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Nanotechnology Spotlight

Behind the buzz and beyond the hype:
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Showing Spotlights 1521 - 1528 of 1756 in category All (newest first):


Size-based sorting and manipulation of nanoparticles becomes possible

The precise positioning of nanoparticles on surfaces is key to most nano- technology applications especially molecular electronics. However, for automated patterning of particles, existing methods are either slow (e.g., dip-pen lithography) or require prefabricated patterns (e.g., by electrostatic positioning or by successive self-assembly, transfer, and integration). Moreover, the sorting of differently sized particles, organelles, and cells in microfluidic networks is important for many biological and medical applications. Purely size-based sorting would offer the greatest control, but an automated method so far does not exist. Researchers in Switzerland now have discovered that acoustic streaming leads to sorting of particles dependent on their size. Nanoparticles aggregate at the antinodes and micrometer-sized particles aggregate on the nodes of oscillation patterns on micro- machined cantilevers. These surprising results open new possibilities for the sorting of nanoparticles.

Posted: Jan 24th, 2007

Self-heating nanoparticles as tumor-destroying hyperthermia agents

Hyperthermia therapy, a form of cancer treatment with elevated temperature in the range of 41-45C, has been recently paid considerable attention because it is expected to significantly reduce clinical side effects compared to chemotherapy and radiotherapy and can be effectively used for killing localized or deeply seated cancer tumors. Accordingly, various forms of hyperthermia have been intensively developed for the past few decades to provide cancer clinics with more effective and advanced cancer therapy techniques. However, in spite of the enormous efforts, all the hyperthermia techniques introduced so far were found to be not effective for completely treating cancer tumors. The low heating temperature owing to the heat loss through a relatively big space gap formed between targeted cells and hyperthermia agents caused by the hard to control agent transport, as well as killing healthy cells attributed to the difficulties of cell differentiations by hyperthermia agents, are considered as the main responsibilities for the undesirable achievements. In a possible breakthrough, researchers in Singapore now report the very promising and successful self-heating temperature rising characteristics of NiFe2O4 nanoparticles. Different from conventional magnetic hyperthermia, in-vivo magnetic nanoparticle hyperthermia is expected to be one of the best solutions for killing tumor cells which are deeply seated and localized inside the human body.

Posted: Jan 23rd, 2007

Nanowire growth through ion beams

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.

Posted: Jan 22nd, 2007

Nanotechnology risks: Clear indications that carbon-based nanomaterials are toxic

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.

Posted: Jan 19th, 2007

Stabilizing antimicrobial nanosilver on a natural porous plant material

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.

Posted: Jan 18th, 2007

Novel nanofluidic device could lead to electrical single molecule detection

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.

Posted: Jan 17th, 2007

Improving the tools for single-cell nanosurgery

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.

Posted: Jan 16th, 2007

Towards a high performance nanotechnology glucose sensor for diabetes sufferers

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.

Posted: Jan 15th, 2007