Nucleophilic Reactions of Phosphorothioate Oligonucleotides

Abstract The nucleophilic reaction between phosphorothioate oligonucleotides and electrophilic reagents has become a cost‐effective and efficient approach for oligonucleotide functionalization. This method allows for the precise incorporation of desired chemical structures at specific sites on the phosphorothioate backbone through conjugation with electrophilic groups. The reaction is characterized by its high reactivity and yield, as well as its ability to enhance the hydrophilicity of otherwise hydrophobic compounds. Importantly, this modification preserves the structural and functional integrity of the oligonucleotides, making it a topic of significant interest in nucleic acid research. This article reviews recent advancements in the covalent conjugation of phosphorothioate oligonucleotides with various electrophilic compounds. The article starts with an overview of the mechanisms and general reaction conditions involved in nucleophilic reactions. It then proceeds to examine the distinctive properties and benefits of various electrophilic reagents, offering insights that can inform the rational design of phosphorothioate oligonucleotide functionalization. Finally, the article addresses both the challenges and opportunities in this field, providing perspectives on future theoretical and practical developments to enhance the application of phosphorothioate oligonucleotides in areas like structural analysis, drug develop, drug delivery, fluorescent labeling, and nucleic acid nanotechnology.