Background: The hypoxic microenvironment promotes tumor resistance to most treatments, especially highly oxygen-dependent sonodynamic therapy (SDT).
Method and Results: In view of the aggravation of hypoxia by oxygen consumption during SDT, a biomimetic drug delivery system was tailored to integrate SDT with hypoxia-specific chemotherapy. In this system, mesoporous titanium dioxide nanoparticles (mTNPs) were developed to deliver the hypoxia-activated prodrug AQ4N with high loading efficiency. Subsequently, a red blood cell (RBC) membrane was coated onto the surface of mTNP@AQ4N. RBC-mTNPs@AQ4N inherited the immune escape ability from RBC membranes, thus efficiently reducing the immunological clearance and improving the work concentration. Upon activation by ultrasound (US), mTNPs as sonosensitizers generate reactive oxide species (ROS), which not only induce apoptosis and necrosis but also disrupt RBC membranes to achieve the US-mediated on-demand release of AQ4N. The released AQ4N was activated by hypoxia to convert into toxic products, which effectively supplemented the inefficiency of SDT in hypoxic tissues. Importantly, SDT-aggravated hypoxia further potentiated this hypoxia-specific chemotherapy of AQ4N.
Conclusion: Based on the sequential strategy, RBC-mTNPs@AQ4N exhibited an excellent synergistic therapeutic effect, thus potentially advancing the development of SDT in cancer treatments.
Keywords: sonodynamic therapy, hypoxia, mesoporous titanium dioxide nanoparticle, biomimetic, sequential therapies