Figure 4.

(A) Schematic that MnO₂ NPs enhance the magnetic resonance contrast under endogenous stimulation. (B) Optical (above) and fluorescent images (below) of MnO₂ nanosheet−sgc8 nanoprobe to target cells. (C) T1- and T2-weighted MRI of MnO₂ nanosheet solution treated with GSH. Reproduced with permission from Zhao ZL, Fan HH, Zhou GF, et al. Activatable Fluorescence/MRI Bimodal Platform for Tumor Cell Imaging via MnO₂ Nanosheet-Aptamer Nanoprobe. Journal of the American Chemical Society. 2014;136(32):11220–11223.⁸² Copyright © 2014 American Chemical Society. (D) Phosphorescence images and T2-weighted MR images of a tumor-bearing mouse and a NEM-pretreated tumor-bearing mouse after injected with Ru(BPY)₃@MnO₂ for 15 mins. Reproduced from Shi W, Song B, Shi W, et al. Bimodal Phosphorescence-Magnetic Resonance Imaging Nanoprobes for Glutathione Based on MnO₂ Nanosheet-Ru(II) Complex Nanoarchitecture. ACS Appl Mater Interfaces. 2018;10(33):27681–27691.⁸³ Copyright © 2018 American Chemical Society. (E) T1- and T2-MRI of tumors with Fe₃O₄@C@MnO₂ NPs. Reproduced from Duan B, Wang D, Wu H, et al. Core–Shell Structurized Fe₃O₄@C@MnO₂ Nanoparticles as pH Responsive T1-T2* Dual-Modal Contrast Agents for Tumor Diagnosis. ACS Biomaterials Science & Engineering. 2018;4(8):3047–3054.⁸⁴ Copyright © 2018 American Chemical Society.

Abbreviation: NEM, N-ethylmaleimide.