Showing Spotlights 153 - 160 of 305 in category Carbon Nanotubes (newest first):
Much effort has been invested into finding a non-toxic replacement for semiconductor quantum dots (Q-dots) possessing bright fluorescence. Intrinsic toxicity of Q-dots composed of elements such as selenium, tellurium, cadmium, and lead severely hinders their in vivo applications for fluorescent imaging. Therefore many carbon nanomaterials have been considered as a replacement for Q-dots for in vivo imaging. However, it is still unclear how safe carbon nanomaterials are, and this is an obstacle for their use in medicine. Nanodiamond has been an exception among nanomaterials in many aspects, but what is important for biomedical applications is that it has shown very little or zero toxicity in all tests done so far. In addition, nanodiamond powders are already produced by detonation on a large commercial scale. This is why fluorescent nanodiamonds currently attract so much attention.
Mar 30th, 2009
Carbon nanotubes (CNTs) have already been explored as drug carriers into mammalian cells. Compared to nanoparticles, CNTs have a larger inner volume which allows more drug molecules to be encapsulated, and this volume is more easily accessible because the end caps can be easily removed, and they have distinct inner and outer surfaces for functionalization. In addition to nanomedicine applications, plant science research focusing on investigation of plant genomics and gene function as well as improvement of crop species has become a nanotechnology frontier. To what degree nanomaterials can be employed in delivering payloads into plant cells is a subject that has not yet been explored very well although there appears to be demand from plant cell biologists to take advantage of nanomaterials.
Mar 27th, 2009
Carbon nanotubes possess physicochemical properties that make them an attractive possibility for nuclear waste management, especially when compared to the current tools involving activated carbon. In the environmental field, carbon nanotubes application is regarded as extremely promising for the development of novel energy-storage techniques, sensors, and sorbent materials for myriad uses including waste management. A group of European scientists want to stimulate a discussion on how the potential of carbon nanomaterials for nuclear waste mangement could be realized. They argue that the significance of the possible role of carbon nanotubes in treating and sequestering nuclear waste stems from a number of recent research results that specifically investigate the interaction between CNTs and actinides or lanthanides.
Mar 23rd, 2009
Buckypaper - in which CNTs collectively behave as a random web - is characterized by its optical transparency, mechanical flexibility, high electric conductivity, uniform dimensions, tunable electronic properties, large specific surface area and smooth surface topology. All of which make this a very promising material as functional element or structural component in a wide range of applications such as optoelectronics, nanocomposites, chemical separations, biocompatible platforms, electronics, and energy conversion and storage. So far it has been difficult to simultaneously retain the intrinsic properties of individual CNTs and to have versatility in creating different shapes, both problems unavoidably resulting from post-growth fabrication processes. A research group in China has now reported a simple approach for the direct and nondestructive assembly of multi-sheeted, single-walled carbon nanotube book-like macrostructures (buckybooks) of several millimeters in thickness with good control of the nanotube diameter, the sheet packing density, and the book thickness.
Mar 9th, 2009
Currently, all existing methods of fabricating CNT-polymer composites involve quite complicated, expensive, time-demanding processing techniques such as solution casting, melting, molding, extrusion, and in situ polymerization. In all of these techniques, nanotubes must either be incorporated into a polymer solution, molten polymer or mixed with the initial monomer before the formation of the final product. In addition, these methods can not be applied in the case of insoluble or temperature sensitive polymers, which decompose without melting. Kevlar is a well known high-strength polymer with a variety of important applications - think bullet-proof vests and car armor plating. However, Kevlar is not soluble in any common solvent and Kevlar fibers must be produced by wet spinning from sulphuric acid solutions. Researchers in Ireland have now found a way to develop a new effective post-processing technique which would allow to incorporate carbon nanotubes into already formed polymer products, such as for example Kevlar yarns.
Feb 25th, 2009
Back in 2006, researchers introduced the concept of a carbon nanotube (CNT) knife that, in theory, would work like a tight-wire cheese slicer. In the meantime, other research groups have developed similar approaches, for instance for cutting and sharpening carbon nanotubes (see for instance: Nanotechnology grinders). Now, the group that introduced the CNT nanoknife in 2006 has refined their design and demonstrated the feasibility of fabricating a nanoknife (compression-cutting tool at the nanoscale) based on an individual CNT. The researchers stretched an individual nanotube between two tungsten needles in a manner that allowed them to test the mechanical strength of assembled device. A force test on the prototype nanoknife indicated that failure was at the weld while the CNT was unaffected by the force we applied. In situ load tests on the nanoknife indicated maximum breaking force to be in micro Newton range.
Feb 18th, 2009
Just a few days ago we covered the exciting and quickly developing world of nanotechnology machinery, specifically nanomotors. In this previous Nanowerk Spotlight we focused on one approach to nanomotors, which is copying nature's catalytic biomotors. Today we will look at an example of mechanical approach that works with carbon nanotubes (CNTs). Some experimental work concerning CNT motor system has already been reported, but new work coming out of Japan could very well be the smallest motor so far. Researchers in Japan investigated the linear and rotary motions of a CNT capsule at room temperature when it is sealed by other CNTs in a hollow space of a host CNT. It is the first observation of linear motion of CNT capsules. Such a system can be obtained by simply heating C60 peapods, and its size is comparable or much smaller than well-known protein-based molecular motors in the bioengineering field.
Feb 17th, 2009
One of the many application areas that carbon nanotubes (CNTs) are experimented with is as a drug carrier in nanomedicine. Typically, nanoparticles have been used for drug delivery and it is only recently that carbon nanotubes have gained attention as potential drug delivery vehicles. Current research has shown the ability of CNTs to carry a variety of molecules such as drugs, DNA, proteins, peptides, targeting ligands etc. into cells - which makes them suitable candidates for targeted delivery applications. Polyethylene glycol (PEG) with molecular weight between 1 and 40 kDa is usually used to coat drug or imaging nanocarriers with the purpose of reducing non-specific interactions with cells and thus increasing the nanocarriers circulation time in vivo. However, when PEG in the form of PL-PEG (adsorbing phospholipid-PEG) has been used to functionalize single-walled CNTs, the finding were not consistent, sometimes even contradictory.
Feb 16th, 2009