Location of small molecules in partially hydrated DOPC bilayers

Title: Location of small molecules in partially hydrated DOPC bilayers: insights into contrasting cryoprotective mechanisms

Speaker: Professor Gary Bryant, School of Science and Centre for Molecular and Nanoscale Physics RMIT University, Melbourne, Australia

Gary is a Professor of physics at RMIT University, Melbourne, Australia. His research focuses on Biological Physics and Soft Matter, in particular using light, neutron and x-ray scattering. He applies these techniques to a broad range of problems, including phase transitions in colloidal suspensions,nanoparticle characterisation, bacterial motility, and the stability and interactions of micelles,nanoparticles, proteins and other molecules of biological interest. He also has a strong research interest in the mechanisms of damage to biological tissue under dehydration and temperature stress, with a focus on freezing damage.

When cells or organisms are subjected to dehydration and/or freezing, a key factor in survival is the interaction between membranes and cryoprotective molecules. We have studied the structure of synthetic membranes in the presence of sugars using Small-angle X-ray (SAXS) and neutron scattering (SANS). More recently, we have conducted membrane diffraction experiments on stacked multilamellar membranes,which provides higher order diffraction information, allowing the Fourier reconstruction of the bilayer structure and the positions of these molecules within the bilayer may be determined with high precision.

In this talk, we will present recent results on DMSO and compare these with previous results on non-penetrating cryoprotectants, highlighting the different modes of action of these two types of molecules. The relevance of these results to our understanding of cryopreservation will be discussed.