Those concerned about existential risks may be interested to learn that, as of last September, the National Science Foundation is funding a Center for Sustainable Nanotechnology.  Though I haven't yet seen anywhere where they explicitly characterize nanotechnology as an existential threat to humanity (they seem mostly to be concerned with the potential hazards of nanoparticle pollution, rather than any kind of grey goo scenario), I was still pleased to discover that this group exists. 

Here is how they describe themselves on their main page:

The Center for Sustainable Nanotechnology is a multi-institutional partnership devoted to investigating the fundamental molecular mechanisms by which nanoparticles interact with biological systems.

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While nanoparticles have a great potential to improve our society, relatively little is yet known about how nanoparticles interact with organisms, and how the unintentional release of nanoparticles from consumer or industrial products might impact the environment.

The goal of the Center for Sustainable Nanotechnology is to develop and utilize a molecular-level understanding of nanomaterial-biological interactions to enable development of sustainable, societally beneficial nanotechnologies. In effect, we aim to understand the molecular-level chemical and physical principles that govern how nanoparticles interact with living systems, in order to provide the scientific foundations that are needed to ensure that continued developments in nanotechnology can take place with the minimal environmental footprint and maximum benefit to society.

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Funding for the CSN comes from the National Science Foundation Division of Chemistry through the Centers for Chemical Innovation Program.

And on their public outreach website:

Our “center” is actually a group of people who care about our environment and are doing collaborative research to help ensure that our planet will be habitable hundreds of years from now – in other words, that the things we do every day as humans will be sustainable in the long run.

Now you’re probably wondering what that has to do with nanotechnology, right? Well, it turns out that nanoparticles – chunks of materials around 10,000 times smaller than the width of a human hair – may provide new and important solutions to many of the world’s problems. For example, new kinds of nanoparticle-based solar cells are being made that could, in the future, be painted onto the sides of buildings.

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What’s the (potential) problem? Well, these tiny little chunks of materials are so small that they can move around and do things in ways that we don’t fully understand. For example, really tiny particles could potentially be absorbed through skin. In the environment, nanoparticles might be able to be absorbed into insects or fish that are at the bottom of the food chain for larger animals, including us.

Before nanoparticles get incorporated into consumer products on a large scale, it’s our responsibility to figure out what the downsides could be if nanoparticles were accidentally released into the environment. However, this is a huge challenge because nanoparticles can be made out of different stuff and come in many different sizes, shapes, and even internal structures.

Because there are so many different types of nanoparticles that could be used in the future, it’s not practical to do a lot of testing of each kind. Instead, the people within our center are working to understand what the “rules of behavior” are for nanoparticles in general. If we understand the rules, then we should be able to predict what different types of nanoparticles might do, and we should be able to use this information to design and make new, safer nanoparticles.

In the end, it’s all about people working together, using science to create a better, safer, more sustainable world. We hope you will join us!