Preparation from DPPC and DPPA phospholipids nano size liposomes and investigation its thermodynamic properties

Author: Tamaz Mdzinarashvili
Co-authors: Mariam Khvedelidze, Eka Shekiladze and Givi Kochoradze
Keywords: Phospholipids, Structure of Liposomes, thermodynamics
Annotation:

By using Differential Scanning Calorimetry it has been studied thermodynamic parameters of Dipalmitoylphosphatidilcholine (L-α-Phosphatidylcholine, Dipalmitoyl-DPPC) liposomes. Research has shown that during heating DPPA liposomes undergo phase transition at the temperature which equals 66°C, however, for DPPC liposomes this temperature is 42°C. Interestingly, for DPPC liposomes it has been observed the small peak (pre-transition peak) before the main transition peak on the calorimetric curve, which has not been observed in the case of DPPA liposomes. It was established that liposomes’ structural integrity does not disrupts at the high temperatures and partially restores during reheating. Experiments have also shown that the melting process of DPPA liposomes is in equilibrium; it does not depend on the heating rate. Particularly, the enthalpy and the melting temperature do not change while heating with different rates. It was investigated the interaction of DPPA liposomes with different dyes: Methylene Blue, Methyl Red and Bromthymol Blue. Investigation has shown that the interaction depends on properties of used dye and the temperature exerts on liposome surface formation. We assume that the optimal distribution of liposome surface charge occurs during heating, so that liposomes are more stabile while interacting with various materials and their affinity for aggregation decreases.