Complexation of Polycations to Anionic Liposomes: Composition and Structure of the Interfacial Complexes Export

@article{citeulike:2298045, abstract = {Abstract: Poly(N-ethyl-4-vinylpyridinium bromide) (a polycation with a degree of polymerization of 1100) was adsorbed onto liposomes composed of egg lecithin with a 0.05-0.20 molar fraction () of anionic headgroups provided by cardiolipin (a doubly anionic lipid). According to electrophoretic mobility data, this led to total charge neutralization of the liposomes, whereupon the liposomes adopted a positive charge as additional polymer continued to adsorb. Although the liposomes aggregated at the charge-neutralization point, they disassembled into individual liposomes after becoming positively charged. The degree of polymer adsorption was shown to reach a limit. Thus, by measuring the free polymer content in a liposome suspension, it was possible to determine the polymer concentration at which the liposome surface became saturated with polymer. Beyond this point, an electrostatic/steric barrier at the surface suppressed further adsorption. Dynamic light scattering studies of liposomes with and without adsorbed polymer allowed calculation of the polymer film thickness which ranged from 22 to 35 nm as the molar fraction of cardiolipin () increased from 0.05 to 0.20. The greater the content on the anionic lipid in the bilayer, the thicker the polymer film. The maximum number of polymer molecules adsorbed onto the liposomes was estimated: 1-2 molecules for = 0.05; 3 molecules for = 0.1; 4- molecules for = 0.15; and 6 molecules for = 0.2. The polymer appears to lie on the liposome surface, rather than embedding into the bilayer, because addition of NaCl easily dislodges the polymer from the liposome into the bulk water.}, address = {Department of Chemistry, M. V. Lomonosov Moscow State University, Leninskie Gory, Moscow 119992, Russia, and Department of Chemistry, Emory University, Atlanta, Georgia 30322}, author = {Sybachin, A. V. and Efimova, A. A. and Litmanovich, E. A. and Menger, F. M. and Yaroslavov, A. A.}, citeulike-article-id = {2298045}, citeulike-linkout-0 = {http://dx.doi.org/10.1021/la701411y}, citeulike-linkout-1 = {http://pubs.acs.org/doi/abs/10.1021/la701411y}, day = {25}, doi = {10.1021/la701411y}, journal = {Langmuir}, keywords = {anionic, cardiolipin, cationic, vesicles}, month = {September}, number = {20}, pages = {10034--10039}, posted-at = {2008-01-28 15:01:43}, priority = {2}, title = {Complexation of Polycations to Anionic Liposomes: Composition and Structure of the Interfacial Complexes}, url = {http://dx.doi.org/10.1021/la701411y}, volume = {23}, year = {2007} }

TY - JOUR ID - citeulike:2298045 L3 - citeulike-article-id:2298045 N2 - Abstract: Poly(N-ethyl-4-vinylpyridinium bromide) (a polycation with a degree of polymerization of 1100) was adsorbed onto liposomes composed of egg lecithin with a 0.05-0.20 molar fraction () of anionic headgroups provided by cardiolipin (a doubly anionic lipid). According to electrophoretic mobility data, this led to total charge neutralization of the liposomes, whereupon the liposomes adopted a positive charge as additional polymer continued to adsorb. Although the liposomes aggregated at the charge-neutralization point, they disassembled into individual liposomes after becoming positively charged. The degree of polymer adsorption was shown to reach a limit. Thus, by measuring the free polymer content in a liposome suspension, it was possible to determine the polymer concentration at which the liposome surface became saturated with polymer. Beyond this point, an electrostatic/steric barrier at the surface suppressed further adsorption. Dynamic light scattering studies of liposomes with and without adsorbed polymer allowed calculation of the polymer film thickness which ranged from 22 to 35 nm as the molar fraction of cardiolipin () increased from 0.05 to 0.20. The greater the content on the anionic lipid in the bilayer, the thicker the polymer film. The maximum number of polymer molecules adsorbed onto the liposomes was estimated: 1-2 molecules for = 0.05; 3 molecules for = 0.1; 4- molecules for = 0.15; and 6 molecules for = 0.2. The polymer appears to lie on the liposome surface, rather than embedding into the bilayer, because addition of NaCl easily dislodges the polymer from the liposome into the bulk water. IS - 20 JF - Langmuir AD - Department of Chemistry, M. V. Lomonosov Moscow State University, Leninskie Gory, Moscow 119992, Russia, and Department of Chemistry, Emory University, Atlanta, Georgia 30322 EP - 10039 TI - Complexation of Polycations to Anionic Liposomes: Composition and Structure of the Interfacial Complexes VL - 23 SP - 10034 KW - anionic KW - cardiolipin KW - cationic KW - vesicles AU - Sybachin, AV AU - Efimova, AA AU - Litmanovich, EA AU - Menger, FM AU - Yaroslavov, AA PY - 2007/09/25/ UR - http://dx.doi.org/10.1021/la701411y ER -