Binary mixtures of long and short chain phospholipids (e.g. DMPC and DHPC) have been extensively used as model membrane systems for NMR protein structure determination, protein crystallization and more recently drug delivery vehicles.  Below the long chain lipid transition temperature the long and short chains are known to segregate, while at higher temperatures the story is less clear.  Recently Yamada and co-workers have suggested the existence of such segregation at high temperature by monitoring dye leakage through DMPC/DHPC vesicles which they suggest is due to segregation leading to short chain rimmed pores.  We use contrast matching SANS technique to demonstrate that the short chains are in fact uniformly distributed in the membrane implying other mechanisms must be responsible for the observed leakage. Understanding if and when (and even how to control) such pores might form will clearly have major implications on their efficacy as delivery vehicles.

Lipid segregation above T<sub>m</sub>: The case against nanopores

245th National Meeting (2013)

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Lipid segregation above Tm: The case against nanopores

Lipid segregation above T_m: The case against nanopores