Friday, November 27, 2009

This week in nanotechnology, Nov.27, 2009

Scientists at the Carnegie Institution have found for the first time that high pressure can be used to make a unique hydrogen-storage material. The discovery paves the way for an entirely new way to approach the hydrogen-storage problem. The researchers found that the normally unreactive, noble gas xenon combines with molecular hydrogen (H2) under pressure to form a previously unknown solid with unusual bonding chemistry.

hydrogen storage material Xe(H2)7

This schematic shows the structure of the new material, Xe(H2)7. Freely rotating hydrogen molecules (red dumbbells) surround xenon atoms (yellow).

Researchers at the University of Illinois have developed a technique for fabricating three-dimensional, single-crystalline silicon structures from thin films by coupling photolithography and a self-folding process driven by capillary interactions. This is a completely different approach to making three-dimensional structures.

Researchers at the Institute of Bioengineering and Nanotechnology (IBN), A*STAR, in Singapore, have developed a new protocol for the synthesis of tiny metal and semiconductor crystals that are a few nanometers in size. The efficiency and structural control provided by this method could revolutionize the production of nanocrystals and their hybrids, which have diverse applications in medicine, electronics and energy.

Scientists from the MESA+ Institute for Nanotechnology of the University of Twente and the FOM Foundation have succeeded in transferring magnetic information directly into a semiconductor. For the first time, this is achieved at room temperature. This breakthrough brings the development of a more energy efficient form of electronics, so-called ‘spintronics’ within reach.

A new generation of ultrasmall transistors and more powerful computer chips using tiny structures called semiconducting nanowires are closer to reality after a key discovery by researchers at IBM, Purdue University and the University of California at Los Angeles. The researchers have learned how to create nanowires with layers of different materials that are sharply defined at the atomic level, which is a critical requirement for making efficient transistors out of the structures.

nanowires with sharply defined layers of silicon and germanium

The researchers have grown the nanowires with sharply defined layers of silicon and germanium, offering better transistor performance. As depicted in this illustration, tiny particles of a gold-aluminum alloy were alternately heated and cooled inside a vacuum chamber, and then silicon and germanium gases were alternately introduced. As the gold-aluminum bead absorbed the gases, it became "supersaturated" with silicon and germanium, causing them to precipitate and form wires.

A lot of the scientific knowledge in chemistry and biology comes from experiments on ensembles of molecules by which a vast number of duplicate behaviors are investigated and averaged responses are recorded. Researchers have now, for the first time, demonstrated direct and amplification-free single molecule detection of biomolecules in sub-nanolitre droplets through application of Cylindrical Illumination Confocal Spectroscopy (CICS) and droplet confinement within a retractable microfluidic constriction.

Friday, November 20, 2009

This week in nanotechnology, Nov.20, 2009

Lots of nanomedicine and nanobiotechnology this week! Let's start with cancer medicine: A team of researchers on the cutting edge of nanomedicine has found a way to capture tumor cells in the bloodstream that could dramatically improve earlier cancer diagnosis and prevent deadly metastasis. The way this works is that the scientists can inject a cocktail of magnetic and gold nanoparticles with a special biological coating into the bloodstream to target circulating tumor cells. A magnet attached to the skin above peripheral blood vessels can then capture the cells.

Research with a similar goal was carried out at UCLA. Just as fly paper captures insects, an innovative new device with nanosized features is able to grab cancer cells in the blood that have broken off from a tumor. Their nanopillar chip captured more than 10 times the amount of cells captured by the currently used flat structure.

Quite a number of serious medical conditions, such as cancer, diabetes and chronic pain, require medications that cannot be taken orally, but must be dosed intermittently, on an as-needed basis, and over a long period of time. Researchers have been trying to develop drug delivery techniques with 'on-off switches' that would allow controlled release of drugs into the body. By combining magnetism with nanotechnology, researchers have now created a small implantable device that encapsulates the drug in a specially engineered membrane, embedded with magnetic iron oxide nanoparticles.

The atomic-level action of a remarkable class of ring-shaped protein motors has been uncovered by researchers at Berkeley Lab using a state-of-the-art protein crystallography beamline at the Advanced Light Source. These protein motors play pivotal roles in gene expression and replication, and are vital to the survival of all biological cells, as well as infectious agents, such as the human papillomavirus, which has been linked to cervical cancer.

