Natural strategies for the molecular engineer
The idea of nature as engineer is an old one, but the realization that this metaphor can be extended (should we say retracted?) to the molecular scale has become common currency only over the past two decades or so. Two reasons for this are perhaps paramount. First, the picture of the cell has been transformed from that of a 'wet chemical' melange—'a vessel, filled with a homogeneous solution, in which all chemical processes take place', as Franz Hofmeister put it in 1901—into an image of a sort of fluid factory, a production plant in which molecular machinery works in near-fantastic orchestration to generate complex products from raw materials. This mechanism is self-assembling, self-repairing and self-replicating. The concept of proteins and nucleic acids as 'molecular machines' is now a mainstream one in cell biology. Second, technological advances have made us accustomed to the idea that engineering can be conducted at scales too small to see with the naked eye, yet employing principles—mechanical, electrical, hydraulic, optical, tribological—familiar from the macroscopic world. Molecular electronics and computing, microelectromechanical devices and nanotechnology, are now mainstream concepts, and are validated by at least some degree of physical realization. In this article I shall briefly review some of nature's principles and practices at the molecular, supramolecular and submicrometre scales, and attempt to illustrate how these can be adapted for developing synthetic chemical and materials systems sharing the kind of superior properties and special functions that natural systems exhibit.