Effect of sugar-phosphate mixtures on the stability of DPPC membranes in dehydrated systems

The stabilizing role of sugars on dehydrated membranes is well established. The formation of a glassy matrix and the direct interaction between the sugars and the lipids are some of the mechanisms proposed to be involved in this stabilizing effect. Phospholipidic systems have been studied extensively as models for biological membranes and also due to the practical applications of liposomes as vehicles for drug delivery. In this work, we evaluate the effect of sugar-phosphate mixtures on the transition temperature of dehydrated 1,2-dipalmitoylphosphatidylcholine, and also examine some physical characteristics of these mixtures, such as the glass transition temperature and water sorption properties. The addition of phosphate salts to sugar systems has several interesting features that merit its consideration in formulations to protect dehydrated labile biomaterials. In particular, sucrose-phosphate mixtures provide an interesting alternative to pure saccharide formulations due to their high glass transition temperatures and their increased ability to maintain a low melting transition temperature in the presence of small amounts of water.