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. 2023 Dec 31;2(2):98–116. doi: 10.1021/cbmi.3c00117

Figure 4.

Figure 4

(a) Schematic illustration of the “smart” FAP-α-activatable FL probe Cbz-GPC(StBu)K(Cou)-CBT to turn the coumarin excimer fluorescence “on” for high-contrast tumor imaging. (b) FL spectra of Cbz-GPC(StBu)K(Cou)-CBT treated with (green) or without (blue) FAP-α and TCEP under the above-mentioned conditions. Inset: corresponding photographs of Cbz-GPC(StBu)K(Cou)-CBT solutions with (or w/o) FAP-α and TCEP [tris(2-carboxyethyl)phosphine] under 365 nm UV irradiation by a handheld UV lamp. (c) In vivo FLI in MIA PaCa-2 tumor-bearing mice after intravenous injection of 5 μmol kg–1 of Cbz-GPC(StBu)K(Cou)-CBT or Ac-GPC(StBu)K(Cou)-CBT. (d) Time course average fluorescence intensities of tumors (dotted circles) of the mice in (c) (mean ± SD, n = 5, ***P < 0.001). Reproduced with permission from ref (55). Copyright 2022 American Chemical Society.