Wednesday, January 14, 2009

Nanotechnology food coming to a fridge near you:

Nanotechnology food coming to a fridge near you:
Nanowerk Spotlight) The potential benefits of Nanofoods – foods produced using nanotechnology – are astonishing. Advocates of the technology promise improved food processing, packaging and safety; enhanced flavor and nutrition; ‘functional foods’ where everyday foods carry medicines and supplements, and increased production and cost-effectiveness. In a world where thousands of people starve each day, increased production alone is enough to warrant worldwide support. For the past few years, the food industry has been investing millions of dollars in nanotechnology research and development. Some of the world’s largest food manufacturers, including Nestle, Altria, H.J. Heinz and Unilever, are blazing the trail, while hundreds of smaller companies follow their lead. Yet, despite the potential benefits, compared with other nanotechnology arenas, nanofoods don't get a lot of publicity. The ongoing debate over nanofood safety and regulations has slowed the introduction of nanofood products, but research and development continue to thrive - though, interestingly, most of the larger companies are keeping their activities quiet (when you search for the term 'nano' or nanotechnology' on the websites of Kraft, Nestle, Heinz and Altria you get exactly zero results). Although the risks associated with nanotechnology in other areas, such as cosmetics and medicine, are equally blurry, it seems the difference is that the public is far less apt to jump on the nanotechnology bandwagon when it comes to their food supply. According to a definition in a recent report (Nanotechnology in Agriculture and Food) food is “nanofood” when nanoparticles, nanotechnology techniques or tools are used during cultivation, production, processing, or packaging of the food. It does not mean atomically modified food or food produced by nanomachines.

Examples for nanofood applications (Source: Nanowerk)

In the forefront of nanofood development is Kraft Foods, which took the industry’s lead when it established the Nanotek Consortium, a collaboration of 15 universities and national research labs, in 2000. Kraft’s focus is on "interactive" foods and beverages. These products will be customized to fit the tastes and needs of consumers at an individual level. Possible products include drinks that change colors and flavors to foods that can recognize and adjust to a consumer's allergies or nutritional needs. Other large companies, such as Nestlé and Unilever, are exploring improved emulsifiers that will make food texture more uniform. These huge Western companies are responsible for the bulk of the food industry’s research and development, however the nanofood industry is truly a global phenomenon. In Australia for instance, nanocapsules are used to add Omega-3 fatty acids to one of the country’s most popular brands of white bread. According to the manufacturer, nanocapsules of tuna fish oil added to Tip Top Bread provide valuable nutrients, while the encapsulation prevents the bread from tasting fishy. NutraLease, a start-up company of the Hebrew University of Jerusalem has developed novel carriers for nutraceuticals in food systems. The nano-sized self-assembled structured liquids (NSSL) technology allows for encapsulation of nutraceuticals, cosmeceuticals, and essential oils and drugs in food, pharmaceuticals, and cosmetics. Another advantage to the NSSL technology is that it allows the addition of insoluble compounds into food and cosmetics. One of the first products developed with this technology – a healthier version of canola oil – is already available to consumers in Israel. In other parts of the world, nanotechnology efforts are focused on the agricultural side of food production. A joint effort among universities in India and Mexico is directed at developing non-toxic nanoscale herbicides. Researchers at Tamil Nadu Agricultural University in India and Monterrey Tech in Mexico are looking for ways to attack a weed’s seed coating and prevent it from germinating. The range of current nanofood research and development is as impressive as the industry’s projected growth. Last August, UK-based Cientifica estimated that nanotechnologies in the food industry were currently valued at $410 million and would grow to $5.8 billion by 2012 ("Nanotechnologies in the Food Industry").

Food Packaging is the Trail Blazer Novel food packaging technology is by far the most promising benefit of nanotechnology in the food industry in the near future. Companies are already producing packaging materials based on nanotechnology that are extending the life of food and drinks and improving food safety. While the nanofood industry struggles with public concerns over safety, the food packaging industry is moving full-speed ahead with nanotechnology products. Leading the way is active or “smart” packaging that promises to improve food safety and quality and optimizes product shelf-life (for example, see a recent Nanowerk News article "Intelligent food wrappers with nanotechnology"). Numerous companies and universities are developing packaging that would be able to alert if the packaged food becomes contaminated; respond to a change in environmental conditions; and self-repair holes and tears. One of the most promising innovations in smart packaging is the use of nanotechnology to develop antimicrobial packaging. Scientists at big name companies including Kraft, Bayer and Kodak, as well as numerous universities and smaller companies, are developing a range of smart packaging materials that will absorb oxygen, detect food pathogens, and alert consumers to spoiled food. These smart packages, which will be able to detect public health pathogens such as salmonella and e. coli, are expected to be available within the next few years. Similar technology is being developed for the U.S. Government as a means of detecting possible terrorist attacks on the U.S. food supply. Scientists in the Netherlands are taking smart packaging a step further with nanopackaging that will not only be able to sense when food is beginning to spoil, but will release a preservative to extend the life of that food. Because of their ability to improve safety and extend the life of food, these nanopackaging solutions are some of the most exciting innovations in the food industry today. However, other less dramatic (but far more practical) developments in nanopackaging are already in use around the world. Clay nanocomposites are being used in plastic bottles to extend the shelf life of beer and make plastic bottles nearly shatter proof. Embedded nanocrystals in plastic create a molecular barrier that helps prevent the escape of oxygen. The technology currently keeps beer fresh for six-months, but developers at several companies are already working on a bottle that will extend shelf life to 18 months. Several large beer makers, including South Korea’s Hite Brewery and Miller Brewing Company, are already using the technology.

