A Multifunctional Nanovaccine based on L-Arginine-Loaded Black Mesoporous Titania: Ultrasound-Triggered Synergistic Cancer Sonodynamic Therapy/Gas Therapy/Immunotherapy with Remarkably Enhanced Efficacy

In order to achieve better antitumor therapeutic efficacy and inhibit tumor metastasis, a multifunctional nanovaccine based on L-arginine (LA)-loaded black mesoporous titania (BMT) is fabricated. In this system, LA is utilized as the exogenous NO supplementation for gas therapy, and BMT is served as acoustic sensitizer for sonodynamic therapy. The ultrasound (US) as the exogenous stimulus can simultaneously trigger BMT and LA to produce singlet oxygen (O-1(2)) and NO gas at tumor sites, respectively. Interestingly, O-1(2) from US-excited BMT can promote the oxidation of LA to produce more NO. The high concentration of O-1(2) and NO in cancer cell can cause intracellular strong oxidative stress level and DNA double-strand breaks to induce cancer cell apoptosis ultimately. The US-triggered BMT@LA "nanovaccine" combining with immune checkpoint inhibitor PD-L1 antibody (alpha PD-L1) can induce strong antitumor immune response thus effectively killing primary tumors and further inhibiting metastatic tumors. Hence, BMT@LA-based "nanovaccine" combining with alpha PD-L1 checkpoint blockade treatment can realize synergetic sonodynamic/gas/immunotherapy with enhanced antitumor therapeutic effects.