Synthesis of oligonucleotides carrying anchoring groups and their use in the preparation of oligonucleotide-gold conjugates

Oligodeoxynucleotide conjugates 1-15 carrying anchoring groups such as amino, thiol, pyrrole, and carboxy groups were prepared. A post-synthetic modification protocol was developed. In this method 2′-deoxy-O⁴-(p-nitrophenyl)uridine-3-phosphoramidite was prepared and incorporated in oligonucleotides. After assembly, the modified nucleoside was made to react with different amines carrying the anchoring groups. At the same time, protecting groups were removed to yield the desired oligonucleotide conjugates. In a second approach, amino, thiol, and carboxylic groups were introduced into the 3′-end of the oligonucleotides by preparing solid supports loaded with the appropriate amino acids. Oligonucleotide-gold conjugates were prepared and their binding properties were examined.