Mitochondria-Targeted Mesoporous Titanium Dioxide Nanoplatform for Synergistic Nitric Oxide Gas-Sonodynamic Therapy of Breast Cancer

BACKGROUND: Sonodynamic therapy (SDT) has rapidly advanced as a promising alternative to conventional photodynamic therapy owing to its preferable therapeutic depth. However, single-modal SDT exhibits limited efficacy due to the long-term hypoxia in tumors. METHOD AND RESULTS: To address these issues, we proposed a synergistic SDT strategy that integrates mitochondrial targeting with nitric oxide (NO) gas therapy by using multifunctional nanoplatforms. The nanoplatform, which was named as T-mTNPs@L-Arg, was composed of mesoporous titanium dioxide loaded with the NO donor precursor L-arginine (L-Arg) and modified with triphenyl phosphonium (TPP), a mitochondria-targeting ligand. Therefore, T-mTNPs@L-Arg could efficiently concentrate into mitochondria and release NO gas as well as generate reactive oxygen species (ROS) with ultrasound stimulus. Importantly, the released NO gas exerted multiple synergies with SDT, including inducing NO poisoning, generating more lethal reactive nitrogen species (RNS) by reaction with ROS, and alleviating hypoxia through NO-mediated mitochondrial respiration inhibition. On account of the synergistic effects, T-mTNPs@L-Arg showed an outstanding SDT efficacy and a reduced side effect. CONCLUSION: This work designed a nanoplatform to integrate mitochondria targeting, SDT and NO gas therapy, providing a new strategy for highly efficient breast cancer therapy.