Multifunctional Sensors for Successive Detection of Endogenous ONOO^- and Mitochondrial Viscosity: Discriminating...

Diagnosing cancer in its early stages can play an important role in prolonging the lifespan of patients, which demands the use of powerful tools to detect biomarkers accurately. However, since most fluorescent probes described for cancer diagnosis are limited to recognizing a single molecule, achieving the high accuracy criteria remains difficult. Here, sensor 1 is constructed for the sequential detection of D, ONOO^-, and viscosity. Initially, sensor 1 detected D and underwent an intramolecular charge transfer mechanism, resulting in the formation of 2 and fluorescence quenching at 587 nm. Subsequently, the intermediate (2) monitored ONOO^- and reproduced sensor 1 reversibly with fluorescence enhancement at 496 nm, showing concentration-related quantitative analysis. Similar sensing processes were observed in monitoring ONOO^- and viscosity by synthetically developed sensor 2. The proposed mechanisms of sensors 1 and 2 are verified through various characterizations (¹H NMR, HR-MS, and HPLC) and DFT calculations. Investigations on endogenous ONOO^- and mitochondrial viscosity in cancer (HeLa) and normal (NCM460) cells were conducted to distinguish cancerous cells from normal cells. We anticipated that sensor 2 could effectively serve as a reliable bioanalytical reagent for cancer diagnosis at an earlier stage through sequential detection of two cancer markers, ONOO^- and mitochondrial viscosity, in living cells. Importantly, sensor 2 has been employed for imaging ONOO^- in normal and liver injury mouse models and tissues, achieving outstanding results.