Multisynergistic Platform for Tumor Therapy by Mild Microwave Irradiation-Activated Chemotherapy and Enhanced Ablation

Microwave (MW) therapy, as a promising type of thermal therapy, has been attracting more and more attention from scientists. The combination of thermal and chemotherapy is of great significance in the latest studies of synergistic tumor therapy. However, the research on the MW therapy mechanism, especially the nonthermal effect applied in the combined cancer therapy, is not thorough enough. Pleasantly, we have discovered that nonthermal MW irradiation can promote the cellular uptake of nanoparticles and anticancer drugs <i>via</i> experiments <i>in vitro</i> and <i>in vivo</i>. Therefore, multifunctional nanoplatforms have been designed for enhanced tumor inhibition by loading ionic liquids (ILs), doxorubicin hydrochloride (DOX), and phase change materials (PCMs) into ZrO₂ hollow nanoparticles. PCMs act as MW switches. The as-made IL-DOX-PCM@ZrO₂ nanoplatforms were injected into H22-tumor-bearing mice <i>via</i> the tail vein. Mild microwave irradiation (0.9 W, 450 MHz) was then applied. The thermal effect of MW could cause the temperature of the tumor site to rise (58 °C). On the other hand, it will trigger the MW switch to open and release DOX when the temperature is high enough. At the same time as drug release, a MW nonthermal effect could improve the cellular uptake of nanomaterials and anticancer drugs. The multisynergistic effect can promote the survival rate of the IL-DOX-PCM@ZrO₂+MW group to 100%. The results of the tumor therapy experiment <i>in vivo</i> demonstrated that as-made multifunctional IL-DOX-PCM@ZrO₂ nanoplatforms could enhance the therapeutic outcome of combined thermal and chemotherapy under mild MW irradiation

Additional file 1: Figures S1–S5. of In Vivo Magnetic Resonance Imaging and Microwave Thermotherapy of Cancer Using Novel Chitosan Microcapsules

Figure S1. Size distribution of chitosan, chitosan/Fe3O4 and chitosan/Fe3O4@IL microcapsules were determined by a panel of more than 200 objects in Figure 1b. Figure S2. EDS spectrum of chitosan, chitosan/Fe3O4 and chitosan/Fe3O4@IL microcapsules. Figure S3. TG curve of chitosan, chitosan/Fe3O4 and chitosan/Fe3O4@IL microcapsules. Figure S4. Tumor weight in different groups of mice after various treatments indicated. Figure S5. Magnetization loops of chitosan/Fe3O4@IL microcapsules. Figure S6. FT-IR spectra of IL. (DOC 259 kb