Researchers from the University of California and Harvard-MIT have developed a new type of biodegradable, non-toxic nanoparticle (NP) that break down readily and can be excreted via the kidneys after delivering a drug payload to the target site thereby avoiding a major drawback with some other nanoparticle delivery systems that may have limited biodegradability, toxicity issues or which are rejected immediately by the body’s immune system.

The novel NPs were formed by electrochemical etching of single-crystal silicon wafers followed by ultrasonication and filtration, yielding NPs with 5-10nm pore diameters. Silicon oxide grown onto the surfaces provides an intrinsic photoluminescence at 650-900nm which is a range where organs and tissues exhibit very low adsorption, thereby providing a mechanism for monitoring accumulation and degradation in-vivo.

In-vivo tests in a mouse model with the anti-cancer drug doxorubicin showed accumulation in a tumour followed by subsequent breakdown of the NPs, probably into soluble silicic acid, and elimination by renal clearance within 1-4 weeks of injection with no indications of toxicity.

Source: Nanowerk

Paper: Nature Materials

Posted: April 16th, 2009 under Chemistry, Nanomedicine.
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Researchers at New York University and Harvard University have created an autonomous, bipedal DNA “walker” that can mimic a cell’s transportation system and which marks a step toward creating more complex synthetic molecular motors.

Previous versions of walkers, which are able to move along a track of DNA, were unable to function autonomously and were liable to become uncoordinated and fall off the DNA “track”.

The New York and Harvard team overcame this problem by employing two DNA “fuel strands” which worked with the walker as a catalytic unit pushing the walker along the DNA tracks. More base pairs are formed at every step and this creates the energy necessary for movement. The fuel strands bind to the track and also release the walker’s legs allowing it to take a “step”.

The researchers hope that the research may mark a step toward creating more complex synthetic molecular motors capable of carrying a cargo from one part of a cell to another.

Video animation of walker

Science paper

Source: Nanowerk

Posted: April 6th, 2009 under Chemistry, Nanomedicine.
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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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There have been a number of attempts to create artificial blood, but most so far have some drawbacks, e.g. risk of heart attacks in the patients, usually trauma cases, that receive such transfusions.

Researchers at the University of Pennsylvania have, however, now succeeded in constructing an artificial protein from scratch that is capable of carrying and delivering oxygen in the body and that is resistant to ingress by water which causes release of oxygen that can cause cellular damage.

Unlike existing blood substitutes, which are usually constructed from modified natural haemoglobin the Pennsylvania team used three amino acids to make a four-helix columnar candelabra-shaped protein structure containing a heme structure similar to the active part of haemoglobin capable of opening and closing to receive and deliver oxygen without letting water in.

While further work is required to ensure that the new protein can hold on to oxygen for long enough to be useful, and to ensure that it can work in a cellular environment and is non-toxic, the research represents a notable step in protein design

Source: MIT Technology Review

Posted: March 30th, 2009 under Chemistry, Nanomedicine.
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One of the problems with implanting material into the human body is that proteins tend to build up on the surfaces of the implanted material. In the case of applications like biosensing surfaces, e.g. for glucose monitoring in diabetes, and membranes this can cause significant problems.

Now a new study by researchers at North Carolina State University led by Dr Roger Narayan, has found that nanoporous ceramic membranes can avoid both protein build-up and rejection by the body. The researchers hope that this may open up new possibilities in developing dialysis membranes, as well as other implant surfaces, where poor biocompatibility has proved a problem in the past.

Source: PhysOrg.com

Posted: November 11th, 2008 under Chemistry, 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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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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The 2007 Nobel Prize in Chemistry has been awarded to Gerhard Ertl of the Fritz-Haber-Institut der Max-Planck-Gesellschaft, Berlin for his ground breaking studies in surface chemistry. Professor Ertl’s work has been instrumental in developing techniques that enable the study of the behaviour of individual atoms or molecules at a surface. Such studies are vital in fields as diverse as corrosion, fuel cells, catalysts, semiconductors, and soil and atmospheric research.

Further details about the award and Professor Ertl’s work can be found at the Nobelprize.org website.

Posted: October 11th, 2007 under Chemistry.
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