Fig. 3. Nanotube stability and preferential uptake by the tumor.

(A) Stability of nanotubes in different concentrations of serum, DNase I, exonuclease III, and T5 exonuclease. (B) Schematic of bilateral intracranial injections of nanotubes to a mouse with GL261 tumor only on the right hemisphere of the brain. NIR fluorescence images of mouse brains excised at different time points: mouse 1 at 45 min, mouse 2 at 70 min, and mouse 3 at 105 min. Control mouse had a GL261 tumor but did not receive intracranial nanotube injections. The radiant efficiency of NIR fluorescently labeled nanotubes is shown with a heat map. (C) Mice bearing orthotopic tumors of GL261 cells expressing GFP (GL261-GFP) were intracranially injected with HEX-labeled nanotubes. Mice were euthanized 3 hours after nanotube injection, and tumor tissues were removed and processed. Maximum-intensity projection of a confocal microscopy image shows colocalization of GL261 cells (green) with the nanotubes (red). Scale bars, 20 μm.