The fight against infections is as old as civilization. Silver, for instance, had already been recognized in ancient Greece and Rome for its infection-fighting properties and it has a long and intriguing history as an antibiotic in human health care. Modern day pharmaceutical companies developed powerful antibiotics - which also happen to be much more profitable than just plain old silver - an apparent high-tech solution to get nasty microbes such as harmful bacteria under control. However, thanks to emerging nanotechnology applications, silver is making a comeback in the form of antimicrobial nanoparticle coatings. As even the most powerful antibiotics become less and less effective, researchers have begun to re-evaluate old antimicrobial substances such as silver and as a result, antimicrobial nano-silver applications have become a very popular early commercial nanotechnology product. Researchers in China have now further advanced the nanotechnology application of silver be developing a novel multi-action nanofiber membrane containing four active components, each playing a different role in the membrane's excellent antibacterial function.
A major concern in microbiology is to determine whether a bacterium is dead or alive. This crucial question has major consequences in food industry, water supply or health care. While culture-based tests can determine whether bacteria can proliferate and form colonies, these tests are time-consuming and work poorly with certain slow-growing or non-culturable bacteria. They are not suitable for applications where real-time results are needed, e.g. in industrial manufacturing or food processing. A team of scientists in France has now discovered that living and dead cells can be discriminated with a nanotechnology technique on the basis of their cell wall nanomechanical properties.
One of the key issues in building implantable neural interfaces is the guidance of axons, the individual nerve fibers that act as the primary transmission lines of the nervous system. The ability to control the connections between neurons by guiding their axons on a chip surface offers several advantages. Among them is the possibility to address axons from different types of neurons, e.g., motor neurons from sensory neurons. This is a prerequisite condition for bidirectional neural implants such as brain machine interfaces. Axonal guidance has been achieved before, and there are various chemical and topographical modification techniques to do so. However, scientists only managed to control the orientation of the nerve fibers. In new work, a Swedish team shows that it is possible to impose a growth direction at a specific location on a substrate, something which is very important for neural chip construction for example. The first application for this research would be in neural network design.
New work at the University of Arkansas has, for the very first time, demonstrated that Raman spectroscopy can be used to detect and monitor circulating carbon nanotubes in vivo and in real time. These findings could have a significant impact on the knowledge of how nanomaterials interact with living biological systems. Carbon nanotubes can be used for various advanced bio-medical applications. Before any clinical application of nanoparticles, it is imperative to determine critical in vivo parameters, namely pharmacological profiles including nanoparticle clearance rate from the circulation and their biodistribution in various tissue and organs. Until now, their distribution was only monitored by collecting samples after various time intervals, but this new research shows the ability of monitoring their concentration in vivo and in real time, while the animal is alive. Moreover, this work can be extended to the detection of circulating cancer cells that have been tagged by carbon nanotubes.
Online breath analysis via an array of chemiresistive random network of single walled carbon nanotubes coated with organic materials showed excellent discrimination between the various breath states. An important implication of these findings, besides the detection of diseases directly related to the respiratory, cardiovascular, and renal systems, is the fact that volatile organic compounds are mainly blood borne and the concentration of biologically relevant substances in exhaled breath closely reflects that in the arterial system. Therefore, breath is predestined for monitoring different processes in the body. The excellent discrimination between the various breath states obtained in this study provides expectations for future capabilities for diagnosis, detection, and screening various stages of kidney disease, especially in the early stages of the disease, where it is possible to control blood pressure, fat, glucose and protein intake to slow the progression.
A number of applications in nanomedicine - imaging, drug delivery or photo therapy for instance - utilize phenomena called two-photon absorption (TPA). In TPA, the simultaneous absorption of two photons excite a molecule from one state to a higher energy electronic state. TPA initially was used only as a spectroscopic tool but new applications emerged over time. Currently approved two-photon absorption-induced excitation is one of the most promising approaches in photo therapies as it increases light penetration. It enables the use of light in the tissue-transparent window (750-1000 nm), allowing deeper light penetration and reduced risk of laser hyperthermia. An uphill energy conversion through the use of two-photon absorbing chromophores and subsequent energy transfer is a promising scientific frontier.
Cancer researchers are therefore experimenting with nanoparticles as both contrast agent and drug carrier capable of pinpointing and destroying individual cancer cells. Targeted nanoparticles consist of a metallic or organic core conjugated with a biomolecule of interest. To be able to navigate nanoparticles to a desired target (i.e. a specific cancer cell), they need the property of specific target recognition. Depending on the type of cancer that is to be targeted, researchers choose biomolecules that show high affinity toward these specific tumor cells. Think of these biomolecules as a navigation aid to transport nanoparticles to the cancerous site or organ of interest. As part of their overall goal of developing target-specific gold nanoparticles for treatment of cancers, scientists at the University of Missouri have carried out a systematic investigation on the design and development of targeted gold nanorods.
Researchers in Korea have developed a novel platform for intracellular delivery of genetic material and nanoparticles, based on vertically aligned carbon nanosyringe arrays of controllable height. Stem cell research is being pursued in laboratories all over the world in the hope of achieving major medical breakthroughs. Scientists are striving to create therapies that rebuild or replace damaged cells with tissues grown from stem cells and offer hope to people suffering from cancer, diabetes, cardiovascular disease, spinal-cord injuries, and many other disorders. Nanotechnology is increasingly playing a role in how researchers think about delivering stem cell therapies into cells. Cell plasma membranes are a formidable barrier to the delivery of exogenous macromolecules in cellular engineering and labeling and cell therapy. Attempts have been made to breach this barrier, particularly using mechanical means such as microinjectors that deliver genetic material into the cell. However, there is concern about damage to the cell membrane caused by intrinsic invasiveness of the micro- or submicrosized needle used in these procedures.