Activist Concerns Because there is little government oversight in this area, says Craig Minowa, an environmental scientist for the Organic Consumers Association (OCA), the public may have little to say about it. "Products are not labeled, so consumers cannot choose to avoid them," he explains. The OCA, a grassroots non-profit public interest organization based in the U.S., is one of many vocal organizations calling for government regulation on nanofoods, at least until more safety testing is completed. These organizations argue that a lack of evidence of harm is not the same as reasonable certainty of safety, which is what food companies must demonstrate to the U.S. Food and Drug Administration (FDA) before introducing a new food additive. "The OCA is focusing its efforts on educating the public about the potential risks of nanofoods and putting pressure on government agencies to increase oversight," says Minowa, adding that ever-tightening federal budgets, at least in the U.S., will make the latter a huge challenge. "There’s a lack of consumer understanding, a lack of government oversight and a lack of labeling," says Minowa. "Combine these with a lack of testing and you have an equation for serious problems." Although there is far less opposition to nanopackaging than there is to nanofoods, there are some who argue that the use of these devices will allow the food industry to further shirk their corporate responsibilities. "While devices capable of detecting food-borne pathogens could be useful in monitoring the food supply, sensors and ‘smart packaging’ will not address the root problems inherent in industrial food production that result in contaminated foods: faster meat (dis)assembly lines, increased mechanization, a shrinking labor force of low-wage workers, fewer inspectors, the lack of corporate and government accountability and the great distances between food producers, processors and consumers," says the ETC Group ("Down on the Farm: The Impact of Nano-scale Technologies on Food and Agriculture" pdf download 1 MB), a conservation and sustainable advancement organization. "Just as it has become the consumer’s responsibility to make sure meat has been cooked long enough to ensure that pathogens have been killed, consumers will soon be expected to act as their own meat inspectors so that industry can continue to trim safety overhead costs and increase profits." Interestingly enough, the Environmental Protection Agency (EPA) in the U.S. declared on November 22, 2006 that it intends to to regulate a large class of consumer items made with silver nanoparticles. The decision, which will affect not only washing machines but other consumer products such as odor-destroying shoe liners, food-storage containers, air fresheners, and a wide range of other products that contain nanosilver, marks a significant reversal in federal policy. Nanosilver containing consumer products that are applied to food packaging are not regulated by the EPA but by the FDA. The FDA is still considering whether it needs new rules for nanomaterials.

Friday, January 9, 2009

How worried should we be?- Military nanotechnology :

(Nanowerk Spotlight) All major powers are making efforts to research and develop nanotechnology- based materials and systems for military use. Asian and European countries, with the exception of Sweden (Swedish Defence Nanotechnology Programme), do not run dedicated programs for defense nanotechnology research. Rather, they integrate several nanotechnology-related projects within their traditional defense-research structures, e.g., as materials research, electronic devices research, or bio-chemical protection research. Not so the U.S. military. Stressing continued technological superiority as its main strategic advantage, it is determined to exploit nanotechnology for future military use and it certainly wants to be No. 1 in this area. The U.S. Department of Defense (DoD) is a major investor, spending well over 30% of all federal investment dollars in nanotechnology. Of the $352m spent on nanotech by the DoD in 2005, $1m, or roughly 0.25%, went into research dealing with potential health and environmental risks. In 2006, estimated DoD nanotechnology expenditures will be $436m – but the risk-related research stays at $1m.

Annual DoD investment in nanotechnology; 2006 estimated. (Source data: DoD "Defense Nanotechnology Research and Development Programs", May 8, 2006) Proposed and actively pursued military nanotech programs cover a wide range of applications to improve the performance of existing systems and materials and allow new ones. The main areas of research deal with explosives (their chemical composition as well as their containment); bio and medicine (for both injury treatment and performance enhancement); biological and chemical sensors; electronics for computing and information; power generation and storage; structural materials for ground, air and naval vehicles; coatings; filters; and fabrics. Structure of the DoD Nanotechnology Program In the mid-1990s the DoD identified nanotechnology as one of six “Strategic Research Areas” (the other five being bioengineering sciences, human performance sciences, information dominance, multifunction materials, propulsion and energetic sciences). The DoD nanotechnology program is grouped into seven program component areas (PCAs), which mirror the PCAs of the U.S. National Nanotechnology Initiative
  • PCA 1: fundamental nanoscale phenomena and processes
  • PCA 2: nanomaterials
  • PCA 3: nanoscale devices and systems
  • PCA 4: instrumentation research, metrology, and standards for nanotechnology
  • PCA 5: nanomanufacturing
  • PCA 6: major research facilities and instrumentation acquisition
  • PCA 7: societal dimensions

About half of the DoD’s nanotech investment goes to DARPA (Defense Advanced Research Projects Agency), with the rest roughly evenly split between Army, Navy and Air Force. Besides DARPA, the major agencies leading the effort are the Naval Research Laboratory (NRL), the Army Research Laboratory (ARL), the Air Force Office of Scientific Research (AFOSR), and MIT's Institute for Soldier Nanotechnologies (ISN). In addition, the DoD established a Defense University Research Initiative on NanoTechnology (DURINT). The DURINT program is intended to enhance U.S. universities’ capabilities to perform basic science and engineering research and related education in nanotechnology critical to national defense.

Most of the DoD dollars spent to date have gone into basic research and engineering. Insofar as these engineering and materials aspects of military nanotechnology incorporate engineered nanomaterials, there are near-term issues that need to be discussed and resolved: the potential toxicity of such materials (which applies to all engineered nanomaterials, not just those for military use), their impact on humans and the environment, and if and how release of such nanomaterials into the environment through military use could exceed release from non-military uses.

While very active in developing nanotech applications, the military is much more passive in assessing the risks and is content to monitor what other agencies do. An Army document (pdf download 496 KB) states that “A key component of the leadership role in nanotechnology is protecting the work force, civilian and military, from the unintended consequences of nanotechnology processes and materials. The Army should take an active role in drafting environmental, safety, and occupational health guidelines for nanomaterials to ensure contractors follow best environmental practices in the development, manufacture, and application of the new technology.” However, this “active role” appears not yet to have materialized.

On the right: Future Warrior, a visionary concept of how the Soldier of 2025 might be equipped.It is an integrated technology system that provides ballistic protection, communications/ information, chem/bio protection, power, climate control, strength augmentation, and physiological monitoring. Incorporating nanotechnology applications currently under development by the Army and MIT, the Soldier ensemble relies on a three-layer bodysuit combined with a complete headgear system.(Source: MIT's Institute for Soldier Nanotechnologies)

A spokesman for the U.S. Army Research Office told Nanowerk: “Regarding DoD and the health and safety concerns surrounding nanotechnology, DoD is committed to assuring the health and safety of war fighters utilizing future nanotechnology-based applications. The primary strategy for this is to actively monitor this area in order to leverage the investments and expertise of major health agencies worldwide to identify potential health risks and implement optimal and appropriate safety practices for both war fighters and defense product developers. By partnering with and relying upon agencies such as NIH (National Institutes of Health), EPA, and NIOSH (National Institute for Occupational Safety and Health), who are the true experts with such matters, we believe we will be able to rapidly and accurately address these concerns while simultaneously avoiding duplicative effort