The genetic material found in cells is not in its free state, but is bound to large protein complexes and tightly wrapped. To activate genes that could well play a role in carcinogenesis, the genetic material first needs to be unwrapped and made accessible to other cell components. Using a new biophysical method called single molecule spectroscopy, scientists in Germany were the first to directly observe these mechanisms and characterise the intermediate stages leading to free genetic material.

Existing solid-state devices to convert heat into electricity are not very efficient. Researchers have been trying to find how close realistic technology could come to achieving the theoretical limits for the efficiency of such conversion. In everything from computer processor chips to car engines to electric powerplants, the need to get rid of excess heat creates a major source of inefficiency. But new research points the way to a technology that might make it possible to harvest much of that wasted heat and turn it into usable electricity.

The University of Ghent and the nanoelectronics research center IMEC demonstrated repulsive and attractive nanophotonic forces, depending on the spatial distribution of the light used. These fundamental research results might have major consequences for telecommunication and optical signal processing.

With a bit of leverage, Cornell researchers have used a very tiny beam of light with as little as 1 milliwatt of power to move a silicon structure up to 12 nanometers. That's enough to completely switch the optical properties of the structure from opaque to transparent, they reported. The technology could have applications in the design of micro-electromechanical systems (MEMS) – nanoscale devices with moving parts – and micro-optomechanical systems (MOMS) which combine moving parts with photonic circuits.

Scanning electron micrograph of two thin, flat rings of silicon nitride, each 190 nanometers thick and mounted a millionth of a meter apart

Scanning electron micrograph of two thin, flat rings of silicon nitride, each 190 nanometers thick and mounted a millionth of a meter apart. Light is fed into the ring resonators from the straight waveguide at the right. Under the right conditions optical forces between the two rings are enough to bend the thin spokes and pull the rings toward one another, changing their resonances enough to act as an optical switch.

Friday, November 6, 2009

This week in nanotechnology, Nov.6, 2009

New research reported this week has established an industrially relevant process for assembling carbon nanotubes that allows them to efficiently be made into fibers, coatings and films – the basic forms of material that can be used in engineering applications. By this advance, materials engineers can now access established technology that had been developed for processing polymers through solution phase methods – the industrial-scale processes that are at the heart of the plastics industry.

Duke University bioengineers have developed a simple and inexpensive method for loading cancer drug payloads into nanoscale delivery vehicles and demonstrated in animal models that this new nanoformulation can eliminate tumors after a single treatment. After delivering the drug to the tumor, the delivery vehicle breaks down into harmless byproducts, markedly decreasing the toxicity for the recipient.

Another nanomedicine report this week showed that a gold nanocage covered with a polymer can be employed as a smart drug delivery system. The smart nanocage is designed to be filled with a medicinal substance, such as a chemotherapy drug or bactericide. Releasing carefully titrated amounts of a drug only near the tissue that is the drug's intended target, this delivery system will maximize the drug's beneficial effects while minimizing its side effects.

Picture the ultimate in miniaturization—functional machines built out of individual molecules, mere atoms in size. In a breakthrough development, researchers from the Institute of Materials Research and Engineering in Singapore have reported the invention of an essential component for single-molecule mechanical machines: a molecular gear that can be controllably rotated with a 100% rate of success.

Representation of a molecular gear pinned to a gold surface, with an STM tip close to one of the gear's teeth

Representation of a molecular gear pinned to a gold surface, with an STM tip close to one of the gear’s ‘teeth’.

Converting sunlight to electricity might no longer mean large panels of photovoltaic cells atop flat surfaces like roofs. Using zinc oxide nanostructures grown on optical fibers and coated with dye-sensitized solar cell materials, researchers at the Georgia Institute of Technology have developed a new type of three-dimensional photovoltaic system. The approach could allow PV systems to be hidden from view and located away from traditional locations such as rooftops.

University of Utah chemists demonstrated the first conclusive link between the size of catalyst particles on a solid surface, their electronic properties and their ability to speed chemical reactions. The study is a step toward the goal of designing cheaper, more efficient catalysts to increase energy production, reduce Earth-warming gases and manufacture a wide variety of goods from medicines to gasoline.

Imitating photosynthesis in plants? If we were to accomplish this, mankind would have a little less to worry about. Chemists from the University of W├╝rzburg have now made progress on the road to achieving artificial photosynthesis. The structure that has been developed in the university's Organic Chemistry laboratory is fascinatingly complex: thousands of similar molecules are packed together to create a capsule that is filled with molecules of a different kind. The diameter of one capsule is a mere 20 to 50 nanometers.