To what degree nanoparticles are uptaken by plants and what their effect is on plant development is an important issue in determining the environmental impact of nanomaterials. Previously we have covered several research projects that have begun to explore nanotechnology's impact on major food crops and some of them have demonstrated quite a negative impact. But some research results also show a possible positive effect, like a recent study that demonstrates that carbon nanotubes (CNTs) can dramatically accelerate the germination and growth of tomato seeds. Work like this contributes to an important body of interdisciplinary research where nanotechnology, plant biology and biotechnology converge to open new perspectives for solving some of the important challenges of our times such as increased food and biofuel production.
Bionanotechnology researchers are experimenting with techniques for attaching DNA nanoarrays to cell surfaces for various reasons: to label cell surfaces with functionalized micrometer-sized patches; to deliver materials such as nanoparticles or carbon nanotubes to cell surfaces; to deliver nucleic acids into the cell for gene silencing; or to engineer microtissues of cell/cell networks by using self-hybridizing properties of single stranded DNA molecules. A team of scientists in California has now successfully attached self-assembled DNA structures to cancer cells using two different methods. This is one of the first illustrations of the biomedical relevance of DNA arrays.
According to the World Health Organization, lung cancer is the leading cancer-related cause of death, accounting for 18 percent of cancer deaths and killing about 1.3 million people worldwide every year. Conventional diagnostic methods for lung cancer occasionally miss tumors and they are costly and unsuitable for widespread screening. Breath testing is a fast, non-invasive diagnostic method that links specific volatile organic compounds (VOCs) in exhaled breath to medical conditions. However, these techniques - gas chromatography/mass spectrometry, ion flow tube mass spectrometry, laser absorption spectrometry, infrared spectroscopy, polymer-coated surface acoustic wave sensors and coated quartz crystal microbalance sensors - are expensive, slow, and require complex instruments. A multidisciplinary research team at Technion - Israel Institute of Technology have now demonstrated a highly sensitive, stable, relatively inexpensive, and fast-response nine-sensor array that consists of gold nanoparticles functionalized with different organic groups that respond to various VOCs that are relevant to lung cancer.
Various forms of hyperthermia - a form of cancer treatment with elevated temperature in the range of 41-45C - have been intensively developed for the past few decades to provide cancer clinics with more effective and advanced cancer therapy techniques. The recent use of nanomaterials has shown promising for developing more effective hyperthermia agents. While most nanomedical hyperthermia research is conducted with various nanoparticles, carbon nanotubes are also of interest in these thermal ablation applications. So far, however, the utility of carbon nanotubes for in vivo use has been limited by self-association - i.e. they stick to each other. A new study has now demonstrated that DNA-encasement of multi-walled carbon nanotubes (MWCNTs) results in well-dispersed, single MWCNTs that are soluble in water and that display enhanced heat production efficiency relative to non-DNA-encased MWCNTs.
Much attention of nanotechnology researchers has recently been paid to the fabrication of free-standing, ultra-thin films. These systems have been developed for use in a wide variety of fields such as nano-separation membranes or nanosensors for electrochemical and photochemical applications. In a first report on the fabrication of free-standing nanosheets for biomedical applications, scientists in Japan have developed a biodegradable thin film of only about 20 nanometers thickness that could replace surgical stitches. In experiments, they found that the sealing operation repaired the incision completely without scars and tissue adhesion. This approach would constitute an ideal candidate for an alternative to conventional suture/ligation procedures, from the perspective not only of a minimally invasive surgical technique but also reduction of operation times.
Carbon nanotubes, like the nervous cells of our brain, are excellent electrical signal conductors and can form intimate mechanical contacts with cellular membranes, thereby establishing a functional link to neuronal structures. There is a growing body of research on using nanomaterials in neural engineering. Most studies simply grow carbon nanotubes over microelectrodes to interface with neurons extracellularly. Such an extracellular interface is non-invasive, but it only allows the action potential of neurons to be recorded. In contrast, an intracellular interface allows all of the sophisticated neural activity to be probed, but it is an invasive approach that usually destroys the neuron. Now, new research by scientists in Taiwan is the first to explore the feasibility of using CNTs to probe neural activity intracellularly, opening the way for intracellular neural probes that minimize damage to the neuron.
Neural interfaces used for such purposes as electroencephalography are noninvasive, but suffer from relatively poor spatial and temporal resolution of signals. The type of neural interface that uses electrodes inserted in the brain and measures neuronal activities is more effective, but might leave behind irreversible lesions in the cerebrum because of the need to implant electrodes in brain tissue. Other problems with this type of neural interface include the difficulty of obtaining information about individual organs. Believing that an effective solution to these problems lies in designing a neural interface that attaches not to the cerebrum but to peripheral nerves, scientists in Japan have developed an electrode for a peripheral nerve interface.
Environmental and behavioral factors may lead the body to produce superoxide radicals known as reactive oxygen species (ROS) that could cause cell damage through oxidation. Oxidative stress from ROS is implicated in aging and most diseases including cancer, heart disease, liver fibrosis, neurodegenerative diseases, autoimmune disorders. An excess of these reactive molecules can lead to oxidative stress and cellular damage, and toxicologists have identified ROS generation as a likely mechanism of nanoparticle toxicity. Since ROS plays an important role in various pathogenic processes, it has been recognized as an early indicator for cytotoxic events and cellular disorders. However, conventional chemical ROS probes have not fulfilled the rising need of in vitro and in vivo analysis of ROS generation due to auto-oxidation problems and poor specificity and sensitivity. Scientists in South Korea have now demonstrated a novel ROS-sensitive gold nanoprobe prepared from bio-inspired immobilization of fluorescein-labeled hyaluronic acid onto the surface of gold nanoparticles. This probe is highly stable under exposure to natural light and laser sources and extremely sensitive and specific to certain oxygen species.