One of the many fascinating concepts in nanotechnology is the vision of molecular electronics where tomorrow's engineers might use individual molecules to perform the functions in an electronic circuit that are performed by semiconductor devices today. This is just another example of scientists taking a cue from nature's playbook, where essentially all electronic processes, from photosynthesis to signal transduction, occur in molecular structures. The basic science on which molecular electronics technology would be built is now unfolding but researchers are still struggling with the most basic requirements for molecular electronics, for instance, how to precisely position individual molecules on a surface or how to reliably measure the resistance of a single molecule. A tremendous amount of painstaking work goes into developing the kind of ultraprecise and ultrasensitive instruments that are required to develop electronics at the nanoscale. A recent example is a new device for measuring the conductance values of single-molecule junctions which are covalently bound to two electrodes.
Separation and purification of bio-molecules such as proteins and viruses are important processes in the biotechnology industry. The risk of contamination with either known or unknown viruses in biological or therapeutic products require production processes that - ideally - completely eliminate the risks of virus contamination. Since the existence of very small amounts of viruses with a size of tens of nanometers causes severe damage to the entire bio-process, the filtration of viruses has to be pretty much perfect. Micro- and ultrafiltration have been successfully used in numerous processes as a robust step for virus reduction but they are not 100% effective. Currently used ultrafiltration membranes still allow smaller-sized virus particles to permeate into a small number of abnormally large-sized pores in the membrane. This broad size distribution of pores in ultrafiltration membranes and the low density of pores in track-etched membranes limit the practical use of virus filtration.
'Reverse engineering' is the process of discovering the technological principles of a device or system through analysis of its structure, function and operation, often by taking it apart and analyzing its workings in detail. This approach is a common practice among industrial companies who use it to analyze the competition's products, be it cars or MP3 players, to understand where the latest product improvements come from and how individual components are made. An increasing number of scientists apply a similar approach to nature's own 'micro- and nanotechnology' systems. They believe that learning from nature's designs and engineering successes is more likely to provide the cues for designing practical nanodevices than by simply applying a 'trial and error' approach. The basic idea is that natural materials and systems can be adopted for human use beyond their original purpose in nature. Some examples of 'reverse' biophysics work and have already proven quite useful, for instance the use of individual red blood cells as reliable, ultrasensitive mechanotransducers.
Nanotechnology researchers have appropriated the name of Janus - the Roman god of gates and doorways, usually depicted with two heads looking in opposite directions - to name a class of amphiphilic (i.e. containing both hydrophobic and hydrophilic portions) nanoparticles composed of two fused hemispheres, each made from a different substance. Their particular structure makes Janus particles an intriguing subject for exploring novel anti-cancer therapies where they, for instance, carry two different and complementary medicines. In a novel use of Janus particles, researchers have now isolated a means of using them to make 're-sealable' pores in lipid bilayer membranes. Described in another way, the localization of the nanoparticles in the pore can be thought of as the placement of a zipper, which allows a specific slit to be opened or closed at will.
High content analysis (HCA) is a powerful platform that combines cell-based assays with traditional microscopy and automated, sophisticated image processing and analysis software. This technology is capable of using living and fixed cells, typically with fluorescently labeled antibodies and reagents. It has been widely adopted in the pharmaceutical and biotechnology industries for target identification and validation. HCA has made particular inroads into research and development applications where high throughput screening has proven inadequate, such as measuring multiple biological pathways simultaneously, or revealing off-target drug effects. HCA has stepped into this void by demonstrating how particular proteins are affected by the application of a molecule to the cell line of interest.
Synthesized carbon nanotubes, especially single-walled carbon nanotubes (SWCNTs), are in the form of bundles with other impurities such as catalyst particles and amorphous carbon debris. In order to be useful for many types of applications, for instance in nanoelectronic devices or biomedical applications, SWCNTs need to be purified and dispersed into individual nanotubes. One method to do this is by surfactant stabilization of the hydrophobic nanotube surface, which overcomes the van der Waals forces among the nanotubes and results in suspensions of individual SWCNTs. Researchers have now investigated the cytotoxicity of SWCNTs suspended in various surfactants. Their experimental results show that the conjugates SDS/CNT and SDBS/CNT are toxic to astrocytoma cells due solely to the toxicity of the SDS and SDBS molecules, which administered alone are toxic to the cells even at a low concentration of 0.05 mg per ml within 30 min. However, the proliferation and viability of the astrocytoma cells were not affected by SWCNTs and the conjugates SC/CNT and DNA/CNT.
Most people in the world know exactly how long a kilometer is, how large a liter is, how much a kilogram weighs, and how warm 25C is. That's because almost all countries in the world have adopted a standard called the metric system - since the 1960s the International System of Units has been the internationally recognized standard system for measurements (only three countries have not adopted this standard: Liberia, Myanmar, and the United States - the latter maybe because the metric system was invented by the French...). The need for standardization also exists in various fields of nanotechnology in order to support commercialization and market development, provide a basis for procurement, and support appropriate legislation/regulation. When it comes to nanotechnology, numerous standard setting organizations around the world are active in defining nanotechnology standards, although no one standard has achieved dominance yet.
The phenomenon behind many color-based biosensor applications is the excitation of surface plasmons by light - called surface plasmon resonance for planar surfaces or localized surface plasmon resonance (LSPR) for nanoscale metallic structures. Surface plasmon resonance of metallic nanoparticles, in particular gold, has become a popular nanotechnology-enabled technique to build increasingly sensitive and fast biosensors. All the nanostructures used for the biosensing applications have two characteristics: Firstly, they contain certain recognition mechanisms specified to the analyte, for example antibodies or enzymes. Secondly, they are able to generate a distinguishing signal from the analyte and this signal could be generated by the nanostructures themselves or produced by signaling molecules immobilized or contained in the nanostructures. However, proper functionalization remains an issue when it comes to real-world applications, in particular, biological relevant samples such as membrane associated proteins and peptides.