Lecturer Kislon Voitchovsky, Physics Department, Durham University, UK

Water-Driven Self-Assembly at the Interface With Solids

The behaviour of liquid molecules in close proximity with solids can be strongly influenced by the local chemical and topographical properties of the solid. As a result, this so-called interfacial liquid does generally not behave like bulk liquid, and is central to countless phenomena ranging from self-assembly processes, electrochemistry, heterogeneous catalysis, heat transfer and the folding and function of biomolecules. Experimentally, nanoscale measurements of liquid-driven processes remain challenging, especially when averaging-based approaches are not possible.

Here I will present several examples of water-driven self-assembly at interfaces observed using atomic force microscopy (AFM). When operated in a particular regime, AFM can map the molecular organisation of the interfacial liquid and gather quantitative information about its local dynamics, including around adsorbed molecules and ions. The results, confirmed by molecular dynamics simulations, show that the interfacial water can induce correlation between single metal ions, inducing order and changing the diffusion timescales. The findings suggest intriguing possibilities for nanotechnology as well as the regulation of molecular exchanges at bio-interfaces.

References

• Ricci, et al, Nat. Commun., 2014, 5, 4400
• Ortiz-Young et al, Nat. Commun., 2013, 4, 2482
• Voitchovsky et al, Nat. Nano., 2010, 5, 401