In many diagnostic processes, the detection of several protein markers is required. Rather than performing several sequential analysis steps, a multiplexed approach allows the simultaneous measurement of multiple biomarkers from the same blood sample. The convergence of nanotechnology, microtechnology, microfluidics, photonics, signal processing, and proteomics allows for the development of increasingly sophisticated and effective multiplexed point-of-care diagnostic devices. The detection of protein biomarkers can done with an optical multiplexing approach that uses dye particles of different colors. In contrast to conventional fluorescence dyes, quantum dots generate a much more powerful fluorescent signal which provides a large increase in sensitivity compared to other methods. Quantum dots are also available in multiple colors, allowing the investigators to tag each antibody with a uniquely colored quantum dot. Researchers have now demonstrated a novel and fast quantum dot-based FRET technique that is suitable for multiplexed ultrasensitive detection.
Solar-powered splitting of water promises an attractive, clean energy source and numerous research projects around the world are working on making this process sufficiently efficient - reducing the systems' cost and extending their lifetimes - to be able to compete with dirty carbon fuels on an industrial scale. Natural photosynthesis uses chlorophyll to absorbe visible light and many solar hydrogen cells are imitating this process by using light-sensitive organic dye molecules as light absorbers and then transfer the absorbed energy to a catalyst that reduces protons to hydrogen. Researchers in the UK have now shown that an inexpensive and environmentally benign inorganic light harvesting nanocrystal array can be combined with a low-cost electrocatalyst that contains abundant elements to fabricate an inexpensive and stable system for photoelectrochemical hydrogen production.
Many nanotechnology applications are plagued by very poor wear resistance of device components at the nanoscale. Gears, bearings, and liquid lubricants can reduce friction in the macroscopic world, but the origins of friction for small devices such as micro- or nanoelectromechanical systems require other solutions. Despite the unprecedented accuracy by which these devices are nowadays designed and fabricated, their enormous surface-volume ratio leads to severe friction and wear issues, which dramatically reduce their applicability and lifetime. Although there is a significant amount of research work going on in the area of nanoscale friction, at present there is much less research conducted on nanoscale wear. Researchers have now demonstrated extremely low wear rates at the nanoscale, representing a technological breakthrough for numerous applications in emerging fields such as nanolithography, nanometrology, and nanomanufacturing.
The discussion about nanotechnology related safety issues so far has focused mainly on three areas - consumers getting exposed to products containing nanomaterials; nanomaterials getting released into the environment and potentially entering the food chain; and industrial workers being exposed to nanomaterials during the production process. There is an increasing number of reports and research papers dealing with these issues. Interestingly, while surveys of nanotechnology safety practices have concentrated on industrial settings, the safety issues of a significant number of people working with nanomaterials have not been addressed in a concerted matter - the researchers at university and private research laboratories who are doing all the early stage research and development. According to a survey conducted by a Spanish research group, it appears that the nanotechnology research community is not exactly at the forefront when it comes to following, not to mention setting, standards for safe practices for handling nanomaterials.
In contrast with microchannel-based fluidics, the manipulation of discrete droplets without using microfluidic channels is a new field. Here, a liquid droplet is not confined to a closed channel and there is no risk of being adsorbed on a channel wall. A liquid marble, a liquid encapsulated by non-wetting powder, could be a new microfluidic device, which is especially useful for handling single liquid droplet. One of the challenges for using liquid marbles as microfluidic devices is the communication between the liquid droplet and the external devices/materials. Researchers in Australia have been trying to develop 'field-responsive smart liquid marbles' which can be opened and closed reversibly on demand, such that the liquid in the marble can be easily taken and other liquid can also be added into the marble easily. The mechanically robust magnetic liquid marble, prepared by coating a water droplet with highly hydrophobic magnetite nanoparticles, can be actuated magnetically.
Materials engineers are keen to exploit the outstanding mechanical properties of carbon nanotubes for applications in fibers, composites, fabrics and other larger-scale structures and devices. The ability to fabricate continuous, multifunctional yarns represents an important step in this direction. The development of a continuous, weavable multilayered CNT yarn with superior mechanical, structural, surface, and electrical properties would open the way for a wide range of structural and functional applications, including composites, intelligent fabrics, catalyst supports, and sensors. Researchers in China now demonstrate the fabrication of a novel continuous yarn of CNTs with a multiple-layer structure by a CVD spinning process. The yarn consists of multiple monolayers of CNTs concentrically assembled in seamless tubules along the yarn axis.
Carbon nanotubes are 'strange' nanostructures in a sense that they have both high mechanical strength and extreme flexibility. Deforming a carbon nanotube into any shape would not easily break the structure, and it recovers to original morphology in perfect manner. Researchers in China are exploiting this phenomenon by making CNT sponges consisting of a large amount of interconnected nanotubes, thus showing a combination of useful properties such as high porosity, super elasticity, robustness, and little weight. The nanotube sponges not only show exciting properties as a porous material but they also are very promising to be used practically in a short time. The production method is simple and scalable, the cost is low, and the sponges can find immediate use in many fields related to water purification.
Bismuth telluride and its alloys are unique materials. They are the best thermoelectric materials known today, and they are as important to the thermoelectric industry - for cooling and energy generation applications - as silicon is important to the electronic industry. It has been predicted theoretically that structuring bismuth telluride into crystalline ultra-thin films (with the thickness of few nanometers) would lead to a drastic improvement of the thermoelectric figure of merit, which defines the efficiency of the thermoelectric energy conversion. The improvement comes as a result of the strong quantum confinement of charge carriers and reduction of the thermal conductivity. In addition to their thermoelectric applications, bismuth telluride thin films recently attracted attention as promising topological insulators - a newly discovered class of materials with unusual properties. Researchers have now succeeded in 'graphene-inspired' mechanical exfoliation of atomically-thin crystals of bismuth telluride.