To reveal the basics of liposome sample preparation and DSC studies, Malvern Instruments uses this fundamental technique to characterize thermotropic phase transitions in lipid bilayer membranes

Margarida Bastos – CIQ-UP, Department of Chemistry and Biochemistry, Faculty of Sciences, University of Porto, Portugal, and Ana C.P. Aguas – Centre of Marine Sciences (CCMAR), University of Algarve, Campus de Gambelas, 8005-139, Portugal.

Liposomes have been widely used as model membranes and in drug delivery, as their basic properties can easily be varied to target desired properties (lipid composition, concentration, water content, media (different buffers, varying ionic strength, pH, etc.) as well as lamellarity (unilamellar, large or small (Large Unilamellar Vesicles, LUVs, and Small Unilamellar Vesicles, SUVs), and multilamellar vesicles, MLVs)). In these studies, one must characterize the pure liposomes as well as their mixtures with other molecules (proteins, peptides, drugs), to ascertain the influence of the added component in the liposome phase behavior.

DSC is a fundamental technique for the characterization of membrane behavior, providing all thermodynamic parameters for temperature-induced transitions. Furthermore, for mixtures of membranes with other components (drugs, proteins, peptides, polymers, etc.) DSC represents a first-line screening method, providing information on the effect(s) of the added components on membrane behavior.