Space and Nano – An Emerging Frontier: A Nano-barrier for composites could strengthen spacecraft payloads – “Great Things from Small Things”

Stress modelling within CFRP and coated components Credit Nature Materials (2019) DOI: 10.1038

The University of Surrey has developed a robust multi-layed nano-barrier for ultra-lightweight and stable carbon fibre reinforced polymers (CFRPs) that could be used to build high precision instrument structures for future space missions.

CFRP is used in current space missions, but its applications are limited because the material absorbs moisture. This is often released as gas during a mission, causing the material to expand and affect the stability and integrity of the structure. Engineers try to minimise this problem with CFRP by performing long, expensive procedures such as drying, recalibrations and bake-out- all of which may not completely resolve the issue.

In a paper published by the journal Nature Materials, scientists and engineers from Surrey and Airbus Defence and Space detail how they have developed a multi-layered nano-barrier that bonds with the CFRP and eliminates the need for multiple bake-out stages and the controlled storage required in its unprotected state.

Surrey engineers have shown that their thin nano-barrier—measuring only sub-micrometers in thickness, compared to the tens of micrometers of current space mission coatings—is less susceptible to stress and contamination at the surface, keeping its integrity even after multiple thermal cycles.

Professor Ravi Silva, Director of the Advanced Technology Institute at the University of Surrey, said: ”

“We are confident that the reinforced composite we have reported is a significant improvement over similar methods and materials already on the market.”

These encouraging results suggest that our barrier could eliminate the considerable costs and dangers associated with using carbon fibre reinforced polymers in space missions.”

Christian Wilhelmi, Head of Mechanical Subsystems and Research and Technology Friedrichshafen at Airbus Defence and Space, said: “We have been using carbon-fibre composites on our spacecraft and instrument structures for many years, but the newly developed nano-barrier together with our ultra-high-modulus CFRP manufacturing capability will enable us to create the next generation of non-outgassing CFRP materials with much more dimensional stability for optics and payload support. Reaching this milestone gives us the confidence to look at instrument-scale manufacturing to fully prove the technology.”

Professor David Sampson, Vice-Provost Research and Innovation at the University of Surrey, said:

“This research project continues the University of Surrey’s long and close partnership with Airbus. Advanced materials for spacecraft is a further excellent example of how Surrey supports the Space Sector. We have been doing so for decades, and we are fully committed to strengthening our support for the sector going forwards.

I look forward to more brilliant advances from the Surrey-Airbus relationship in years to come.”

More information: Dimensionally and environmentally ultra-stable polymer composites reinforced with carbon fibres, Nature Materials (2019). DOI: 10.1038/s41563-019-0565-3 , https://nature.com/articles/s41563-019-0565-3

Journal information: Nature Materials

Provided by University of Surrey

Electrons flow like water in ultra-pure Graphene – Likely to play an Important role in New Generations of Devices

A river made of graphene with the electrons flowing like water. Courtesy: Ryan Allen and Peter Allen, Second Bay Studios

Electrons can behave like a viscous liquid as they travel through a conducting material, producing a spatial pattern that resembles water flowing through a pipe. So say researchers in Israel and the UK who have succeeded in imaging this hydrodynamic flow pattern for the first time using a novel scanning probe technique. The result will aid developers of future electronic devices, especially those based on 2D materials like graphene in which electron hydrodynamics is important.

We are all familiar with the distinctive patterns formed by water flowing in a river or stream. When the water encounters an obstacle – such as the river bank or a boat – the patterns change. The same should hold true for electron flow in a solid if the interactions between electrons are strong. This rarely occurs under normal conditions, however, since electrons tend to collide with defects and impurities in the material they travel through, rather than with each other.

Making electrons hydrodynamic

Conversely, if a material is made very clean and cooled to low temperatures, it follows that electrons should travel across it unperturbed until they collide with its edges and walls. The resulting ballistic transport allows electrons to flow with a uniform current distribution because they move at the same rate near the walls as at the centre of the material.

If the temperature of this material is then increased, the electrons can begin to interact. In principle, they will then scatter off each other more frequently than they collide with the walls. In this highly interacting, hydrodynamic regime, the electrons should flow faster near the centre of a channel and slower near its walls – the same way that water behaves when it flows through a pipe.

