8th Liquid Matter Conference September 6-10, 2011 Wien, Austria ...

P2.46Tue 611:23-14:00The hydrophobic interaction at high hydrostatic pressureDiarmuid Lloyd, 1 Rosalind Allen, 1 and Paul Clegg 11 The University of Edinburgh, SUPA, School of Physics and Astronomy, University ofEdinburgh, Mayfield Road EH9 3JZ, Edinburgh, United KingdomThe hydrophobic interaction is the primary driving force in many biological and other soft-matterself assembly systems. Manifestations include micelle formation, protein stabilisation and strongadhesion between macroscopic hydrophobic surfaces. However, despite many years of research,aspects of this peculiar effect are still not fully understood, including its dependence on hydrostaticpressure. This is particularly relevant when considering protein stabilisation, where it has beenshown a degree of consistency exists between the pressure dependency of hydrophobic interactionsand protein denaturation. However, differences between the two phenomena do exist, whichwarrants focused study of the hydrophobic interaction’s sole dependence on hydrostatic pressure.Previous work investigating the effect pressure has on the potential of mean force between twomethane molecules in water has shown that pressure causes the solvent separated minimum of thesolutes to become more favourable, implying a decrease in the hydrophobic interaction. Here wepresent experimental results probing this decrease using an innovative microscope pressure celldeveloped in Edinburgh, and micron sized hydrophobic particles to directly observe and quantifythe degree of clustering in water.46