Military Nanotech Risk Factors Go Beyond Civilian Risk

Some of the military-motivated research could clearly have a positive impact on everyday life (e.g., more powerful batteries, bio and chemical sensors to detect pollutants, filters to remove nanoscale pollutants and toxins, smart fabrics). Others not only pose the same potential risk that commercially used engineered nanomaterials do, for instance during production, but, due to their intended area of use, could have a greater chance of reaching and affecting the environment. Two examples: 1) Military activities often result in stuff being blown up. Blasts by high-tech weaponry could release toxic nanoparticles (which already is the case with depleted uranium munitions) as well as large quantities of nanoengineered particles contained in both munitions and defensive weapons systems and armors (e.g., coatings could release particles into the environment, especially during weapons impact). 2) Large-scale use of nanotech sensors could have an impact on the environment when these sensors start to degrade and engineered nanoparticles leak into the soil. Of considerable concern is the question to what degree military nanotech could lead to destabilization (when one military power develops a technology that others cannot effectively defend against) and undermine arms-control agreements like the Biological Weapons Convention. A NATO study group states that “the potential for nanotech-driven innovations in chemical and biological weapons are particularly disquieting as they can considerably enhance the delivery mechanisms of agents or toxic substances. The ability of nanoparticles to penetrate the human body and its cells could make biological and chemical warfare much more feasible, easier to manage and to direct against specific groups or individuals.” Other, longer-term risk factors arise from hotly debated concepts dealing with molecular assembly and self-replicating nanomachinery or from societal issues such as the potential destabilization posed by military nanotechnology applications (e.g., What will be the impact of omnipresent sensor nets and autonomous fighting systems? What are the ethical implications of non-medical implants in soldiers?).

Some examples Here are current and near-term (from today until 2010) projects that will incorporate “free” engineered nanoparticles, i.e., where at some stage in production or use individual nanoparticles of a substance are present (compiled from public information on various DoD websites):

· Field-responsive particles impregnated in microchannels, fibers, and foam packages to be used as load-transfer devices to remove/relieve skeletal loads (e.g., for built-in splints) (ISN - Institute for Soldier Nanotechnologies)

· Thin films made of carbon nanotubes that can be deposited onto surfaces for electrically active coatings (Naval Research Laboratory - NRL)

· Quantum dots for sensors (NRL)

· Advanced coatings containing polymer nanocomposites (DARPA - Defense Advanced Research Projects Agency and AHPCRC – Army High Performance Computing Research Center)

· Nanocomposites and engineered nanoparticles for high-energy munitions (ICB – Institute for Collaborative Biotechnologies)

· Bio-molecular motors (DARPA)

· Polymeric and nanostructured materials for biological and chemical sensors (NRL)

· Nanometallics for armaments (Army Research Laboratory - ARL)

· Energy-absorbing nanomaterials (ISN)

· Nanostructured magnetic materials for controlled adhesives (DARPA and AHPCRC) and as transduction mechanism for monitoring and controlling biological activity at the cellular and, ultimately, single-molecule level (DARPA)

· Self Decontaminating Surfaces exploiting surface structures of nanomaterials (DARPA)

· Nanowires and carbon nanotubes for nanoelectronics (NRL)

· Neural-electronic interfaces for visual, auditory and motor prostheses implanted into the body (DARPA, NRL)

· Gold nanocluster-based sensors and electronics (NRL)

· Incorporating carbon nanotubes into continuous high-strength and high-stiffness structural carbon fiber (DARPA)

· Energy-absorbing and mechanically active nanomaterials in clothing and body armor that will be part of the future soldier's battlesuit (ISN) This list is far from exhaustive. More visionary applications and materials such as performance- enhancing nanoengineered protheses and bio-engineered weapons are conceptually feasible but are unlikely to see realization within the next 10-15 years.

Nanotechnology

Nanotechnology :

Nanotechnology is engineering of functional systems at the molecular scale. This covers current work and concepts that are more advanced. In its original sense, nanotechnology refers to the projected ability to construct items from the bottom up. IBM's nanotechnology research aims to devise new atomic- and molecular-scale structures and devices for enhancing information technologies, as well as discover and understand their scientific foundations. Leading the development of nanotechnology, IBM's scientists have made numerous breakthroughs in the study of these nano-scale technologies. In particular, carbon nanotubes and scanning probes derived from the atomic force microscope -- cousin of the scanning tunneling microscope -- show particular promise in enabling dramatically improved circuits and data storage devices. Research on nanoparticles leads to applications in biomedicine as well as hard disk drive storage. Photonic bandgap materials -- on-chip nanoscale structures the size of a wavelength of light -- will manipulate light as optical waveguides, splitters and routers. Research into nanomechanical information storage, such as IBM's Millipede project, continues to increase the possibilities for increased areal storage density. nanotechnology IBM's research into nano-scale structures that self-assemble may one day obviate the need to "hand-position" atoms. Nanotechnology will allow the design and control of the structure of an object on all length scales, from the atomic to the macroscopic enabling more efficient and vastly less expensive manufacturing processes and providing the hardware foundation for future information technology.

Interesting Facts about Nanotechnology:

1.Nanotechnology In water treatment:
2.Bullet proof t-shirts can me made from Carbon nanotubes :
3.Freedom Car requirements surpassed by New carbon nanotube hydrogen storage results: 4.Invisible electronics made with carbon nanotubes:
5.On beating cancer (with nanotechnology):
6.How worried should we be?- Military nanotechnology :
7.Nanotechnology food coming to a fridge near you:

Thursday, January 8, 2009

On beating cancer (with nanotechnology)

On beating cancer (with nanotechnology)

(Nanowerk Spotlight) Cancer is an enormous socio-economic problem. According to the National Cancer Institute (NCI), it is estimated that in 2007 there will be over 1.4 million new cases of cancer (of any type) and over 550,000 deaths from cancer in the United States (you can download a detailed Cancer Statistics 2007 Presentation; ppt download, 808 KB) from the American Cancer Society. This makes cancer the second deadliest disease category, after heart diseases. But while the mortality rates for heart diseases have dropped by more than half from 1950 to 2004, and other major disease categories show similar trends, cancer death rates have stayed pretty much the same. Shocking but true, if you are a male living in the U.S., your lifetime probability of developing some type of cancer is 1 in 2. If you are female, your probability is 1 in 3. Equally dismal are the economic cost associated with this disease: The amount of direct cancer-related costs (treatment, care and rehabilitation) have reached $74 billion in the U.S. in 2005, and growing fast, while the overall economic costs (including loss of economic output due to days off and premature death) are estimated to be over $200 billion per year (2005 data). This Spotlight will discuss existing and new approaches to fight cancer and their limitations. The goal is to stimulate readers to support and participate in interdisciplinary research and teaching efforts toward relieving suffering and death due to cancer. Fighting cancer involves three phases: (i) detection, (ii) treatment, and (iii) monitoring. Success depends on matching science to the actual practical needs. We'll take a look at - in particular nanotechnology - efforts underway in the direction of these three phases and comment on some of the practical problems encountered fighting cancer. We also speculate about some unconventional research that might be successful fighting cancer in the future.

