Characterization of Archaea Tetraether Hybrid Liposomal Doxorubicin

We have previously shown that liposomes made of the polar lipid fraction E (PLFE) isolated from the thermoacidophilic archaeon Sulfolobus acidocaldarius exhibit enhanced vesicle stability in comparison to conventional diester or diether lipids (reviewed in Chong et al (2012) Archaea, doi:10.1155/2012/138439). In the present study, we have characterized several physical properties of tetraether hybrid liposomes composed of PLFE and non-archaeal diester lipids such as dipalmitoylphosphatidylcholine or porcine brain sphingomyelins/cholesterol. Particle size, zeta-potential and membrane packing of the hybrid liposomes are examined using dynamic light scattering, laser Doppler electrophoresis, Laurdan's generalized polarization, respectively. In addition, entrapment efficiency and spontaneous release of anti-cancer drug doxorubicin is studied by using absorption spectroscopy and fluorescence de-quenching method. These physical measurements are performed on liposomes with varying PLFE molar ratios at different temperatures. The obtained results may help to optimize and design liposomal drugs with greater stability and higher therapeutic efficacy. (supported by NSF DMR1105277)