Radiosynthesis, biodistribution and micro-SPECT imaging study of dendrimer-avidin conjugate

Partially acetylated generation five polyamidoamine (PAMAM) dendrimer (G5-Ac) was reacted with biotin and 2-(p-isothiocyanatobenzyl)-6-methyl-diethylenetria minepentaacetic acid (1B4M-DTPA), respectively to form the complex Bt-G5-Ac-1B4M which was further conjugated with avidin to give the conjugate Av-G5-Ac-1B4M. Then both of the conjugates were radiolabeled with technetium-99m (Tc-99m), respectively. Their in vitro cellular uptake study shows that the conjugate of Av-G5-Ac-1B4M-Tc-99m exhibits much higher cellular uptake in HeLa cells than that of Bt-G5-Ac-1B4M-Tc-99m. Accordingly the following evaluation such as in vitro/in vivo stability, biodistribution and micro-SPECT imaging was observed only for the conjugate of Av-G5-Ac-1B4M-Tc-99m. (C) 2011 Elsevier Ltd. All rights reserved.