Here on Nanodot we mentioned earlier a nanotechnology survey article titled Synthetic Molecular Motors and Mechanical Machines by Euan Kay, David Leigh, and Francesco Zerbetto. I have a paper copy now and have to admit that it is indeed worth $25, but that the 24-hour online access offered by the publisher at that price would not be nearly enough. This tome could be a book. Presumably an online purchase enables downloading for later viewing.

I have not read the whole thing, and probably never will — this is for serious researchers. However, I was glad to see the conclusion address and, in my view, resolve the ongoing fuss of whether molecular machine systems should be built using the “hard matter” approach inspired by physics and engineering or the “soft matter” approach inspired by biology. This was always an unnecessary dispute, as the paper makes clear:

As outlined in this Review, both sets of design philosophies have already had many notable successes and they are not mutually exclusive. No doubt their combination will become increasingly important in the future.

The article also disposes of the complexity argument against artificial molecular machine systems:

In this regard, we do not subscribe to the view that it will be impossible for synthetic chemists to develop molecular-level machine systems that use controlled motion to perform functions similar to those of biological machines simply because of the complexity of the latter (just as the tremendous successes in homogeneous and heterogeneous catalysis have been achieved without the need for the de novo design of enzymes).

Quite so. For Nanodot readers unable to afford $25 for one article, no matter how lengthy, author David Leigh has offered to send an electronic version. See the comment by Dave L. —Christine