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Capitalizing on Nanotechnology's Enormous Promise
suzzane.jpg (6486 bytes) Suzanne Shelley
Guest Columnist and Freelance Writer
Suzanne Shelley is a Manhattan-based freelance writer specializing in science, engineering and technology (Email: suzanneashelley”at”yahoo.com). A 16-year veteran and former Managing Editor of Chemical Engineering magazine, Suzanne now writes about a broad array of engineering and business topics related to the chemical, petroleum refining, pharmaceutical and related industries, for both corporate clients and technical trade magazines. She currently serves as Contributing Editor to several magazines, including Chemical Engineering, Chemical Engineering Progress, Turbomachinery International, and Pharmaceutical Commerce. Suzanne holds a B.S. in geology (honors) from Colgate University, and an M.S. in geology from the University of South Carolina (Columbia).

Medical advances

Some of nanotechnology’s most exciting and futuristic prospects are being pursued in the medical arena, where the ingenious application of nanotechnology-based concepts, materials and systems has the potential to revolutionize both therapeutic and diagnostic medicine. For instance, today nanoscaled materials and structures are being developed that can deliver potent, yet often toxic chemotherapy drugs more effectively, and with fewer side effects, within the human body, and can deliver contrast-imaging agents more precisely to improve the 

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Because the electronic and optical properties of quantum dots (particles of inorganic, semi-conductive materials with nanometer-scale dimensions) change with changing diameter, they can be made to absorb and emit light of different wavelength (and thus, they can be color-coded). Researchers are exploiting these characteristics in both medical diagnostic, and light-emitting diode (LED) applications

Source: Philips

efficiency of diagnostic testing.

While more-detailed discussion of the promising medical advances that are mentioned below is beyond the scope of this report (which aims to focus on industrial applications of

nanotechnology), further details (including many of the companies, universities and research institutes that are involved) can be found in another recent article written by this author (See “Suggested Reading” Reference [5] at the end of this article).

Advanced diagnostic techniques. The prevailing wisdom in cancer care is that when they are detected early, many cancers are treatable, and early intervention leads to better outcomes. As a result, devising more-effective strategies to detect cancer —before advanced-stage tumors have formed — is also an ongoing area of interest for nano-related medical researchers. Today, researchers are pursuing the use of fluorescent semiconductor nanocrystals (known as quantum dots), which are typically made from  cadmium selenide, cadmium sulfide or cadmium telluride, and have an inert polymer coating that both safeguards human cells from potential cadmium toxicity, and allows drug developers to attach a variety of molecules that facilitate preferential uptake by targeted cells. By changing their diameter, quantum dots can be made to absorb and emit light of different wavelengths, and thus they can be used to color-code and track different cell processes, different cancers or different stages of the same cancer.

Similarly, several company and university researchers are using magnetic nanoparticles that are labeled with a particular antibody (i.e., one that binds tightly to breast cancer cells) to improve the efficiency of magnetic resonance imaging (MRI).

 

Targeting tumors. Today, an imaginative array of nanoscaled particles and dendrimers are being investigated to reduce the dose-limiting effects of potent, often toxic cancer-killing drugs. These include biocompatible and biodegradable polymeric nanoparticles, branch-shaped dendrimers, and silica-gold nanoshells and other nanoscaled carriers, which can target a tiny payload of anti-cancer drugs and imaging agents more effectively in the human body allowing these potent drugs to accumulate preferentially within tumors and other cancerous cells, while minimizing collateral damage to healthy surrounding tissue. The ability to target these therapeutic yet toxic compounds more precisely can reduce the devastating side effects that are so often associated with so many chemotherapy and radiation-based treatments.

When it comes to nanoscaled drug-delivery applications, encapsulating the cancer drug or imaging agent represents only half the battle. Formidable engineering challenges are also associated with getting the tiny particles to accumulate preferentially within target cells, and to release their payload on demand.

