Platelet-mimicking nanoparticles co-loaded with W18O49 and metformin alleviate tumor hypoxia for enhanced photodynamic therapy and photothermal therapy

W18O49-mediated photodynamic therapy (PDT) and photothermal therapy (PTT) are limited by the easily oxidized property and tumor hypoxia. Here, we report the development of platelet membranes as nanocarriers to co-load W18O49 nanoparticles (NPs) and metformin (PM-W18O49-Met NPs). Platelet membranes can protect W18O49 from oxidation and immune evasion, and increase the accumulation of W18O49 in tumor sites via the passive EPR effect and active adhesion between platelets and cancer cells. The introduction of metformin (Met), a typical anti-diabetic drug, can alleviate the tumor hypoxia through reducing oxygen consumption. As a result, ROS and heat generation are both greatly increased, as revealed by ROS/hypoxia imaging in vitro, IR thermal imaging in vivo and PET imaging in vivo. PM-W18O49-Met NPs show the improved therapeutic effects with greatly inhibited tumor growth and induced tumor cell apoptosis. Therefore, our work provides a novel strategy for simultaneous enhanced PDT and PTT, which is promising in bioapplication. (C) 2018 Acta Materialia Inc. Published by Elsevier Ltd.