Purple-bacterial photosynthetic reaction centers and quantum-dot hybrid-assemblies in lecithin liposomes and thin films.

Quantum dots (QDs) absorb ultraviolet and long-wavelength visible light energy much more efficiently than natural bacterial light-harvesting proteins and can transfer the excitation energy to photosynthetic reaction centers (RCs). Inclusion of RCs combined with QDs as antennae into liposomes opens new opportunities for using such hybrid systems as a basis for artificial energy-transforming devices that potentially can operate with greater efficiency and stability than devices based only on biological components or inorganic components alone. RCs from Rhodobacter sphaeroides and QDs (CdSe/ZnS with hydrophilic covering) were embedded in lecithin liposomes by extrusion of a solution of multilayer lipid vesicles through a polycarbonate membrane or by dialysis of lipids and proteins dispersed with excess detergent.

Dipole potential as a driving force for the membrane insertion of polyacrylic acid in slightly acidic milieu.

In this work, we report on the interaction of polyacrylic acid with phosphatidylcholine bilayers and monolayers in slightly acidic medium. We found that adsorption of polyacrylic acid on liposomes composed of egg lecithin at pH 4.2 results in the formation of small pores permeable for low molecular weight solutes.