Today, to improve nanoparticle uptake by target cells, researchers are working to attach a variety of targeting ligands, such as peptides, proteins or antibodies, to nanoparticle surfaces.  Meanwhile, to get these pint-sized Trojan horses — once they have been able to smuggle their payload into target cancer cells — to release their payload on demand, either suddenly or in a sustained, time-release fashion, some researchers are focusing on the use of pH-sensitive nanoparticles that dissolve when they encounter the acidic pH found inside cancer cells. Others are using polymer-based nanoparticles whose gold linings can be made to rupture (releasing the drug contents) when bombarded with a single, nanoscecond pulse of laser light.

Still other nanotechnology-related researchers are focusing on destroying malignant cells using not drugs, but heat. While the specific approaches vary, they all rely on a unifying concept — first, some type of magnetic nanoparticle is introduced to cancer cells or tumors, and then, an exogenous energy source (such as laser light or an oscillating magnetic field) is applied to generate cell-killing heat that destroys the diseased cells. Various researchers are evaluating the use of carbon nanotubes, magnetic iron oxide nanoparticles, gold nanoshells and gold nanocages to function as such “thermal scalpels.”

Nanotechnology-related research and development efforts are also leading the way to the development of improved artificial tissues and organs, and hip- and knee-replacement materials, which are not only more robust, but are also less susceptible to rejection by the body.

Nanotechnology critics urge caution

At a time when most industrialized nations are investing heavily in nanotechnology-related research and development, and potential applications spanning countless industries are being pursued, cautious observers say that the potential environmental, health and safety (EHS) risks — to those who develop and manufacture nanoscaled materials, those who use products that contain them, and anyone else who may otherwise be exposed to nanomaterials — are not being studied adequately or systematically enough.

For instance, many skeptics are worried that because many of the materials that are being handled as nanoparticles —metals and metal oxides, polymers, ceramics and carbon derivatives — are not biodegradable, these tiny particles can invade all types of cells within the human body. They claim that rigorous ongoing investigation is needed to determine what the behavior of such nanoparticles will be in various ecosystems, in terms of absorption, biotic uptake, and accumulation in plants and animals.

In addition, a growing chorus of critics within the scientific community, and the populace at large, are calling for more systematic funding to ascertain the potential toxicity of exposure to ultrafine, nanoscaled materials in humans (via skin absorption, ingestion and inhalation, among other mechanisms), and to determine any potential for organ or tissue damage, inflammation, a triggering of auto-immune diseases, and other health-related consequences. Critics also claim that better models, analytical tools and methods to study complex, nanoscaled systems are needed in order to anticipate and avoid potentially harmful consequences.

For instance, in April 2006, the non-profit think tank Rand Corp.(rand.org) issued a 34-page report, based on an October 2005 workshop it had conducted, involving strategic representatives from industry, occupational health and safety organization, insurance firms, and labor unions. Rand’s report states that the U.S. government is providing insufficient funding and other resources to adequately understand and manage the potential risks that nanomaterials pose to the health of workers in the rapidly growing nanotechnology industry. The report claims that the federal government has already directed more than $1 billion annually toward the development of nanotechnology, but of this, only $10 million (1% of the total) is being spent on research that is relevant to understanding and managing the risks of occupational exposure to nanomaterials.

Similarly, in July 2006, the Woodrow Wilson International Center for Scholars (Washington, D.C.; wilsoncenter.org) issued a report that cites a critical lack of strategic focus, priority and funding on behalf of the U.S. government’s efforts to adequately address the unanswered EHS questions associated with nanotechnology-related activities. The 43-page report recommends that the U.S. — through the Environmental Protection Agency (Washington, D.C., epa.gov), the National Institute for Occupational Health and Safety (Washington, D.C.; niosh.gov), and other government agencies — should establish a minimum budget of $50 million/year over the next two years, to develop highly relevant, targeted risk-based research to systematically identify nanotechnology’s possible risks and determine adequate measures for managing them. The Wilson Center report also proposes a comprehensive framework for how the research should be prioritized and implemented. Some of the most pressing research priorities identified by the Wilson Center report are shown in Table 1:

nanotech_table1.gif (139155 bytes)

