Nanotechnology in context – Size matter

In July 2007, a specially convened task force of the United States Food and Drug Administration (FDA) concluded that size does in fact matter (FDA 2007).  The focus of the task force was not on the importance of “largeness”, but rather on the technology of the unimaginably small—nanotechnology.

Nanotechnology is the technology of manipulating matter at near-atomic levels; typically, but not exclusively, within the size range of 1 – 100 nanometers.  Working at this scale, it becomes possible to combine materials in ways and forms unimaginable more than a few decades ago.  Imagine the contrast between eighteenth century surgery and modern microsurgery, and you begin to get an idea of what this emerging technology offers.

According to the FDA task force, “properties of a material relevant to the safety and (as applicable) effectiveness of FDA-regulated products might change repeatedly as size enters into or varies within the nanoscale range”. But as Professor James Moor and Professor John Wecker point out in the Spring 2007 edition of Medical Ethics [PDF, 805 KB], nanotechnology not only raises safety and regulatory issues, but ethical questions as well (Moor and Wecker 2007).

At the heart of the buzz surrounding nanotechnology is its potential to extend what can be achieved with conventional technologies, and the tantalizing possibility of developing radical new technologies.  Nanotechnology is not so much a specific technology as a new way of doing things, or a new technological tool kit.  In the words of Moor and Wecker, “[n]anotechnology offers us the general capability of material malleability”.

The idea of engineering at the nanoscale conjures up images of everyday mechanical objects shrunk to the scale of molecules; nano-gears, nano-engines, even nano-machines—conventional engineering, but at a miniscule scale.  Such nano-engineering would enable us to build complex devices from handfuls of atoms, increasing the performance and utility of human-scale products.  It would also help use limited resources expediently—making products molecule by molecule, with minimal waste.  In other words, this is a vision of nanotechnology that would emulate the biological world and lead to a synthetic biology; augmenting existing natural nano-machines and “molecular assemblers” that have evolved over billions of years, with an inorganic counterpart over which we have full control.

Eric Drexler envisaged such a world in his book Engines of Creation: The Coming Era of Nanotechnology (Drexler 1986).  Yet, while some of these concepts may one day become a reality, the nanotechnology of today looks very different.  Returning to the idea of engineering at the nanoscale, the chemist and Nobel Laureate Richard Smalley is credited with describing nanotechnology as “the art and science of building stuff that does stuff at the nanometer scale”.  Scientists and technologists alike are drawn to nanotechnology because of the unconventional behavior exhibited by many nanoscale materials, and their ability to “do stuff” in ways conventional materials do not.  As atoms and molecules are formed into nanoscale structures, intrinsic material properties like conductivity, transparency and chemical reactivity diverge from those observed in the constituent molecules or the bulk material.

But engineered nanomaterials can also demonstrate unconventional behavior that is associated with extrinsic attributes like size and shape. For instance, engineering a material as discrete nanometer-diameter particles might make it easier to incorporate into products, deliver to specific areas of use, or substantially increase the surface area to mass ratio.  In these cases, the intrinsic physical and chemical properties of the engineered nanomaterial are not necessarily scale-specific, but the ways in which the material is used are.

The scale-specific behavior of engineered nanomaterials takes on a special significance in interactions with biological systems and processes. Biology is inherently nanoscale, and purposely-engineered nanoscale materials allow the possibility of modulating biological processes at a fundamental level. Nano-bio interactions may result from scale-specific physical and chemical properties intrinsic to some nanoscale materials.  But they may just as likely result from nanoscale materials having access to biological processes that are inaccessible to larger scale materials.

In this way, nanotechnology provides a high-precision tool kit for exploring and influencing living systems.  The biological utility of nanotechnology is demonstrated effectively through its use in potential cancer treatments. Researchers at Rice University for example are combining the scale-dependent photonic properties of nanometer-thick gold shells, with the size-dependent biological properties of nanoscale particles, to create composite particles capable of preferentially treating tumors.  Gold-coated nanometer-diameter silica particles are introduced into the bloodstream, from where they preferentially pass through the leaky vasculature around tumors.  Once sufficient material has accumulated around the diseased cells, irradiating the particles with a laser tuned to the gold nanoshells causes localized heating, destroying the growth while leaving healthy tissue unharmed (O’Neal, Hirsch et al. 2004).

Going a step further, researchers at the University of Michigan are developing multifunctional nanoparticles for treating specific cancers.  Starting with generic nanoparticles, various functional components are added: ligands that attach to specific biological targets; contrast agents to allow particles to be tracked round the body; and sensitizing agents, enabling particles to receive and respond to external signals.  With these components, nanoparticles are being developed that selectively target and destroy cancer cells, while minimally impacting the rest of the body (Koo, Fan et al. 2007).

