One dimensional (1D) magnetic nanostructures exhibit anisotropic magnetic properties and thereby differ from unstructured materials. However, magnetic chains are energetically unstable and ring structures are often formed. We have produced magnetite nanoparticles that form colloidally stable chains in aqueous environment. These 1D assemblies exhibit complex substructures involving its inorganic (magnetite) and organic (polyarginine) components. We propose here to use small angle neutron scattering (SANS) with contrast variation and isotopic substitution to resolve the distributions of magnetite, polyarginine, and water at the different hierarchical levels and at different stages of the formation process. The results will provide a basis for the understanding of formation and stability of 1D magnetic structures.