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Showing Spotlights 1353 - 1360 of 2115 in category (newest first):

 

Novel technique for real-time detection of carbon nanotubes in the body

nanotube_detectionNew work at the University of Arkansas has, for the very first time, demonstrated that Raman spectroscopy can be used to detect and monitor circulating carbon nanotubes in vivo and in real time. These findings could have a significant impact on the knowledge of how nanomaterials interact with living biological systems. Carbon nanotubes can be used for various advanced bio-medical applications. Before any clinical application of nanoparticles, it is imperative to determine critical in vivo parameters, namely pharmacological profiles including nanoparticle clearance rate from the circulation and their biodistribution in various tissue and organs. Until now, their distribution was only monitored by collecting samples after various time intervals, but this new research shows the ability of monitoring their concentration in vivo and in real time, while the animal is alive. Moreover, this work can be extended to the detection of circulating cancer cells that have been tagged by carbon nanotubes.

Posted: May 12th, 2009

New morphologies of graphitic carbon in nanotechnology applications

nanocupsMany nanotechnology research efforts have explored the use of hollow nanochannels formed by carbon nanotubes (CNTs). However, the usually large length/diameter aspect ratio of CNTs has made it challenging to insert other materials into them in a controlled manner. A team of scientists has now developed the idea of using a nanocup morphology to solve this problem. The length/diameter ratio of these new graphitic architectures is 1,000 to 100,000 times smaller compared to conventional carbon nanotubes. This will allow researchers to build highly engineered and multicomponent functional nano building blocks for various applications including nanomedicine and nanometrology.

Posted: May 11th, 2009

Nanotechnology breath analyzer for kidney failure

kidneysOnline breath analysis via an array of chemiresistive random network of single walled carbon nanotubes coated with organic materials showed excellent discrimination between the various breath states. An important implication of these findings, besides the detection of diseases directly related to the respiratory, cardiovascular, and renal systems, is the fact that volatile organic compounds are mainly blood borne and the concentration of biologically relevant substances in exhaled breath closely reflects that in the arterial system. Therefore, breath is predestined for monitoring different processes in the body. The excellent discrimination between the various breath states obtained in this study provides expectations for future capabilities for diagnosis, detection, and screening various stages of kidney disease, especially in the early stages of the disease, where it is possible to control blood pressure, fat, glucose and protein intake to slow the progression.

Posted: May 7th, 2009

Carbon encapsulation of gold nanoparticles increases their stability

Carbon-shell_on_gold_nanoparticleThe use of gold nanoparticles in numerous biological and chemical nanotechnology applications experiences limitations due to the stability of the particles and their tendency for non-specific binding. One method to overcome these problems has been the use of carbon nanoshells to encapsulate gold and other noble metal particles. A graphene-like carbon shell is ideal for surface passivation of the metal nanoparticles for several reasons: it is nonreactive with the metallic surface; it provides unsurpassed stability; and it possesses a convenient handle for functionalization. A research team in the U.S. has now demonstrated a new fabrication method to encapsulate gold nanoparticles in a graphene-like carbon shell.

Posted: Apr 28th, 2009

Photo-triggered on demand drug release of nanoparticles

nanoparticle_drug_releaseA number of applications in nanomedicine - imaging, drug delivery or photo therapy for instance - utilize phenomena called two-photon absorption (TPA). In TPA, the simultaneous absorption of two photons excite a molecule from one state to a higher energy electronic state. TPA initially was used only as a spectroscopic tool but new applications emerged over time. Currently approved two-photon absorption-induced excitation is one of the most promising approaches in photo therapies as it increases light penetration. It enables the use of light in the tissue-transparent window (750-1000 nm), allowing deeper light penetration and reduced risk of laser hyperthermia. An uphill energy conversion through the use of two-photon absorbing chromophores and subsequent energy transfer is a promising scientific frontier.

Posted: Apr 27th, 2009

Self-assembled DNA nanocapsules for drug delivery

icosahedronStudies have already shown the complexity of architecture that is achievable using DNA as building blocks. For instance, nanofabrication via molecular self-assembly has already resulted in simple DNA polyhedra with connectivities of a cube, octahedron, and a tetrahedron. Platonic solids - any one of five solids whose faces are congruent regular polygons and whose polyhedral angles are all congruent - are the most efficient at enclosing large volumes. The more complex the polyhedron, the greater its ability to encapsulate cargo, because the capsule size can be maximized while keeping the pore-size of the capsule minimal. The most complex platonic solid is the icosahedron and therefore this would be most suitable for achieving cargo encapsulation. The DNA shell of such a capsule could protect vulnerable drugs from degradation by proteins until they reach their target site. It could also prevent dangerous drugs from leaking out until the capsule reaches its intended target. The DNA shell could also allow attachment to a protein that could ferry the drug-loaded capsule to a target.

Posted: Apr 24th, 2009

Nanoantenna boosters for carbon nanotube infrared detectors

cnt_infrared_detectorInfrared (IR) detectors are used in imaging applications that include for instance medical diagnosis, environmental monitoring, space science, and security and military sensor devices. High-quality detectors require cryogenic cooling in order for the image not to be distorted by the detectors own radiation. This makes them expensive both to produce and to run. Although uncooled IR detectors are made, their resolution and image quality tend to be much lower than cooled detectors. It appears that carbon nanotubes (CNTs) could be used as novel IR detector material that would allow the fabrication of highly efficient detectors that do not require cooling. Researchers at Michigan State University have now, for the first time, experimentally demonstrated the design, manufacturing and experimental testing of an integrated nanoantenna concept for CNT based IR sensors.

Posted: Apr 22nd, 2009

Pinpointing catalytic reaction sites on carbon nanotube walls

carbon_nanotube_catalystsCarbon nanotubes have been recognized as promising materials for catalysis, either as catalysts themselves, as catalyst additives or as catalyst supports. Researchers are particularly excited by the promise of single-walled carbon nanotubes as electrocatalysts or electron harvesting materials for electron-to-fuel conversion. Nanotubes act as catalysts when an electric current is passed through them. This enables them to donate electrons to molecules that come in contact with the reaction sites. In trying to explain carbon nanotubes' role as catalyst, scientist have long proposed that the reactive sites for catalysis can be discrete, specific sites rather then the entire sidewall of the nanotubes. But observing them directly has been challenging. A team at Cornell University has now filled in an important blank by pinpointing unique sites where the reactions take place on SWCNTs. The scientists showed that the reactions do not occur all along the tubes, but at the ends of the tubes or at defects along the tubes.

Posted: Apr 21st, 2009