While a large number of colours in nature are produced by pigments some, like the vibrant feathers of many types of birds, are instead produced by nanostructures.

An interdisciplinary team at Yale University has found that these structures, which appear sponge-like with air bubbles, form by a process of self-assembly. They compared the natural nanostructures to examples of materials undergoing phase separation in which mixtures of different materials become unstable and separate from one another. In the case of feathers, bubbles of water form in a protein-rich soup inside the living cells and are replaced by air as the feather grows forming ?-keratin and air nanostructures. The colour produced depends on the exact size and shape of the individual nanostructure.

The research provides important insights into how organisms use self-assembly of materials at the nanoscale to produce colour. The researchers are also interested in the potential technological applications of their finding to produce novel optical materials.

Publication: Soft Matter

Source: Nanowerk

Posted: April 6th, 2009 under Advanced materials, Chemistry.
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Using the world’s most advanced electron microscope, Eindhoven University of Technology researchers have, for the first time, captured high-resolution images of the earliest stages of bone formation. Utilizing the FEI Company’s cryoTitan microscope they imaged small clusters of calcium carbonate and showed that clusters consisting of around ten ions formed the basis for the process resulting in nucleation into larger, unstructured nanoparticles with an average diameter of around thirty nanometers through which the crystalline biominerals are formed.

The work, published in Science magazine offers increased understanding of bone, tooth and shell formation and could have important implications for creating industrial biomimetic materials.

Source: Nanowerk

Posted: March 13th, 2009 under Advanced materials, Advanced medtech, Nanomedicine.
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Researchers at Sandia National Laboratories, Livermore, California have succeeded in developing a device based on carbon nanotubes that can detect the entire visible spectrum of light and which may find potential uses in artificial retinas and other light gathering applications such as solar cells and miniature cameras for use in low light conditions. Earlier attempts at similar devices were only able to detect specific wavelengths.

The device utilizes carbon nanotubes decorated with three different types of chromophores, which are molecules that change shape in response to particular wavelengths of light… in the case of the Sandia research red, green and blue wavelengths. This change in shape alters the orientation of the chromophores in relation to the nanotube which, in turn, alters the conductivity of the nanotube to give a signal that can be measured. Because of their size, the nanotubes have intrinsically high resolution… around the diameter of each nanotube or 1nm.

The researchers believe that the process of manufacturing such devices could be scaled up and are also working on versions of the device that can detect infrared light, and which are more sensitive.

Source: MIT Technical Review

Posted: March 10th, 2009 under Advanced materials, Physics, Advanced medtech, Nanomedicine, Nanotechnology.
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Silk has been considered a useful material for some time for biological scaffold for some time, due to the fact that it is very strong and biocompatible. Researchers at Tuft’s University in the USA have now found that silkworm silk may also serve as an optical material for biosensors and other devices.

The team, led by Fiorenzo Omenetto, noted that a Tuft’s colleague, David Kaplan, was using the silk as a tissue engineering scaffold to build engineered corneal implants and wondered whether the material might also therefore be useful for optical devices. They found that the silk worked as well as traditional optical materials like glass and plastic and, in some cases, better, without the need for high temperature or harsh chemical processing enabling biosensing molecules such as proteins, antibodies and even enzymes to be easily attached.

The silk from the silkwork coccoons was extracted by the team into an aqueous solution providing an ideal medium into which to mix various biosensing molecules. A variety of moulds can then be used to create optical devices in different forms. A sample device incorporating haemoglobin and capable of sensing oxygen was constructed but the team believes that a whole variety of biosensing molecules could be utilised for a range of biosensing applications including glucose monitoring for diabetes, the detection of cancer markers, colour-changing sensors and sensors that can be incorporated into tissue-engineered devices to provide feedback about their performance.

Source: MIT Technology Review

Posted: January 12th, 2009 under Advanced materials, Advanced medtech, Nanomedicine.
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Researchers at Oxford University have succeeded in creating a molecular machine that can walk along a strand of DNA and which can be powered by nearby molecules. The design improves upon earlier attempts in that the walker can move in a definite direction, rather than randomly, and that the walker can stop or start according to the amount of available fuel.

The walker comprises two connected feet made from a sequence of DNA bases that attach to complementary sequences on the DNA track. As one foot attaches, the back foot is forced to lift off. The base sequences in the feet act as catalysts to release energy from the surrounding molecules to power the device.

Although some problems remain to be overcome, such as the DNA track becoming tangled, the team has hopes that the walker could be used to transport molecular loads in a “nanofactory”.

