Liquid crystal displays (LCD) have become an integral part of our everyday life. LCDs are everywhere, on your digital watches, cameras, iPods, laptop computers, television screens or car navigation displays. LCDs get their name from the special liquid crystal solution that is contained between two thin glass plates inside the display. Recent research findings suggest that embedding doped metal nanoparticles (MNP) in liquid crystal materials increases the performance of certain display devices. So far, however, the main problem with this approach has been that the inclusion of nanoparticles destabilizes the LC material. Researchers have now succeeded in synthesizing metal nanoparticle embedded stable liquid crystals in a single step, without using any external reducing and stabilizing agents. As a bottom-up strategy, this work is a further step towards synthesizing three-dimensional macro structures using small nanoparticles as building blocks, and an elegant method in fabricating soft organic architectures; particularly when it is combined with electronic, magnetic or photonic properties of inorganic materials.
Magnetic resonance imaging (MRI) is a powerful imaging technology that serves as a non-invasive method to render images of the inside of an object. It is primarily used in medical imaging to demonstrate pathological or other physiological alterations of living tissues. MRI also has uses outside of the medical field, for instance as a non-destructive testing method to characterize the quality of products such as produce and timber. Conventional MRI usually operates at the scale of millimeters to micrometers - 3 micrometers at best - which is good enough for the mostly medical diagnostic purposes it is used for. Researchers have now shown that the imaging of nuclear spins using magnetic resonance, the basis for MRI, can be pushed to sub-100nm resolution into the nanoscale realm. They demonstrated that using an emerging technique based on force detection, they can image nuclear spins with a sensitivity that is 60,000 times better than MRI. The resolution is about 30 times better than the most advanced conventional MRI imaging. By improving this technique, researchers will be able to push deeper into the nanometer regime and approach the capability needed for direct three-dimensional imaging of individual macromolecules.
It its more than 25 years of existence, Scanning Tunneling Microscopy (STM) has predominantly brought us extremely detailed images of matter at the molecular and atomic level. STM - not to be confused with the scanning electron microscope (SEM) - 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. The STM 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. Researchers have now taken a further step by using STM to perform real-time single-molecule imaging of an entire chemical reaction. Many chemical reactions are catalyzed by metal complexes, and insight into their mechanisms is essential for the design of future catalysts. These new findings have demonstrated that the STM approach to studying chemical reactions in a dynamic environment can provide valuable information about reaction mechanisms and rates, as well as catalyst activity and stability.
Currently, the most common carrier vehicles to deliver therapeutic drugs, genes or proteins to a patient's target cells are viruses that have been genetically altered to carry the desired payload. These viruses infect cells, deposit their payloads, and take over the cells' machinery to produce the desirable proteins. One problem with this method is that the human body has developed a very effective immune system that protects it from viral infections and another problem is that viral-based delivery vehicles may integrate into the host genome. Thanks to advances in nanotechnology fabrication techniques, the development of nonviral nanocarriers for gene and drug delivery has become possible. Besides viruses, polymeric systems and various inorganic nanomaterials are under intensive investigation as nonviral delivery vehicles. Finding new candidates for vehicles is still of great interest because most existing synthetic vehicles exhibit intrinsic cytotoxicity and show relatively low delivery efficiency. Enter the carbon nanohorn (CNH). This recently recognized member of the fullerene family has a unique dahlia flower-like structure, huge surface areas and can be fabricated with high purity. Researchers believe that CNHs may have potential advantages over normal nanoparticles, nanorods and nanotubes as synthetic intracellular delivery vehicles.
One of the newly emerging areas of semiconductor technology is the field of transparent electronics. These thin-film materials hold the promise of a new class of flexible and transparent electronic components that would be more environmentally benign than current electronics. Being able to print transparent circuits on low-cost, flexible, plastic substrates opens up the possibility of a wide range of new applications, ranging from windshield displays and flexible solar cells to clear toys and artificial skins and even sensor implants. It is likely that such flexible see-through structures will find wide uses in military, biosensing and consumer goods due to the advantages of high transparency and reliable electrical characteristics. However, the emerging transparent electronics technology is facing manufacturing problems: current fabricating processes do not separate the device manufacturing from material synthesis. The transparent electronic materials, which are largely inorganic oxides. are directly deposited on the device substrate under harsh conditions which may cause damage to the existing layer or flexible substrate. The etching of small dimension oxide multilayer is also difficult due to the low selectivity of the etching recipe. New research results demonstrate that nanofabrication techniques could solve these problems.
Nanotechnology has begun to find potential applications in the area of functional food by engineering biological molecules toward functions very different from those they have in nature, opening up a whole new area of research and development. Of course, there seems to be no limit to what food technologists are prepared to do to our food (read this delightful romp through the food processing industry to get the idea: "Twinkie, Deconstructed". For the non-U.S. reader: a Twinkie is a processed foodlike substance that has reached iconic status in this country) and nanotechnology will give them a whole new set of tools to go to new extremes. We have taken a critical view of food nanotechnology before in this column and in our news coverage, just take a look at "Nanotechnology food coming to a fridge near you" or "Are you ready for your nano-engineered wine?". Today, though, we look at the potentially beneficial effects nanotechnology-enabled innovations could have on our foods and, subsequently, on our health.
Synthesis of carbon nanotubes (CNTs) is a rapidly advancing field, but there is a lot that researchers don't know about how nanotubes form and grow. Synthesis, while rapidly developing, is currently the weakest link for most nanotube applications, with high yield and high precision diameter and chirality control being important goals. Historically, in situ characterization tools have accelerated progress in synthesis for many advanced materials, and there is widespread recognition that in situ tools have the potential to improve CNT synthesis as well. Ideally one would like to detect individual nanotubes and ensembles as they grow and measure their physical properties while imposing minimal constraints on the synthesis method. In other words, with a good understanding of the synthesis process we would be better able to control the product. It is feasible that by actually observing nanotubes as they grow one will gain a better understanding of the growth process and also better characterize the grown product. Greater control over the physical characteristics of the nanotube product is essential to enable many applications, as well as many fundamental studies. Although chemical vapor deposition (CVD) is now a very standard method to synthesize CNTs, there aren't really standard in situ tools to characterize nanotubes during growth. Researchers in Canada have now shown how global Raman imaging (GRI) can be used to characterize the CVD growth of CNTs in situ and in real time.
The promise of revolutionary bottom-up nanotechnology is based on a vision of molecular assembly technologies where nanoscale materials and structures self-assemble to microscale structures and finally to macroscopic devices and products. We are a long way from realizing this vision but researchers are busily laying the foundation for the things to come. Assembling nanoscopic components into macroscopic materials has been an appealing goal but one of the enormous difficulties lies in bridging approximately six orders of magnitude that separate the nanoscale from the macroscopic world. New research at Northwestern University in the U.S. helps to overcomes this difficulty by dividing the assembly process into two manageable sub-steps. First, nanoparticles are assembled into larger, 100 nm-size, spherical building blocks, which are both deformable and "sticky" towards one another. Once assembled, these components "glue" together like pieces of clay to give millimeter or even centimeter-sized structures. The novelty of this technique is both the hierarchical assembly approach (i.e., atoms to nanoparticles to supraspheres to macroscopic materials) and the resulting "soft" structures, which contrast with previously reported hard and brittle nanoparticles assemblies/crystals. This research takes a further step in making nanoscale discoveries relevant to our everyday - macroscopic - world.