Figure 7.

Strategies for controlling rotational dynamics of mutimeric, targeted contrast agents. A) a single targeting group results in significant internal motion when the complex is bound to the protein, resulting in decreased relaxivity. B) Binding through two sites rigidifies the complex at the target, minimizes internal motion and increases relaxivity. C) Heteroditopic approach to control dynamics: incorporate second, low affinity binding moiety into molecule to anchor complex at the target and increase relaxivity.