Figure 7.

Mechanism of molecular MRI for intracellular TF proteins. A) The 3 major components of the nanoparticle-dsDNA aptamer: short dsDNA aptamer, avidin-biotin linkage or direct linkage, and MR contrast agent or microscopy agent. B) Proposed endocytosis pathway of DNA-mediated nanoparticle uptake. C) Once internalized, DNA aptamer binds to TF protein, whereby the nanoparticles remain within the unique cells that express the TF protein. C1–C3) Potential applications after target binding. D) If dsDNA does not bind to TF protein, the nanoparticles are excluded from the cell, and no image data can be acquired (Fig. 6D3). When the dose is sufficient to compete for intracellular TF protein, modulation by the TF protein is prevented (C3).