Aptamer-incorporated DNA Holliday junction for the targeted delivery of siRNA

There have been unmet needs of developing carrier-free siRNA delivery systems to overcome the undesirable cellular toxicity and immunogenicity of conventional delivery systems such as cationic lipids and polymers. Various nucleic acid nanostructures have been proposed to achieve this goal, however many of them required potent ligands for the intracellular delivery of siRNA. Among various ligands, aptamers received much interest due to their facile preparation process as well as a high binding affinity toward target receptors. In addition, nucleic acid based aptamers can be easily incorporated with various nucleic acid nanostructures through a simple base-pair hybridization. In this study, aptamer incorporated siRNA (Apt-siRNA) was self-assembled with DNA Holliday junction for enhancing targeted delivery of siRNA to the Mucin 1 (MUC1) overexpressing cancer cells. Molecularly self-assembled Holliday DNA junction with Apt-siRNA was analyzed to confirm their cellular uptake and gene silencing as compared to the Apt-siRNA alone in the GFP expressing KB cells. The multivalent Apt-siRNA DNA nanostructure (Holliday-Apt-siRNA) clearly showed their superior potency over the Apt-siRNA alone suggesting their use in carrier-free siRNA delivery systems.