Hollow Manganese Dioxide Nanoparticles for Drug Delivery and Imaging

Nanodrug delivery system (NDDS) has been widely used in tumor diagnosis, chemotherapy, and image-guided surgery. In this work, hollow manganese dioxide nanoparticles (H-MnO2 NPs) were prepared by the template method, followed by loading with Methotrexate (MTX), coating with dopamine (PDA), and coupling with fluorescent dye Cy5.5. Finally, NDDC (MnO2/MTX@PDA-Cy5.5 NPs, MMPC NPs), capable of dual-mode imaging and chemotherapy, was successfully synthesized. MMPC NPs can realize high-efficiency loading of MTX and continuous release of the pH response in vitro. The NPs loaded with MTX showed higher cytotoxicity than free MTX. A confocal laser scanning microscope showed the high-level uptake of MMPC NPs by 8305C cells. Both the near-infrared fluorescence imaging and magnetic resonance (MR) imaging demonstrated a notable long-term accumulation and retention of MMPC NPs in model mouse tumors. Therapeutic experiments in vivo showed that MCPC has excellent tumor therapeutic effects and biological safety. These results suggest that MnO2-based nanodrug delivery systems capable of delivering MTX for tumor therapy and enhancing MR imaging contrast are good candidates for cancer diagnosis and treatment.