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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Researchers at Penn State College of Medicine, USA, have used nanoparticles filled with small interfering RNA (siRNA) to inhibit the development of melanoma, the most aggressive form of skin cancer.

The team, led by Dr Gavin Robertson, targeted two genes, a mutated form of B-Raf and Akt3 that play a key role in the development of melanoma. They speculated that siRNA could be used to turn off these genes without affecting normal cells thereby enabling the cancer to be treated more effectively.

To prevent degradation of the siRNA before reaching the target genes, the team incorporated it into the hollow interiors of nanoliposomes. In a laboratory skin construct, they then created microscopic holes in the skin to allow the filled siRNA-filled nanoparticles to leak into the tumour cells. After 10 days they observed a 60% - 70% reduction in the ability of cells containing mutant B-Raf to multiply and, after 3 weeks melanoma lesions in the constructs were more than halved in size. Notable reductions in tumour size were also observed in mice.

The approach is seen to have considerable potential in that it is able to target individual genes rather than affecting a wide range of proteins and other biomolecules as with many other drugs.

Paper published in Cancer Research

Source: PhysOrg.com

Posted: October 30th, 2008 under Nanomedicine.
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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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There has much recent research aimed at exploiting the potential of nanoparticles such as carbon nanotubes, nanoshells and other nanostructures as carriers for drugs because of their ability to pass through cell and even subcellular membranes. However, because of their tiny size and physical effects they tend to diffuse rather slowly, e.g. a 200nm particle may only diffuse 400µm in 9h, which could limit their therapeutic usefulness.

Researchers at Ghent University in Belgium, led by Dr Bruno De Geest, have now found a way to propel nanoparticles up to 800 times faster by packaging them in an “exploding” microcapsule.

The microsized “grenades”, between 100µm and 400µm in diameter, are made from a porous polymer membrane containing a gel based on the polysaccharide dextran with the nanoparticles under study embedded in the gel. As water diffuses through the membrane it degrades the cross-links in the gel causing it to swell and burst the capsule open, vigorously expelling the contents.

While 400µm microcapsules are too big for delivery of drugs through the bloodstream, Dr De Geest thinks that they may lend themselves to subcutaneous implantation which could be useful for some drugs such as vaccines. Smaller microcapsules may be produced by altering the membrane and payload properties and the gel also responds to temperature and pH changes opening up the possibility of using the system to deliver drugs to other tissue environments.

Original article: New Scientist

Publication: Journal of the American Chemical Society

University of Ghent

Posted: October 23rd, 2008 under Nanomedicine, Nanotechnology.
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So-called “superbugs” like MRSA (methicillin-resistant Staphylococcus aureus) are becoming a huge burden on healthcare systems. In the UK alone, despite strenuous efforts to tackle the problem, there was still around 7000 cases during 2007 and a rise in cases during the last quarter of 2007 as compared with the previous quarter.

Vancomycin is one antibiotic that can still be used to fight MRSA and now researchers at the London Centre for Nanotechnology (LCN) at University College London are using nanotechnology to investigate how it works to provide insight into the possible development of other effective drugs. The team, led by Dr Rachel McKendry and Professor Gabriel Aeppli, used nanoscale silicon-based cantilever arrays to study the process that takes place when vancomycin binds to the surface of the bacteria. Comparing non-resistant and resistant strains, they found that the “superbugs” were resistant because of a simple mutation that deletes a single hydrogen bond from part of their cell wall resulting in a 1000-fold increase in difficulty for the vancomycin molecule to attach to the mucopeptide in the wall of the bacteria, thereby greatly reducing its effectiveness.

Dr McKendry believes that the knowledge of both the binding mechanism and the related mechanical influences on the bacterial cell structure will provide useful insight into the development of more powerful and effective future antibiotics.

Read the original article from the London Centre for Nanotechnology .

Posted: October 23rd, 2008 under Physics, Nanomedicine, Nanotechnology.
Comments: 1

Structural DNA nanotechnology, where the nucleotides or base pairs of DNA, namely adenine (A) and thymine (T), and guanine (G) and cytosine (C) are made to self-fold into a number of different building blocks, and  is a fast-growing field within nanomedicine. Up until now, the technology has been somewhat limited by the need to synthesise all of the material from scratch. Now researchers at
Arizona State University’s Biodesign Institute, led by Hao Yan, have managed to harness the cell’s ability to copy DNA to make them into “factories” to replicate artificial DNA-based nanostructures.

The team started by taking two simple cross-shaped, four-armed shape nanostructures created from DNA, and placing them inside a phagemid, a virus-like particle infecting bacterial cells. Once inside the bacterial cell, the cell started reproducing the nanostructures. From a single infection and 1mL of cultured cells, the team found they could synthesise trillions of identical copies of the DNA nanostructures. Furthermore, the cells continued their other functions whilst tolerating the copied artificial nanostructures. Whilst acknowledging that this is an early step the team is excited that artificial structures can be copied by cells in this way which opens up the possibility of many exciting future applications

Original article at:  Small Times

Posted: October 23rd, 2008 under Advanced medtech, Nanomedicine, Nanotechnology.
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Researchers at the University of Rochester Medical Centre have published a recent paper that provides strong evidence that some types of nanoparticles with dimensions under 10nm can pass directly through the skin.

The team, led by Lisa DeLouise, used quantum dots that fluoresce when exposed to light and which are therefore easier to track. The work has potential significance in both studies of nanoparticle safety and in designing transdermal drug delivery systems.

Further information available at Physorg.Com.

Posted: October 2nd, 2008 under Safety and risk, Nanomedicine.
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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.
Comments: 1