Programmable Tetrahedral DNA‐RNA Nanocages Woven with Stimuli‐Responsive siRNA for Enhancing Therapeutic Efficacy of Multidrug‐Resistant Tumors

Abstract Multidrug resistance (MDR) is a major obstacle limiting the effectiveness of chemotherapy against cancer. The combination strategy of chemotherapeutic agents and siRNA targeting drug efflux has emerged as an effective cancer treatment to overcome MDR. Herein, stimuli‐responsive programmable tetrahedral DNA‐RNA nanocages (TDRN) have been rationally designed and developed for dynamic co‐delivery of the chemotherapeutic drug doxorubicin and P‐glycoprotein (P‐gp) siRNA. Specifically, the sense and antisense strand sequences of the P‐gp siRNA, which are programmable bricks with terminal disulfide bond conjugation, are precisely embedded in one edge of the DNA tetrahedron. TDRN provides a stimuli‐responsive release element for dynamic control of functional cargo P‐gp siRNA that is significantly more stable than the “tail‐like” TDN nanostructures. The stable and highly rigid 3D nanostructure of the siRNA‐organized TDRN nanocages demonstrated a notable improvement in the stability of RNase A and mouse serum, as well as long‐term storage stability for up to 4 weeks, as evidenced by this study. These biocompatible and multifunctional TDRN nanocarriers with gold nanocluster‐assisted delivery (TDRN@Dox@AuNCp) are successfully used to achieve synergistic RNAi/Chemo‐therapy in vitro and in vivo. This programmable TDRN drug delivery system, which integrates RNAi therapy and chemotherapy, offers a promising approach for treating multidrug‐resistant tumors.