Exosomes are released by cells are responsible for cell-cell communication of macromolecules and the development of disease such as cancer. These nanoparticles are loaded with biologically active macromolecules, such interfering RNA and message RNA that mediate effects on the recipient cell. The discovery that Anthrax toxin can delivers toxins to neighbouring cells using exosome biogenesis has afforded an opportunity to develop a novel strategy for the investigation of this important pathological process, and to investigate a manufacturing process for the development of therapeutic exosomes for the treatment of common diseases using macromolecular therapies. We propose to investigate the ability of this toxin based system to package cell-derived exosomes with therapeutic macromolecules using neutron reflectometry to chart the translocation of these molecules in to the exosome.