Current production methods for carbon nanotubes (CNTs) result in units with different diameter, length, chirality and electronic properties, all packed together in bundles, and often blended with some amount of amorphous carbon. These mixtures are of little practical use since many advanced applications, especially for nanoelectronics, are sensitively dependent on tube structures. Consequently, the separation of metallic and semiconducting CNTs is essential for future applications and studies. The tube diameter of semiconducting nanotubes is also important because the band gap depends on it. Separation of nanotubes according to desired properties is still proving to be a challenging task, especially single-walled carbon nanotube (SWCNT) sorting, because the composition and chemical properties of SWCNTs of different types are very similar, making conventional separation techniques inefficient. The separation techniques for SWCNTs explored to date rely on preferential electron transfer on metallic SWCNTs treated with diazonium salts, dielectrophoresis, enhanced chemical affinity of semiconducting SWCNTs with octadecylamine, and wrapping of SWCNTs with single-stranded DNA.
Complex technical and scientific issues means complex intellectual property issues. This especially is the case with nanotechnologies, which are not easy to classify. Patents are of critical importance for start-ups and smaller companies because they may help in negotiations over infringement of their patents during competitive posturing with larger corporations. There is also ample evidence that companies, start-ups, and universities are ascribing ever-greater value and importance to patents. Increasingly, they are willing to risk a larger part of their budgets to acquire and defend patents. A new book on bionanotechnology lists nine key considerations and strategies that bionanotechnology inventors must follow in order to adequately protect an invention even before a patent application is drafted or filed.
Using nanoparticles to combat cancer and a host of other diseases is an active area of research for many scientists. For decades, treating cancer has mostly involved injecting patients with toxic drugs. A practice, in which only a fraction of the drugs reach the intended target, killing healthy cells in the process and causing harmful side effects. Previous studies have shown that drug-carrying nanoparticles can accumulate in and attack tumors, in part because of their extremely small size, which helps allow them to pass through cell membranes. However, up until now, existing techniques have meant that targeting agents could only be delivered using spherical or granular shaped particles. Now, a team of scientists have demonstrated that nanoparticles designed with a specific shape, size and surface chemistry are taken up into cells and behave differently within cells depending on the characteristics of the particle.
Carbon nanotubes are considered a promising material system not only for nanoelectronics but also for nanophotonics - the manipulation and emission of light using nanoscale materials and devices. By trying to understand the electrical properties of carbon nanotubes (CNTs) through their light emission, scientists are paving the way for CNTs' integration in optical applications. Embedding spatially isolated CNTs into an optical microcavity is a promising means of controlling and improving their radiative properties. The control of these CNT properties, including emission wavelength, spectral width, emission direction and radiative yield through optical confinement, opens the door for their use in integrated nanophotonic circuits. Cavity controlled nanotube emitters could potentially find use in quantum optics, quantum communication, and integrated nanophotonic circuits and may ultimately lead to low threshold on-chip nanolasers.
Carbon nanomaterials have been extensively used in electroanalysis, and the most common forms are spherical fullerenes, cylindrical nanotubes, and carbon fibers and blacks. Since the discovery that individual carbon nanotubes (CNTs) can be used as nanoscale transistors, researchers have recognized their outstanding potential for electronic detection of biomolecules in solution, possibly down to single-molecule sensitivity. To detect biologically derived electronic signals, CNTs are often functionalized with linkers such as proteins and peptides to interface with soluble biologically relevant targets. Now, for the first time, scientists have tested nanometal decorated graphene (actually graphite nanoplatelets, a thickness of 10 nm would contain approximately 30 graphene sheets, considering an interlayer spacing of 0.335 nm) in biosensor application. As it turned out, this novel biosensor is among the best reported to date in both sensing performance and production cost.
Several aspects determine how effective a pharmaceutical drug is. Probably the key issue is how well a drug molecule is able to reach its intended target. This need for target specific delivery of drugs has been well accepted in modern drug therapy. Many research efforts are geared towards improving not just the tissue accumulation, but also the cell-specific accumulation of drug molecules in the hope of improving the efficacy of these drug molecules. The ability to target nanoparticles to specific types of cancer cells is one of the main reasons that nanoparticles have gained favor as a promising drug delivery vehicle. By increasing the amount of an anticancer agent that gets to tumor cells, as opposed to healthy cells, researchers hope to minimize the potential side effects of therapy while maximizing therapeutic response. Now, a group of scientists has taken this approach one step farther by targeting the specific location inside a tumor cell, where a cancer drug then exerts its cell-killing activity.
Borrowing from nature's micro- and nanoscale propulsion systems, nanotechnology researchers have successfully used motor proteins to transport nanosized cargo in molecular sorting and nano-assembly devices. In so-called gliding assays, surface-attached motors propel cytoskeletal filaments, which in turn transport a cargo. However, cargo and motors both attach to the filament lattice and will affect each other. While an effect of cargo loading on transport speed has been described before, it has never been explained very well. To study this effect, scientists in Germany have observed single kinesin-1 molecules on streptavidin coated microtubules. They found that individual kinesin-1 motors frequently stopped upon encounters with attached streptavidin molecules. This work helps to understand the interactions of kinesin-1 and obstacles on the microtubule surface. An interesting, possibly even more important side result is that this understanding will not only help to optimize transport assays, balancing speed and cargo-loading, but can be used as a novel method for the detection of proteins as well.
Laser-based analytical techniques such as Raman spectroscopy, fluorescence spectroscopy or the state-of-the-art laser-induced breakdown spectroscopy (LIBS) are highly sophisticated techniques to analyze minute amounts of matter with regard to its structure, elemental composition, and other chemical properties. LIBS has been shown to be capable of analyzing extremely small samples with high sensitivity - nanoliter volumes with levels of detection in water of part per million. LIBS works by focusing short laser pulses onto the surface of a sample to create a hot plasma with temperatures of 10,000 - 20,000 C. The plasma emits radiation that allows the observation of the characteristic atomic emission lines of the elements. On the downside, LIBS is complicated by the need for multiple laser pulses to generate a sufficiently hot plasma and the need for focusing and switching a powerful laser, requiring relatively large and expensive instruments.
New research coming out of Drexel University has now shown that light emitted from a new form of cold plasma in liquid permits Optical Emission Spectroscopy (OES) analysis of the elemental composition of solutions within nanoseconds from femtoliter volumes.