Showing Spotlights 1929 - 1936 of 2140 in category (newest first):
Nanowires are expected to play an important role in the emerging fields of nanoelectronics and nanooptics. In particular, the permanently growing complexity of integrated circuit designs requires a further reduction of the size of IC components that nanowires could facilitate. Nanowires are also a possible candidate for future functional nanostructures in plasmonic devices, i.e. for information (light) propagation and manipulation below the optical diffraction limit. For these purposes, cobalt disilicide (CoSi2) is a very promising contact material due to its extremely useful properties such as low resistance, its metallic behavior, its low lattice mismatch to Si of only -1.2%. the plasmon wavelength of 1.2 micrometer, and its compatibility with modern silicon technology. Many efforts have been made to fabricate silicide nanowires employing the bottom-up approach without elaborate microlithography. Researchers in Germany now have demonstrated a promising technique that allows the defect-induced formation and placing of cobalt disilicide nanowires by focused ion beam synthesis in silicon directly where it is needed.
Jan 22nd, 2007
The discovery of numerous nanomaterials has added a new dimension to the rapid development of nanotechnology. Consequently, the professional and public exposure to nanomaterials is supposed to increase dramatically in the coming years. Especially, carbon-based nanomaterials (CBNs) are currently considered to be one of the key elements in nanotechnology. Their potential applications range from biomedicine through nanoelectronics to mechanical engineering. Thus, it is primordial to know the health hazards related to their exposure. As the public calls for safety studies get louder more and more researchers begin to study the potential toxicity of nanomaterials. Especially carbon-based nanomaterials, due to their numerous and wide-ranging applications and increasing real life usage, get nanotoxicological attention. Scientists in Switzerland studied the toxicity of carbon- based nanomaterials (nanotubes, nanofibers and nanowires) as a function of their aspect ratio and surface chemistry. Their work clearly indicates that these materials are toxic while the hazardous effect is size-dependent.
Jan 19th, 2007
Silver has long been recognized for its infection-fighting properties and it has a long and intriguing history as an antibiotic in human health care. In ancient Greece and Rome, silver was used to fight infections and control spoilage. In the late 19th century, the botanist von Naegeli discovered that minute concentrations of silver contained microbiocidal properties. However, as the first antibiotics were discovered, this old household remedy was quickly forgotten. In an alarming trend, bacteria and other microorganisms that cause infections are becoming remarkably resilient and can develop ways to survive drugs meant to kill or weaken them. This antibiotic resistance is due largely to the increasing use of antibiotics. This led researchers to re-evaluate old antimicrobial substances such as silver. Silver nanoparticles have become the promising antimicrobial material in a variety of applications because they can damage bacterial cells by destroying the enzymes that transport cell nutrient and weakening the cell membrane or cell wall and cytoplasm. Unfortunately, in practical applications, the pure silver nanoparticles are unstable with respect to agglomeration. In most cases, this aggregation leads to the loss of the properties associated with the nanoscale of metallic particles. The stabilization of metallic colloids and thus the means to preserve their finely dispersed state is a crucial aspect to consider during their applications. Researchers in China have successfully demonstrated the use of a natural macroporous matrix for fabricating a stable, biocompatible nanocomposite with high silver content for antimicrobial purposes.
Jan 18th, 2007
The ability to detect few or individual molecules in solution is at present largely limited to fluorescence techniques, and a comparable method using electrical detection has so far remained elusive. Such a technique would be highly desirable for lab-on-a-chip applications and when labeling with fluorophores is invasive or impossible. More importantly, it would pave the way for fluidic devices in which individual ions are electrically detected and manipulated, allowing a new class of fundamental experiments on nonequilibrium statistical physics, transport at the molecular scale, and a broad range of biophysical systems. Researchers in The Netherlands now have demonstrated a new nanofluidic device for the detection of electrochemical active molecules with an extremely high sensitivity. A prototype device allows detecting fluctuations due to Brownian motion of as few as approx. 70 molecules, a level heretofore unachieved in electrochemical sensors. Ultimately, the researchers hope the device will not only be able to detect single molecules in the device, but also discriminate between various species.
