Sticking Point: Nanotechnology, Lizard Feet, and Taping Grown Men to the Ceiling

Cal Baier-Anderson, Ph.D., is a Health Scientist.

We often think of nanotechnology as the latest product of ultra-modern science, but humans did not invent the nanoscale. We were not even the first to use materials with nanoscale features: The gecko beat us to it by several million years. Even more impressive, this little reptile has managed to use nanoscale materials apparently without experiencing any ill effects. It remains to be seen if we will be able to do this.

Intriguing nanoscale features can be found in nature, including the “hairs” on the foot pads of the gecko, which have provided inspiration for the development of artificial adhesives, shown below in a figure from a paper recently published in the Proceedings of the National Academy of Sciences:

The photo collage illustrates how the researchers have tried to model the assembly of nanoscale features found on the gecko’s foot to engineer materials that have strong adhesive properties. The first two photos show the nanoscale features of the gecko’s foot, which consists of micrometer-sized “setae” (photo A) that are actually bundles of 100 – 200 nanometer “spatulas” (photo B). Photos C – H illustrate the researchers’ efforts to mimic these structures, by planting multi-walled carbon nanotubes (MWCNTs) on a thin, flexible surface to create a “gecko tape.” The researchers report that a 1-cm2 area of gecko tape can support nearly 4 kilograms of weight! This means that a 180-pound (82-kilogram) man could be suspended by a piece of tape no larger than the cross-section of a 2 x 4.

While I am amazed and intrigued by this novel nanoscale material, as a toxicologist, my job is to also think about the potential downsides of new technology. In a recent post, my colleague John Balbus discussed some of the serious concerns emerging about possible health effects of certain MWCNTs.

So what measures are prudent to consider before we start making and using gecko tape all over the place? Certainly, we hope that workers in the laboratory making the stuff are already taking appropriate steps to prevent incidental inhalation or ingestion. But should we be concerned about tape capable of suspending grown men from falling, for example, into the hands of college fraternities?

I also wonder whether the MWCNTs will slough off of the tape during use. If they do and are inhaled, what kind of hazard might they pose to consumers? And then there is the question of how such tape is to be disposed of ….

So while I can get as excited about these new, cool technologies as the next person, I think all of us – researchers, manufacturers, regulators and consumers – need to take the broader view and think this through before we find ourselves in a sticky situation.