Synthesis and properties of radiolabeled CPTA–oligonucleotides

Abstract

SummaryA solid phase technique for the preparation of antisense oligodeoxynucleotides (ODNs) is described featuring 5 0 -end conjugated 4-[(1,4,8,11-tetraazacyclotetradec-1-yl)-methyl]benzoic acid (CPTA). Using Fmoc-protected CPTA-C6 amidite, CPTA was conjugated to ODNs at the end of an automated DNA synthesis. To illustrate successful conjugations, the CPTA-ODNs were labeled with 99m Tc using the stannous-chloride reduction method. The resulting 99m Tc complexes showed differences of stability between CPTA-conjugated and CPTA-unconjugated as well as 3 0 -protected and 3 0 -unprotected ODNs. Propane-1,3-diol 3 0 -modification enhanced efficiently the stability of 99m Tc labeled ODN against exonuclease degradation. Fmoc 3 CPTA-C6 amidite turned out to be a versatile ligand for radiometal complexation at the 5 0 -end.