Spider silk is a fascinating biopolymer that is stronger than steel and more elastic than rubber. Most of the world's 40,000 species of spiders produce a silken thread that possesses a unique combination of mechanical properties: strength (its tensile strength is about five times as strong a steel of the same density), extensibility (up to 30%) and toughness (its ability to absorb a large amount of energy without breaking). Researchers are experimenting with spider silk to design better adhesives; advanced materials that are both stretchy and strong; and to get clues for protein engineering. Yet the impressive performance of spider silk is not limited solely to tensile mechanics. Researchers have now shown that silk also exhibits powerful cyclic contractions that are precisely controlled by changes in humidity, allowing it to act as a high performance mimic of biological muscles.
In animal cells, the well known cytoskeletal proteins actin microfilaments and microtubules are accompanied by a third filament system that in humans consist of a family of more than 70 proteins. These fibrous proteins are absent from both plants and fungi, and have been linked to serious human diseases including cancer, muscle dystrophies and rapid aging disease. Their name, intermediate filament, was coined back in 1978 because their diameters - about 10 nanometers - appeared to be intermediate in size between those of microtubules and microfilaments. Their atomistic-level molecular structure remains elusive, and as a consequence, the understanding of the biological role in physiological and disease states is still in its infancy. Researchers now report a breakthrough in explaining the structural and mechanistic origin of the unique mechanical properties of intermediate filaments. By combining atomistic and molecular modeling with experimental studies, the researchers report a multi-scale analysis that showed that the mechanical properties of intermediate filaments are controlled by their characteristic hierarchical makeup.
Surface-plasmon resonance is a quantum-electromagnetic phenomenon arising from the interaction of light with free electrons at the planar interface of a metal and a (nonconducting) dielectric material. This resonance arises when the energy carried by photons in the dielectric material is transferred to collective excitations (called plasmons) of free electrons in the metal at that interface. As the free electrons in the metal are coupled to the photons in the polarizable dielectric material, the quantum is called a surface plasmon-polariton (SPP). Typically, a SPP wave is launched on a metal-dielectric interface at one particular frequency. That wave has a certain polarization state. Researchers have now shown theoretically and experimentally that by modifying the dielectric material, novel surface-plasmon-polariton wave behavior can be created with the result that the same interface can independently guide more than one SPP wave.
Researchers have developed a self-sensing nanotechnology composite material for traffic monitoring by using piezoresistive multi-walled carbon nanotubes as an admixture. In experiments, they studied the response of the piezoresistive properties of this composite to compressive stress and they investigated with vehicular loading experiments the feasibility of using self-sensing CNT/cement composite for traffic monitoring. This nanocomposite cement has great potential for traffic monitoring use such as in vehicle detection, weigh-in-motion measurement and vehicle speed detection. An interesting aspect of this work is that, from the eventual traffic application's point of view, the pavement itself would become the traffic detection, thus eliminating the need for separate traffic flow detection sensors.
Today, in our Application Note series, we are covering Scanning Thermal Microscopy (SThM) - an atomic force microscopy (AFM) imaging mode that maps changes in thermal conductivity across a sample's surface. Similar to other modes that measure material properties, SThM data is acquired simultaneously with topographic data. The SThM mode is made possible by replacing the standard contact mode cantilever with a nanofabricated thermal probe with a resistive element near the apex of the probe tip. This resistor is incorporated into one leg of a Wheatstone bridge circuit, which allows the system to monitor resistance. This resistance correlates with temperature at the end of the probe, and the Wheatstone bridge may be configured to either monitor the temperature of a sample or to qualitatively map the thermal conductivity of the sample.
Here is a no-brainer (excuse the pun): 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 nanomedicine drug delivery systems that are able to cross this barrier bring us closer to this vision of brain cancer destroying drugs.
Graphene is an impressive condensed matter system that, to all appearances, never ceases to impress and challenge our entrenched intuitions regarding solid state systems. But graphene is a highly atypical electronic system in that it consists of nothing but a surface. Researchers at Boston University have found that local deformations in a graphene sheet can strongly influence electron flow across the system, causing suppression of conductance at low densities, and making electrons behave as if they were living in a nanoribbon or quantum dot. All this without cutting the graphene sheet, which opens the prospect towards a reversible and controllable transport gap in monolayer graphene via strain engineering.
In their effort to develop a fast, sensitive, selective, inexpensive, and easy-to-use method for detecting and quantifying pathogenic bacterial cells, researchers in Spain have now demonstrated a carbon nanotube based potentiometric biosensor for selectively detecting one single colony-forming unit of the bacterium Salmonella Typhi in close to real time. The most important strength of this biosensor is that simple positive/negative tests can be carried out in real zero-tolerance conditions and without cross reaction with other types of bacteria. The ease with which measurements are taken in potentiometric analysis opens the door to greater simplicity in microbiological analysis.