From relatively simple nanotechnology applications to the possibilities of synthetic life, nanotechnology provides us with tools for developing radical new processes and products.  And with these tools come the social and ethical responsibilities to use them wisely.  Concerns have already been expressed over potential new risks to humans and the environment that nanoscale-specific material behavior present. Little is known about how nanomaterials released into the environment will be transported, transformed and accumulated, or their impact on sensitive ecosystems (Oberdörster, Oberdörster et al. 2005).  Animal studies have demonstrated that nanoscale particles can enter and be transported within bodies in ways that larger particles cannot, and research suggests some nanomaterials are more potent in organs such as the lungs than their larger scale counterparts (Oberdörster, Stone et al. 2007). There are also early indications that nanoscale materials might interfere with protein conformation, and even lead to enhanced fibrillation rates in proteins associated with amyloid diseases such as Parkinsons and Alzheimers (Linse, Cabaleiro-Lago et al. 2007).

Studies remain inconclusive as to what might make nanomaterials harmful and what can be done to avoid harm.  Recommendations have been made for better-focused and funded strategic research (e.g. Maynard, Aitken et al. 2006).  But the responsible use of nanotechnologies will depend on more than good risk management.  In their article, Moor and Wecker suggest that nanotechnology has the potential to raise one of the ultimate ethical and medical issues: therapy versus enhancement.  At what point do we cross the line between restorative biocompatible materials and implanted sensors (for instance), and the enhancements such technologies will offer to healthy individuals?

Already, there is serious discussion on how nanotechnologies might extend a person’s lifespan, or even be used to enhance an individual’s intelligence (Roco and Bainbridge 2003). But the ethical issues raised by nanotechnology go further:  Who will receive the benefits of these new technologies, and who will pay the price?  Will nanotechnologies widen social, economic and cultural divides, or close them?   What are the implications of research into emulating biological systems?  And what are the consequences of not grasping the opportunities being offered by nanotechnology?

Many of these issues are not unique to nanotechnology, but as Moor and Wecker intimate, the possibilities that nanotechnologies offer to do things differently throw them into sharp relief.  Nanotechnology has the potential to improve living standards around the world, and offers solutions to some of the most pressing challenges we face: renewable energy, plentiful supplies of clean water, effective treatments for cancer, to name just three.  If our aim is to improve quality of life and do good, it would be irresponsible and even unethical to deny the world what nanotechnology has to offer.  Yet this potential for good must be weighed against the very real possibilities of causing harm, widening equity imbalances and reducing autonomy.  A future without nanotechnology would be a poorer, harsher place.  But a world where nanotechnology is not developed within a clear ethical and social framework could be immeasurably worse.  Either way, we have a challenge on our hands to move forward responsibly.  When it comes to navigating through the implications of emerging technologies on our lives, size, it would seem, really does matter.

Drexler, E. (1986). Engines of creation: The coming era of nanotechnology. New York, Anchor Books.
FDA (2007). Nanotechnology.  A report of the U.S. Food and Drug Administration Nanotechnology Task Force. Washington DC, Food and Drug Administration.
Koo, Y. E. L., W. Fan, et al. (2007). “Photonic explorers based on multifunctional nanoplatforms for biosensing and photodynamic therapy.” Applied Optics 46(10): 1924-1930.
Linse, S., C. Cabaleiro-Lago, et al. (2007). “Nucleation of protein fibrillation by nanoparticles.” Proc. Natl. Acad. Sci. U. S. A. doi:10.1073/pnas.0701250104.
Maynard, A. D., R. J. Aitken, et al. (2006). “Safe handling of nanotechnology.” Nature 444(16): 267-269.
Moor, J. H. and J. Wecker (2007). “Nanotechnology and nanoethics.” Medical Ethics 14(2): 1-2.
O’Neal, D. P., L. R. Hirsch, et al. (2004). “Photo-thermal tumor ablation in mice using near infrared-absorbing nanoparticles.” Cancer Letters 209(2): 171-176.
Oberdörster, G., E. Oberdörster, et al. (2005). “Nanotoxicology: An emerging discipline evolving from studies of ultrafine particles.” Environ. Health Perspect. 13 (117): 823-840.
Oberdörster, G., V. Stone, et al. (2007). “Toxicology of nanoparticles: A historical perspective.” Nanotoxicology 1(1): 2 – 25.
Roco, M. C. and W. S. Bainbridge, Eds. (2003). Converging technologies for improving human performance.  Nanotechnol;ogy, biotechnology, information technology and cognitive science. Norwell MA, USA, Kluwer Academic Publishers.
___________________________________

First published in the Lahey Clinic Medical Ethics Journal, Fall 2007 [PDF, 215 KB]

Advertisements

Comments are closed.

%d bloggers like this: