Photonic crystals are very suitable for fabricating sensor devices because the optical signals of these responsive materials are tightly coupled with various external stimuli and modulations. They could also play a significant role on the way to all-optical devices in communication and information technology - they form a basis material for the future realization of optical components and circuits, and maybe even complex optical circuits or optical computers. One application area that has seen a lot of activity recently is photonic paper and ink. One advantage of photonic papers and displays is that they are brilliant and free of glare in sunlight, which are superior to the characteristics of other emissive display technologies for outdoor usage such as advertising billboards. Another advantage is that, for recording purposes, the structural colors of photonic paper are usually more durable than traditional pigments and dyes. However, there are still a number of issues and problems that prevent the practical applications of the photonic crystal based materials. Researchers in California have now addressed some of them by reporting a new type of rewritable photonic paper on which a durable ink mark can be written or erased by introducing or removing a hygroscopic salt in the surface layer of the paper.
Various forms of hyperthermia - a form of cancer treatment with elevated temperature in the range of 41-45C - have been intensively developed for the past few decades to provide cancer clinics with more effective and advanced cancer therapy techniques. The recent use of nanomaterials has shown promising for developing more effective hyperthermia agents. While most nanomedical hyperthermia research is conducted with various nanoparticles, carbon nanotubes are also of interest in these thermal ablation applications. So far, however, the utility of carbon nanotubes for in vivo use has been limited by self-association - i.e. they stick to each other. A new study has now demonstrated that DNA-encasement of multi-walled carbon nanotubes (MWCNTs) results in well-dispersed, single MWCNTs that are soluble in water and that display enhanced heat production efficiency relative to non-DNA-encased MWCNTs.
It its more than 25 years of existence, Scanning Tunneling Microscopy has predominantly brought us extremely detailed images of matter at the molecular and atomic level. The Scanning Tunneling Microscope (STM) is a non-optical microscope that scans an electrical probe over a surface to be imaged to detect a weak electric current flowing between the tip and the surface. It allows scientists to visualize regions of high electron density and hence infer the position of individual atoms and molecules on the surface of a lattice. Now, researchers in Japan have managed to partially sequence a single DNA molecule with a STM - a significant step towards the realization of electronic-based single-molecule DNA sequencing.
The term bio-interface describes the boundary between synthetic materials such as plastics, and biological systems. This rapidly growing research area, where biology and material sciences overlap, is creating new opportunities for the design, synthesis, and optimization of biologically-enabled and biologically-inspired materials. It involves manufacturing and characterization of functional surfaces for specific interactions with bio-systems and studies of the molecular and kinetic processes occurring at such interfaces, ranging from small molecule and biomolecular interactions, to cell adhesion, differentiation and tissue formation at the interface. For example, the incorporation of proteins into polymers can result in hybrid materials that combine the properties of the polymer as a cost-effective and easy to process material with the highly evolved biological functionality of the protein, enabling new concepts for construction of sensors and biomedical materials. While researchers so far have been focusing on altering the properties of a polymer by adding the functionality of a biomolecule, a group in California has now demonstrated the reverse situation, where changes in the polymer can alter the properties of the protein.
In today's Spotlight we take a look at a specific example of the challenges researchers face in improving fuel cell technology and the important role that modern laboratory instruments such as electron microscopes play in their work. Fuel cells have gained a lot of attention because they provide a potential solution to our addiction to fossil fuels. Energy production from oil, coal and gas is an extremely polluting, not to mention wasteful, process that consists of heat extraction from fuel by burning it, conversion of that heat to mechanical energy, and transformation of that mechanical energy into electrical energy. In contrast, fuel cells are electrochemical devices that convert a fuel's chemical energy directly to electrical energy with high efficiency and without combustion (although fuel cells operate similar to batteries, an important difference is that batteries store energy, while fuel cells can produce electricity continuously as long as fuel and air are supplied).
The degree of mobility of a semiconductor, i.e. how well it conducts, is crucial to the effectiveness of nanoelectronic devices. Mobility determines the carrier velocity, and hence switching speed, in FETs. Researchers have determined that the theoretical mobility of an individual single-walled carbon nanotube is about 1000 times higher than any other known semiconductor. However, practical applications would require massive manufacturing of large scale nanoelectronic devices. Despite progress being made with integrating individual nanotubes in lab environments, many of today's nanomanufacturing techniques for nanoelectronic devices rely on the use of 'carbon nanotube network films' comprised of multiple carbon nanotubes. The major problem here is that the electronic properties of CNT network films are usually very poor. Researchers in South Korea have now developed a powerful strategy to solve these fundamental problems simply by controlling the connectivity of nanotube/nanowire networks.
Much attention of nanotechnology researchers has recently been paid to the fabrication of free-standing, ultra-thin films. These systems have been developed for use in a wide variety of fields such as nano-separation membranes or nanosensors for electrochemical and photochemical applications. In a first report on the fabrication of free-standing nanosheets for biomedical applications, scientists in Japan have developed a biodegradable thin film of only about 20 nanometers thickness that could replace surgical stitches. In experiments, they found that the sealing operation repaired the incision completely without scars and tissue adhesion. This approach would constitute an ideal candidate for an alternative to conventional suture/ligation procedures, from the perspective not only of a minimally invasive surgical technique but also reduction of operation times.
Many of the properties of a given nanoparticle not only depend on its chemical composition but also on its size and shape, i.e. its morphology. These morphological factors have significant impact on a nanoparticle's optical and catalytic properties. Accordingly, nanoparticle manufacturers have developed numerous 'recipes' for synthesizing particles with desired size and shape. To facilitate systematic investigation on the morphology-property relationship, it would be highly desirable if one reaction system can be engineered to yield as many different shapes as possible with minimal degree of parameter tuning. To that end, researchers proposed a way to systematically engineer the morphologies of nanoparticles by constructing an evolutionary tree, which consists of several pathways, each showing a 'string' of evolving shapes over the courses of a single reaction. The tree not only displays the relationship between different shapes, but also offers designing principles for producing more complex shapes by crossing over different pathways during nanoparticle growth.