Altered metabolism has been recognized as a core feature of cancer; however, spatiotemporal tracking of metabolic pathway-specific imaging in cancer cells remains a challenging task. Here we have successfully developed a photochromic fluorescent probe CM generated by coupling coumarin fluorophore and spiropyran (SP) to precisely monitor Cysteine (Cys) metabolic processes by remote light control. Cys was endogenously metabolized to produce SO2, equilibrating with sulfites (SO32–)/bisulfites (HSO3–). The dynamic dual-fluorescence signal was released only after endogenous production of SO2 by Cys and the light-triggered. Consequently, a novel strategy employing light-triggered, synchronized dual-fluorescence blinking was successfully used as a “double-check” assay for Cys metabolism, and the unique response of the probe to Cys/HSO3– in the different spectral behaviors were theoretically characterized using ultraviolet (UV)–visible (vis), fluorescence, density functional theory (DFT) calculations and 1H NMR. What more, the fluorescent imaging of using CM was achieved through the integrated mechanisms of the Forster resonance energy transfer (FRET) and intramolecular charge transfer (ICT). We further show that the in situ UV-activation strategy will significantly reduce interference from false-positive signals during probe transport within cells, thereby offering practical potential for accurate early cancer diagnosis.
Zhu et al. (Thu,) studied this question.