Collective Dynamics of Nanoconfined Water in Phospholipid Multilamellar Vesicles Studied by Broadband Dielectric Relaxation Spectroscopy

We present the first experimental characterization, using GHz to THz dielectric relaxation spectroscopy, of the collective rearrangement of the hydrogen bond network of water molecules nanoscopically confined in phospholipid multilamellar vesicles. We determined a distinct relaxation peak at ~40 GHz and the Kirkwood correlation factor of approximately 1.2, which are the indication of acceleration of the collective reorientation dynamics with nanoconfinement, and strong disruption of the hydrogen bond network compared with that of bulk water. Combined with X-ray observation, it has estimated that ~70% of the nanoconfined water contributes to the accelerated relaxation mode.