*3.2. Synthesis and Radiochemical Synthesis of [64Cu]***1***–***4**

DOTA-compounds **1**–**4** were prepared in >97% isolated purity after RP-HPLC purification. DOTA-EB-αvβ6-BP **1** had an RP-HPLC retention time of 17.22 min with a MALDI-TOF m/z [M + Na]<sup>+</sup> for C261H460N46NaO102S<sup>2</sup> calc'ed 5958.1556; found 5958.1756 (Figure S5). DOTA-IP-αvβ6-BP **2** had an RP-HPLC retention time of 17.07 min with a MALDI-TOF m/z [M + H]<sup>+</sup> for C251H458IN44O<sup>98</sup> calc'ed 5786.1314; found 5786.1209 (Figure S8). DOTA-EB-ABM **3** had an RP-HPLC retention time of 14.18 min with a MALDI-TOF m/z [M + H]<sup>+</sup> for C50H66N11O17S<sup>2</sup> calc'ed 1156.4074; found 1156.4079 (Figure S11). DOTA-IP-ABM **4** had an RP-HPLC retention time of 14.46 min with a MALDI-TOF m/z [M + H]<sup>+</sup> for C40H63IN9O<sup>13</sup> calc'ed 1004.3585; found 1004.3590 (Figure S14).

The <sup>64</sup>Cu-radiolabeled compounds ([64Cu]**1**–**4**) were produced in near quantitative yields (*n* = 2–4/compound/molar activity ranging between 16 and 20 GBq/µmol) by reaction of with [64Cu]CuCl<sup>2</sup> in 1.0 M NH4OAc-buffer (pH = 8) at 37 ◦C for 30 min (Scheme 1B). The radiochemical purities were ≥97% as determined analytical radio-RP-HPLC and compounds [64Cu]**1**–**4** used without further purification. Analytical radio-RP-HPLC retention times were: [64Cu]**1**—19.05 min (Figure S6); [64Cu]**2**—18.68 min (Figure S9); [64Cu]**3**— 17.01 min (Figure S12); and [64Cu]**4**—16.73 min (Figure S15).
