Hydrophobic Gating in Membrane Nanopores: Water at the Nanoscale

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The properties of water play a key role in biology, underlying all aspects of cellular structure and function. All cells are surrounded by lipidic membranes, in which there exist pore-like proteins which allow communication and exchange between the inside and outside of cells. Such nanoscale pores ('nanopores') are of great importance both in cell biophysics and as potential components of novel biosensors. Nanopores are filled with water. However, water behaves differently on the nanoscale, inside pores whose diameter is 10 millionths of diameter that of a human hair. In particular, nanopores can undergo spontaneous de-wetting if their lining is sufficiently hydrophobic (i.e. 'oily'). This provides a possible way in which to control the activity of nanopores if we can control their wetting/de-wetting.We consequently need to understand and be able to model the physicochemical basis of wetting and de-wetting at a level of accuracy good enough for predictions to aid design of novel nanopores. This can be achieved by computer simulations - combining advanced algorithms and the power of modern supercomputers.In this way, we will determine the behaviour of water in nanopores, understanding how they can be functionally 'opened and closed' by wetting and de-wetting, and how the imposition of a voltage difference across a nanopore-containing membrane can cause the nanopores to electrowet, thereby switching them from an inactive (closed) to an active (open) state.This fundamental research will allow us to design controllable opening/closing of new nanopores for use in biosensors and other healthcare related applications.