“One-for-All”-Type, Biodegradable Prussian Blue/Manganese Dioxide Hybrid Nanocrystal for Trimodal Imaging-Guided Photothermal Therapy and Oxygen Regulation of Breast Cancer

Multimodal imaging-guided diagnosis and therapy has been highlighted in the area of theranostic nanomaterials. To provide more suitable theranostic candidates, Prussian blue (PB)/manganese dioxide (MnO 2 ) hybrid nanoparticles (PBMn) smaller than 50 nm are prepared by a one-pot method. MnO 2, which is reduced from KMnO 4, not only controls the particle size, the optical properties, and the transverse relaxation rate ( r 2 ) of PB but also enhances the catalysis efficacy of PB to H 2 O 2 for oxygen generation. PBMn can serve as a photoacoustic imaging (PAI) and longitudinal relaxation (T 1 ) mode magnetic resonance imaging contrast agent (14 times and 1.8 times of the saline-treated group, respectively). Injection of PBMn can regulate the oxygen partial pressure of the tumor tissue from 2.1 ± 0.2 to 9.3 ± 0.4 kPa and rearrange the ratio of oxygenated hemoglobin and deoxygenate hemoglobin inside the tumor, which favor the enhancement of the diamagnetic T 2 -weighted imaging (T 2 WI) signal intensity (two times that of the saline-treated group). Furthermore, PBMn-mediated PTT can efficiently inhibit the growth of the MCF-7 tumor in vitro and in vivo. PBMn can serve as a PAI/T 1 /T 2 trimodal contrast agent and in imaging-guided PTT, as well as in the oxygen regulation of the exografted breast cancer.