Figure 6.

Biodistribution and NIR fluorescence recovery of SiNc-PNPs in nude mice and tumors. (A) Fluorescence images of the nude mice with subcutaneous cancer tumors before and 2, 10, and 24 h after i.v. administration of activatable and always-ON SiNc-PNP and compared to IR775-NP. (B) Fluorescence images of various organs and tumors were acquired at 24 h post-injection. (C) Fluorescence image of tumor cross-section (the core of the 300 mm³ tumor). Scale bar is 100 µm. (D) Tumor-to-normal tissue (T/N) analysis of fluorescence intensity in subcutaneous tumors and organs harvested from mice 24 h after injection with IR775-NP, activatable and always-ON nanoparticles. *P < 0.05 when activatable nanoparticles are compared with always-ON nanoparticles. ^†P < 0.05 when activatable nanoparticles are compared with IR775-NP. Distribution of (E) bioluminescence and (F) SiNc-generated NIR fluorescence in the abdominal cavity 24 h after i.p. injection of activatable SiNc-PNP into mice with intraperitoneal xenograft of luciferase-labeled ES2 ovarian cancer cells. Note: only cancer tissues generate bioluminescence signal in D-luciferin-injected animals.