Delivery Pathway Regulation of 3',3″-Bis-Peptide-siRNA Conjugate via Nanocarrier Architecture Engineering

Small interfering RNA (siRNA) has been continuously explored for clinical applications. However, neither nanocarriers nor conjugates have been able to remove the obstacles. In this study, we employed a combined nanochemistry strategy to optimize its delivery dilemma, where different interactions and assembly modes were cooperatively introduced into the forming process of siRNA/lipids nanoplexes. In the nanoplexes, the 3',3″-bis-peptide-siRNA conjugate (pp-siRNA) and gemini-like cationic lipids (CLDs) were employed as dual regulators to improve their bio-behavior. We demonstrated that the "cicada pupa"-shaped nanoplexes of MT-pp-siRNA/CLDs (MT represented the mixed two-phase method) exhibited more compact multi-sandwich structure (∼25 layers), controllable size (∼150 nm), and lower zeta potential (∼22 mV) than other comparable nanoplexes and presented an increased siRNA protection and stability. Significantly, the nanoplex was internalized into melanoma cells by almost caveolae-mediated endocytosis and macropinocytosis (∼99.46%), and later reduced/avoided lysosomal degradation. Finally, the nanoplex facilitated the silencing of mRNA of the mutant B-Raf protein (down by ∼60%). In addition, pp-siRNA had a high intracellular sustainability, a significantly prolonged circulating time, and accumulation in tumor tissues in vivo. Our results have demonstrated that the combined approach can improve the intracellular fate of siRNA, which opens up novel avenues for efficient siRNA delivery.