A newly published antibacterial activity mechanism study demonstrates how a single walled carbon nanotube (SWCNT) kills bacteria by the physical puncture of bacterial membranes. The nanotubes would constantly attack the bacteria in solution, degrading the bacterial cell integrity and causing the cell death. This work elucidates several factors controlling the antibacterial activity of pristine SWCNTs and provides an insight in their toxicity mechanism. With regard to carbon nanotubes, in early toxicological studies, researchers obtained confounding results - in some studies nanotubes were toxic; in others, they were not. The apparent contradictions were actually a result of the materials that the researchers were using.
One of the promises of medical nanotechnology is a drug-delivery nanodevice that can image, target, and deliver drugs to a specific cancer location inside the body and monitor and if necessary adjust the drug release at the target location. Researchers in Taiwan have now designed a nanodevice that comes pretty close to this vision. They have successfully demonstrated that our multifunctional drug-delivery nanodevice - a polymer core/single-crystal iron oxide shell nanostructure bonded to a quantum dot - can image, target, and deliver drugs via remote control. The device shows outstanding release and retention characteristics via an external on/off manipulation of a high-frequency magnetic field. Furthermore, the quantum dot bonded to the nanodevice provides optical information for in situ monitoring of the drug release.
New research reported this week has now established an industrially relevant process for assembling carbon nanotubes that allows them to efficiently be made into fibers, coatings and films - the basic forms of material that can be used in engineering applications. The most common of processing nanotubes into neat fibers - apart from 'dry' methods where they are spun directly into ropes and yarns - are 'wet' methods where CNTs are dispersed into a liquid and solution-spun into fiber. Currently, these processes yield fibers whose properties are not sufficiently close to optimal. Successful carbon nanotube assembly begins with control of dispersion and phase behavior and requires a scientific understanding of flow, colloidal interactions and solvent removal.
The potential use of antimicrobial surface coatings ranges from medicine, where medical device infection is associated with significant healthcare costs, to the construction industry and the food packaging industry. Thin films which contain silver have been seen as promising candidate coatings. There now are even anti-odor, anti-bacterial socks that are treated with silver nanoparticles. Researchers in Switzerland have now examined what happens to these silver nanoparticle-treated textiles during washing. The scientists studied release of nanoparticles in laundry water from nine different textiles, including different brands of commercially available anti-odor socks. Studies like these will help address the question what the chances are of nanoparticles from nanofinished textiles being released into the environment.
The physical properties of nanostructures have been investigated extensively both theoretically and experimentally. Among these properties, melting temperature, superconductive temperature, Curie temperature and Debye temperature are key physical quantities since they are the characteristic temperatures of melting, superconduction, ferromagnetism and vibration. When the size of materials approaches the nanoscale, the surface-to-volume ratio increases and matter begins to behave exotically. Considering this, scientists can predict size effects on material properties from macroscopic laws, the so-called top-down approach. They present a general equation that is based only on the surface area to volume ratio of nanostructures and statistics (Fermi-Dirac or Bose-Einstein) followed by the particles involved in the considered phenomena (melting, ferromagnetism, vibration and superconduction).
In today's addition to our Application Note series we are looking at the future of electronics and the implications for research instrumentation. We are showing two examples of atomic force microscope (AFM) applications employed in this research. Current CMOS (complementary metal-oxide-semiconductor) technology used for making integrated circuits is constantly being scaled down. These devices will reach their ultimate physical limits in 10 to 15 years. As chip structures - which currently already have reached nanoscale dimensions - continue to shrink below the 20 nanometer mark, ever more complex challenges arise and scaling appears not to be economically feasible any more. And below 10 nm, the fundamental physical limits of CMOS technology will be reached. Researchers are therefore exploring novel concepts for future nanoelectronic devices.
Traditional techniques in cell biology involve chemical or pharmaceutical treatments of entire cells; however, in many cases it would be advantageous to target a single organelle or other structure within a cell without damaging overall cell structure. If scientists could inject a drug into a chosen organelle within the cell, or even destroy, extract or isolate the whole organelle without significantly harming the cell itself, new insight could be gained into the inner workings of the cell. In recent years, techniques have been developed which allow the manipulation of the individual nanoscale structures within biological cells. This manipulation, or 'nanosurgery', has the potential to provide new insight into the internal structure and dynamics of cells. Nanosurgical methods have been developed to target the cell's internal organelles, the cell membrane, and the structural protein filaments within the cell.
Due to their unique structural and electrical properties, carbon nanotubes have been extensively investigated as promising catalyst supports to improve the efficiency of direct ethanol/methanol fuel cells. CNTs have a significantly higher electronic conductivity and an extremely higher specific surface area in comparison with the most widely-used Vulcan XC-72R carbon support. Several approaches, such as electrochemical reduction, electroless deposition, spontaneous reduction, sonochemical technique, microwave-heated polyol process, and nanoparticle decoration on chemically oxidized nanotube sidewalls, have been reported to form CNT-supported platinum catalysts. Some remarkable progress has been made in synthesis techniques; however, pioneering breakthroughs have not been made yet in terms of cost-effectiveness catalyst activity, durability, and chemical-electrochemical stability. Nanotechnology researchers in the U.S. have now discovered that platinum nanoparticles selectively grow on carbon nanotubes in accordance with single-stranded DNA locations.