NTSR1 and neoplasm: We next assessed its capability to ultimately afford effective contrast levels (ie, TBRs) upon bioreductive activation by NTR activity post‐administration of NO2‐Rosol to murine GBM39 tumor models by assessing the ability of the NIR fluorescent smart probe to (i) promptly diffuse throughout the tumor tissue upon its administration, (ii) immediately undergo biochemical transformation into its active form, and (iii) maintain a sufficient retention and clearance profile for repeated imaging.