Effects of trehalose on the phase behavior of DPPC-cholesterol unilamellar vesicles

SATOSHI OHTAKE; CAROLINA SCHEBOR; JUAN J. DE PABLO

BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES

Elsevier

Año: 2006 vol. 1758 p. 65 - 73

0005-2736

Asystematic study is presented of the effects of trehalose on the physical properties of extruded DPPC–cholesterol unilamellar vesicles. Particularemphasis is placed on examining how the interactions present in the hydrated state translate into those in the dehydrated state. Observations fromHSDSC and DSC are used to examine the phase behavior of hydrated and dehydrated vesicles, respectively. The concentration of trehalose inside andoutside the vesicles is manipulated, and is shown to affect the relative stability of the membranes. Our results show for the first time that a combination of high inner and low outer trehalose concentration is able to decrease the gel-to-liquid crystalline phase temperature (Tm), while any other combination will not. Upon dehydration, the Tm of all lipid mixtures increases. The extent of the increase depends on the trehalose distribution across the bilayer. The Tm changes in the same direction with trehalose concentration for both freeze-dried and fully hydrated samples, suggesting that the trehalose distribution across the vesicle membrane, as well as the trehalose–phospholipid interaction, is maintained upon lyophilization. The results presented in this work may aid in the formulation of systems to be used in the lyophilization of liposomes for drug delivery applications.