Chains for the better: A poly(L-lysine)-mediated self-assembly of citrate-functionalized Fe3O4 nanoparticles and hydroxy pyrene trisulfonate (HPTS) forms magnetoresponsive fluorescent spheres (MFS) in the presence of glutaric dialdehyde (GA). If the assembly is performed in the presence of a permanent magnet then 1D magnetic beaded-chain structures are formed (see scheme). Detailed facts of importance to specialist readers are published as "Supporting Information". Such documents are peer-reviewed, but not copy-edited or typeset. They are made available as submitted by the authors. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.