The impact of pore geometry and functionality on the dynamics of water nanoconfined in porous media are the subject of some debate. We report the synthesis and smallangle X-ray scattering (SAXS) characterization of a series of perdeuterated gemini surfactant lyotropic liquid crystals (LLCs), in which convex, water-filled nanopores of welldefined dimensions are lined with carboxylate functionalities. Quasielastic neutron scattering (QENS) measurements of the translational water dynamics in these dicarboxylate LLC nanopores as functions of the surfactant hydration state and the charge compensating counterion (Na + , K + , NMe 4 + ) reveal that the measured dynamics depend primarily on surfactant hydration, with an unexpected counterion dependence that varies with hydration number. We rationalize these trends in terms of a balance between counterion−water attractions and the nanopore volume excluded by the counterions. On the basis of electron density maps derived from SAXS analyses of these LLCs, we directly show that the volume excluded by the counterions depends on both their size and spatial distribution in the water-filled channels. The translational water dynamics in the convex pores of these LLCs are also slower than those reported in the concave pores of AOT reverse micelles, implying that water dynamics also depend on the nanopore curvature.

Water mobility in cancer cells could be a powerful parameter to predict the progression or remission of tumors. In the present descriptive work, new insight into this concept was achieved by combining neutron scattering and thermal analyses. The results provide the first step to untangle the role played by water dynamics in breast cancer cells (MCF-7) after treatment with a chemotherapy drug. By thermal analyses, the cells were probed as micrometric reservoirs of bulk-like and confined water populations. Under this perspective we showed that the drug clearly alters the properties of the confined water. We have independently validated this idea by accessing the cellular water dynamics using inelastic neutron scattering. Finally, analysis of the quasi-elastic neutron scattering data allows us to hypothesize that, in this particular cell line, diffusion increases in the intracellular water in response to the action of the drug on the nanosecond timescale.

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Neutron scattering is exquisitely sensitive to the position, concentration, and dynamics of hydrogen atoms in materials and is a powerful tool for the characterization of structure-function and interfacial relationships in biological systems. Modern neutron scattering facilities offer access to a sophisticated, nondestructive suite of instruments for biophysical characterization that provides spatial and dynamic information spanning from Ångstroms to microns and from picoseconds to microseconds, respectively. Applications in structural biology range from the atomic-resolution analysis of individual hydrogen atoms in enzymes through to meso- and macro-scale analysis of complex biological structures, membranes, and assemblies. The large difference in neutron scattering length between hydrogen and deuterium allows contrast variation experiments to be performed and enables H/D isotopic labeling to be used for selective and systematic analysis of the local structure, dynamics, and interactions of multi-component systems. This overview describes the available techniques and summarizes their practical application to the study of biomolecular systems.

Commercial thin silicon wafers are shown to be superb focusing crystals in three-axis spectrometers. With fully open beams, they allow resolutions that in conventional flat-crystal arrangements can only be achieved with Soller collimators of 2min of arc. At given resolution, intensities are much higher than in conventional arrangements with vertically focusing pyrolytic graphite crystals. Resolution ellipsoids were measured by diffraction from powder samples. The ellipsoid orientation is controlled by the crystal curvatures and can be set to any specified value, in particular turned by 90" to pass from high resolution in energy transfer to high resolution in wavevector transfer. At neutron energies on the peak of cold sources spectra the focusing technique gives energy transfer resolutions around 10 p V . The technique fills the resolution gap between back-scattering instruments and conventional three-axis spectrometers.