Interactions of Adriamycin, Cytochrome c, and Serum Albumin withLipid Monolayers Containing Poly(ethylene glycol)-Ceramide

AbstractPoly(ethylene glycol)2000C20ceramide (PEG-Cer) containing monolayers at an air/water interface were characterized by measuring their surface pressure versus area/molecule (π-A) and surface potential versus area/molecule (ΔV-A) isotherms. The behavior of π-A as well as ΔV versus lipid density (ΔV-n) and ΔV-π isotherms for PEG-Cer are in keeping with two transitions of the lipopolymer, starting at π≈9 and 21mN/m. We also investigated the effects of PEG-Cer on the binding of adriamycin, cytochrome c and bovine serum albumin to monolayers containing varying mole fractions X of PEG-Cer. PEG-Cer impedes the penetration of these ligands into lipid monolayers with similar effects at both X=0.04 and 0.08. This effect of PEG-Cer depends on the conformation of the lipopolymer and the interactions between the lipid surface and the surface-interacting molecule as well as the size of the latter