Co-Delivery of Doxorubicin and Survivin shRNA-Expressing Plasmid Via Microenvironment-Responsive Dendritic Mesoporous Silica Nanoparticles for Synergistic Cancer Therapy.

The present study is aimed at designing an appropriate co-delivery system for chemotherapeutic drugs and gene drugs with high loading capacity, on-demand release behaviors, efficient endosomal escape, and enhanced nucleic localization, thereby providing efficacious antitumor activity. Schiff-base linked imidazole dendritic mesoporous silica nanoparticles (SL-IDMSN) were developed and employed to load doxorubicin (DOX) and survivin shRNA-expressing plasmid (iSur-pDNA) to form nanocomplexes. The nanoparticles were assessed by structural characterization, drug loading and release, cellular uptake, intracellular distribution, gene transfection, in vitro anti-proliferation of hepatoma cells, and in vivo tumor growth inhibition in H-22 tumor bearing mice. SL-IDMSN showed high loading capacity for both DOX and iSur-pDNA due to their hierarchical mesostructures. The cleavage of Schiff-base linkage on SL-IDMSN in the weakly acidic endosomes/lysosomes led to microenvironment-specific release of both DOX and iSur-pDNA. Meanwhile, the imidazole modification could trigger the efficient endosomal escape via proton sponge effect, thereby enhancing nuclear accumulation of iSur-pDNA and gene silencing efficiency. More importantly, these superior performances of SL-IDMSN resulted in their improved inhibitory effects on in vitro cancer cell proliferation and in vivo tumor growth. SL-IDMSN is a microenvironment-sensitive and biocompatible nanocarrier for the co-delivery of DOX and iSur-pDNA, which might be a promising carrier for co-delivery of chemotherapeutic drugs and gene drugs for synergistic cancer therapy.