Source: New Scientist

Posted: January 12th, 2009 under Advanced materials, Advanced medtech, Nanomedicine.
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Researchers at Gothenburg’s Chalmers University of Technology have succeeded in making self-assembling DNA strands capable of guiding light along their length. The team, led by Bo Albinsson, used a mixture of DNA and light-sensitive molecules called YO chromophores to make strands with a light absorbing molecule at one end and a light emitting molecule at the other. In testing the assembled strands, the team found that they transmitted around 30% of the light received by the absorbing chromophore to the emitting chromophore. The system resembles the photonic mechanisms that organisms such as algae use to transport light to parts of the cell where the energy can be converted.

While it is currently impossible to know exactly where the chromophores insert themselves into the DNA strands during self assembly, researchers believe that the scale distances involved may offer opportunities to develop the system for use in nanoscale electronics interconnects, molecular computers and artificial photosynthetic systems.

Source: New Scientist

Paper: Journal of the American Chemical Society

Posted: November 18th, 2008 under Advanced materials, Nanomedicine, Nanotechnology.
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It’s well-known that a gecko can cling to almost any surface, including smooth glass, due to the anatomy of its feet. Each toe is covered in microscopic hairs called setae which have yet smaller branches, called spatulae, at the tips. These present a large surface area to the substrate maximising the effect of van der Waals forces.

Researchers, led by Liming Dai at the University of Dayton in Ohio and Zhong Lin Wang at the Georgia Institute of Technology, have now made a material from carbon nanotubes that is up to 10 times stickier than gecko feet. They grew the carbon nanotubes on a silicon wafer to form a “forest” of vertical nanotube trunks with a canopy of tangled ends at the canopy level, mimicking the gecko’s spatulae and presenting a large surface area to any surface in contact. The new material is superior to some earlier competitors in that it can be easily loosened by varying the angle of pull.

Liming sees some potential applications for the sticky material… as carbon nanotubes are excellent conductors the material could replace solder in electronics in some situations or traditional adhesives in space where vacuum causes the adhesives to dry out and fail quickly.

Source: New Scientist

Posted: October 30th, 2008 under Advanced materials, Physics, Chemistry, Nanotechnology.
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Nanotechnology is producing a wealth of new products based on utilising features and characteristics at the nanoscale including microelectronics and micromachines with moving parts. One problem at such a tiny scale is how to switch them on and off or control them as needed.

In a new study, Dr Harold Zandvliet and colleagues at the University of Twente in the
Netherlands have developed a nanoscale mechanical device, grown on a wafer of germanium, that can respond to a tiny electrical current from the tip of a scanning tunneling microscope to make two atom pairs move like the flippers of a nanoscale pinball machine. The researchers state that understanding the mechanism can provide insights into the opportunities for future atomic-scale devices.

Paper published in Nano Letters

Source: Nanotechnology Now

Posted: October 30th, 2008 under Advanced materials, Physics, Chemistry, Advanced medtech, Nanotechnology.
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Scientists from the John Innes Centre (UK), Institut Pasteur (France) and Scripps Research Institute (California, USA) have shown that a virus that withstands extreme conditions and that can infect bacteria living in temperatures of up to 80⁰C and pH 2-3, may be used as a stable nanobuilding block.

The virus, a rod-shaped rudivirus called SIRV2, infects the thermoacidiphilic bacterium Sulfolobus islandicus which is found in hot volcanic springs. The team subjected the virus to a variety of harsh environments within the laboratory and found that the viral capsule was able to withstand such conditions which make it a promising candidate as a viral nanoparticle (VNP), a form of particle that can self-assemble with high precision. To be suitable as a VNP, however, the particles must be amenable also to chemical or genetic modification and the team was able to successfully target modifications to both the ends and the body of the virus enabling it to be built up into layers or arrays.

The team thinks that the new VNP, by virtue of its stability under extreme conditions and possibility for alignment in different ways, may find useful applications in liquid crystal assembly, nanoscale templates, nanoelectronics, and biomedical applications.

Source: PhysOrg

Posted: October 28th, 2008 under Advanced materials, Advanced medtech, Nanotechnology.
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Researchers at the University of Texas at Dallas (UTD) and CSIRO have succeeded in developing a commercially-viable process that could allow carbon nanotubes to be formed into transparent sheets stronger than steel sheets of the same weight.

The process differs from earlier methods of making carbon nanotube sheets or papers, which relied on dispersions of the nanotubes in liquids, in that it is a dry process that can utilise longer carbon nanotubes resulting in superior properties for many potential applications. The sheets can currently be produced at up to seven metres per minute from self-assembled, aligned nanotube structures. The nanotubes have also been spun into ribbons that are up to five times stronger than steel and which are efficient electrical conductors.

The team foresees a wide range of potential commercial applications for the new process and carbon nanotubes materials.

Further information available at Physorg.com.

Posted: October 2nd, 2008 under Advanced materials, Nanotechnology.
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