An Efficient and Versatile Solid-Phase Synthesis of 5‘- and 3‘-Conjugated Oligonucleotides

Abstract

[reaction: see text] An easy and efficient solid-phase strategy to obtain 5'- and 3'-oligonucleotide conjugates in highly pure form has been developed. Ad hoc derivatized solid supports, to which the first nucleoside unit can be attached through a phosphate linkage, have been exploited both in a pre- and post-DNA assembly conjugation approach. A number of 5'- or 3'- oligonucleotide conjugates, incorporating a variety of labels covalently linked through a phosphodiester or a phosphoramidate bond, have been synthesized and characterized.

PEGylation of therapeutic oligonucletides: From linear to highly branched PEG architectures

“…Gel permeation chromatography (GPC) is rarely conducted to purify linear PEG-ON conjugates, owing to the limited size increase after PEGylation. Solid-phase coupling of PEG to CPG-supported ONs simplifies the purification by ensuring that there is no unreacted PEG, and also produces conjugates with the correct ON sequence (failed strands are capped during synthesis and therefore cannot be PEGylated) [75]. Nevertheless, as is the case for PEG phosphoramidites, the PEG M W is a limiting factor for solid-phase synthesis, and the synthesis is generally limited to small-to-medium scale.…”

Impacts of PEGylation on the gene and oligonucleotide delivery system

“…Several methods for the synthesis of PEGylated oligonucleotides have been reported . Most of these are based on a conjugation between end‐reactive PEG and oligonucleotides in the liquid phase.…”

Synthesis of Oligonucleotide Conjugates and Phosphorylated Nucleotide Analogues: An Improvement to a Solid Phase Synthetic Approach

“…Initially, inspired by Pedroso's procedure previously developed for the solid phase synthesis of cyclic ODNs [36], we prepared a small library of thymidine analogues conjugated at the 5 -position with a set of representative • NH 4 OH conc., 1 h, 50 ∘ C. alcohols and amines [22]. Later, a number of 5 -or 3 -ODN and 3 -oligoribonucleotide conjugates, incorporating a variety of labels covalently linked through a phosphodiester or a phosphoramidate bond, were synthesised and characterised [23,24,37]. In all cases, ad hoc derivatised solid supports, to which the first nucleoside unit was attached through a phosphate linkage, have been exploited (Scheme 1).…”

“…As part of our continuing effort towards the synthesis of new solid supports that are useful for generating pharmacologically interesting molecule libraries [22][23][24][25][35][36][37][38][39][40] of high quality in large quantities, we present here an improvement of our solid phase strategy discussed above. Aiming to achieve the synthesis of a solid support with a higher load than that currently available and that is also compatible with phosphoramidite and phosphotriester chemistry, we devised a straightforward and efficient synthetic protocol to prepare a new support in which the loading of the o-chlorofunctional group is very high (0.20-0.50 meq/g).…”