Yesterday's 'Impossible' Nanobots are Taking Flight Today
Here's an edited version of what he had to say about the "nanobot" issue. As you can see, he is reluctant to give in totally to the sci-fi vision, yet recognizes the power the metaphor holds on the public:
As far as nanorobots go --- cells are microrobots, with amazing nanomachines in them like the ribosome, which translates DNA genes via RNA messages into protein. Designing such systems (either ribosomes or much more complicated whole cells) is impossible for us now. But over the next century we will learn how to design such systems de novo. My guess is that DNA nanotechnology will play a large role in this. This is the broad vision, and I think fixating on nanobots, per se, is too narrow/sort of a red herring.
The work of Douglas et al, which they term "logic-gated nanorobots" takes us one more step along the path from the smartest drugs of today to the kind of medical nanobots we might imagine. Their DNA origami structures, which might be best likened to "programmable
clam-shells." Inside the clamshells is a "payload." For example in the current paper the payload was a set of antibodies that could act on the target cell. Along the edge of the clamshell were DNA aptamer "locks," which were programmed to open only upon binding antigens presented by specific cell types. Thus the researchers could create clam-shells that would bind -only- NKL aggressive leukemia cells (and not other cells) and deliver a payload which inhibited NKL growth.
Whether the structures in Douglas et al should be thought of as nanorobots is a matter of taste. Often one thinks of robots as capable of more than one different kind of motion, or as capable of repetitive motion. The "clamshells" of the current work are capable of neither of these, and they might be better thought of as "backward mousetrap" which gives up its cheese when triggered. (This seems like a crappy metaphor.)
Nevertheless the incorporation of logic into the trigger does make the structures seem more robot-like (because robots exhibit programmable motion) and the current work suggests that while we may never have medical robots which function as they do in science fiction our drugs can be much smarter than we might have imagined.
Rothemund also told me that he is grateful that the government is supporting his "field of dreams" research "based on promise alone," although the amount is "tiny" compared to "the largely unsuccessful 'war on cancer' and even tinier compared to the money spent on foreign misadventures in the 'war on terror.'"
His words are worth pondering as we discuss what the government should and should not be spending our money on. DNA origami? Yeah, I'll buy that. For a comparatively tiny investment, DNA origami research could unfold into some wonderful breakthroughs and cures for my great-great-grandkids, who may or may not be reading this.
If they are, let me state for the record that I believe heavier-than-air flying machines are possible.
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