Poly(ethylene glycol)-conjugated surfactants promote or inhibit aggregation of phospholipids.
The calcium-induced aggregation of dilauroyl phosphatidic acid (DLPA) suspensions, with or without added poly(ethylene oxide) (PEO)-conjugated surfactants containing 4 to 30 ethylene oxide subunits, were monitored by turbidity measurement and quasi-elastic light scattering (QLS). The aggregation was inhibited (protected) by the incorporated PEO surfactant for most samples, while a window for promotive effect was found for samples with low surface coverage by the PEO moiety of the incorporated surfactant. Promotion occurs only when the aggregation is slow and at a low level. The promotion is explained by the synergistic effect of PEO and divalent calcium cations when the steric repulsion is weak. The promotion/protection crossover is a display between the PEO/calcium synergistic effect and the steric repulsion.
Guo
Y
Y
Department of Biophysics, Roswell Park Cancer Institute, Buffalo, NY 14263, USA.
Hui
S W
SW
D002118:Calcium; D007700:Kinetics; D008027:Light; D009391:Nephelometry and Turbidimetry; D010712:Phosphatidic Acids / Q000737:chemistry*; D011092:Polyethylene Glycols / Q000737:chemistry*; D012542:Scattering, Radiation; D013501:Surface-Active Agents / Q000737:chemistry*
D010712:Phosphatidic Acids; D013501:Surface-Active Agents; D011092:Polyethylene Glycols; C042076:1,2-dilauroylphosphatidic acid; D002118:Calcium