Detecting Cancer Detection at the earliest stage provides the greatest chance of survival. Cancer has a logarithmic growth rate. A one cubic centimeter size tumor may have 40-50 cell divisions and typically we don’t see 80% of the life of a tumor. Detection can be done using a number of techniques – including standard immunoassays and biopsies. Nanotechnology offers new detection approaches such as targeted contrast agents, nanoscale cantilevers coated with antibodies against tumor markers, and magnetic nanoparticles coated with DNA labeling. But the problem is daunting because there are over 50 common types of cancer and in practice it is difficult to ask people to come to the clinic on a regular basis for cancer screening. Early detection may require identifying a single cancer cell in 3,000 normal cells. Amplification strategies and simple tests are needed. Physicians ideally would like a quick digital readout sensor that can tell cancer is there or not. Nanotube electronic biosensors are being developed that might help in the detection of cancer (further reading: Edited Book to be published in 2008: Nanomedicine Science and Engineering; Mark J. Schulz, Vesselin N. Shanov, YeoHeung Yun, (Artech House Publishers, "Engineering in Medicine & Biology" book series); and: YeoHeung Yun, Zhongyun Dong, Vesselin Shanov, William R. Heineman, H. Brian Halsall, Amit Bhattacharya, Laura Conforti, Raj K. Narayan, William S. Ball, and Mark J. Schulz: Carbon Nanotube Electrodes and Biosensors, NanoToday Online Journal; to be published in Dec. 2007, vol. 2, no. 6).

Treatment Cancer treatment typically involves chemotherapy, radiotherapy, or surgery, and – depending on the stage of the disease – often is unsuccessful. Many new techniques to treat cancer are under development. Bioactive immune stimulation and attacking integrin expressing vasculature using nanoparticles with gas bubbles that can explode by ultrasound are two novel approaches. Delivery of drugs to the cancer site using nanoparticles is currently being widely investigated. Nanoparticles such as multifunctional polymers, gold nanoshells, and carbon nanotubes are also being used as contrast agents to identify cancer, deliver drugs, and to ablate cancer cells. Nanoparticle devices hold great promise because they can treat cancer locally, potentially without harming the rest of the body. Based on presentations at the 3rd annual meeting of the American Academy of Nanomedicine, development of nanoparticles against cancer is an intense area of nanomedicine research. such as micro-cantilever sensors and tiny cameras that can operate in the body are also under development. Micro and nano devices hold promise because they can go throughout the body to find cancer. Tumors have certain general characteristics that might be weak links that allow developing simpler generic techniques to treat cancer. The generic techniques might be successful especially where cancer cells become resistant to medication. The difficulty of treating cancer is shown by testing using mouse models. Artificially induced cancer can be cured in mice using several new techniques, but in humans the therapies are often not as effective. Some characteristics of cancer that might be taken advantage of to develop simple therapies are high pressure in the tumor (which is why drug delivery is difficult), high pH levels, elevated temperature, different elasticity of the tissue, and new vasculature and blood supply. Nanodevices are being designed conceptually at the University of Cincinnati's Smart Structures Bio-Nanotechnology Laboratory that focus on identifying and destroying cancer cells based on the material properties of the cells, rather than on complex cancer biology. Simple tools are needed when cancer cells become resistant to drugs. Biosensors to measure physiological variables such as pressure, temperature, pH, cell membrane and neural potentials, and chemical and inorganic ion concentrations are considered feasible to develop and may identify and locate cancer without the need for complex biochemistry. Responsive biosensors may also react to the cancer by coupling to RF signals to ablate cancer cells, or release drugs, or radiation, or to block the vasculature. Miniature sensors that operate in the body could be developed based on electro-mechanical-systems built from nanoparticles such as nanotubes, nanowires, nanobelts, and nanosphere chains that have smart materials properties including sensing, actuation, and power generation.

Monitoring for the Recurrence of Cancer Monitoring involves detection of the recurrence and spread of cancer after initial treatment and remission. Physicians would be helped by an easy to use sensor that can perform a quick check for cancer. Monitoring prostate cancer, for instance, would be one important application for the sensor. In 2005 in the United States, there were an estimated 230,000 new cases of prostate cancer and 30,000 deaths due to prostate cancer. Most prostate cancer deaths are caused by metastases that are resistant to conventional therapies. As detection techniques improve, an increasing number of patients are diagnosed with localized prostate cancer, whereas the number of patients with disseminated disease is on the decline. But in many patients, metastasis occurs prior to initial diagnosis, and hence eradication of primary tumors by either surgery or radiation therapy is not curative. Currently, there is no technology to differentiate patients with disseminated disease from others diagnosed as having clinically localized prostate cancer. An electronic needle sensor would be useful to predict the metastatic potential of diagnosed prostate tumors which would improve the efficiency of point-of-care and clinical testing, and may provide near real-time diagnostics during surgery. Detection of cancer cells in blood is another approach that would provide information about the metastatic potential of the cancer, and therefore clinical outcomes. The treatment for metastasis is much more severe to the patient than the treatment for no metastasis, and avoiding the former treatment is a significant benefit to the patient. A small needle biosensor inserted directly into the blood or a tumor might provide the information needed to differentiate between metastatic and non-metastatic cancer. A cell sensor would identify the circulation of cancer cells in the blood related to prostate cancer in its early stages when this critical information is needed to determine the most efficacious course of treatment. Initial testing of a cell biosensor described in a recent paper in Nanotechnology ("Electrochemical impedance measurement of prostate cancer cells using carbon nanotube array electrodes in a microfluidic channel") showed that a nanotube electrode can characterize different solutions of LNCaP prostate cancer cells. The testing suggests that a cell-based biosensor may be used for metastasis detection. Further development of this sensor is needed to discriminate cancer cells from other types of cells. Selectivity of cells will be attempted using gold functionalized nanotube array electrodes with bio conjugation using antibodies, or special receptors. It is hoped this electronic sensor can detect different types of cancer cells in the blood in a quick electronic measurement. Once cancer has occurred, we usually know what type of cancer to look for to check for metastasis. In this case, the sensor can be designed specifically to detect that type of cancer cell using antibodies.

