Showing Spotlights 1649 - 1656 of 2284 in category All (newest first):
Carbon nanotubes are considered a promising material system not only for nanoelectronics but also for nanophotonics - the manipulation and emission of light using nanoscale materials and devices. By trying to understand the electrical properties of carbon nanotubes (CNTs) through their light emission, scientists are paving the way for CNTs' integration in optical applications. Embedding spatially isolated CNTs into an optical microcavity is a promising means of controlling and improving their radiative properties. The control of these CNT properties, including emission wavelength, spectral width, emission direction and radiative yield through optical confinement, opens the door for their use in integrated nanophotonic circuits. Cavity controlled nanotube emitters could potentially find use in quantum optics, quantum communication, and integrated nanophotonic circuits and may ultimately lead to low threshold on-chip nanolasers.
Sep 9th, 2008
Carbon nanomaterials have been extensively used in electroanalysis, and the most common forms are spherical fullerenes, cylindrical nanotubes, and carbon fibers and blacks. Since the discovery that individual carbon nanotubes (CNTs) can be used as nanoscale transistors, researchers have recognized their outstanding potential for electronic detection of biomolecules in solution, possibly down to single-molecule sensitivity. To detect biologically derived electronic signals, CNTs are often functionalized with linkers such as proteins and peptides to interface with soluble biologically relevant targets. Now, for the first time, scientists have tested nanometal decorated graphene (actually graphite nanoplatelets, a thickness of 10 nm would contain approximately 30 graphene sheets, considering an interlayer spacing of 0.335 nm) in biosensor application. As it turned out, this novel biosensor is among the best reported to date in both sensing performance and production cost.
Sep 8th, 2008
Several aspects determine how effective a pharmaceutical drug is. Probably the key issue is how well a drug molecule is able to reach its intended target. This need for target specific delivery of drugs has been well accepted in modern drug therapy. Many research efforts are geared towards improving not just the tissue accumulation, but also the cell-specific accumulation of drug molecules in the hope of improving the efficacy of these drug molecules. The ability to target nanoparticles to specific types of cancer cells is one of the main reasons that nanoparticles have gained favor as a promising drug delivery vehicle. By increasing the amount of an anticancer agent that gets to tumor cells, as opposed to healthy cells, researchers hope to minimize the potential side effects of therapy while maximizing therapeutic response. Now, a group of scientists has taken this approach one step farther by targeting the specific location inside a tumor cell, where a cancer drug then exerts its cell-killing activity.
Sep 5th, 2008
Borrowing from nature's micro- and nanoscale propulsion systems, nanotechnology researchers have successfully used motor proteins to transport nanosized cargo in molecular sorting and nano-assembly devices. In so-called gliding assays, surface-attached motors propel cytoskeletal filaments, which in turn transport a cargo. However, cargo and motors both attach to the filament lattice and will affect each other. While an effect of cargo loading on transport speed has been described before, it has never been explained very well. To study this effect, scientists in Germany have observed single kinesin-1 molecules on streptavidin coated microtubules. They found that individual kinesin-1 motors frequently stopped upon encounters with attached streptavidin molecules. This work helps to understand the interactions of kinesin-1 and obstacles on the microtubule surface. An interesting, possibly even more important side result is that this understanding will not only help to optimize transport assays, balancing speed and cargo-loading, but can be used as a novel method for the detection of proteins as well.
Sep 4th, 2008
Laser-based analytical techniques such as Raman spectroscopy, fluorescence spectroscopy or the state-of-the-art laser-induced breakdown spectroscopy (LIBS) are highly sophisticated techniques to analyze minute amounts of matter with regard to its structure, elemental composition, and other chemical properties. LIBS has been shown to be capable of analyzing extremely small samples with high sensitivity - nanoliter volumes with levels of detection in water of part per million. LIBS works by focusing short laser pulses onto the surface of a sample to create a hot plasma with temperatures of 10,000 - 20,000 C. The plasma emits radiation that allows the observation of the characteristic atomic emission lines of the elements. On the downside, LIBS is complicated by the need for multiple laser pulses to generate a sufficiently hot plasma and the need for focusing and switching a powerful laser, requiring relatively large and expensive instruments.
New research coming out of Drexel University has now shown that light emitted from a new form of cold plasma in liquid permits Optical Emission Spectroscopy (OES) analysis of the elemental composition of solutions within nanoseconds from femtoliter volumes.
Sep 3rd, 2008
The demand for the raw materials of the nanotechnology revolution - nanoparticles, carbon nanotubes, fullerenes, quantum dots, etc - is rising explosively and large chemical companies keep expanding their production capacities. These industrial scale systems often depend on precious input materials and energy-hogging processes. However, there are vast amounts of 'useless' natural materials literally lying around - rocks and stones - which could find their way into nanotechnology.Researchers in Germany have made a proof of concept demonstration that using natural nanostructures found in lava rocks is suitable for nanomaterial synthesis and for use in catalysis for production of butadiene and styrene.
Sep 2nd, 2008
The motor proteins of the cytoskeleton accomplish nanotransport tasks by moving 'cargo' along microtubules that are about 25 nm wide but can grow up to 1,000 times as long. Nanotechnology engineers are fascinated by this transport mechanism and several efforts are underway in various labs to unravel and, researchers hope, eventually copy nature's engineering feat. A particularly promising setup consists of surface-attached linear motor proteins that drive the motion of cytoskeletal filaments. Some researchers expect that artificial molecular transport systems which utilize microtubules motility will be an alternative to pressure-driven or electrokinetic flow-based microfluidic devices. Researchers in Germany describe a novel method to characterize the rotational movement of cytoskeletal filaments gliding over motor-coated substrate surfaces. This technique allows exploring the detailed paths that motors take on cytoskeletal filaments. This is also important in understanding situations of heavy intracellular traffic, where motors might have to switch lanes.
Aug 29th, 2008
Nanomedicine, especially drug delivery with nano-sized drug carriers, is all the rage these days. The concept sounds simple: make nanoscale containers that can escape detection by the body's defense mechanisms, fill them with a drug, get them to the desired location within the body, release the drug payload and, presto, you've got a very effective and efficient weapon for instance to fight cancer. That this model works in principle has already been demonstrated in numerous studies. The same studies show the complicated nature and the many difficulties that scientists are facing in fabricating the right nanocontainers, getting them to the right location, controlling the release mechanism of the drug, measuring the drugs' efficacy, and monitoring the now empty delivery vehicles' fate. Researchers from the Indian Institute of Technology Guwahati present experimental results which suggest that the specificity of release of encapsulated nanoparticles could be achieved with an appropriate combination of encapsulating materials and the choice of an appropriate enzyme that would cleave the encapsulation to release the nanoparticles.
Aug 28th, 2008