “mesoscale” represents the connection between microscale structures and macroscale properties. For instance, how does cement’s microscopic arrangement affect the overall strength and durability of a tall building or a long bridge? Understanding this connection would help engineers identify features at various length scales that would improve concrete’s overall performance.

“We’re dealing with molecules on the one hand, and building a structure that’s on the order of kilometers in length on the other,” Buyukozturk says. “How do we connect the information we develop at the very small scale, to the information at the large scale? This is the riddle.”

Building from the bottom, up

To start to understand this connection, he and his colleagues looked to biological materials such as bone, deep sea sponges, and nacre (an inner shell layer of mollusks), which have all been studied extensively for their mechanical and microscopic properties. They looked through the scientific literature for information on each biomaterial, and compared their structures and behavior, at the nano-, micro-, and macroscales, with that of cement paste.

They looked for connections between a material’s structure and its mechanical properties. For instance, the researchers found that a deep sea sponge’s onion-like structure of silica layers provides a mechanism for preventing cracks. Nacre has a “brick-and-mortar” arrangement of minerals that generates a strong bond between the mineral layers, making the material extremely tough.

“In this context, there is a wide range of multiscale characterization and computational modeling techniques that are well established for studying the complexities of biological and biomimetic materials, which can be easily translated into the cement community,” says Masic.

Applying the information they learned from investigating biological materials, as well as knowledge they gathered on existing cement paste design tools, the team developed a general, bioinspired framework, or methodology, for engineers to design cement, “from the bottom up.”

The framework is essentially a set of guidelines that engineers can follow, in order to determine how certain additives or ingredients of interest will impact cement’s overall strength and durability. For instance, in a related line of research, Buyukozturk is looking into volcanic ash [emphasis mine] as a cement additive or substitute. To see whether volcanic ash would improve cement paste’s properties, engineers, following the group’s framework, would first use existing experimental techniques, such as nuclear magnetic resonance, scanning electron microscopy, and X-ray diffraction to characterize volcanic ash’s solid and pore configurations over time.

Researchers could then plug these measurements into models that simulate concrete’s long-term evolution, to identify mesoscale relationships between, say, the properties of volcanic ash and the material’s contribution to the strength and durability of an ash-containing concrete bridge. These simulations can then be validated with conventional compression and nanoindentation experiments, to test actual samples of volcanic ash-based concrete.

Ultimately, the researchers hope the framework will help engineers identify ingredients that are structured and evolve in a way, similar to biomaterials, that may improve concrete’s performance and longevity.

“Hopefully this will lead us to some sort of recipe for more sustainable concrete,” Buyukozturk says. “Typically, buildings and bridges are given a certain design life. Can we extend that design life maybe twice or three times? That’s what we aim for. Our framework puts it all on paper, in a very concrete way, for engineers to use.”

This is not the only team looking at new methods for producing the material, my Dec. 24, 2012 posting features a number of ‘concrete’ research projects.

Also, I highlighted the reference to ‘volcanic ash’ as it reminded me of Roman concrete which has lasted for over 2000 years and includes volcanic sand and volcanic rock.  You can read more about it in a Dec. 18, 2014 article by Mark Miller for Ancient Origins where he describes the wonders of the material and what was then a recent discovery of the Romans’ recipe.

I have two links and citations, first, the MIT paper, then the paper on Roman concrete.

Roadmap across the mesoscale for durable and sustainable cement paste – A bioinspired approach by Steven D. Palkovic, Dieter B. Brommer, Kunal Kupwade-Patil, Admir Masic, Markus J. Buehler, Oral Büyüköztürk.Construction and Building Materials Volume 115, 15 July 2016, Pages 13–31.  doi:10.1016/j.conbuildmat.2016.04.020

Mechanical resilience and cementitious processes in Imperial Roman architectural mortar by Marie D. Jackson, Eric N. Landis, Philip F. Brune, Massimo Vitti, Heng Chen, Qinfei Li, Martin Kunz, Hans-Rudolf Wenk, Paulo J. M. Monteiro, and Anthony R. Ingraffea. Proceedings of the National Academy of Sciences  vol. 111 no. 52 18484–18489, doi: 10.1073/pnas.1417456111

The first paper is behind a paywall but the second one appears to be open access.

Injectable medicine made safer?

The lede for this May 19, 2016 news item on Nanowerk is great,

Bring the drugs, hold the suds.

The May 19, 2016 University of Buffalo news release (also on EurekAlert) by Cory Nealon, which originated the news item, quickly gets to the point,

That summarizes a promising new drug-making technique designed to reduce serious allergic reactions and other side effects from anti-cancer medicine, testosterone and other drugs that are administered with a needle.

Developed by University at Buffalo researchers, the breakthrough removes potentially harmful additives – primarily soapy substances known as surfactants – from common injectable drugs.

