title: Poly(ethylene glycol) amphiphile adsorption and liposome partition.
abstract: Surface localized poly(ethylene glycol) (PEG) amphiphiles of type C16:0-EO151 and C18:2-EO151 were studied via ellipsometry at macroscopic, flat methylated silica (MeSi), phosphatidic acid (PA), and phosphatidylcholine (PC) surfaces. At these surfaces the amphiphiles adsorb similarly, in a non-cooperative manner, achieving a plateau (approximately 0.1 PEG chains/nm2) well below amphiphile critical micelle concentration (CMC). The resultant PEG-enriched layers were 10-15 nm thick, with a polymer concentration (approximately 0.07 g/cm3) greater than the PEG-enriched phase of many dextran, PEG aqueous two-phase systems. PEG-amphiphile adsorption (mg/m2) at hydrophobic and phospholipid flat surfaces correlated with changes in the partition (log K) of PC liposomes in such two-phase systems. PEG-amphiphile adsorption at macroscopic surfaces appears to represent a balance between hydrophobic attraction and repulsive intra-chain interactions which promote chain elongation normal to the surface.
authors.affiliation: Department of Chemistry, University of Alabama, Huntsville, 35899, USA.
authors.forename: J M
authors.initials: JM
authors.lastname: Van Alstine
authors.forename: M
authors.initials: M
authors.lastname: Malmsten
authors.forename: D E
authors.initials: DE
authors.lastname: Brooks
mesh_terms: D000327:Adsorption; D003651:Decanoates / Q000737:chemistry; D004952:Esters / Q000737:chemistry; D008081:Liposomes / Q000737:chemistry; D008823:Micelles; D009994:Osmolar Concentration; D010712:Phosphatidic Acids / Q000737:chemistry; D010713:Phosphatidylcholines / Q000737:chemistry; D010743:Phospholipids / Q000737:chemistry*; D011092:Polyethylene Glycols / Q000737:chemistry*; D011108:Polymers / Q000737:chemistry*; D012822:Silicon Dioxide / Q000737:chemistry*; D013499:Surface Properties; D013501:Surface-Active Agents / Q000737:chemistry*; D013997:Time Factors
chemical_list: D003651:Decanoates; D004952:Esters; D008081:Liposomes; D008823:Micelles; D010712:Phosphatidic Acids; D010713:Phosphatidylcholines; D010743:Phospholipids; D011108:Polymers; D013501:Surface-Active Agents; D011092:Polyethylene Glycols; D012822:Silicon Dioxide