Phospholipid monolayers

Interaction of polysilicic acid with monolayers of substances containing quaternary ammonium groups

“…The lack of interaction at pH < 4.2 shows that the -COOH group is not involved in hydrogen bonds with silicic acid; while at pH > 4.2 comparison with lecithin (which does interact [29]) suggests that the difference in behaviour between the two phospholipids must be due to the -CO0-group preventing electrostatic interaction of silica with the -NH~-group of phosphatidyl serine, as was suggested by Depasse [15].…”

ZERO FIELD OPTICAL DETECTION OF MAGNETIC RESONANCE OF TRIPLET STATE OF CHLOROPHYLL a IN LIPID BILAYER VESICLES

“…The generally accepted view about the location of Chl in lipid bilayers, as mentioned in the Introduction of this article, is that the hydrophobic phytyl tail is anchored into the hydrocarbon core of the lipid bilayer and the porphyrin ring is between the polar groups of the lipid and possibly makes contact with the aqueous phase with its hydrophilic groups. The monolayer studies of phospholipids at the air/water interface have shown that the polar head of the lipid is completely submerged in water (Minones et a/., 1981). Furthermore, according to Neagle (1976) the behavior of lipid molecules in lipid bilayers (vesicles or liposomes) is identical to those in monolayers at surface pressure of 50 mN/m.…”

The action of polysilicic acid on mixed monolayers of cholesterol and lecithins

“…9). The lecithin film would therefore be more expanded in the presence of silicic acid owing to both the increase in intermolecular electrostatic repulsion and to the hydrogen bonds that have been suggested to form between un-ionized silicic acid molecules and the oxygen atoms of the phosphate groups [15].…”

“…At present there are various opinions concerning the nature of the membrane components involved, but proteins [3][4][5] and lipids [6][7][8] are known to be among them. This paper extends our earlier studies concerning the action of polymerized silicic acid upon proteins [9][10][11][12] and pure phospholipids [13][14][15] to the consideration of its effects on mixed cholesterol-lecithin monolayers, the components of both of which are found in natural membranes, have therefore been used in an attempt to work with an in vitro model for lipid that is as real as possible membranes. The action of silanol groups on the artificial membrane has been studied by varying its composition between pure cholesterol and pure lecithin and comparing the 7c-A curves obtained when it is spread on silicic acid substrates with those of silica-flee substrates.…”