Figure 3. Schematic illustration of loading Gd-HPDO3A into the interiors of ferritins.

The nanocages were first disassembled by lowering the pH to 2. Gd-HPDO3A (designated as Gd in the figure) was added to the solution at the low pH. When the pH was tuned back to neutral, the nanocages were reconstituted and Gd-HPDO3A was encapsulated. Reprinted with permission from ref [29].