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« C-R-Newsletter #24 | Main | Mechanical Engineering and Nanotechnology »

November 06, 2004


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Michael Vassar

I generally understand the distinction that you make between complex and complicated, but I suspect that most readers do not. Even if they do, it would definitely be informative to have a good formal definition of the distinction. I don't think that you just mean chaotic by complex, but I'm not sure.

Richard Jones

A nice article, Chris. A couple of points: it's worth mentioning that the combination of self-assembly and post-processing, for example via precursor routes or templating, can go some way towards mitigating the stiffness and strength limitations of the products of self-assembly. This is how tendons and mollusc shells get to be so tough. The second point arises from a very striking contrast between the way self-assembly is used by nature and by biomimetic nanotechnologists like Ned Seeman, and the way it is currently used in industry. On the one hand, a 100- unit protein, each unit one of 20 possible amino acids, say, codes an absolutely prodigious amount of information, and is correspondingly difficult to mass produce. On the other hand, the state of the art in the bulk chemical industry is a triblock copolymer like Kraton or Pluronics, a sequence of three sub-units chosen from two possibilities, with rather a small information content. There has to be a middle way; a mass manufacturable sequenced copolymer with significantly more complexity than the current copolymers but still much cruder than a protein or nucleic acid. The new controlled free radical polymerisations, and the controlled routes to polymers of natural and synthetic amino acids, that Tim Deming has pioneered must point the way.

Chris Phoenix, CRN

By wet-chemical-synthetic standards, 20^100 or 10^130 is an absolutely prodigious amount of information. But to a computer scientist, that's only 144 bytes of information. This paragraph contains more.

(Of course, the protein, like text, will be somewhat redundant; most of that design space will never be used.)

A 100-unit protein is not difficult to produce, even with high accuracy, if you have well-designed (or well-evolved) programmable nanoscale machinery working at its own level. And if you can build the machinery using the machinery, then you can mass produce the protein (or other polymer).

A highly engineered copolymer would surely be useful for some things. But I don't think it would incorporate enough programmability to build a nanocomputer. Or an engineerable chemical binding/sensing array. Or a rotational actuator. In short, I think it would be good for materials but not machines.

Thanks for the mention of Deming. Do you think his biomineralization work (item 4) might be used to build structures under programmed control?


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