Tetrahedral Gold nanocrystal

Scientist at Hongkong have recently grown Elongated tetrahexahedral Au nanocrystals in high yields using a seed-mediated growth method.

Morphological and structural characterizations show that these Au nanocrystals are single-crystalline and enclosed by 24 high-index {037} facets. They are more electrochemically active than octahedral Au nanocrystals that are enclosed by 8 low-index {111} facets. To date, there have been only a few reports of metal nanocrystals that are enclosed exclusively by high-index facets, including trisoctahedral Au nanocrystals enclosed by 24 {122} facets and tetrahexahedral Pt nanocrystals enclosed by 24 {037} facets. These newly designed tetrahexahedral Au nanocrystals will be an important addition to the family of metal nanocrystals that are enclosed exclusively by high-index facets and will also be useful for fundamental catalytic studies on metal nanocrystals.

Research is published in Journal of Americal Chemical Society,2009, 131 (45), pp 16350–16351

Carbon nanotube sponge!

Scientists from China have invented a carbon-based sponge that can soak up organic pollutants, such as oils and solvents, from the surface of water. No water is absorbed and the sponge can then be wrung out and reused, like an ordinary household sponge. Absorbing up to 180 times its own weight in organic matter, the sponge is light and tough and has the potential to dramatically enhance oil spill cleanup.

This newly invented sponges are made from interconnected carbon nanotubes; tiny, strong and hollow cylinders of interconnected carbon atoms. The tubes are 30 - 50 nanometres across and tens to hundreds of micrometers long . The surface of the tubes is naturally hydrophobic (water-hating), therefore no further modification is needed for the sponges to repel water. At the same time, they love to absorb oil on their surface. As the sponges are over 99% porous or empty, they float on water and there is a lot of room for oil to be absorbed, leading to the extremely high capacity for retention for example, 143 times the sponge's weight for diesel oil and 175 for ethylene glycol.

However, potential applications reach beyond oil spill recovery. According to Researchers, the nanotube sponges can be used as filters, membranes, or absorbents to remove bacteria or contaminants from liquid or gas. They could also be used as noise-absorption layers in houses, and soldiers might benefit by using these sponges in impact energy absorbing components while adding little weight. Thermally insulated clothing is also possible.

Large-scale production is currently being investigated.

This research is published in Scientific Journal Advance Materials, 2009.

Paper is available at www.materialsviews.com/matview/display/en/1220/TEXT

Magnetic charge behaving as electric charge for the first time

The research at London Centre for Nanotechnology find prove for the existence of atom-sized magnetic charges called ‘magnetic monopoles’. These monopoles behave and interact just like more familiar electric charges.Research also demonstrates a perfect symmetry between electricity and magnetism – a phenomenon dubbed ‘magnetricity'.

In order to prove experimentally the existence of magnetic current for the first time, the research team mapped Onsager's 1934 theory of the movement of ions in water onto magnetic currents in a material called spin ice. They then tested the theory by applying a magnetic field to a spin ice sample at a very low temperature and observing the process using muon relaxation at ISIS, a technique which acts as a super microscope allowing researchers to understand the world around us at the atomic level.

The experiment allowed the team to detect magnetic charges in the spin ice (Dy2Ti2O7), to measure their currents, and to determine the elementary unit of the magnetic charge in the material. The monopoles they observed arise as disturbances of the magnetic state of the spin ice, and can exist only inside the material.

This research, reported in Nature, was led by Steven Bramwell of the London Centre for Nanotechnology in the UK. Bramwell was a member of a team, led by Tom Fennell of the Laue-Langevin Institute in Grenoble, that reported neutron results in September.

Nobel prize 2009 in chemistry

Two Americans and one Israeli share this year's Nobel Prize in Chemistry for their work showing how the DNA code is translated into life itself.

Americans Venkatraman Ramakrishnan and Thomas Steitz and Ada Yonath from Israel were all instrumental in showing how proteins are made at the atomic level.

The three laureates have accomplished what many scientists thought impossible, namely to determine the three-dimensional structure of the molecular machine that makes all the proteins in a cell, the so-called ribosome.While DNA molecules contain the blueprint for life inside each cell of every organism, it is the ribosome that translates that information into life.

Using x-ray crystallography to obtain snapshots of the ribosome in action, they have been able to explain how the ribosome selects and couples together amino acids to form proteins.

The three recipients share the $1.4 million prize. The chemistry award is the third in the 2009 Nobel series. Prizes for medicine were handed out Monday and for physics on Tuesday.

(Prizes for the sciences and for peace have been handed out annually since 1901. )

Pt Nanowires Synthesized by Novel Green Approach

Scientists at Pacific Northwest National Laboratory, Richland have developed a complete "green" approach for synthesis of Platinum nanoparticles followed by the formation of nanowires by self assemblies in in an aqueous beta-D-glucose solution.

Since, carbohydrates are not strong enough to reduce Pt(IV) into Pt(0) at ambient temperature, researchers have used hydrothermal treatement to reduce Pt(IV) ions in an autoclave at 100 ◦C.
Thermal treatment initiated reduction of Pt(IV) ions into Pt nanoparticles, which were stabilized in the aqueous Beta-D-glucose solution. Pt nanoparticles transformed into nanowires upon continuous heating and eventually became cubic Pt crystal with a rough needle appearance.
TEM and FT-IR studies reveal that carboxylate groups, which are generated by the oxidation of
Beta-d-glucose, strongly interact with and stabilize the surface of these Pt nanostructures.

Reference: Colloids and Surfaces A: Physicochem. Eng. Aspects (2009), Article is in Press

Tunable Hollow Metal Nanorods- A Novel Approach

An adaptable approach for preparing nano-materials of engineered size, shape, composition, and porosity has been developed by researchers at Simon Fraser University, Canada.
They have developed a simple technique to engineer hollow metal nanostructures of well-defined properties.
The nanostructures have a tunable diameter, length, and shape that are defined by the sacrificial template used to grow the hollow product. The electrochemically synthesized templates are
regular, polycrystalline cylindrical silver nanorods with dimensions dictated by both the physical mold that confines their growth as well as the conditions for electrodeposition. This template can be selectively etched to isolate a porous hollow nanostructure.
These robust hollow metal nanostructures have potential applications in the selective delivery and release of reagents such as medicinal drugs.
The photothermal properties of metal nanostructures have been investigated for destroying cancer cells.


Reference: ACSNano,VOL.3,NO. 6, 1365–1372 , 2009

Thiolate Ligand Stabilization of Gold Nanoparticles

Polydentate amphiphilic thiols possess excellent properties for gold nanoparticle stabilization and functionalization and resistant to exchange reactions.

Gold -thiol bond is generally believed to be one of tightest link for gold surface functionalization and well-known for its thermodynamic stability. In biological environment, where thiol groups are presents, prevention of thiolate-thiol excahnge is also an important consideration. In such situations, a reliable functionalization can provide kinetic stability against ligand exchange.

Different efforts have been made to improve the exchange stability of thiolate ligands on gold nanoparticles.
Recently, German scientist have synthesized the trithiol
1,1,1-tris(mercaptomethyl)undecane as a model to investigate the particle stabilization and exchange properties of tripodal organothiolate.

for further details, refer to: Chem. Commun., 2006, 3693–3695 | 3693