The possibility of introducing azido functions onto polydopamine by diazo transfer making use of existing aminoethyl moieties was verified at polydopamine-coated magnetite nanoparticles. The resulting azido-functionalized Fe₃O₄@polydopamine nanoparticles serve as a magnetic nano-platform for the introduction of interesting applicatory functions by click-chemistry (CuAAC) as exemplified by linking biotin, tetraacetylglucose, dansyl and proline.