Responsive Materials and Devices The nanotechnology approaches that are being taken toward beating cancer that are described above are considered to have a likelihood of success for many applications. On the other hand, some cancers are drug resistant or mutate after initial therapy and treatment is mostly ineffective. This is where drastic approaches and new medicine are needed to combat cancer. A revolutionary approach is to develop responsive materials and devices to go inside the body to combat cancer. Responsive materials have an intrinsic ability to sense and respond to external stimuli. Examples are multi-wall carbon nanotubes that act as bearings and also telescope and change electrical resistance, carbon nanotubes that strain based on electrochemical bond expansion, nanowires that generate power, and piezoelectric nanobelts that bend. Devices that could be fabricated from responsive materials include inductors and solenoids built from nanowires and coiled nanotubes, electronic components such as transistors, antennas, and wires, and simple motors and pumps. Three factors must be considered to develop responsive materials as medical devices for in vivo applications: (i) delivery; (ii) monitoring; and (iii) retrieval of the devices. It is conceivable to develop a sub-millimeter diameter sensor device with a mm long antenna tail:

Concept in-body responsive device: Injectable wireless tumor sensor. (Image: Prof. Schulz) This device could be delivered and injected into the body to receive, sense, and transmit limited information about physiological variables that could identify a tumor. Ion flux propulsion might provide mobility of the device. On a smaller scale, micron size electronic responsive particles could circulate in the blood stream and receive wireless signals to release drugs, or heat to kill cells, or vibrate to clean arteries and report their location as the sensor circulates in the body. A still simpler responsive-material approach is to use micron size particles functionalized with antibodies to capture cancer cells in the blood, or the particles could sample fluids from certain areas of the body based on capillarity:


Concept in-body responsive device: Circulating magnetic microsphere with antibodies to capture cancer cells for examination outside the body. (Image: Prof. Schulz) The sensor or functionalized particles would be magnetically removed from the blood and analyzed to identify metastasis potential. Going further, mobile microscopic robots using nanomanipulators built using nanowire solenoids would do surgery and repairs in the body. Methods of retrieval of devices using surgery or other ways or the effects of leaving the device in the body are practical problems that must be solved. Biocompatibility and biological integration may be solved using coatings or by responsive sensors that can self-clean their electrodes.


Conclusion Looking ahead, it appears that eradicating cancer will require integrating basic science, engineering, and medical knowledge to develop a toolbox of general methods to treat different cancers. Also needed is development of the most advanced technologies and devices ever conceived by mankind that will operate in the body to treat disease at the cellular and molecular levels. Development of this new medicine will be a fantastic voyage that we are literally betting our lives on.

Invisible electronics made with carbon nanotubes

Invisible electronics made with carbon nanotubes

The emerging field of transparent and flexible electronics not only holds the promise of a new class of device components that would be more environmentally benign than current electronics; being able to print transparent circuits on low-cost and flexible plastic substrates also opens up the possibility of a wide range of new applications, ranging from windshield displays and flexible solar cells to clear toys and artificial skins and even sensor implants. Three broad application areas for this technology are taking shape: Transparent displays. These are of interest for applications such as heads-up displays on windshields and informational displays on eyeglasses or even contact lenses. Flexible displays. Emerging applications such as electronic paper require flexible electronics to be integrated within the pixel array of the display area. Reliable thin-film transistors (TFTs) on flexible substrates represent an important step toward the required circuitry. While TFTs suitable for static images have already been demonstrated, the required transistors will have to operate at much higher speeds to allow full-motion video. Transparent/flexible electronics. Applications such as electronic bar codes, RFID tags, and smart credit cards would be advanced by the availability of relatively high performance electronics that could be integrated on a variety of substrates. Flexible circuitry would allow integration on curved and non-rigid surfaces. Transparency would allow integration into multi-layer packaging, in a fashion such that product information could be seen beneath the electronics. Traditional materials used for transparent electronics include InGaO3(ZnO)5 films, indium tin oxide films, and indium oxide nanowires. In their search for materials that can offer even higher mobility and therefore even better performance, researchers have turned to single-walled carbon nanotubes (see for instance the work of John Rogers' group at the University of Illinois "Linear arrays of nanotubes offer path to high-performance electronics" and "'Nanonet' circuits closer to making flexible electronics reality"). New work at the University of Southern California (USC) has now demonstrated the great potential of massively aligned single-walled carbon nanotubes for high-performance transparent electronics. "We fabricated transparent thin-film transistors on both rigid and flexible substrates with transfer printed aligned carbon nanotubes as the active channel and indium-tin oxide as the source, drain, and gate electrodes," Chongwu Zhou, Jack Munushian Associate Professor in USC's Department of Electrical Engineering, tells Nanowerk. "We have fabricated these transistors through low-temperature processing, which allowed device fabrication even on flexible substrates." A fully transparent aligned single-walled carbon nanotube transistors on a 4 inch glass wafer.

(Reprinted with permission from American Chemical Society)



This work by Zhou's group, first-authored by graduate students Fumiaki Ishikawa and Hsiaoh-Kang Chang and reported in the December 10, 2008 online edition of ACS Nano ("Transparent Electronics Based on Transfer Printed Aligned Carbon Nanotubes on Rigid and Flexible Substrates"), demonstrates two advances on route to high-performance transparent electronics: Aligned nanotubes are established as viable active material for transparent transistors and they are shown to offer higher mobility than traditional materials for transparent electronics. As a matter of fact, the USC team has achieved the highest device mobility among transparent transistors reported so far (mobility is a number related to how fast electrons and holes can move inside a semiconductor). Zhou explains that earlier attempts at transparent devices used other semiconductor materials with disappointing electronic results, enabling one kind of transistor (n-type), but not p-types; both types are needed for most applications. The critical improvement in performance came from the ability to produce extremely dense, highly patterned lattices of nanotubes, rather than random tangles and clumps of the material. The Zhou lab has pioneered this technique over the past three years. Zhou's team first grew the nanotubes on quartz substrates and then transferred them to glass or PET substrates with pre-patterned indium-tin oxide gate electrodes, followed by patterning of transparent source and drain electrodes. "In contrast to random networked nanotubes, the use of massively aligned nanotubes enables the devices to exhibit high performance, including high mobility, good transparency, and mechanical flexibility," says Zhou. "In addition, our aligned nanotube transistors are easy to fabricate and integrate, as compared to individual nanotube devices. The transfer printing process allows the devices to be fabricated through a low temperature process, which is particularly important for realizing transparent electronics on flexible substrates". As a proof-of-concept demonstration, the researchers constructed a fully transparent and flexible logic inverter on a plastic substrate and used it to control commercial gallium nitrate light-emitting diodes, which changed their luminosity by a factor of 1,000 as they were energized. One of the challenges that Zhou's team is struggling with is the difficulty of achieving a highly separated sample of nanotubes. Current production methods for carbon nanotubes result in units with different diameter, length, chirality and electronic properties, all packed together in bundles. These mixtures are of little practical use since especially nanoelectronics applications are sensitively dependent on tube structures. In conventional synthesis processes, a significant proportion of the nanotubes (20-30%) is metallic and a highly reliable and effective separation of metallic and semiconducting CNTs is essential for large-scale commercial manufacturing processes for future nanoelectronic devices. Developing novel and efficient ways to remove metallic nanotubes is one of the tasks Zhou's team is now working on.

