By: Chenfeng Ke, Dartmouth College

Nanomachines are tiny molecules – more than 10,000 lined up side by side would be narrower than the diameter of a human hair – that can move when they receive an external stimulus. They can already deliver medication within a body and serve as computer memories at the microscopic level. But as machines go, they haven’t been able to do much physical work – until now. The Conversation

My lab has used nano-sized building blocks to design a smart material that can perform work at a macroscopic scale, visible to the eye. A 3-D-printed lattice cube made out of polymer can lift 15 times its own weight – the equivalent of a human being lifting a car.

Nobel-winning roots are rotaxanes

The design of our new material is based on Nobel Prize-winning research that turned mechanically interlocked molecules into work-performing machines at nanoscale – things like molecular elevators and nanocars.

Rotaxanes are one of the most widely investigated of these molecules. These dumbbell-shaped molecules are capable of converting input energy – in the forms of light, heat or altered pH – into molecular movements. That’s how these kinds of molecular structures got the nickname “nanomachines.”

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By: Mike Williams, Rice University

Graphene

Rice University researchers have modeled a nanoscale sandwich, the first in what they hope will become a molecular deli for materials scientists.

Their recipe puts two slices of atom-thick graphene around nanoclusters of magnesium oxide that give the super-strong, conductive material expanded optoelectronic properties.

Rice materials scientist Rouzbeh Shahsavari and his colleagues built computer simulations of the compound and found it would offer features suitable for sensitive molecular sensing, catalysis and bio-imaging. Their work could help researchers design a range of customizable hybrids of two- and three-dimensional structures with encapsulated molecules, Shahsavari said.

The research appears this month in the Royal Society of Chemistry journal Nanoscale.

The scientists were inspired by experiments elsewhere in which various molecules were encapsulated using van der Waals forces to draw components together. The Rice-led study was the first to take a theoretical approach to defining the electronic and optical properties of one of those “made” samples, two-dimensional magnesium oxide in bilayer graphene, Shahsavari said.

“We knew if there was an experiment already performed, we would have a great reference point that would make it easier to verify our computations, thus allowing more reliable expansion of our computational results to identify performance trends beyond the reach of experiments,” Shahsavari said.

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By using one of the world’s most powerful electron microscopes, a team of researchers from Lawrence Berkeley National Laboratory has successfully mapped the exact location and chemical type of 23,000 atoms in a nanoparticle made of iron and platinum. The team believes this work could reveal more information about material properties at the single-atom level, opening the doors to improving magnetic performance for next-generation hard drives.

“Our research is a big step in this direction. We can now take a snapshot that shows the positions of all the atoms in a nanoparticle at a specific point in its growth,” says Mary Scott, who conducted the research. “This will help us learn how nanoparticles grow atom by atom, and it sets the stage for a materials-design approach starting from the smallest building blocks.”

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Nano-chimney to Cool Circuits

Overheating has emerged as a primary concern in the development of new electronic devices. A new study from Rice University looks to provide a solution to that, offering a strategy to vent heat away from nano-electronics through cone-like chimneys.

By putting these “chimneys” between the graphene and nanotube, the researchers effectively eliminate a barrier that typically blocks heat from escaping.

This from Rice University:

Researchers at Rice University discovered through computer simulations that removing atoms here and there from the two-dimensional graphene base would force a cone to form between the graphene and the nanotube. The geometric properties of the graphene-to-cone and cone-to-nanotube transitions require the same total number of heptagons, but they are more sparsely spaced and leave a clear path of hexagons available for heat to race up the chimney.

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Detecting Disease Through Your Breath

One of the major challenges in modern medicine is how to accurately detect disease when people are still feeling healthy. Researchers and doctors alike have long since wondered how to diagnose diseases such as cancer before it progresses too far.

Now, the medical community may find that answer in a new development out of Technion – Israel Institute of Technology called the Na-Nose.

The Na-Nose is a newly developed device that can analyze the chemical signature of exhaled gases to diagnose diseases with 86 percent accuracy. The science behind the device uses carbon nanotubes and gold particles to isolate volatile biomarkers in a patient’s breath.

Researchers then used a computer algorithm to recognize the biomarkers, creating a tool that can quickly and accurately detect diseases such as ovarian cancer or multiple sclerosis in early stages without any invasive procedures.

“It works in the same way we’d use dogs in order to detect specific compounds,” Hossam Haick, co-author of the study, told Smithsonian. “We bring something to the nose of a dog, and the dog will transfer that chemical mixture to an electrical signature and provide it to the brain, and then memorize it in specific regions of the brain … This is exactly what we do. We let it smell a given disease but instead of a nose we use chemical sensors, and instead of the brain we use the algorithms. Then in the future, it can recognize the disease as a dog might recognize a scent.”

A scanning tunneling microscope image shows two three-wheeled nanoroadsters.Image: Alex Saywell/Leonhard Grill

A scanning tunneling microscope image shows two three-wheeled nanoroadsters.
Image: Alex Saywell/Leonhard Grill

Past ECS lecturer James Tour and his team at Rice University have developed a tiny three-wheeled, single-molecule call they’ve dubbed the “nanoroadster.”

