Effect of phospholipids on membrane characteristics and storage stability of liposomes

The membrane characteristics and storage stability of liposomes prepared by different phospholipids were investigated, including soybean phosphatidylcholine (SPC), egg yolk phosphatidylcholine (EPC) and hydrogenated soy phosphatidylcholine (HSPC). The mean vesicle size of HSPC liposomes was 437.8 nm, while the size of SPC and EPC liposomes were 112.3 and 121.3 nm, respectively. The AFM and TEM images demonstrated that SPC and EPC liposomes exhibited a more uniform distribution and greater membrane fluidity. The liposomes demonstrated different crystallization behavior and phase transition temperatures by XRD and DSC, respectively. Due to high saturated fatty acids content of HSPC, these liposomes displayed a tighter membrane packing as evident by FTIR and Raman spectra. The membrane hydrophobicity and micropolarity decreased with storage time. During storage, HSPC liposomes maintained a more compact membrane structure. HSPC liposomes were the most stable during storage as evident by significantly lower levels of lipid hydrolysis and oxidation. Schematic diagrams of membrane characteristics and storage stability of liposomes • The HSPC liposomes displayed a tighter membrane packing. • The membrane hydrophobicity and micropolarity decreased with storage time prolonged. • The HSPC liposomes was more stable for long term storage. • Some micelles formed with phospholipid hydrolysis products.