Lipid oxidation is linked to many adverse health effects. In this proposal we will use QENS in combination with contrast variation as a non-invasive method to detect and characterize the presence and size of microdomains formed in vesicles of biologically relevant lipids as a function of oxidized lipid levels and temperature. The domain forming lipid mixture system to be used in the present study will be composed of a saturated phospholipid, DPPC, an unsaturated phospholipid, POPC, and cholesterol (Chol) where a portion of the POPC is systematically replaced with the oxidized version of POPC, POnPC.