Hydrates in the binary system water–dimethylsulfoxide

Mixture of water and dimethylsulfoxide (DMSO) are useful as preservative liquids for the storage of living cells at very low temperatures, such that they can be revived and used in therapeutic procedures. For example, liver cells generated from a patient's own stem-cells can be stored, recovered and grown for later re-implantation using a cryopreservation protocol developed at UCL and evaluated in recent beam-time on IRIS. However, mixtures of water and DMSO are able to crystallise hydrates of DMSO when suitably annealed; the crystal structures and properties of these hydrates are unknown. It is essential for a complete understanding of DMSO solutions and how they respond to flash-freezing, devitrification and melting, that these hydrates be characterised. The objective of this work is to collect the first data on the crystalline hydrates of DMSO.