Researchers at Northwestern University and the Brookhaven National Laboratory have shown that strands of DNA can be used to assemble 10nm gold nanoparticles into 3D structures in a bottom-up approach.

While 2D structures have previously been created using DNA this is the first time 3D structures have been engineered. The two groups, led by Chad Mirkin and Oleg Gang respectively, achieved this by making the DNA “arms” more flexible, thereby allowing them to link with their neighbours. On mixing the nanoparticles with their DNA arms, the DNA linked the particles to one another to form a crystal-like spongy lattice rather than the amorphous clumps formed in previous attempts to assemble 3D structures.

According to Mirkin, who described the constructs, comprising crystal-like structures of around one million gold nanoparticles, as “…fundamentally new structures of matter”, the technique could be used to build materials for many applications including optical communications and medicine.

By varying the sequence of base pairs in the DNA strands, the particles can be programmed to bind together in particular ways to construct materials with different properties. The Northwestern team are already working with the same technique on other types and shapes of nanoparticles, opening up the possibility to create more complex types of structures.

Read more at NewScientistTech.

Posted: January 31st, 2008 under Nanomedicine, Nanotechnology.
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The world’s most powerful microscope, a Transmission Electron Aberration-corrected Microscope known as TEAM 0.5, has been installed at the US Department of Energy’s National Center for Electron Microscopy at the Lawrence Bereley National Laboratory. TEAM 0.5 is capable of resolving images down to 0.5Å (ångström) or 0.05nm or, described in different terms, less than the diameter of a single hydrogen atom. The construction of TEAM 0.5 by a US-European team has only been made possible by advances in a number of other areas such as ultra-stable electronics, very bright electron sources and greatly improved aberration correctors.

The microscope itself, together with its sister microscope TEAM 1 that will additionally correct for chromatic aberration, will be housed in the multistory silo that used to accomodate the historic high-voltage electron microscope and the atomic resolution microscope, once the world’s most powerful instruments. Because the aberration correction allows high resolution to be maintained at lower beam energies, the microscope will be useful for studies where the sample is easily damaged, more example in biological or medical research. Imaging using tomographic techniques that allow 3D imaging, is also possible.

Read the full story at Innovations Report.

Posted: January 24th, 2008 under Physics, Nanotechnology.
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Creating artificial sensors that mimic those of the body has proved difficult when it comes to the chemical senses, i.e. smell and taste. These are generally less advanced than man-made sensors for vision and hearing. One such example is the “artificial nose”.

Now researchers at the company CogniScent in Massachusetts and at Tufts University have now come up with a new design that incorporates single strands of DNA around 20-30 amino acids long that has the potential to create billions of sensor types for different volatile compounds. One such combination that has been identified can detect TNT in land mines down to six parts per billion which signals the potential usefulness of the technology across a range of disciplines.

More information available at MIT Technology Review or read the synopsis at PLoS Biology.

Posted: January 23rd, 2008 under Chemistry, Nanotechnology.
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Everyone is familiar with inkjet printing technology. Inkjet printers capable of printing in 3D, one layer on top of the other, have also been around for several years. But now a patent has been filed that claims that complex tissues could be printed in 3D using the same technology.

James Yoo, a surgeon and researcher at the Institute of Regenerative Medicine at Wake Forest University in Winston-Salem, North Carolina has used current 3D inkjet printing technology to build up layers of viable cells into complex structures. As in naturally-formed tissues and organs, the cells may comprise a number of different types and growth factors may also be incorporated as well as dyes to help visualise the 3D tissue construct. Yoo claims that the method could be used to make a wide variety of engineered animal or human tissues.

See NewScientistTech for the story or view the patent application abstract.

Posted: January 22nd, 2008 under Regenerative medicine, Nanomedicine, Nanotechnology.
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New research, published in Nature Nanotechnology, has shown that cell functions can be controlled using physical, rather than chemical, means. The research team, led by Professor Donald Ingber of Harvard Medical School and the Harvard Insitute for Biologically Inspired Engineering, attached nanoparticles with iron oxide cores to immune-system cells using biomolecules that bind to receptors on the immune cells. In the presence of a weak magnetic field, the nanoparticles became magnetic charged and drew the immune cells together in clusters, causing them to take up calcium. In-vivo, this would be part of a chain of reactions leading to the cells releasing histamine. When the magnetic field was released, uptake of calcium ceased.

According to Professor Ingber, this calcium uptake function is a result of proximity rather than chemistry.The research herald interesting possibilities for drug design and delivery as many drugs rely on the activation of cell receptors. Ingber himself sees a number of potential applications including magnetic pacemakers working through direct action on cells rather than by means of electrodes. Other researchers see possibilities also in controlling man-machine interface systems in the longer term while, in the shorter term, it may give important insights into the mechanisms of cell signaling.

More information available at MIT Technology Review.

Posted: January 21st, 2008 under Physics, Nanomedicine, Nanotechnology.
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Colloidal gold has been used for some 50 years in the treatment of rheumatoid arthritis but recent research shows that gold nanoparticles also have promise in imaging many cancers including individual malignant cells.

Working from the premise that colloidal gold can amplify the efficiency of Raman scattering by 14-15 orders of magnitude, researchers at Emory University/Georgia Institute of Technology took gold nanoparticles and stabilized them using thiol-modified polyethylene glycols (a process called PEGylation) which both rendered them biocompatible and non-toxic to cells for up to six days and well as maintaining their chemical stability. The resulting particles showed high efficiency as imaging agents when the PEG was linked with an antibody that bound to epidermal growth factor receptor which is expressed in many types of cancer. Untargeted particles, on the other hand, tended to accumulate in the liver.

The research was published in the journal Nature Biotechnology (abstract here) and further information is available at Physorg.com.

Posted: January 17th, 2008 under Nanomedicine.
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In a letter published in Nature Cell Biology, Sowinski et al report on research that shows that membrane nanotubes, formed when T-cells routinely contact one another and subsequently part, could present a newly-identified route for the transmission of HIV-1 from infected to uninfected cells. While this a laboratory-based study and it is not yet known whether T-cells produce such nanotubes in the human body, the research is promising in relation to both HIV and other viral studies, and as a potential mechanism for drug targeting. More information on this story is available at Nature Cell Biology and Physorg.com.

Posted: January 15th, 2008 under Nanomedicine.
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