Extremely clean 2D materials

In recent years, researchers have created extremely clean samples from 2D materials such as graphene to act as testbeds for studying electron hydrodynamics. The vast majority of this work, however, involved measuring electron transport, which only probes the physics of electrons at fixed positions along the perimeter of the device.

“Hydrodynamics, on the other hand, brings to mind dynamic images of electrons swirling around with interesting spatial patterns,” says Joseph Sulpizio, who is one of the lead authors of this new study. “Such patterns have been predicted in theory but never imaged spatially.”

Poiseuille current profile

Sulpizio and the other researchers, led Shahal Ilani at Israel’s Weizmann Institute for Science in collaboration with Andre Geim’s group at Manchester University, have now imaged the most fundamental spatial pattern of hydrodynamic electron flow for the first time. They obtained this parabolic or Poiseuille current profile by studying electrons travelling through a conducting graphene channel sandwiched between two hexagonal boron nitride layers equipped with electrical contacts.

Under an applied electric field, the electrons produce a voltage gradient along the current flow direction. Unfortunately, this local voltage gradient is the same for both hydrodynamic and ballistic electron flow and so cannot be used to distinguish between the two regimes. Ilani and colleagues overcame this problem by applying a weak magnetic field to the sample, which produces another voltage – the Hall voltage – perpendicular to the direction of the current. The gradient of this voltage is very different for hydrodynamic and ballistic flow.

The researchers imaged the Hall voltage profile for both flow regimes using a scanning probe recently developed in their laboratory. This ultraclean carbon nanotube single-electron-transistor-based device is held at cryogenic temperatures and is extremely sensitive to local electrostatic fields. The current flowing through it is thus indicative of the local potential of the sample and voltage gradients associated with the Hall voltage.

By measuring this current, the team was also able to observe the transition between the regime in which electron-electron scattering dominates and that in which the electrons flow ballistically. “As expected, we observed a flat Hall field profile across the graphene channels at low temperatures,” Sulpizio tells Physics World. “Upon heating, however, the profile becomes strongly parabolic, revealing less current flow near the walls and more near the centre, which indicates the transition to hydrodynamic/Poiseuille flow.”

READ MORE: “Magic-angle graphene reveals a host of new states”

Magic-angle graphene reveals a host of new states

Implications for device development

The implications of the work, which has been published in Nature, are many, he says. Electron hydrodynamics only emerges at elevated temperatures (in contrast to many other kinds of electronic phenomena that exist only at very low temperatures) and this will be relevant for technological devices like computer chips that operate at room temperature. It will also be relevant in 2D van der Waals heterostructures like those made from graphene, and especially when they are super-clean. This behaviour is likely to play an important role in new generations of devices made from these materials.

“Looking further ahead, it might even be possible one day to engineer fundamentally new kinds of electronic devices that directly exploit electron hydrodynamics,” Sulpizio says. “When electrons interact hydrodynamically, their viscosity results in highly non-local spatial flow patterns that might be technologically advantageous.”

The Two Directions of Nanomedicine in the Treatment of Cancer

The cancer nanomedicine field is heading in two directions — debating whether the clinical translation of nanomaterials should be accelerated or whether some of the long-standing drug delivery paradigms have to be challenged first.

At the International Conference on Nanomedicine and Nanobiotechnology that was held in Munich, 16–18 October, the most striking talk was not given by a scientist, nor a clinician, but by Lora Kelly — a six-year pancreatic cancer survivor.

By telling her story of how it actually feels to receive chemotherapy, immunotherapy and radiation, she reminded everyone about the urgent need to improve cancer treatment regimes. The main goal remains to kill the cancer; however, it has become more evident how equally important it is to improve the quality of life of patients during treatment, that is, to reduce the often devastating side effects.

This is where nanomedicine comes in. Nanomaterials have the potential to direct drugs to specific tissues and to improve drug activity, as well as its transport in blood. Indeed, nanoparticles could ensure that therapeutic treatments act locally and not systemically, and thus improve anti-cancer efficacy while reducing damage to healthy tissues.

However, recent setbacks, including the bankruptcy of a prominent nanomedicine company¹ and the less than 1% delivery efficiency claim² (quoted at every cancer nanomedicine conference on at least one slide) have stirred discussions about the usefulness of nanomedicines for cancer treatment.

Some argue that the field is stuck in preclinical animal models owing to a lack of insight into the basics of nanomaterial–tissue interactions in the human body, from traversing biological barriers to clearance.

