Preparation of 177Lu-DOTA/DTPA-Bz-Cys-RGD dimer and biodistribution evaluation in normal mice

177Lu-DOTA-Bz-Cys-RGD dimer and 177Lu-DTPA-Bz-Cys-RGD dimer were prepared, and the in vitro and in vivo properties were compared. TLC and HPLC show that the labeling yields of two radiolabeled compounds are more than 95% under optimal conditions (pH=5.0, reacting at 100 degree C for 15-20 min), and the two radiolabeled compounds show pretty good in vitro stability. HPLC analyses and lg P values reveal that lipophilicity of 177Lu-DOTA-Bz-Cys- RGD dimer is higher than 177Lu-DTPA-Bz-Cys-RGD dimer. The uptake of 177Lu-DTPA-Bz-Cys- RGD dimer in other tissues is significantly higher than that of 177Lu-DOTA-Bz-Cys-RGD dimer at 4 h postinjection, except for blood and spleen. The in vivo stability of 177Lu-DOTA-Bz-Cys-RGD dimer is much better than 177Lu-DTPA-Bz-Cys-RGD dimer. Bz-DOTA is an ideal bifunctional chelator for 177Lu labeling of RGD dimer. (authors)