Characterization of lipid bilayers adsorbed on spherical LbL-support

Abstract

Structural and dynamic properties of membranes composed of phosphatidylcholine (PC) and phosphatidylserine (PS) on layer-by-layer (LbL) polyelectrolyte coated particles were investigated using solid-state nuclear magnetic resonance (NMR) and fluorescence methods. These spherically supported membranes showed structural, dynamic, and elastic properties similar to free-standing membranes as proved by ³¹P and ²H NMR. Small differences between behaviour of PC and PS on LbL support due to interaction with the polyelectrolyte were observed. Fluorescence lifetime imaging microscopy (FLIM) using 7-nitro-2-1,3-benzoxadiazol (NBD) labeled PC and PS showed a stronger impact of the outermost polyelectrolyte (PAH) on the fluorescence lifetimes of NBD-PS compared to NBD-PC. Although small defects in nm range allowing passage of Mn²⁺ to both layers of the membrane coat were present, a rather homogeneous coating observed by fluorescence microscopy, complete fluorescence recovery after photobleaching, and NMR results reveal that somewhat continuous lipid bilayers were formed around the LbL particles.