 

While less than 1% delivery efficiency might not be much, pharmacological parameters, such as peak drug concentration, clearance rate and elimination half-life, are often not as bad³, and these should be considered with equal importance.

Moreover, there are also clinical success stories of nanomedicines. Onpattro, a lipid nanoparticle-based short interfering RNA (siRNA) drug for the treatment of polyneuropathies, was approved by the US Food and Drug Administration in 2018, marking the first approved nanoparticle for nucleic acid delivery.

In a Comment in this issue, Akinc et al. report the endeavour of developing this nanomedicine, from the idea to preclinical and clinical testing⁴, to the final approval. There are further many opportunities for nanomaterials complementary to drug delivery, including bioimaging, modulation of the immune system and the tumour microenvironment, and, of course, local administration.

 

From an Editorial perspective, the ongoing discussion is reflected in the many manuscripts we receive, which often include both basic investigations and claims of clinical application. Naturally, this can lead to mixed peer-review reports echoing the disconnection between clinical vision and fundamental science.

Reviewers with a background in materials science or biomedical engineering often point out the gaps in the basic understanding of how a nanomaterial interacts with the biological environment, and clinicians would like to see more preclinical animal work. Indeed, a thorough fundamental study does not always need the claim of a specific application, as it might be exactly such overstatements that have precluded the field to deliver on the promise of revolutionizing drug delivery.

Along the same line, studies of nanoparticle transport through specific cells or nanomaterial–cell interactions at a molecular scale, do not necessarily require complex in vivo models; by contrast, applied studies claiming a therapeutic benefit need a robust in vivo validation in a relevant animal model — preferably with an intact immune system.

 

Going back to the goal of improving a patient’s life, possible side effects and impact on tissues other than tumours should also be reported. However, this data is often found, at best, somewhere in the supplementary information.

Regardless of the mouse model, the discussion rarely goes beyond the weight loss and the histology of organs. If the idea is to improve therapies, side effects need to be thoroughly investigated — even at an early preclinical stage. Similarly, we will make sure that studies claiming superiority of a therapeutic treatment compared to state-of-the-art treatment regimes are reviewed by clinical experts to ensure that clinical translation is — at least — possible and feasible.

Also, keeping regulatory requirements in mind, the more complex the new nanoparticle or nanoscale delivery agent, the more difficult it will be to get approval; and this is a valid criticism.

 

At Nature Nanotechnology, we consider both clinically relevant manuscripts and fundamental studies investigating the various barriers nanoparticles face on their journey through the body. We endeavour to assess the manuscripts we receive as fairly and consistently as possible, with the ongoing discussion in mind. We look forward to learning about possible alternative mechanisms and the heterogeneity of the enhanced permeability and retention (EPR) effect, nanoparticle interactions in the liver, spleen and kidneys during clearance, migration of nanomaterials through the tumour microenvironment, and nanoparticle uptake, lysosomal escape (or not) and transport in different cell types.

Such studies will shine a light on nanomaterial–tissue interactions, and also greatly contribute to the development of improved nanomedicines. Equally important, detailed investigations of nanoparticles in preclinical animal models as well as relevant organoid cultures will allow the optimization of treatment strategies and the reduction of side effects. Regardless of the aim, we urge authors to calibrate their claims in accordance with their data and scope of the investigation to preserve trust in cancer nanomedicine as a whole.

Scientists devise catalyst that uses light to turn carbon dioxide to fuel

Looking into the hard X-ray nanoprobe synchrotron chamber while measuring a response of an individual cuprous oxide particle to the exposure of carbon dioxide, water and light. (Image by Tijana Rajh / Argonne National Laboratory.)

 

Researchers find new way to convert carbon dioxide into a usable fuel source.

The concentration of carbon dioxide in our atmosphere is steadily increasing, and many scientists believe that it is causing impacts in our environment. Recently, scientists have sought ways to recapture some of the carbon in the atmosphere and potentially turn it into usable fuel — which would be a holy grail for sustainable energy production.

In a recent study from the U.S. Department of Energy’s (DOE) Argonne National Laboratory, scientists have used sunlight and a catalyst largely made of copper to transform carbon dioxide to methanol. A liquid fuel, methanol offers the potential for industry to find an additional source to meet America’s energy needs.