“We’re excited because this process can be scaled up, which could make existing injectable drugs safer and more effective for millions of people suffering from serious diseases and ailments,” says Jonathan F. Lovell, a biomedical engineer at UB and the study’s corresponding author.

Pharmaceutical companies use surfactants to dissolve medicine into a liquid solution, a process that makes medicine suitable for injection. While effective, the process is seldom efficient. Solutions loaded with surfactant and other nonessential ingredients can carry the risk of causing anaphylactic shock, blood clotting, hemolysis and other side effects.

Researchers have tried to address this problem in two ways, each with varying degrees of success.

Some have taken the so-called “top down” approach, in which they shrink drug particles to nanoscale sizes to eliminate excess additives. While promising, the method doesn’t work well in injectable medicine because the drug particles are still too large to safely inject.

Other researchers work from the “bottom up” using nanotechnology to build new drugs from scratch. This may yield tremendous results; however, developing new drug formulations takes years, and drugs are coupled with new additives that create new side effects.

The technique under development at UB differs because it improves existing injectable drug-making methods by taking the unusual step of stripping away all of the excess surfactant.

In laboratory experiments, researchers dissolved 12 drugs – cabazitaxel (anti-cancer), testosterone, cyclosporine (an immunosuppressant used during organ transplants) and others – one at a time into a surfactant called Pluronic. Then, by lowering the solution’s temperature to 4 degrees Celsius (most drugs are made at room temperature), they were able to remove the excess Pluronic via a membrane.

The end result are drugs that contain 100 to 1,000 times less excess additives.

“For the drugs we looked at, this is as close as anyone has gotten to introducing pure, injectable medicine into the body,” says Lovell, PhD, assistant professor in the Department of Biomedical Engineering in UB’s School of Engineering and Applied Sciences. “Essentially, it’s a new way to package drugs.”

The findings are significant, he says, because they show that many injectable drug formulations may be improved through an easy-to-adopt process. Future experiments are planned to further refine the method, he says.

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

Therapeutic surfactant-stripped frozen micelles by Yumiao Zhang, Wentao Song, Jumin Geng, Upendra Chitgupi, Hande Unsal, Jasmin Federizon, Javid Rzayev, Dinesh K. Sukumaran, Paschalis Alexandridis, & Jonathan F. Lovell. Nature Communications 7, Article number: 11649 doi:10.1038/ncomms11649 Published 19 May 2016

This is an open access paper.

A few years back, a friend got a flu shot and became ill (not the flu). Suspicions  (my friend is a doctor) centered on the additives in the shot as that particular year a number of people got sick from the shot.

#BCTECH: being at the Summit (Jan. 18-19, 2016)

#BCTECH Summit 2016*, a joint event between the province of British Columbia (BC, Canada) and the BC Innovation Council (BCIC), a crown corporation formerly known as the Science Council of British Columbia, launched on Jan. 18, 2016. I have written a preview (Jan. 17, 2016 post) and a commentary on the new #BCTECH strategy (Jan. 19, 2016 posting) announced by British Columbia Premier, Christy Clark, on the opening day (Jan. 18, 2016) of the summit.

I was primarily interested in the trade show/research row/technology showcase aspect of the summit focusing (but not exclusively) on nanotechnology. Here’s what I found,

Nano at the Summit

  • Precision NanoSystems: fabricates equipment which allows researchers to create polymer nanoparticles for delivering medications.

One of the major problems with creating nanoparticles is ensuring a consistent size and rapid production. According to Shell Ip, a Precision NanoSystems field application scientist, their NanoAssemblr Platform has solved the consistency problem and a single microfluidic cartridge can produce 15 ml in two minutes. Cartridges can run in parallel for maximum efficiency when producing nanoparticles in greater quantity.

The NanoAssemblr Platform is in use in laboratories around the world (I think the number is 70) and you can find out more on the company’s About our technology webpage,

The NanoAssemblr™ Platform

The microfluidic approach to particle formulation is at the heart of the NanoAssemblr Platform. This well-controlled process mediates bottom-up self-assembly of nanoparticles with reproducible sizes and low polydispersity. Users can control size by process and composition, and adjust parameters such as mixing ratios, flow rate and lipid composition in order to fine-tune nanoparticle size, encapsulation efficiency and much more. The system technology enables manufacturing scale-up through microfluidic reactor parallelization similar to the arraying of transistors on an integrated chip. Superior design ensures that the platform is fast and easy to use with a software controlled manufacturing process. This usability allows for the simplified transfer of manufacturing protocols between sites, which accelerates development, reduces waste and ultimately saves money. Precision NanoSystems’ flagship product is the NanoAssemblr™ Benchtop Instrument, designed for rapid prototyping of novel nanoparticles. Preparation time on the system is streamlined to approximately one minute, with the ability to complete 30 formulations per day in the hands of any user.

The company is located on property known as the Endowment Lands or, more familiarly, the University of British Columbia (UBC).

