Atherosclerosis is the leading cause of death in western society, its consequences such as strokes and heart attacks arise from the build-up of plaques of fat which accumulate in the artery walls. Lipoprotein particles were shown to play a role in this disease, however they role is still not fully understood. For example, the specific apolipoprotein variants in lipoproteins can give either a protective or a detrimental effect. Understanding these developments and determining the importance of the lipoprotein particle composition in terms of both apolipoprotein variant and lipid cargo is fundamental in the diagnosis and treatment of the disease as today clinical lipid profiling fails to properly predict the risk to develop this disease. The goal of this project is to undertand the role of apolipoprotein variant on lipid dynamics at model cellular membranes by neutron reflection.