“Carbon dioxide is such a stable molecule and it results from the burning of basically everything, so the question is how do we fight nature and go from a really stable end product to something useful and energy rich.” — Argonne Distinguished Fellow Tijana Rajh

The study describes a photocatalyst made of cuprous oxide (Cu­₂O), a semiconductor that when exposed to light can produce electrons that become available to react with, or reduce, many compounds. After being excited, electrons leave a positive hole in the catalyst’s lower-energy valence band that, in turn, can oxidize water.

“This photocatalyst is particularly exciting because it has one of the most negative conduction bands that we’ve used, which means that the electrons have more potential energy available to do reactions,” said Argonne Distinguished Fellow Tijana Rajh, an author of the study.

Previous attempts to use photocatalysts, such as titanium dioxide, to reduce carbon dioxide tended to produce a whole mish-mash of various products, ranging from aldehydes to methane. The lack of selectivity of these reactions made it difficult to segregate a usable fuel stream, Rajh explained.

“Carbon dioxide is such a stable molecule and it results from the burning of basically everything, so the question is how do we fight nature and go from a really stable end product to something useful and energy rich,” Rajh said.

The idea for transforming carbon dioxide into useful energy comes from the one place in nature where this happens regularly. ​“We had this idea of copying photosynthesis, which uses carbon dioxide to make food, so why couldn’t we use it to make fuel?” Rajh said. ​“It turns out to be a complex problem, because to make methanol, you need not just one electron but six.”

By switching from titanium dioxide to cuprous oxide, scientists developed a catalyst that not only had a more negative conduction band but that would also be dramatically more selective in terms of its products. This selectivity results not only from the chemistry of cuprous oxide but from the geometry of the catalyst itself.

“With nanoscience, we start having the ability to meddle with the surfaces to induce certain hotspots or change the surface structure, cause strain or certain surface sites to expose differently than they are in the bulk,” Rajh said.

Because of this ​“meddling,” Rajh and Argonne postdoctoral researcher Yimin Wu, now an assistant professor at the University of Waterloo, managed to create a catalyst with a bit of a split personality. The cuprous oxide microparticles they developed have different facets, much like a diamond has different facets. Many of the facets of the microparticle are inert, but one is very active in driving the reduction of carbon dioxide to methanol.

According to Rajh, the reason that this facet is so active lies in two unique aspects.  First, the carbon dioxide molecule bonds to it in such a way that the structure of the molecule actually bends slightly, diminishing the amount of energy it takes to reduce. Second, water molecules are also absorbed very near to where the carbon dioxide molecules are absorbed.

“In order to make fuel, you not only need to have carbon dioxide to be reduced, you need to have water to be oxidized,” Rajh said. ​“Also, adsorption conformation in photocatalysis is extremely important — if you have one molecule of carbon dioxide absorbed in one way, it might be completely useless. But if it is in a bent structure, it lowers the energy to be reduced.”

Argonne scientists also used scanning fluorescence X-ray microscopy at Argonne’s Advanced Photon Source (APS) and transmission electron microscopy at the Center for Nanoscale Materials (CNM) to reveal the nature of the faceted cuprous oxide microparticles. The APS and CNM are both DOE Office of Science User Facilities.

A paper based on the study, ​“Facet-dependent active sites of a single Cu₂O particle photocatalyst for CO₂ reduction to methanol,” appeared in the November 4 online edition of Nature Energy. Other contributors to the study include Argonne’s Ian McNulty, Cong Liu, Kah Chun Lau, Paul Paulikas, Cheng-Jun Sun, Zhonghou Chai, Jeff Guest, Yang Ren, Vojislav Stamenkovic, Larry Curtiss and Yuzi Liu. Qi Liu of the City University of Hong Kong also contributed.

The work was funded by an Argonne Laboratory-Directed Research and Development grant and by the DOE’s Office of Science.

 

About Argonne’s Center for Nanoscale Materials
The Center for Nanoscale Materials is one of the five DOE Nanoscale Science Research Centers, premier national user facilities for interdisciplinary research at the nanoscale supported by the DOE Office of Science. Together the NSRCs comprise a suite of complementary facilities that provide researchers with state-of-the-art capabilities to fabricate, process, characterize and model nanoscale materials, and constitute the largest infrastructure investment of the National Nanotechnology Initiative. The NSRCs are located at DOE’s Argonne, Brookhaven, Lawrence Berkeley, Oak Ridge, Sandia and Los Alamos National Laboratories. For more information about the DOE NSRCs, please visit https://​sci​ence​.osti​.gov/​U​s​e​r​-​F​a​c​i​l​i​t​i​e​s​/​U​s​e​r​-​F​a​c​i​l​i​t​i​e​s​-​a​t​-​a​-​G​lance.

