NNI confused by SciFi: Howard Lovy's blog Nanobot brings to our attention this item under "Nanotech Facts" on the NNI website (your tax dollars at play): What are nanobots? And are they fantasy or reality? (near bottom of page).
Such creatures do not exist and many scientists believe they never will, saying nanoscale materials are simply too small to manipulate for such purposes – and if someone wanted to create something destructive, there are many easier ways to do so.
That said, technologies, starting with fire, are abused at times. For this reason, laboratories are closely monitored and research is peer-reviewed. Research funding is withheld from less-than-worthy projects and from those with questionable credentials or reputation.
One safeguard against potential abuses is training scientists to consider the ethical implications of the research they perform. Government regulations are always possible should there appear need. Today-and as far as scientists can see-anything resembling nanobots remains in the realm of science fiction.