Figure 4.

(A) Synthetic route for histidine-modified dextran and the fabrication of pH-responsive metallo-supramolecular nanogels. Reprinted with permission from ref (19). Copyright 2015 Elsevier. (B) Preparation of extremely small iron oxide nanoparticles encapsulated with poly(carboxybetaine methacrylate) nanogels and modification with the c(RGD) ligand as an activatable MRI contrast agent with switchable function from a T₂ contrast agent to a T₁ one through the stimuli-responsiveness toward glutathione. Reprinted with permission from ref (32). Copyright 2020 American Chemical Society.