A few comments before moving on, being able to standardize the production of medicine-bearing nanoparticles is a tremendous step forward which is going to help scientists dealing with other issues. Despite all the talk in the media about delivering nanoparticles with medication directly to diseased cells, there are transport issues: (1) getting the medicine to the right location/organ and (2) getting the medicine into the cell. My Jan. 12, 2016 posting featured a project with Malaysian scientists and a team at Harvard University who are tackling the transport and other nanomedicine) issues as they relate to the lung. As well, I have a Nov. 26, 2015 posting which explores a controversy about nanoparticles getting past the ‘cell walls’ into the nucleus of the cell.

The next ‘nano’ booths were,

  • 4D Labs located at Simon Fraser University (SFU) was initially hailed as a nanotechnology facility but these days they’re touting themselves as an ‘advanced materials’ facility. Same thing, different branding.

They advertise services including hands-on training for technology companies and academics. There is a nanoimaging facility and nanofabrication facility, amongst others.

I spoke with their operations manager, Nathaniel Sieb who mentioned a few of the local companies that use their facilities. (1) Nanotech Security (featured here most recently in a Dec. 29, 2015 post), an SFU spinoff company, does some of their anticounterfeiting research work at 4D Labs. (2) Switch Materials (a smart window company, electrochromic windows if memory serves) also uses the facilities. It is Neil Branda’s (4D Labs Executive Director) company and I have been waiting impatiently (my May 14, 2010 post was my first one about Switch) for either his or someone else’s electrochromic windows (they could eliminate or reduce the need for air conditioning during the hotter periods and reduce the need for heat in the colder periods) to come to market. Seib tells me, I’ll have to wait longer for Switch. (3) A graduate student was presenting his work at the booth, a handheld diagnostic device that can be attached to a smartphone to transmit data to the cloud. While the first application is for diabetics, there are many other possibilities. Unfortunately, glucose means you need to produce blood for the test when I suggested my preference for saliva the student explained some of the difficulties. Apparently, your saliva changes dynamically and frequently and something as simple as taking a sip of orange juice could result in a false reading. Our conversation (mine, Seib’s and the student’s) also drifted over into the difficulties of bringing products to market. Sadly, we were not able to solve that problem in our 10 minute conversation.

  • FPInnovations is a scientific research centre and network for the forestry sector. They had a display near their booth which was like walking into a peculiar forest (I was charmed). The contrast with the less imaginative approaches all around was striking.

FPInnovation helped to develop cellulose nanocrystals (CNC), then called nanocrystalline cellulose (NCC), and I was hoping to be updated about CNC and about the spinoff company Celluforce. The researcher I spoke to was from Sweden and his specialty was business development. He didn’t know much about CNC in Canada and when I commented on how active Sweden has been its pursuit of a CNC application, he noted Finland has been the most active. The researcher noted that making the new materials being derived from the forest, such as CNC, affordable and easily produced for use in applications that have yet to be developed are all necessities and challenges. He mentioned that cultural changes also need to take place. Canadians are accustomed to slicing away and discarding most of the tree instead of using as much of it as possible. We also need to move beyond the construction and pulp & paper sectors (my Feb. 15, 2012 posting featured nanocellulose research in Sweden where sludge was the base material).

Other interests at the Summit

I visited:

  • “The Wearable Lower Limb Anthropomorphic Exoskeleton (WLLAE) – a lightweight, battery-operated and ergonomic robotic system to help those with mobility issues improve their lives. The exoskeleton features joints and links that correspond to those of a human body and sync with motion. SFU has designed, manufactured and tested a proof-of-concept prototype and the current version can mimic all the motions of hip joints.” The researchers (Siamak Arzanpour and Edward Park) pointed out that the ability to mimic all the motions of the hip is a big difference between their system and others which only allow the leg to move forward or back. They rushed the last couple of months to get this system ready for the Summit. In fact, they received their patent for the system the night before (Jan. 17, 2016) the Summit opened.

It’s the least imposing of the exoskeletons I’ve seen (there’s a description of one of the first successful exoskeletons in a May 20, 2014 posting; if you scroll down to the end you’ll see an update about the device’s unveiling at the 2014 World Cup [soccer/football] in Brazil).

Unfortunately, there aren’t any pictures of WLLAE yet and the proof-of-concept version may differ significantly from the final version. This system could be used to help people regain movement (paralysis/frail seniors) and I believe there’s a possibility it could be used to enhance human performance (soldiers/athletes). The researchers still have some significant hoops to jump before getting to the human clinical trial stage. They need to refine their apparatus, ensure that it can be safely operated, and further develop the interface between human and machine. I believe WLLAE is considered a neuroprosthetic device. While it’s not a fake leg or arm, it enables movement (prosthetic) and it operates on brain waves (neuro). It’s a very exciting area of research, consequently, there’s a lot of international competition. [ETA January 3, 2024: I’m pretty sure I got the neuroprosthetic part wrong]

  • Delightfully, after losing contact for a while, I reestablished it with the folks (Sean Lee, Head External Relations and Jim Hanlon, Chief Administrative Officer) at TRIUMF (Canada’s national laboratory for particle and nuclear physics). It’s a consortium of 19 Canadian research institutions (12 full members and seven associate members).

