Remote loading of doxorubicin into liposomes driven by a transmembrane phosphate gradient.

This study examines a new method for the remote loading of doxorubicin into liposomes. It was shown that doxorubicin can be loaded to a level of up to 98% into large unilamellar vesicles composed of egg phosphatidylcholine/cholesterol (7/3 mol/mol) with a transmembrane phosphate gradient. The different encapsulation efficiencies which were achieved with ammonium salts (citrate 100%, phosphate 98%, sulfate 95%, acetate 77%) were significantly higher as compared to the loading via sodium salts (citrate 54%, phosphate 52%, sulfate 44%, acetate 16%).

pH-induced release from P2VP-PEO block copolymer vesicles.

The pH-induced release of hydrophilic dyes from poly(2-vinylpyridine-b-ethylene oxide) (P2VP-PEO) block copolymer vesicles is investigated. The structure of the vesicles is characterized using small-angle neutron scattering (SANS) and cryo-electron microscopy (cryo-TEM). A decrease of the pH below 5 leads to protonation and dissolution of the poly-2-vinylpyridine blocks which induces rupture and dissolution of the vesicle membrane.

Optimized targeting of polyethylene glycol-stabilized anti-intercellular adhesion molecule 1 oligonucleotide/lipid particles to liver sinusoidal endothelial cells.

We prepared polyethylene glycol (PEG)-stabilized antisense oligonucleotide (ODN)/lipid particles from a lipid mixture including the positively charged amphiphile 1,2-dioleoyl-3-trimethylammonium-propane (DOTAP) and anti-intercellular adhesion molecule 1 (ICAM-1) antisense ODN by an extrusion method in the presence of 40% ethanol. These particles were targeted to scavenger receptors on liver endothelial cells by means of covalently coupled polyanionized albumin. Two types of such targeted particles were prepared, one with the albumin coupled to a maleimide group attached to the particle's lipid bilayer and the other with the protein coupled to a maleimide group attached at the distal end of added bilayer-anchored PEG chains.

Large-scale production of lipoplexes with long shelf-life.

The instability of lipoplex formulations is a major obstacle to overcome before their commercial application in gene therapy. In this study, a continuous mixing technique for the large-scale preparation of lipoplexes followed by lyophilisation for increased stability and shelf-life has been developed. Lipoplexes were analysed for transfection efficiency and cytotoxicity in human aorta smooth muscle cells (HASMC) and a rat smooth muscle cell line (A-10 SMC).