Thermodinamic Study of DPPA and DPPC Liposomes

Author: eka shekiladze
Co-authors: Tamaz Mdzinarashvili, Mariam Khvedelidze
Keywords: Liposomes, Nanoparticles, calorimetry.
Annotation:

Using calorimetry method it was investigated the thermodynamic parameters of liposomes, prepared from Dipalmitoyl Phosphatidylcholine (L-α-Phosphatidylcholine, Dipalmitoyl-DPPC) and contain Cholesterol. We have studied liposomes with approximately 200 nm and 450 nm sizes, because nanoparticles up to 500 nm could penetrate into the cell. Carried out experiments show that as 200 nm, also 450 nm DPPC+Cholesterol liposomes undergo the phase transisiton at 41°C and have identical stability and structural order. It was determined that the structural entirety of liposomes does not break at high temperature and they wholly recover their structure after reheating. Fluorescein was added during preparation of liposomes with the purpose to investigate using confocal microscope. From calorimetric experiments it is evident that there is difference between “native” liposomes and liposomes with fluorescein. The stability of liposomes with fluorescein are decreased compared with “native” liposomes, but their wholly recover its structure after rehating. We supplemented fluoprescein to already prepared liposomes. In this case there was no different between “native” liposomes and liposomes with fluorescein in calorimetric experiments, which indicate that here is no structural changes in liposome structure. Consequently the properties and structure of liposomes dependes on the preparation method. Experimetns were carried our as on fresh prepared liposomes, also using the sample, prepared 3 monthes before. Results were identical, which points that liposomes with such composition has long storage life. It is important, because Dipalmitoyl Phosphatidylcholine liposomes can be used as drug delivery systems.