Nanoconfinement and phase transitions of water in protein crystals

The structure, equilibrium states, and phase transitions of water is altered by nanoconfinement. Protein crystals provide a unique platform to study nanoconfined water as they can be grown large enough to perform macroscopic measurements, their electron densities can be reconstructed through x-ray diffraction, a large array of confinement geometries are available, and the confinement is truely biologically relevant. By monitoring the time dependence of crystal diffraction during and following cooling to temperatures between 180 and 260K, we have studied how and when ice forms and the properties of this ice. We have also performed high precision density measurements allowing us to estimate the density of solvent confined within the solvent cavities.