Biomedical uses of amphiphilic macromolecules include the use of such macromolecules in the form of nanoparticle formulations for the sequestration and/or removal of LDL, and for the treatment and prevention of atherosclerosis and atherosclerotic development. The invention also provides the use of amphiphilic macromolecule encapsulates for treating diseases including cancer and inflammation, as well as targeted amphiphilic macromolecules and their use in therapy.