 

About the Advanced Photon Source
This research used resources of the Advanced Photon Source, a U.S. DOE Office of Science User Facility operated for the DOE Office of Science by Argonne National Laboratory under Contract No. DE-AC02–06CH11357.

Argonne National Laboratory seeks solutions to pressing national problems in science and technology. The nation’s first national laboratory, Argonne conducts leading-edge basic and applied scientific research in virtually every scientific discipline. Argonne researchers work closely with researchers from hundreds of companies, universities, and federal, state and municipal agencies to help them solve their specific problems, advance America’s scientific leadership and prepare the nation for a better future. With employees from more than 60 nations, Argonne is managed by UChicago Argonne, LLC for the U.S. Department of Energy’s Office of Science.

The U.S. Department of Energy’s Office of Science is the single largest supporter of basic research in the physical sciences in the United States and is working to address some of the most pressing challenges of our time. For more information, visit https://​ener​gy​.gov/​s​c​ience.

DNA Nanomachines Are Opening Medicine to the World of Physics

When I imagine the inner workings of a robot, I think hard, cold mechanics running on physics: shafts, wheels, gears. Human bodies, in contrast, are more of a contained molecular soup operating on the principles of biochemistry.

Yet similar to robots, our cells are also attuned to mechanical forces—just at a much smaller scale. Tiny pushes and pulls, for example, can urge stem cells to continue dividing, or nudge them into maturity to replace broken tissues. Chemistry isn’t king when it comes to governing our bodies; physical forces are similarly powerful. The problem is how to tap into them.

In a new perspectives article in Science, Dr. Khalid Salaita and graduate student Aaron Blanchard from Emory University in Atlanta point to DNA as the solution. The team painted a futuristic picture of DNA mechanotechnology, in which we use DNA machines to control our biology. Rather than a toxic chemotherapy drip, for example, a cancer patient may one day be injected with DNA nanodevices that help their immune cells better grab onto—and snuff out—cancerous ones.

“For a long time,” said Salaita, “scientists have been good at making micro devices, hundreds of times smaller than the width of a human hair. It’s been more challenging to make functional nano devices, thousands of times smaller than that. But using DNA as the component parts is making it possible to build extremely elaborate nano devices because the DNA parts self-assemble.”

Just as the steam engine propelled civilization through the first industrial revolution, DNA devices may fundamentally change medicine, biological research, and the development of biomaterials, further merging man and machine.

Why DNA?

When picturing a tiny, whirling machine surveying the body, DNA probably isn’t the first candidate that comes to mind. Made up of long chains of four letters—A, T, C, and G—DNA is normally secluded inside a tiny porous “cage” in every cell, in the shape of long chains wrapped around a protein “core.”

Yet several properties make DNA a fascinating substrate for making mechano-machines, the authors said. One is its predictability: like soulmates, A always binds to T, and C with G. This chemical linking in turn forms the famous double helix structure. By giving the letters little chemical additions, or swapping them out altogether with unnatural synthetic letters, scientists have been able to form entirely new DNA assemblies, folded into various 3D structures.

Read More: Detecting HIV diagnostic antibodies with DNA nanomachines

Rather than an unbreakable, immutable chain, DNA components are more like Japanese origami paper, or Lego blocks. While they can’t make every single shape—try building a completely spherical Death Star out of Lego—the chemistry is flexible enough that scientists can tweak its structure, stiffness, and coiling by shifting around the letters or replacing them with entirely new ones.

 

The Rise of DNA Machines

In the late fall of 1980, Dr. Nadrian Seeman was relaxing at the campus pub at New York University when he noticed a mind-bending woodcut, Depth, by MC Escher. With a spark of insight, he realized that he could form similar lattice shapes using DNA, which would make it a lot easier for him to study the molecule’s shape. More than a decade later, his lab engineered the first artificial 3D nanostructure—a cube made out of DNA molecules. The field of DNA nanotechnology was born.