Source: www.nanowerk.com

Freedom Car requirements surpassed by New carbon nanotube hydrogen storage results:

Freedom Car requirements surpassed by New carbon nanotube hydrogen storage results:

Nanowerk Spotlight) Two of the major challenges of our modern, mobile society are the shrinking of available fossil energy resources on one hand and climate change associated with global warming on the other. Continuing population growth multiplied by the increase in consumption and living standards, especially in developing countries, will require more and more oil, coal and natural gas to 'power' humanity. Notwithstanding efforts like the Kyoto Protocol - which wasn't signed by the two major CO2 polluters China and the U.S. - an ever increasing rate of fossil fuel usage means that the increasing emission of CO2 is likely to cause an acceleration of the climate change that is in progress already. Transportation, in particular passenger cars, is one of the areas where new technology could lead to environmental beneficial change. Never mind that GM is still selling 15-20,000 Hummers a year, or that Tata is planning to sell millions of its new Nano car. One of the much touted technological solutions is to substitute fossil hydrocarbon based energy with the energy from carbon-free sources like the sun, nuclear energy, or the hot interior of the Earth and use hydrogen as an energy carrier (read more about this in "The Hydrogen Economy"). Hydrogen can be produced from water using energy from carbon-free sources [editor's note: unfortunately it can also be produced from dirty fossil fuels; see the Nanowerk Spotlight "Nanotechnology could clean up the hydrogen car's dirty little secret"] and can serve as fuel in fuel cells to generate electricity, either stationary or on board of vehicles. Considerable research efforts are going into the evaluation of various nanostructures, such as carbon nanotubes, to find the most suitable hydrogen storage materials. Safe, efficient and compact hydrogen storage is a major challenge in order to realize hydrogen powered transport. According to the DOE Freedom CAR program roadmap the on-board hydrogen storage system should provide 6 weight % (wt%) of hydrogen capacity to be considered for the technological implementation. Currently, the storage of hydrogen in the absorbed form is considered as the most appropriate way to solve this problem. Thus, a media capable of absorbing and releasing large quantities of hydrogen easily and reliably is being actively sought. Since claims by Dillon et al. that single-walled carbon nanotubes (SWCNT) can store hydrogen, this material has been considered as a candidate for hydrogen storage media ("Storage of hydrogen in single-walled carbon nanotubes"). Physisorption and chemisorption both have been proposed as possible mechanisms for hydrogen storage in carbon nanotubes. While most of the previous studies have focused on the hydrogen storage through physisorption, recent Density Functional Theory (DFT) calculations for single-walled carbon nanotubes (SWCNT) indicate the potential for up to 7.5 wt% hydrogen storage capacity for this material through chemisorption by saturating the C-C double bonds in the nanotube walls and forming C-H bonds (see "Generalized Chemical Reactivity of Curved Surfaces: Carbon Nanotubes" and "Theoretical evaluation of hydrogen storage capacity in pure carbon nanostructures"). However, direct experimental evidence of the high values of the hydrogen capacity through chemisorption has not been demonstrated yet. In this regard, we studied the chemical interaction of hydrogen with carbon nanotubes using such techniques like X-ray Photoelectron Spectroscopy (XPS) and X-ray Absorption Spectroscopy (XAS). These methods allow us to observe the formation of C-H bonds through the modification of the local electronic structure around specific carbon atoms and to quantify the amount of hydrogen that is chemically adsorbed in terms of per carbon atom. For our experiments we used two different types of as grown SWCNT thin films (T1 and T2) with different diameter distributions. The T1 SWCNT film had an average diameter around 1.6 nm and the average diameter for the T2 SWCNT film sample was equal to 2.0 nm. We also used in situ atomic H-beam treatment of the studied samples for the hydrogenation to escape complexities related to the H2 molecule dissociation. It was demonstrated before that atomic hydrogen treatment of SWCNT film does cause the formation of C-H bonds ("Hydrogenation of Single-Walled Carbon Nanotubes"). Using C1s XPS as a probing tool we studied the interaction of the atomic hydrogen with T1 and T2 samples of SWCNT. The C1s XPS spectra measured during hydrogenation sequence for T1 and T2 samples are shown in figure 1 below.

Figure 1. C1s XPS spectra measured during the hydrogenation sequence of T1 SWCNT (left) and T2 SWCNT (right) samples. (Credit: Anton Nikitin, SSRL) These measurements demonstrate dramatic differences in the behavior of the different nanotube samples under the H treatment. In the case of the T1 sample H treatment allows to hydrogenate 30% of the carbon atoms in the walls of the nanotubes. Additional doses of the atomic hydrogen do not increase the degree of the sample hydrogenation but cause the etching of the material that is directly indicated by the C1s line shape and intensity dependences on the total H dose. In the case of the T2 sample the H treatment can hydrogenate the surface of the SWCNT film up to much higher values before hydrogenated SWCNT become unstable and can be etched under the beam of atomic hydrogen. The observed difference in the maximal degree of the hydrogenation between T1 and T2 samples are due to the differences in the diameter distribution of the nanotubes. It was observed before that SWCNT with smaller diameter are less resistant to the hydrogen plasma induced etching ("Hydrogenation and Hydrocarbonation and Etching of Single-Walled Carbon Nanotubes"). Using single nanotube AFM measurements (see fig. 2 below) we also found that the same H treatment dose causes the appearance of the cuts in the thinner nanotubes while the thicker ones preserve integrity.