It’s a little disappointing that TRIUMF wasn’t featured in the opening for the Summit since the institution houses theoretical, experimental, and applied science work. It’s a major BC (and Canada) science and technology success story. My latest post (July 16, 2015) about their work featured researchers from California (US) using the TRIUMF cyclotron for imaging nanoscale materials and, on the more practical side, there’s a Mar. 6, 2015 posting about their breakthrough for producing nuclear material-free medical isotopes. Plus, Maclean’s Magazine ran a Jan. 3, 2016 article by Kate Lunau profiling an ‘art/science’ project that took place at TRIUMF (Note: Links have been removed),

It’s not every day that most people get to peek inside a world-class particle physics lab, where scientists probe deep mysteries of the universe. In September [2015], Vancouver’s TRIUMF—home to the world’s biggest cyclotron, a type of particle accelerator—opened its doors to professional and amateur photographers, part of an event called Global Physics Photowalk 2015. (Eight labs around the world participated, including CERN [European particle physics laboratory], in Geneva, where the Higgs boson particle was famously discovered.)

Here’s the local (Vancouver) jury’s pick for the winning image (from the Nov. 4, 2015 posting [Winning Photographs Revealed] by Alexis Fong on the TRIUMF website),

Caption: DESCANT (at TRIUMF) neutron detector array composed of 70 hexagonal detectors Credit: Pamela Joe McFarlane

Caption: DESCANT (at TRIUMF) neutron detector array composed of 70 hexagonal detectors Credit: Pamela Joe McFarlane

With all those hexagons and a spherical shape, the DESCANT looks like a ‘buckyball’ or buckminsterfullerene or C60  to me.

I hope the next Summit features TRIUMF and/or some other endeavours which exemplify, Science, Technology, and Creativity in British Columbia and Canada.

Onto the last booth,

  • MITACS was originally one of the Canadian federal government’s Network Centres for Excellence projects. It was focused on mathematics, networking, and innovation but once the money ran out the organization took a turn. These days, it’s describing itself as (from their About page) “a national, not-for-profit organization that has designed and delivered research and training programs in Canada for 15 years. Working with 60 universities, thousands of companies, and both federal and provincial governments, we build partnerships that support industrial and social innovation in Canada.”Their Jan. 19, 2016 news release (coincidental with the #BCTECH Summit, Jan. 18 – 19, 2016?) features a new report about improving international investment in Canada,”Opportunities to improve Canada’s attractiveness for R&D investment were identified:1.Canada needs to better incentivize R&D by rebalancing direct and indirect support measures

    2.Canada requires a coordinated, client-centric approach to incentivizing R&D

    3.Canada needs to invest in training programs that grow the knowledge economy”

    Oddly, entrepreneurial/corporate/business types never have a problem with government spending when the money is coming to them; it’s only a problem when it’s social services.

    Back to MITACS, one of their more interesting (to me) projects was announced at the 2015 Canadian Science Policy Conference. MITACS has inaugurated a Canadian Science Policy Fellowships programme which in its first year (pilot) will see up up to 10 academics applying their expertise to policy-making while embedded in various federal government agencies. I don’t believe anything similar has occurred here in Canada although, if memory serves, the Brits have a similar programme.

    Finally, I offer kudos to Sherry Zhao, MITACS Business Development Specialist, the only person to ask me how her organization might benefit my business. Admittedly I didn’t talk to a lot of people but it’s striking to me that at an ‘innovation and business’ tech summit, only one person approached me about doing business.  Of course, I’m not a male aged between 25 and 55. So, extra kudos to Sherry Zhao and MITACS.

Christy Clark (Premier of British Columbia), in her opening comments, stated 2800 (they were expecting about 1000) had signed up for the #BCTECH Summit. I haven’t been able to verify that number or get other additional information, e.g., business deals, research breakthroughs, etc. announced at the Summit. Regardless, it was exciting to attend and find out about the latest and greatest on the BC scene.

I wish all the participants great and good luck and look forward to next year’s where perhaps we’ll here about how the province plans to help with the ‘manufacturing middle’ issue. For new products you need to have facilities capable of reproducing your devices at a speed that satisfies your customers; see my Feb. 10, 2014 post featuring a report on this and other similar issues from the US General Accountability Office.

*’BCTECH Summit 2016′ link added Jan. 21, 2016.

