Antisense DNA and siRNA are widely used for gene silencing in research and medical applications. An effective delivery of the oligonucleotides into cells is important for clinical applications. As oligonucleotides are negatively charged the efficiency of the cell membrane permeability is low. Previous methods took several hours to deliver oligonucleotides to cytoplasm. Oligonucleotides modified with low molecular weight disulfide groups at their terminal residues reached the cytoplasm in 10 minutes as a result of disulfide exchange reactions with the thiol groups on cell surface.1)
Due to the hydrophobic character of the disulfide units, a less hydrophobic stationary phase is necessary for the analysis of the modified oligonucleotides. Even C18 columns with lower hydrophobicity such as Hydrosphere C18 achieve poor peak shapes. Also, the target disulfide modified oligonucleotides are not completely eluted.
Figure 1: Structure of disulfide modified oligonucleotides.>> Download the full Application Note as PDF
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