Originally considered a novelty, technologists rushed to make increasingly complex shapes, such as smiley faces, snowflakes, a tiny world map, and more recently, the world’s smallest playable tic-tac-toe set. It wasn’t just fun. Along the way, scientists uncovered sophisticated principles and engineering techniques to shape DNA strands into their desired structures, forming a blueprint of DNA engineering.

Then came the DNA revolution. Reading and writing the molecule from scratch became increasingly cheaper, making it easier to experiment with brand-new designs. Additional chemical or fluorescent tags or other modifications gave scientists a direct view of their creations. Rather than a fringe academic pursuit, DNA origami became accessible to most labs, and the number of devices rapidly exploded—devices that can sense, transmit, and generate mechanical forces inside cells.

“If you put together these three main components of mechanical devices, you begin to get hammers and cogs and wheels and you can start building nano machines,” said Salaita.

The Next Generation

Salaita is among several dozen labs demoing the practical uses of DNA devices.

For example, our cells are full of long-haul driver proteins that carry nutrients and other cargo throughout their interior by following specific highways (it eerily looks like a person walking down a tightrope). Just as too much traffic damages our roadways, changes in our cells’ logistical players can also harm the cell’s skeleton. Here, scientists have used DNA “handles” to measure force-induced changes like stretching, unfolding, and rupture of molecules involved in our cells’ distribution system to look for signs of trouble.

Then there are DNA tension sensors, which act like scales and other force gauges in our macroscopic world. Made up of a stretchable DNA “spring” to extend with force, and a fluorescent “ruler” that measures the extension, each sensor is anchored at one end (generally, the glass bottom of a Petri dish) and binds to a cell at the other. If the pulling force exceeds a certain threshold, the “spring” unfolds and quenches the fluorescent light in the ruler, giving scientists a warning that the cellular tugging is too strong.

The work may sound abstruse, but its implications are plenty. One is for CAR-T, the revolutionary cancer treatment that uses gene therapy to amp up immune cells with better “graspers” to target tumor cells. The “kiss of death” between graspers and tumors are extremely difficult to measure because it’s light and fleeting. Using a DNA tension sensor, the team was able to track the force during the interaction, which could help scientists engineer better CAR-T therapies. A similar construct, the DNA tension gauge tether, irreversibly ruptures under too much force. The gauge is used to track how stem cells develop into brain cells under mechanical forces, and how immune cells track down and recognize foreign invasion.

“[Immune] T cells are constantly sampling cells throughout your body using these mechanical tugs. They bind and pull on proteins on a cell’s surface and, if the bond is strong, that’s a signal that the T cell has found a foreign agent,” explained Salaita. DNA devices provide an unprecedented look at these forces in the immune system, which in turn could predict how strongly the body will mount an immune response.

To the authors, however, the most promising emerging DNA devices don’t just observe—they can also generate forces. DNA walkers, for example, uses DNA feet to transport (and sort) molecular cargo while walking down a track also made of DNA strands. When the feet “bind” to the “track” (A to T, C to G), it releases energy that propel the walker forward.

Even more exciting are self-assembling DNA machines. The field has DNA-based devices that “transmit, sense and generate mechanical forces,” the authors said. But eventually, their integration will produce nanomachines that “exert mechanical control over living systems.”

The Fourth Industrial Revolution

As costs keep dropping, the authors believe we’ll witness even more creative and sophisticated DNA nanomachines.

Several hiccups do stand in the way. Like other biomolecules, foreign DNA can be chopped up by the body’s immune system as an “invader.” However, the team believes that the limitation won’t be a problem in the next few years as biochemistry develops chemically-modified artificial DNA letters that resist the body’s scissors.

Another problem is that the DNA devices can generate very little force—less than a billionth the weight of a paperclip, which is a little too low to efficiently control forces in our cells. The authors have a solution here too: coupling many force-generating DNA units together, or engineer “translators” that can turn electrical energy into mechanical force—similar to the way our muscles work.

Fundamentally, any advancements in DNA mechanotechnology won’t just benefit medicine; they will also feed back into the design of nanomaterials. The “techniques, tools and design principles…are not specific” to DNA, the authors said. Add in computer-aided design templates, similar to those used in 3D printing, and “potentially anyone can dream up a nano-machine design and make it a reality,” said Salaita.