Self-assembly with porphine molecules

A Jan. 12, 2016 American Institute of Physics (AIP) news release by John Arnst (also on EurekAlert but dated Jan. 14, 2016) describes computational research into self-assembling nanodevices based on porphine molecules,

As we continue to shrink electronic components, top-down manufacturing methods begin to approach a physical limit at the nanoscale. Rather than continue to chip away at this limit, one solution of interest involves using the bottom-up self-assembly of molecular building blocks to build nanoscale devices.

Successful self-assembly is an elaborately choreographed dance, in which the attractive and repulsive forces within molecules, between each molecule and its neighbors, and between molecules and the surface that supports them, have to all be taken into account. To better understand the self-assembly process, researchers at the Technical University of Munich have characterized the contributions of all interaction components, such as covalent bonding and van der Waals interactions between molecules and between molecules and a surface.

“In an ideal case, the smallest possible device has the size of a single atom or molecule,” said Katharina Diller, who worked as a postdoctoral researcher in the group of Karsten Reuter at the Technical University of Munich. Reuter and his colleagues present their work this week in The Journal of Chemical Physics, from AIP Publishing.

One such example is a single-porphyrin switch, which occupies a surface area of only one square nanometer. [emphasis mine] The porphine molecule, which was the object of this study, is even smaller than this. Porphyrins are a group of ringed chemical compounds which notably include heme – responsible for transporting oxygen and carbon dioxide in the bloodstream – and chlorophyll. In synthetically-derived applications, porphyrins are studied for their potential uses as sensors, light-sensitive dyes in organic solar cells, and molecular magnets.

The researchers from TU Munich assessed the interactions of the porphyrin molecule 2H-porphine by using density functional theory, a quantum mechanical computational modelling method used to describe the electronic properties of molecules and materials. Their simulations were performed at the high-performance supercomputer SuperMUC at Leibniz-Rechenzentrum in Garching.

The metallic substrates the researchers chose for the porphyrin molecules to assemble on, the close packed single crystal surfaces of copper and silver, are widely used as substrates in surface science. This is due to the densely packed nature of the surfaces, which allow the molecules to exhibit a smooth adsorption environment. Additionally, copper and silver each react differently with porhyrins – the molecule adsorbs more strongly on copper, whereas silver does a better job of keeping the electronic structure of the molecule intact – allowing the researchers to monitor a variety of competing effects for future applications.

In their simulation, porphyrin molecules were placed on a copper or silver slab, which was repeated periodically to simulate an extended surface. After finding the optimal geometry in which the molecules would adsorb on the surface, the researchers altered the size of the metal slab to increase or decrease the distance between molecules, thus simulating different molecular coverages. The computational setup gave them a switch to turn the energy contributions of neighboring molecules on and off, in order to observe the interplay of the individual interactions.

Diller and Reuter, along with colleagues Reinhard Maurer and Moritz Müller, who is first author on the paper, found that the weak long-range van der Waals interactions yielded the largest contribution to the molecule-surface interaction, and showed that the often employed methods to quantify the electronic charges in the system have to be used with caution. Surprisingly, while interactions directly between molecules are negligible, the researcher found indications for surface-mediated molecule-molecule interactions at higher molecular coverages.

“The analysis of the electronic structure and the individual interaction components allows us to better understand the self-assembly of porphine adsorbed on copper and silver, and additionally enables predictions for more complex porphyrine analogues,” Diller said. “These conclusions, however, come without yet considering the effects of atomic motion at finite temperature, which we did not study in this work.”

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

Interfacial charge rearrangement and intermolecular interactions: Density-functional theory study of free-base porphine adsorbed on Ag(111) and Cu(111) by Moritz Müller, Katharina Diller, Reinhard J. Maurer, and Karsten Reuter. J. Chem. Phys. 144, 024701 (2016); http://dx.doi.org/10.1063/1.4938259

This paper appears to be open access.

Finally, the researchers have made this illustrative diagram titled ‘Energy’ available,

Caption: Schematic depiction of different energy terms contributing to the adsorption energy, and charge density difference of 2H-P after adsorption onto Cu(111) at 12.8 Angstrom separation. Credit: M. Müller/TU Munich

Caption: Schematic depiction of different energy terms contributing to the adsorption energy, and charge density difference of 2H-P after adsorption onto Cu(111) at 12.8 Angstrom separation. Credit: M. Müller/TU Munich

Controlling crystal growth for plastic electronics

A July 4, 2013 news item on Nanowerk highlights research into plastic electronics taking place at Imperial College London (ICL), Note: A link has been removed,

Scientists have discovered a way to better exploit a process that could revolutionise the way that electronic products are made.

The scientists from Imperial College London say improving the industrial process, which is called crystallisation, could revolutionise the way we produce electronic products, leading to advances across a whole range of fields; including reducing the cost and improving the design of plastic solar cells.

The process of making many well-known products from plastics involves controlling the way that microscopic crystals are formed within the material. By controlling the way that these crystals are grown engineers can determine the properties they want such as transparency and toughness. Controlling the growth of these crystals involves engineers adding small amounts of chemical additives to plastic formulations. This approach is used in making food boxes and other transparent plastic containers, but up until now it has not been used in the electronics industry.

