Methanol solutions à 5 mM for PAC3Imi+ or 10 mM for PAC16 and PAC10Ph were added to dispersions of SPIONs (3 mg mL -1 ) also in methanol at a volumetric ratio of 3:10 respectively. These concentrations were determined to saturate the surface beforehand. The mixture was sonicated for 30 min at 25 °C in a Sonocool 255 from Bandelin. Unbound phosphonic acid molecules were removed by two washing cycles consisting of sedimenting the functionalized SPIONs with a Multifuge X1R from Heraeus (13,000 rpm at 5 °C) followed by redispersion in fresh methanol. Finally, the coated SPIONs were sedimented again and dried at 60 °C overnight. For binary shells, the PAC3Imi+ functionalized SPIONs (PAC3Imi+@SPIONs) were not dried in the last step but redispersed in the initial methanol volume and then mixed with solutions of PAC16 or PAC10Ph à 10 mM in the same ratio as for the first iteration. Sonication as well as both washing cycles were repeated and the particles finally dried at 60 °C over-night.