*2.2. Labelling of IP-001 with Indium-111*

IP-001 was labelled with a solution of indium-111 chloride in an acetate-buffered environment (pH 4.6). Incorporation was generally higher than 95% when 50 µg of precursor were used, and the total volume of the reaction was maintained at around 1 mL, achieving a molar activity of about 10 MBq/nmol. Impurities were mainly due to unlabeled indium-111 only. Further purification with solid phase extraction (SPE) enabled a radiochemical purity (RCP) higher than 99%, but the procedure was generally avoided for the in vitro and in vivo studies due to the high concentration of EtOH used in the process that may have been detrimental for cells and animals. Quality controls were performed by means of a reverse phase HPLC (R<sup>t</sup> : free-[111In]In3+ = 1.1 min; [111In]In-IP-001 = 6.0 min) and radio-TLC (thin-layer chromatography) (R<sup>f</sup> : free-[111In]In3+ = 0.0; [111In]In-IP-001 = 0.6). Paradigmatic examples of chromatograms are reported in Figures S8 and S9.
