Lipid bilayer blanketing versus penetrating silica colloidal crystals

Fluorescence intensities and diffusion coefficients were measured for a labeled lipid in 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) bilayers deposited by vesicle fusion on two types of silica colloidal crystals, one made from 145 nm particles and the other from 490 nm particles. The bilayer is shown to blanket the top of the silica colloidal crystal for the 145 nm case and to coat the entire surface area for the 450 nm case. The diffusion coefficient of the labeled lipid is shown to be the same in both cases, showing that the diffusion coefficient is not an indicator of bilayer penetration.