Jan 17th, 2007
Nanosurgery holds the promise of studying or manipulating and repairing individual cells without damaging the cell. For instance, nanosurgery could remove or replace certain sections of a damaged gene inside a chromosome; sever axons to study the growth of nerve cells; or destroying an individual cell without affecting the neighboring cells. While the cell nucleus has been transplanted between cells during cloning using micropipette technologies, these methods are too crude for other subcellular structures. First steps towards nanosurgery have been made using so-called 'optical tweezers', where the energy of laser light is used to trap and manipulate nanoscale objects, for instance the nucleus of a cell, without mechanical contact. Combined with a laser scalpel (use of lasers for cutting and ablating biological objects) optical tweezers have been used to study cell fusion, DNA-cutting, etc. Unfortunately, while optical tweezers offer exquisite sensitivity in their ability to position micro- and nanoparticles, they suffer from one important disadvantage: the trapped particle is localized at the laser focus where light intensity is the highest. As a result, the laser light used to trap a particle also has a propensity to photobleach and photodamage the particle, especially when the particle is fragile and small (e.g., a subcellular organelle that is fluorescently labeled). Minimizing this drawback, new research describes the use of polarization-shaped optical vortex traps for the manipulation of particles and subcellular structures.
Jan 16th, 2007
As the most common endocrine metabolic disorder for human beings, diabetes mellitus with an obvious phenomenon of high blood glucose concentrations results from a lack of insulin. Despite the availability of treatment, diabetes has remained a major cause of death and serious vascular and neuropathy diseases. Continuously monitoring the blood glucose level and intermittent injections of insulin are widely used for effective control and management of diabetes. Extensive research has been conducted to develop optimal glucose sensors for diagnostic purposes. Currently, the commercially available glucose biosensors still have some problems to overcome, such as time consuming, relatively low sensitivity, bad reliability. The performance of a glucose sensor is largely dependent upon the materials which construct the sensor. Recent research effort for glucose sensing have turned to on nanomaterials. Nanomaterial-based biosensors already have shown the capability of detecting trace amounts of biomolecules in real time. New research has studied the electrochemical characteristics of platinum decorated carbon nanotubes (CNTs) as a promising candidate for glucose sensing. Its improved performance may encourage further exploration of this novel nanomaterial in the field of bioapplications.
Jan 15th, 2007
Thermolysis (from thermo- meaning heat and -lysis meaning break down) is a chemical process by which a substance is decomposed into other substances by use of heat. In photothermolysis the transfer of laser energy is used to generate the required heat. And finally, nanophotothermolysis is the process where nanoparticles, when irradiated by short laser pulses, get hot so quickly that they explode. This thermal explosion of nanoparticles (nanobombs) may be accompanied by optical plasma, generation of shock waves with supersonic expansion and particle fragmentation with fragments of high kinetic energy, all of which can contribute to the killing of cancer cells they are attached to. By engineering the laser wavelength, pulse duration and particle size and shape, this technology can provide highly localized damage in a controlled manner, potentially varying from a few nanometers (for DNA) to tens of microns (the size of a single cancer cell) without damaging the surrounding tissue.
Jan 12th, 2007
If you had brain tumor, would you rather receive your medicine through an injection in the arm or have a hole drilled in your skull? Even if you opted for the 'hole-in-the-skull' method, brain cancers are often inoperable due to their location within critical brain regions or because they are too small to detect. Nanotechnology offers a vision for a 'smart' drug approach to fighting tumors: the ability of nanoparticles to locate cancer cells and destroy them with single-cell precision. One of the most important applications for such nanoparticulate drug delivery could be the delivery of the drug payload into the brain. However, crossing the brains protective shield, the blood-brain barrier, is a considerable challenge. Novel targeted nanoparticulate drug delivery systems that are able to cross this barrier bring us closer to this vision of brain cancer destroying drugs.
Jan 11th, 2007