The team from Imperial have now demonstrated that these additives can also be used to improve how an advanced type of flexible circuitry called plastic electronics is made.

The team found that when the additives were included in the formulation of plastic electronic circuitry they could be printed more reliably and over larger areas, which would reduce fabrication costs in the industry.

The team reported their findings this month in the journal Nature Materials (“Microstructure formation in molecular and polymer semiconductors assisted by nucleation agents”).

The June 7, 2013 Imperial College London news release by Joshua Howgego, which originated the news item, describes the researchers and the process in more detail,

Dr Natalie Stingelin, the leader of the study from the Department of Materials and Centre of Plastic Electronics at Imperial, says:

“Essentially, we have demonstrated a simple way to gain control over how crystals grow in electrically conducting ‘plastic’ semiconductors. Not only will this help industry fabricate plastic electronic devices like solar cells and sensors more efficiently. I believe it will also help scientists experimenting in other areas, such as protein crystallisation, an important part of the drug development process.”

Dr Stingelin and research associate Neil Treat looked at two additives, sold under the names IrgaclearÒ XT 386 and MilladÒ 3988, which are commonly used in industry. These chemicals are, for example, some of the ingredients used to improve the transparency of plastic drinking bottles. The researchers experimented with adding tiny amounts of these chemicals to the formulas of several different electrically conducting plastics, which are used in technologies such as security key cards, solar cells and displays.

The researchers found the additives gave them precise control over where crystals would form, meaning they could also control which parts of the printed material would conduct electricity. In addition, the crystallisations happened faster than normal. Usually plastic electronics are exposed to high temperatures to speed up the crystallisation process, but this can degrade the materials. This heat treatment treatment is no longer necessary if the additives are used.

Another industrially important advantage of using small amounts of the additives was that the crystallisation process happened more uniformly throughout the plastics, giving a consistent distribution of crystals.  The team say this could enable circuits in plastic electronics to be produced quickly and easily with roll-to-roll printing procedures similar to those used in the newspaper industry. This has been very challenging to achieve previously.

Dr Treat says: “Our work clearly shows that these additives are really good at controlling how materials crystallise. We have shown that printed electronics can be fabricated more reliably using this strategy. But what’s particularly exciting about all this is that the additives showed fantastic performance in many different types of conducting plastics. So I’m excited about the possibilities that this strategy could have in a wide range of materials.”

Dr Stingelin and Dr Treat collaborated with scientists from the University of California Santa Barbara (UCSB), and the National Renewable Energy Laboratory in Golden, US, and the Swiss Federal Institute of Technology on this study. The team are planning to continue working together to see if subtle chemical changes to the additives improve their effects – and design new additives.

There are some big plans for this discovery, from the news release,

They [the multinational team from ICL, UCSB, National Renewable Energy Laboratory, and Swiss Federal Institute of Technology]  will be working with the new Engineering and Physical Sciences Research Council (EPSRC)-funded Centre for Innovative Manufacturing in Large Area Electronics in order to drive the industrial exploitation of their process. The £5.6 million of funding for this centre, to be led by researchers from Cambridge University, was announced earlier this year [2013]. They are also exploring collaborations with printing companies with a view to further developing their circuit printing technique.

For the curious, here’s a link to and a citation for the published paper,

Microstructure formation in molecular and polymer semiconductors assisted by nucleation agents by Neil D. Treat, Jennifer A. Nekuda Malik, Obadiah Reid, Liyang Yu, Christopher G. Shuttle, Garry Rumbles, Craig J. Hawker, Michael L. Chabinyc, Paul Smith, & Natalie Stingelin. Nature Materials 12, 628–633 (2013) doi:10.1038/nmat3655 Published online 02 June 2013

This article is open access (at least for now).

A twist in my DNA

Professor Hao Yan’s team at Arizona State University (ASU) has created some new 2D and 3D DNA objects according to a Mar. 21, 2013 news release on EurekAlert,

In their latest twist to the technology, Yan’s team made new 2-D and 3-D objects that look like wire-frame art of spheres as well as molecular tweezers, scissors, a screw, hand fan, and even a spider web.

The Yan lab, which includes ASU Biodesign Institute colleagues Dongran Han, Suchetan Pal, Shuoxing Jiang, Jeanette Nangreave and assistant professor Yan Liu, published their results in the March 22 issue of Science.

Here’s where the twist comes in,

The twist in their ‘bottom up,’ molecular Lego design strategy focuses on a DNA structure called a Holliday junction. In nature, this cross-shaped, double-stacked DNA structure is like the 4-way traffic stop of genetics — where 2 separate DNA helices temporality meet to exchange genetic information. The Holliday junction is the crossroads responsible for the diversity of life on Earth, and ensures that children are given a unique shuffling of traits from a mother and father’s DNA.

