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

Yu, J., University of Chicago
Tirrell, M. V., University of Chicago
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 37oC. 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.