Shown here are the most pressing research needs identified by the Wilson Center report are shown here

Source: Reprinted with permission from The Woodrow Wilson International Center for Scholars

In the spring of 2006, The Max Bergmann Center for Biomaterials (Dresden, Germany; mbc-dresden.de), with participation from various companies and research institutes, and funding from the German government (one million Euros) has embarked on a three-year research project to assess the effect of engineered nanoparticles on human health and the environment. The group plans to make its data available to the public, and hopes to ultimately establish a certified laboratory that can provide risk assessment studies on engineered nanoparticles, especially for small to medium companies involved in their manufacture and use.

While many in the scientific community are drawing attention to the unanswered questions associated with nanotechnology’s potential EHS and calling for further study and public policy actions to manage the risk, some of nanotechnology’s more ardent opponents see nanoscientists as recklessly dabbling with dangerous forces they cannot control. These opponents argue that there has been woefully little meaningful study and public debate related to the societal, legal and ethical implications associated with this powerful new technology.

Because the absence of definitive data can trigger a host of fears and alarmist scenarios, some nanotechnology opponents point out that the invisible nature of nanoscaled materials, devices and systems could lead to a significant invasion of privacy, while sophisticated nanoscaled devices could be used as artificial disease-inducing agents, with terrifying consequences. They also point out that any intentional abuse of this powerful technology — should terrorists, criminals, dictators and irresponsible users ever be able to co-opt or misappropriate nanotechnology’s unprecedented technological capabilities and use them for evil purposes — could have menacing or diabolical consequences.

Critical also claim that rapid advances in nanoscaled manufacturing techniques also make it more possible to produce horrifically compact, powerful chemical and biological weapons and highly effective, concealed delivery systems. Others envision terrifying devices, such as remote assassination weapons, that would be difficult to detect or avoid.

To balance the interests of today’s most ardent nanotechnology supporters and those who feel this new technological paradigm should be reigned in, vigorous balanced public discussions and debate should continue, involving the science, engineering and medical communities, lawmakers, stakeholder groups and others who can influence public opinion, to showcase the potential benefits and manage the potential risks associated with this new technology. Through educational campaigns designed to promote better scientific literacy, the public should also be given the information they need to help them differentiate science from science fiction.

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References

1.       Wilson, M., Kannangara, K., Smith, G., Simmons, M., and Raguse, B., “Nanotechnology Basic Science and Emerging Technologies,” Chapman & Hall/CRC, Boca Raton, Fla., 2002, reprinted 2004.

2.       Fink, U., Davenport, R.E., Bell, S.L., and Ishikawa, Y., Nanoscale Chemicals and Materials – An Overview on Technology, Products and Applications, Specialty Chemicals Update Program, SRI Consulting, Menlo Park, CA, December 2002.

Suggested reading

The author has published several other nanotechnology-related works:

Shelley, S.A., and Ondrey, G., Nanotechnology – The Sky’s the Limit, Chemical Engineering, December 2002, pp. 23-27, continued on p. 72.

Shelley, S.A., Carbon Nanotubes: A Small-Scale Wonder, Chemical Engineering, January 2003, pp. 27-29.

Shelley, S.A., Nanotechnology: Turning Basic Science into Reality, appears as Chapter 2 in “Nanotechnology: Environmental Implications and Solutions,” Theodore, L, and Kunz, Z., John Wiley and Sons, 2005.

Shelley, S.A., Nanotechnology — Don’t Let Science Fiction Trump Science, Chemical Engineering, February 2005, p. 7.

Shelley, S.A., Nanobiotechnology – Cancer’s Newest Deadly Foe, appears in Special Supplement: The Promise of Nanobiotechnology, Chemical Engineering Progress, February 2006, pp. 43-47.

Shelley, S.A., Trend Report: Nanotechnology Continues to Broaden its Reach, prepared for the Achema 2006, Dechema e.V., Frankfurt, Germany; achema.de/trendreports.html


By: Suzanne Shelley, Guest Columnist and Freelance Writer

 

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