Precise Preparation of Supramolecular Spherical Nucleic Acids for Nucleolin‐Targeted Gene Delivery

Molecular spherical nucleic acids (m‐SNAs) are a second generation of spherical nucleic acids (SNAs), which are of significance in potential application of targeted delivery of nucleic acids or gene regulation due to their defined molecular structures. Nevertheless, m‐SNAs typically involve a single DNA sequence which greatly limits its functions as either targeting purpose or gene regulation. In response, we proposed here a third generation, supramolecular spherical nucleic acids (Supra‐SNAs) with two different sequences to achieve both above‐mentioned functions. Specifically, we constructed a series of supramolecular self‐assembly structures by coupling a cell membrane receptor (i.e., nucleolin)‐recognizing aptamer (AS1411)‐modified adamantine as targeting probe and human epithelial growth factor receptor 2 (HER2) antisense‐functionalized β‐cyclodextrin to specifically inhibit the overexpression of HER2 proteins for gene regulations. In comparison to the m‐SNA precursors, such Supra‐SNA structures exhibited enhanced levels of resistance to nuclease degradation, cellular uptake, gene regulation capabilities and tumor retention capacity. We demonstrated that Supra‐SNAs exhibited optimal cell suppression rates and cell apoptosis via a phosphatidylinositol 3‐kinase/protein kinase B signaling pathway. The well‐defined molecular structures provide an attractive platform for investigating interrelationship between structure and property at the molecular level.