In nature, the Holliday junction twists the double-stacked strands of DNA at an angle of about 60-degrees, which is perfect for swapping genes but sometimes frustrating for DNA nanotechnology scientists, because it limits the design rules of their structures.

“In principal, you can use the scaffold to connect multiple layers horizontally,” [which many research teams have utilized since the development of DNA origami by Cal Tech’s Paul Rothemund in 2006]. However, when you go in the vertical direction, the polarity of DNA prevents you from making multiple layers,” said Yan. “What we needed to do is rotate the angle and force it to connect.”

Making the new structures that Yan envisioned required re-engineering the Holliday junction by flipping and rotating around the junction point about half a clock face, or 150 degrees. Such a feat has not been considered in existing designs.

“The initial idea was the hardest part,” said Yan. “Your mind doesn’t always see the possibilities so you forget about it. We had to break the conceptual barrier that this could happen.”

In the new study, by varying the length of the DNA between each Holliday junction, they could force the geometry at the Holliday junctions into an unconventional rearrangement, making the junctions more flexible to build for the first time in the vertical dimension. Yan calls the backyard barbeque grill-shaped structure a DNA Gridiron.

“We were amazed that it worked!” said Yan. “Once we saw that it actually worked, it was relatively easy to implement new designs. Now it seems easy in hindsight. If your mindset is limited by the conventional rules, it’s really hard to take the next step. Once you take that step, it becomes so obvious.”

The DNA Gridiron designs are programmed into a viral DNA, where a spaghetti-shaped single strand of DNA is spit out and folded together with the help of small ‘staple’ strands of DNA that help mold the final DNA structure. In a test tube, the mixture is heated, then rapidly cooled, and everything self-assembles and molds into the final shape once cooled. Next, using sophisticated AFM and TEM imaging technology, they are able to examine the shapes and sizes of the final products and determine that they had formed correctly.

This approach has allowed them to build multilayered, 3-D structures and curved objects for new applications.

In addition to the EurekAlert version, you can find the full text, images, and video about the team’s paper in the Mar. 21, 2013 news item on ScienceDaily (a citation and link to the team’s paper is also included) or you can read the original Mar. 21, 2013 ASU news release. (Hao Yan’s work was last mentioned here in an Aug. 7, 2012 post.)

All of this talk of twists reminded me of a song by Tanita Tikaram, Twist in My Sobriety. I found this video of an acoustic performance (two guitars and a bass [the musical instrument not the fish]) which is even more sultry than original hit version,

Happy weekend!

Chad Mirkin, spherical nucleic acids, and a new ‘periodic table’

There was a big splash in July 2012 with the announcement that Chad Mirkin’s team at Northwestern University (Chicago, Illinois) had devised a skin cream that penetrated the skin barrier to deliver medication (my July 4, 2012 posting),

A team led by a physician-scientist and a chemist — from the fields of dermatology and nanotechnology — is the first to demonstrate the use of commercial moisturizers to deliver gene regulation technology that has great potential for life-saving therapies for skin cancers.

The topical delivery of gene regulation technology to cells deep in the skin is extremely difficult because of the formidable defenses skin provides for the body. The Northwestern approach takes advantage of drugs consisting of novel spherical arrangements of nucleic acids. These structures, each about 1,000 times smaller than the diameter of a human hair, have the unique ability to recruit and bind to natural proteins that allow them to traverse the skin and enter cells.

Mirkin has just finished presenting (Feb. 15, 2013 and Feb. 17, 2013) more information about spherical nucleic acids and their implications at the AAAS  (American Association for the Advancement of Science) 2013 meeting in Boston, Massachusetts. From the Feb. 15, 2013 news release on EurekAlert,

Northwestern University’s Chad A. Mirkin, a world-renowned leader in nanotechnology research and its application, has invented and developed a powerful material that could revolutionize biomedicine: spherical nucleic acids (SNAs).

Potential applications include using SNAs to carry nucleic acid-based therapeutics to the brain for the treatment of glioblastoma, the most aggressive form of brain cancer, as well as other neurological disorders such as Alzheimer’s and Parkinson’s diseases. Mirkin is aggressively pursuing treatments for such diseases with Alexander H. Stegh, an assistant professor of neurology at Northwestern’s Feinberg School of Medicine.

“These structures are really quite spectacular and incredibly functional,” Mirkin said. “People don’t typically think about DNA in spherical form, but this novel arrangement of nucleic acids imparts interesting chemical and physical properties that are very different from conventional nucleic acids.”

