But in all of these techniques there’s a big difference between nature and human engineering. The synthetic techniques may mimic nature but the result is a finished artefact: once assembled that’s all you’re going to get. But some of nature’s self-assembled nanostructures are in constant flux, adjusting to new conditions. The most striking is the intricate scaffolding of the cell, composed of two kinds of filaments: slim actin strands and thicker microtubules. These are always growing and shrinking in a constant churn of activity to maintain the shape and powers of the cell. It is as if the scaffolding round a house was always in parts going up whilst other parts were dismantling themselves. This process in the cell is fed by energy. So long as energy is being provided the dynamic structure of the cell is maintained. Ordinary materials assembly reaches equilibrium with the final product but the cell is always out of equilibrium, needing a constant influx of energy. For the cell, equilibrium = death.
Now, a research team based at at Delft and Munich have created a purely chemical system in which fibres form from a gel which lengthen and contract as the reaction goes on – so long as energy is supplied. This work takes us a great step forward in the quest to create self-maintaining cellular systems based entirely on synthetic ingredients and systems. The metabolism of living cells is not the only possible self-maintaining cell. The artificial cell fibre systems have the ability to regenerate after perturbation: a key characteristic of living cells. As the authors state: the fibres show “dynamics reminiscent of microtubule behaviour”.
Science, 4 September, 2015, pp. 1075-79
Peter Forbes and Tom Grimsey, Nanoscience: Giants of the Infinitesimal, Papadakis, 2014.