Alternative methods of determining phase transition temperatures of phospholipids that constitute liposomes on the example of DPPC and DMPC

Abstract

Abstract In this work, alternatives to differential scanning calorimetry (DSC) as a method of determining the main phospholipid phase transition temperature are presented. The bilayer phase transitions from the ripple gel phase ( P β ′ ) to the liquid-crystal phase ( L α ) of 1,2-dipalmitoyl- sn -glycerol-3-phosphocholine (DPPC) and 1,2-dimyristoyl- sn -glycero-3-phosphocholine (DMPC) were studied by differential scanning calorimetry (DSC), Fourier transform infrared (FT-IR), nuclear magnetic resonance (NMR), and electron paramagnetic resonance (EPR) methods. In this work, two correlations between the DSC and FT-IR methods, and NMR and EPR methods are shown. The proposed methods allow for determining the T C temperature with a high degree of accuracy. Furthermore, a comparison of results obtained using the DSC and FT-IR methods allowed for an observation of a new DMPC phase transition. The liposomes analyzed in this work were obtained by the modified reverse-phase evaporation method (mREV).