Saturday, March 20, 2010

This week in nanotechnology - March 19, 2010

In findings that took the experimenters three years to believe, engineers have demonstrated that light itself can twist ribbons of nanoparticles. Matter readily bends and twists light. That's the mechanism behind optical lenses and polarizing 3-D movie glasses. But the opposite interaction has rarely been observed. While light has been known to affect matter on the molecular scale - bending or twisting molecules a few nanometers in size - it has not been observed causing such drastic mechanical twisting to larger particles.

A new high-performance anode structure based on silicon-carbon nanocomposite materials could significantly improve the performance of lithium-ion batteries used in a wide range of applications from hybrid vehicles to portable electronics. Produced with a "bottom-up" self-assembly technique, the new structure takes advantage of nanotechnology to fine-tune its materials properties, addressing the shortcomings of earlier silicon-based battery anodes. The simple, low-cost fabrication technique was designed to be easily scaled up and compatible with existing battery manufacturing.

For two decades, scientists have been pursuing a potential new way to treat bacterial infections, using naturally occurring proteins known as antimicrobial peptides (AMPs). Now, MIT scientists have recorded the first microscopic images showing the deadly effects of AMPs, most of which kill by poking holes in bacterial cell membranes.

This image, taken with atomic force microscopy, shows E. coli bacteria after they have been exposed to the antimicrobial peptide CM15. The peptides have begun destroying the bacteria’s cell walls

This image, taken with atomic force microscopy, shows E. coli bacteria after they have been exposed to the antimicrobial peptide CM15. The peptides have begun destroying the bacteria’s cell walls.

Here's an exaple of apractical application of nanotechnology: Cassava is a tropical root vegetable and staple crop for millions of people in sub-Saharan Africa. However, it's tricky to handle: Once the root is removed from the ground, it spoils within one to three days, so farmers must get it to processing centers as soon as possible after harvesting it. If they don’t, the crop goes to waste. A simple way to prolong cassava's shelf life could help farmers avoid that waste and sell their crop beyond their local region. Paula Hammond, MIT professor of chemical engineering, and other scientists are now working on an innovative way to help them do that, using nanotechnology. Their idea is to design a plastic storage bag lined with nanoparticles that would react with oxygen, preventing the roots’ oxygen-induced rotting.

Scientists have devised a molecular 'LEGO toolkit' which can be used to assemble a vast number of new and functional chemical compounds. Using molecules as building blocks they have been able to construct a molecular scaffold based on tiny (nano-scale) storage cubes. This new ‘designer route’ opens the door to many new compounds that, potentially, are able to act as the ion sensors, storage devices, and catalysts of the future.

Artificial photosynthesis can offer a clean and portable source of energy supply as durable as the sunlight. Using sunlight to split water molecules and form hydrogen fuel is one of the most promising tactics for kicking our carbon habit. Of the possible methods, nature provides the blueprint for converting solar energy in the form of chemical fuels. A natural leaf is a synergy of the elaborated structures and functional components to produce a highly complex machinery for photosynthesis in which light harvesting, photoinduced charge separation, and catalysis modules combined to capture solar energy and split water into oxygen and hydrogen efficiently. Chinese researchers have now demonstrated the design of an efficient, cost-effective artificial system to mimic photosynthesis by copying the elaborate architectures of green leaves, replacing the natural photosynthetic pigments with man-made catalysts and thereby realizing water splitting- a major advance in energy conversion.