This new research builds on Tour’s light-driven nanocars, which he developed six years ago. Since then, additional research efforts have allowed researchers to drive fleets of the nanoroadsters at once.

“It is exciting to see that motorized nanoroadsters can be propelled by their light-activated motors,” Tour says. “These three-wheelers are the first example of light-powered nanovehicles being observed to propel across a surface by any method, let alone by scanning tunneling microscopy.”

This from Rice University:

Rather than drive them chemically or with the tip of a tunneling microscope, as they will do with other vehicles in the upcoming international NanoCar Race in Toulouse, France, the researchers used light at specific wavelengths to move their nanoroadsters along a copper surface. The vehicles have rear-wheel molecular motors that rotate in one direction when light hits them. The rotation propels the vehicle much like a paddle wheel on water.

Read the full article.

“If we have to ‘wire’ the car to a power source, like an electron beam, we would lose a lot of the cars’ functionality,” Tour says. “Powering them with light frees them to be driven wherever one can shine a light—and eventually we hope they will carry cargo.”

The ability to activate multiple fleets of nanocars at once opens possibilities of using nanomachines like ants, in which they could work collectively to perform some construction.

By: Sameer Sonkusale, Tufts University

Nanowires

Image: Alonso Nichols, Tufts University, CC BY-ND

Doctors have various ways to assess your health. For example, they measure your heart rate and blood pressure to indirectly assess your heart function, or straightforwardly test a blood sample for iron content to diagnose anemia. But there are plenty of situations in which that sort of monitoring just isn’t possible.

To test the health of muscle and bone in contact with a hip replacement, for example, requires a complicated – and expensive – procedure. And if problems are found, it’s often too late to truly fix them. The same is true when dealing with deep wounds or internal incisions from surgery.

In my engineering lab at Tufts University, we asked ourselves whether we could make sensors that could be seamlessly embedded in body tissue or organs – and yet could communicate to monitors outside the body in real time. The first concern, of course, would be to make sure that the materials wouldn’t cause infection or an immune response from the body. The sensors would also need to match the mechanical properties of the body part they would be embedded in: soft for organs and stretchable for muscle. And, ideally, they would be relatively inexpensive to make in large quantities.

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Carbon nanotubes have a potentially wide variety of applications due to their strength, flexibility, and other promising properties. While many researchers have been focused on applying carbon nanotubes in nanotechnology and electronics, ECS members Kris Dahl and Mohammad Islam are looking to give the nanotubes a new use in medical applications.

Dahl, a chemical and biomedical engineer; and Islam, a materials scientists; are taking their respective skills and putting them to use in the novel interdisciplinary development, making possible carbon nanotubed-based structures for drug delivery.

This from Carnegie Mellon University:

Picture feeding a dog a pill. In order to do so, one would wrap it in cheese to mask the medicine and make it more appealing. In a similar vein, to enhance drug delivery, Dahl and Islam have engineered proteins that wrap around the drug-coated carbon nanotubes. The cells, which love these proteins, more readily take up the drug—much as a dog would more readily eat the cheese-coated pill.

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Nanowire cooling

Flexible electrocaloric fabric of nanowire array can cool.
Image: Qing Wang/Penn State

The utilization of nanowires has opened a new branch of science for many researchers. While some have focused on applying this technology to energy systems, researchers from Penn State are using the nanowires to develop solid state personal cooling systems.

A new study from the university shows that nanowires could help develop a material for lightweight cooling systems, which could be incorporated into firefighting gear, athletic uniforms, and other wearables.

“Most electrocaloric ceramic materials contain lead,” says Qing Wang, professor of materials science and engineering at Penn State. “We try not to use lead. Conventional cooling systems use coolants that can be environmentally problematic as well. Our nanowire array can cool without these problems.”

This from Penn State:

Electrocaloric materials are nanostructured materials that show a reversible temperature change under an applied electric field. Previously available electrocaloric materials were single crystals, bulk ceramics, or ceramic thin films that could cool, but are limited because they are rigid, fragile, and have poor processability. Ferroelectric polymers also can cool, but the electric field needed to induce cooling is above the safety limit for humans.

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Improving Energy Storage

Nanoparticles have been central to many recent developments, including computing, communications, energy, and biology. However, because nanoparticles are hard to observe, it’s often difficult to pick the best shapes and sizes to perform specific tasks at optimal capacity.

That may be a problem no longer thanks to research out of Stanford University, where researchers gazed inside phase-changing nanoparticles for the first time – allowing them to understand how shape and crystallinity can have dramatic effects on performance.

Practically, this means that the design of energy storage materials could begin to change.

Take the lithium-ion battery, which stores and releases energy due to the electrode’s ability to sustain large deformations over several charge and discharge cycles without degrading. By nanosizing the electrode, researchers recently improved upon the efficiency process.

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