Figure 2. AFM images of the same tubes before and after hydrogenation. (a) Before hydrogenation, a SWCNT with the diameter of 1.8 nm; (b) diameter of the tube in (a) increased to 2.1 nm after hydrogenation; (c) before hydrogenation, a SWNT with diameter of 1.0 nm; (d) the tube in (c) is cut after hydrogenation (marked with arrow) and diameter of the tube increased to 1.3 nm. (Credit: Anton Nikitin, SSRL) The decomposition of the C1s line measured from the highly hydrogenated T2 sample (see fig. 3 below) provided the information about the exact degree of the maximal hydrogenation value for this material. The ratio between peak 1 (clean carbon atoms) and peak 2 and 3 (hydrogenated carbon atoms) is 1 to 10. If we assume that there is one hydrogen atom per one hydrogenated carbon atom then the observed more than 90% hydrogenation corresponds to more than 7 wt% of hydrogen storage capacity. This value is already above the requirement in the Freedom CAR Hydrogen Storage Technologies Roadmap goal for 2010.

Figure 3. The decomposition of XPS C1s spectrum of the H treated T2 sample at maximal hydrogenation degree. For the comparison C1s spectrum of clean T2 SWCNT sample is shown. (Credit: Anton Nikitin, SSRL) Using XPS as a probing tool we also studied the hydrogen desorption from the hydrogenated SWCNT. Our results showed that most of the C-H bonds dissociate in the temperature range between 200°C and 300°C. The DFT based modeling of the H recombinative desorption mechanism demonstrated that the H desorption temperature is mainly controlled by the reaction kinetics and nanotube curvature can be used to tune the energy of C-H bonds in the hydrogenated SWCNT to minimize the energy overhead to form hydrogenated SWCNT. The present results indicate that for certain types of SWCNT the hydrogen chemisorption can provide more than 7 wt% of hydrogen storage capacity and the optimal C-H bond energetics can be tuned by the choice of the nanotube curvature range to minimize the energy losses of the hydrogen desorption/adsorption process. To fully realize hydrogen storage in SWCNTs it is essential to find means to hydrogenate SWCNTs using molecular hydrogen. A possible way to do this is to use the so-called spillover process. In this case, the H2 molecules dissociate at the surface of catalyst nanoparticles deposited on the nanotube surface and H radicals spill over from the catalyst to the surface of the nanotubes and form C-H bonds. It has been shown that the presence of platinum nanoparticles inside nanotube materials results in a 5-fold increase of the hydrogen uptake (Lee, Y.-W.; Clemens, B.M. Appl. Phys. J., submitted). Thus we can assume that by choosing non-bundled nanotubes with appropriate diameter distribution, optimizing the nanostructure of deposited catalyst and by choosing appropriate hydrogenation temperature to enhance H species diffusion along nanotube surface we can use the spillover process to form the H-SWCNT complexes without compromising the hydrogen weight capacity of the material. Our work ("Hydrogen Storage in Carbon Nanotubes through the Formation of Stable C-H Bonds") was supported by the Global Climate Energy Project and carried out at the Stanford Synchrotron Radiation Laboratory, national user facility supported by the U.S. Department of Energy, Office of Basic Energy Sciences. Source: nanowerk.com

Bullet proof t-shirts can me made from Carbon nanotubes :

Bullet proof t-shirts can me made from Carbon nanotubes :

(Nanowerk Spotlight) Carbon nanotubes (CNTs) have great potential applications in making ballistic-resistance materials. The remarkable properties of CNTs makes them an ideal candidate for reinforcing polymers and other materials, and could lead to applications such as bullet-proof vests as light as a T-shirt, shields, and explosion-proof blankets. For these applications, thinner, lighter, and flexible materials with superior dynamic mechanical properties are required. A new study by researchers in Australia explores the energy absorption capacity of a single-walled carbon nanotube under a ballistic impact. The result offers a useful guideline for using CNTs as a reinforcing phase of materials to make devices to prevent from ballistic penetration or high speed impact. Professor Liangchi Zhang from the School of Aerospace, Mechanical and Mechatronic Engineering at the University of Sydney explained the new research to Nanowerk: " Especially in making bullet-proof vests, shields, and explosion proof blankets, the best protective material will have a high level of elastic storage energy that will cause the projectile to bounce off or be deflected, i.e., the objective is to reduce the effects of 'blunt trauma' on the wearer after being struck by a bullet. We therefore tried to understand the impact behavior of CNTs." Zhang published his recent findings, titled "Energy absorption capacity of carbon nanotubes under ballistic impact", in the September 18, 2006 issue of Applied Physics Letters. Zhang's study analyzes the impact of a bullet on nanotubes of different radii in two extreme cases. For a nanotube with one end fixed, the maximum nanotube enduring bullet speed increases and the energy absorption efficiency decreases with the increase in relative heights at which the bullet strikes; these values are independent of the nanotube radii when the bullet hits at a particular relative height. For a nanotube with both ends fixed, the energy absorption efficiency reaches minimum when the bullet strikes around a relative height of 0.5. Bullet strikes the nanotube at a relative height of 0.31 (a) with both ends fixed and (b) with one end fixed.


(Reprinted with permission from the American Institute of Physics)


"Specifically, we investigated the relationship between the nanotube radius, the relative position at which the bullet strikes, the bullet speed, and the energy absorbed by the nanotube for a particular bullet size and shape" says Zhang. A piece of diamond having 1903 atoms was used as a bullet with its speed varying from 100 to 1500 m/s. The bullet dimension was selected such that the width is larger than the width of the biggest nanotube after flattening. The bullet was released from a target about 15 Â from the center axis of the nanotube and moved at a constant speed in the horizontal direction i.e., perpendicular to the nanotube axis, as shown in the graphic above. The nanotube performance was examined for bullet released with various speeds at various positions using the classical molecular dynamics method. In his experiments, Zhang found that, for a nanotube with one end fixed, the CNT could be resilient to projectile traveling at speeds of 200–1400 m/s (for comparison, the initial velocity of modern rifle bullets is somewhere between 180 and 1500 m/s, depending on gun and bullet type. For a typical over-the-counter gun the speed is below 1000 m/s); the nanotube enduring projectile speed increases whereas the absorption efficiency decreases with the increase in relative height ρ. For a nanotube with both ends fixed, the absorption energy reaches maximum whereas the absorption efficiency reaches minimum when the bullet strikes the nanotube in the middle. Zhang is excited by the great potential offered by CNTs in making ballistic-resistance materials and his research in this area is ongoing: "We'll continue to try to understand the impact behavior of CNTs under more complicated loading conditions."Source:Nanowerk.com

Nanotechnology In water treatment:

Nanotechnology In water treatment:

Nanotechnology and water treatment (Nanowerk Spotlight) Only 30% of all freshwater on the planet is not locked up in ice caps or glaciers (not for much longer, though). Of that, some 20% is in areas too remote for humans to access and of the remaining 80% about three-quarters comes at the wrong time and place - in monsoons and floods - and is not always captured for use by people. The remainder is less than 0.08 of 1% of the total water on the planet (Source: World Water Council). Expressed another way, if all the earth's freshwater were stored in a 5-liter container, available fresh water would not quite fill a teaspoon. The problem is that we don't manage this teaspoon very well. Currently, 600 million people face water scarcity. Depending on future rates of population growth, between 2.7 billion and 3.2 billion people may be living in either water-scarce or water-stressed conditions by 2025:

he terms 'stress' and 'scarcity' do not take into account physical access to water sources, or the quality of the water, or the irregularity of availability due to droughts and storms, or seasonal change. Instead, the terms give an indication of the close relation between population dynamics and renewable freshwater availability. (Source: Environment Canada, Freshwater Website 2004) We have written about this in a previous Spotlight (Water, nanotechnology's promises, and economic reality): Freshwater looks like it will become the oil of the 21st century - scarce, expensive and the reason for armed conflicts. While in our previous article we have only talked about nanotechnology and water in general terms, a new paper gives us the opportunity to look in more detail at the role that nanotechnology could play in resolving issues relating to water shortage and water quality. This review highlights the uses of nanotechnology in areas relevant to water purification, including separation and reactive media for water filtration, as well as nanomaterials and nanoparticles for use in water bioremediation and disinfection. "The potential impact areas for nanotechnology in water applications are divided into three categories, i.e., treatment and remediation, sensing and detection, and pollution prevention" Prof. Eugene Cloete tells Nanowerk. "Within the category of treatment and remediation, nanotechnology has the potential to contribute to long-term water quality, availability, and viability of water resources, such as through the use of advanced filtration materials that enable greater water reuse, recycling, and desalinization. Within the category of sensing and detection, of particular interest is the development of new and enhanced sensors to detect biological and chemical contaminants at very low concentration levels in the environment, including water." Cloete is Head of the Microbiology Department at the University of Pretoria in South Africa and Chairperson of the university's School of Biological Sciences. Together with Associate Professor Jacques Theron and J.A. Walker he published the review article, titled "Nanotechnology and Water Treatment: Applications and Emerging Opportunities", in the February 2008 issue of Critical Reviews in Microbiology.



Nanomaterials and water filtration Membrane processes are considered key components of advanced water purification and desalination technologies and nanomaterials such as carbon nanotubes, nanoparticles, and dendrimers are contributing to the development of more efficient and cost-effective water filtration processes. There are two types of nanotechnology membranes that could be effective: nanostructured filters, where either carbon nanotubes or nanocapillary arrays provide the basis for nanofiltration; and nanoreactive membranes, where functionalized nanoparticles aid the filtration process. The researchers also note that advances in macromolecular chemistry such as the synthesis of dendritic polymers have provided opportunities to refine, as well as to develop effective filtration processes for purification of water contaminated by different organic solutes and inorganic anions.

Nanotechnologies for water remediation Many areas, especially in developing countries, are seriously contaminated or damaged with consequent impoverishment of natural resources and serious effects on human health. Remediation of contaminated water – the process of removing, reducing or neutralizing water contaminants that threaten human health and/or ecosystem productivity and integrity – is a field of technology that has attracted much interest recently. In general, remediation technologies can be grouped into categories using thermal, physico-chemical or biological methods. The various techniques usually work well when applied to a specific type of water pollution, though no readily available treatments were discovered that could clean all types of pollutants. Due to the complex nature of many polluted waters, it is frequently necessary to apply several techniques to soil from a particular location to reduce the concentrations of pollutants to acceptable levels. Cloete and his co-authors write that most of the traditional technologies such as solvent extraction, activated carbon adsorption, and common chemical oxidation, whilst effective, very often are costly and time-consuming: "Biological degradation is environmentally friendly and cost-effective; but it is usually time-consuming. Thus, the ability to remove toxic contaminants from these environments to a safe level and doing so rapidly, efficiently, and within reasonable costs is important. Nanotechnology could play an important role in this regard. An active emerging area of research is the development of novel nanomaterials with increased affinity, capacity, and selectivity for heavy metals and other contaminants. The benefits from use of nanomaterials may derive from their enhanced reactivity, surface area and sequestration characteristics. A variety of nanomaterials are in various stages of research and development, each possessing unique functionalities that is potentially applicable to the remediation of industrial effluents, groundwater, surface water and drinking water." The report provides detailed examples of various nanoparticles and nanomaterials that could be used in water remediation: zeolites, carbon nanotubes, self-assembled monolayer on mesoporous supports (SAMMS), biopolymers, single-enzyme nanoparticles, zero-valent iron nanoparticles, bimetallic iron nanoparticles, and nanoscale semiconductor photocatalysts.

Bioactive nanoparticles for water disinfections There is a growing threat of water-borne infectious diseases, especially in the developing world. This threat is rapidly being exacerbated by demographic explosion, a global trend towards urbanization without adequate infrastructure to provide safe drinking water, increased water demand by agriculture that draws more and more of the potable water supply, and emerging pollutants and antibiotic-resistant pathogens that contaminate our water resources. No country is immune. Even in OECD countries, the number of outbreaks reported in the last decade demonstrates that transmission of pathogens by drinking water remains a significant problem. It is estimated that water-borne pathogens cause between 10 and 20 million deaths a year worldwide. According to Cloete, nanotechnology may present a reasonable alternative for development of new chlorine-free biocides. Among the most promising antimicrobial nanomaterials are metallic and metal-oxide nanoparticles, especially silver, and titanium dioxide catalysts for photocatalytic disinfections.

What about toxicity? As with any other nanotechnology application where there is a possibility that engineered nanoparticles could eventually appear in various environments, the potential human and ecological risk factors associated with this are largely unknown and subject to much debate. Cloete and co-authors discuss various toxicity studies of nanomaterials and also point out several recent studies of the toxicological impact of nanoparticles on different aquatic organisms. The bottomline seems to be that it might be advisable to come to some definite conclusions regarding nanoparticle ecotoxicology before we embark an large-scale use of engineered nanoparticles in water applications. Nevertheless, there is a growing body of research and development that will lead to nanomaterials playing a key role in future water and wastewater treatment. Source: www.nanowerk.com