Tandem Oligonucleotide Synthesis Enabled by a Reducible Linker

Tandem oligonucleotide synthesis (TOS) is accomplished via the introduction of a cleavable backbone linker within a single sequence. Multiple oligonucleotide fragments are released upon immolation of the cleavable linker(s). Here, we revisit the use of a commercially available disulfide-containing building block, typically utilized for the introduction of terminal thiol functionality in DNA/RNA oligomers to perform TOS in various contexts. As expected, the disulfide linkage is orthogonal to the standard DNA/RNA production workflow. Upon reduction, the disulfide is efficiently cleaved, resulting in the corresponding strand fragments, each containing thiol modification(s). We showcase the utility of this methodology by assembling a model crosslinked small interfering RNA (siRNA) construct. Furthermore, we report compatibility of this TOS with selected (bio)conjugation techniques. Overall, our development will find applications in various biotechnology contexts.