Nanobots are a pet peeve of mine ... Mostly because, despite the claims of feverish- and well-sponsored research, it's so hard to meet anybody working on them even theoretically. I work as a postdoctoral research fellow in theoretical solid state physics - that'd be the physics part of what is popularly called 'nanotech'. Let's just say I cannot confirm that researching nanobots is a 'hot topic'
If it were, it would show up in the condensed-matter section of the archive-server arXiv.org, where nearly all physicist upload the pre-print versions of their papers (mostly in order to document their claim to a specific result in a timely manner).
-> Google-search for
"condmat, nanobots" gives 518 hits (and many aren't even on condmat). Google-search for
"condmat, topological insulators" (one of the currently hot topics in solid state physics) gives
62.800 ...