Spherical nucleic acids consist of densely packed, highly oriented nucleic acids arranged on the surface of a nanoparticle, typically gold or silver.  [emphasis mine] The tiny non-toxic balls, each roughly 15 nanometers in diameter, can do things the familiar but more cumbersome double helix can’t do:

  • SNAs can naturally enter cells and effect gene knockdown, making SNAs a superior tool for treating genetic diseases using gene regulation technology.
  • SNAs can easily cross formidable barriers in the human body, including the blood-brain barrier and the layers that make up skin.
  • SNAs don’t elicit an immune response, and they resist degradation, resulting in longer lifetimes in the body.

“The field of medicine needs new constructs and strategies for treating disease,” Mirkin said. “Many of the ways we treat disease are based on old methods and materials. Nanotechnology offers the ability to rapidly create new structures with properties that are very different from conventional forms of matter.”

“We now can go after a whole new set of diseases,” Mirkin said. “Thanks to the Human Genome Project and all of the genomics research over the last two decades, we have an enormous number of known targets. And we can use the same tool for each, the spherical nucleic acid. We simply change the sequence to match the target gene. That’s the power of gene regulation technology.”

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A member of President Obama’s Council of Advisors on Science and Technology, Mirkin is known for invention and development of biological and chemical diagnostic systems based upon nanomaterials. He is the inventor and chief developer of Dip-Pen Nanolithography, a groundbreaking nanoscale fabrication and analytical tool, and is the founder of four Chicago-based companies: AuraSense, AuraSense Therapeutics, Nanosphere and NanoInk.

Mirkin, in addition to his work with spherical nucleic acids, has been busy with other nanoparticles and possible dreams of a new ‘periodic table of elements’, from the Feb. 17, 2013 news release on EurekAlert,

Forging a new periodic table using nanostructures

Northwestern University’s Chad A. Mirkin, …, has developed a completely new set of building blocks that is based on nanoparticles and DNA. Using these tools, scientists will be able to build — from the bottom up, just as nature does — new and useful structures.

“We have a new set of building blocks,” Mirkin said. “Instead of taking what nature gives you, we can control every property of the new material we make. We’ve always had this vision of building matter and controlling architecture from the bottom up, and now we’ve shown it can be done.”

Using nanoparticles and DNA, Mirkin has built more than 200 different crystal structures with 17 different particle arrangements. Some of the lattice types can be found in nature, but he also has built new structures that have no naturally occurring mineral counterpart.

Mirkin can make new materials and arrangements of particles by controlling the size, shape, type and location of nanoparticles within a given particle lattice. He has developed a set of design rules that allow him to control almost every property of a material.

New materials developed using his method could help improve the efficiency of optics, electronics and energy storage technologies. “These same nanoparticle building blocks have already found wide-spread commercial utility in biology and medicine as diagnostic probes for markers of disease,” Mirkin added.

With this present advance, Mirkin uses nanoparticles as “atoms” and DNA as “bonds.” He starts with a nanoparticle, which could be gold, silver, platinum or a quantum dot, for example. The core material is selected depending on what physical properties the final structure should have.

He then attaches hundreds of strands of DNA (oligonucleotides) to the particle. The oligonucleotide’s DNA sequence and length determine how bonds form between nanoparticles and guide the formation of specific crystal lattices.

“This constitutes a completely new class of building blocks in materials science that gives you a type of programmability that is extraordinarily versatile and powerful,” Mirkin said. “It provides nanotechnologists for the first time the ability to tailor properties of materials in a highly programmable way from the bottom up.”

If I read these two news releases rightly, the process (nanoparticles as atoms and DNA as bonds), Mirkin uses to create new structures is the same process he has used to create spherical nucleic acids. Given Mirkin’s entrepreneurial inclinations, I am curious as to how many and what kind of patents might be ‘protecting’ this work.

Maskwriting facilities at 4D Labs and some bottom-up engineering news

Following up on yesterday’s news from Simon Fraser University (SFU), I gather that maskwriting has to do with fabricating nanoscale materials and the facility they will be building for their 4D Labs will allow them to create nanoscale structures that measure less than 20 nanometres.

“This capability will eventually be as key to nanoscale materials fabrication as the photocopier is to information dissemination,” explains [Byron] Gates, 4D LABS’ director of nanofabrication. “With our new maskwriting facility, we’ll be able to fabricate the next generation of technologies, particularly in the fields of alternative energy and biomedical engineering.”

Local companies will not have send off to Alberta to get this work done and it will give 4D Labs some revenue.  Given that universities are under pressure these days to develop new revenue streams, this has to be good news.

Meanwhile, scientists at the California Institute of Technology (Caltech) have recently published a paper describing their work on bottom-up engineering of DNA ‘seeds’. The two main approaches to engineering in nanotechnology (and this is simplified) are top-down and bottom-up. Traditional enginerring has been top-down; we make things smaller and smaller. The bottom-up approach means taking your cue from biological processes (or nature) and encouraging objects to build themselves or to ‘grow’. There’s more here.

The Project for Emergining Nanotechnologies’ June 17, 2009 event (mentioned in yesterday’s posting) has been rescheduled to Fall 2009.