pH-Triggered Pinpointed Cascading Charge-Conversion and Redox-Controlled Gene Release Design: Modularized Fabrication for Nonviral Gene Transfection

Although pH and reduction responses are widely applied on gene and drug delivery system, the undefined molecule and disconnected response to corresponding transfection barriers still hamper their further application. Here, a multistage-responsive lipopeptides polycation-DNA nanoparticles (namely KR-DC) as gene vector is designed, consisting of three functional modules. It provides the following outstanding “smart” characteristics: i) facile manufacture and ease to adjust ingredients for different conditions, ii) negatively charged surface to remain stable and increase biocompatibility in physiological environment, iii) pH-triggered cascading charge-conversion corresponding to tumor extracellular pH and endo/lysosomal pH, iv) the first stage of charge reversal for uptake enhancement at tumor site, v) the second stage of charge conversion for rapid endosomal escape, vi) the third stage of redox degradation aiming at DNA controlled release and nuclear entry, vii) cell-penetrating peptides mimicking arginine-rich periphery targeting to membrane penetration capacity improvement, and viii) lipid forming hydrophobic cavity for potential fat-soluble drug encapsulation. Finally, KR-DC nanoparticles achieve significantly enhanced in vitro transfection efficiency by almost four orders of magnitude in manual tumor environment with reduced side effects and satisfying gene expression in Hela xenograft tumor model in vivo.