Synthesis of Tc-99m-labeled, modified RNA

The synthesis of Tc-99m-labeled, modified RNA is reported. This new class o f radiopharmaceuticals is of potential interest as target specific imaging agents. The preparation of NBS-conjugated RNA was achieved by coupling S-pr otected MAG(2)-units to amino modified RNA in solution or on solid support. The starting S-protected MAG(2) building blocks (R-1-S-CH2-CO-Gly-Gly-R-2: R-1 = Ac, Bu-t-S; R-2 = OH, OSu) were obtained by a simple 4- or Ei-step s ynthesis. The MAG,amide-RNA-conjugates were successfully Tc-99m-labeled wit h high yield and specific activities of 37MBq/nmol leading to 1:1-Tc-99m-N3 S-aptamers. (C) 1998 Elsevier Science Ltd. All rights reserved.