Figure 12.

(A): Confocal red fluorescence images of NQO1-positive cancer cells and NQO1-negative normal cells after incubation of 10 µM NIR-ASM for 1 h. The cell nuclei were counterstained with Hoechst 33342 (reproduced from ref. [168] with permission). (B): Results of live animal fluorescence imaging of endogenous NQO1 activity in A549 tumor xenografts after intravenous administration of NIR-ASM (5 mg/kg) to tumor-bearing nude mice (reproduced from ref. [168] with permission). The upper panel shows mice with NQO1-proficient A549 tumors and the lower panel shows the same animal with both A549 and NQO1-deficient MDA-MB-231 tumors on the left and right flanks respectively. Tumors and organs were harvested from the A549 tumor-bearing mice after NIR-ASM injections and imaged for ex vivo fluorescence as well. Fluorescence only in the tumor but not in the spleen (Sp), pancreas (Pa), lungs (Lu), brain (B), heart (H), kidneys (Ki), liver (Li), and intestine is evident, showing specificity.