H. Matsumura et al., FLOCCULATION BEHAVIOR OF EGG PHOSPHATIDYLCHOLINE LIPOSOMES CAUSED BY CA2+ IONS, Colloids and surfaces. A, Physicochemical and engineering aspects, 98(1-2), 1995, pp. 175-184
The interaction between bilayer phospholipid membranes has been studie
d through flocculation phenomena of phospholipid liposomes. Unlike lip
osomes composed of other phospholipids, liposomes made of egg phosphat
idylcholine (PC) have a strong resistance against aggregation. This ph
enomenon can be attributed to the hygroscopic nature of the choline gr
oup, i.e. the repulsion force that is the so-called ''hydration force'
' or the ''steric force'' with hydration is the origin of the phenomen
on. By changing the diameter of the PC liposomes, we observed a differ
ent flocculation behavior of the liposomes when the electrostatic surf
ace potential of the liposomes is zero. For diameters above 320 nm, a
weak flocculation occurred, but liposomes with diameters below 200 nm
are stable as colloidal dispersions. This diameter dependency of flocc
ulation has been explained by Derjaguin-Landau-Verwey-Overbeek (DLVO)
theory together with hydration forces.