The fundamental structure of cell membranes is bilayers composed of phospholipids, and the vital function of the phospholipids in the membrane is to help keep it fluid and semi-permeable. Conventional glycerophospholipids have acyl chains attached to the sn-1 and sn-2 positions of the glycerol backbone via an ester bond. Ether lipids are a unique class of glycerophospholipids that have an alkyl chain attached to the sn-1 position by an ether bond (glycerol-ether lipids). In ether lipids, the alcohol group attached to the phosphate is generally choline or ethanolamine. Ether-linked phospholipids such as 1-alkyl-2-acyl-phosphatidylcholine and dialkylphosphatidylcholine are also found in the plasma and organelle membranes of mammalian species. Ether lipids form approximately 20% of the total phospholipid in mammals with different tissue distribution; brain, heart, spleen and white blood cells have the highest levels, while liver have a very little amount of ether lipids.

Studies on the formation and thermodynamic properties of ether-linked phospholipid bilayer membranes have indicated that in contrast to ester-linked phospholipid, the formation of the non-bilayer structure takes place spontaneously. This is attributed to the weaker interaction between polar headgroups in the ether-linked than that in the ester-linked phospholipids. It has also shown that the phase behavior of the ether-linked phospholipid bilayer membranes in ambient pressure is almost equivalent to that of the ester-linked phospholipid bilayer membranes under high temperatures and pressures, and the difference in the phase behavior decrease as the alkyl-chain length increases.

Due to distinctive properties of ether lipids, liposomes made from ether lipids exhibit very unique characteristics and performance: a) the ether bonds are more stable than ester linkages over a wide range of acidic or alkaline pH; b) stability properties of the liposomes is enhanced by bipolar lipids, and the saturated alkyl chains gives stability towards degradation in oxidative conditions; c) the unusual stereochemistry of the glycerol backbone enhance the resistance against the attacks by other organism phospholipases.

Phospholipase A2 (PLA2) cannot hydrolyze the ether lipid liposomes. Diether lipids do not go through hydrolysis due to having an ether bond instead of an acyl bond and therefore to do that, they are a suitable candidate for experiments that needs to be performed at a higher temperature for an extended period of time. For more information about hydrolysis and oxidation of phospholipids see here.

Saturated diether lipids can neither be hydrolyzed nor oxidized.