Mitoxantrone as photothermal agents for ultrasound/fluorescence imaging-guided chemo-phototherapy enhanced by intratumoral H₂O₂-Induced CO

Multimodal imaging integrated theranostic nanomaterials provides broad prospects for noninvasive and precise cancer treatment. However, the uncertain physiological metabolism of the existing phototherapy nanoagents greatly prevents its clinical application. Herein, a smart nanoplatform based on clinically chemotherapeutic drugs mitoxantrone (MTO) was prepared to realize ultrasound/fluorescence imaging-guided chemo-photothermal combined therapy. The nanoplatform encapsulating MTO and manganese carbonyl (MnCO), which denoted as MCMA NPs, could accumulate at tumor sites by enhanced permeability and retention (EPR) effect and effectively induce cell apoptosis. MTO with near-infrared absorption (~676 nm) not only acted as chemotherapy drug, but also served as photothermal reagent with high photothermal conversion efficiency (ƞ = 42.2%). Especially, H₂O₂ in tumor sites and the photothermal effect of MTO could trigger MnCO to generate CO, which made cancer cells more sensitive to MTO and significantly alleviated cell resistance. Simultaneously, CO released in tumor also could act as contrast agent for tumor ultrasound imaging to provide accurate guidance for anticancer treatment. Moreover, MCMA NPs could further promote oxidative stress damage in mitochondria and protect normal cells from side effects of chemotherapy. Both in vivo and in vitro studies indicated that MCMA NPs possessed excellent synergetic tumor inhibition ability with high efficiency and low chemotherapy resistance.