(722e) The Structure and Elasticity of Lipid Vesicles Interacting with End-Phosphorylated Polyethylene Glycol

The structure and dynamics of lipid membranes in the presence of extracellular macromolecules are critical for cell membrane functions and many pharmaceutical applications. End-phosphorylation of a triblock polyethylene glycol (PEG), ABAPEG 11K, markedly changes the interactions between the polymer and vesicle membranes, preventing PEG-induced vesicle phase separation. Small angle neutron scattering (SANS) shows that the phosphorylated version, Pi-ABAPEG 11K, interacts weakly with DMPC vesicle membranes but does not change the structure of DMPC unilamellar vesicles significantly at 37^oC. Neutron spin-echo results show that the adsorption of Pi-ABAPEG 11K on DMPC vesicle membranes increases the membrane bending modulus κ. X-ray reflectivity measurements confirm the weak adsorption of Pi-ABAPEG 11K on DMPC monolayer resulting in a more compact DMPC monolayer structure.