Near-infrared BODIPY-based two-photon ClO− probe based on thiosemicarbazide desulfurization reaction: naked-eye detection and mitochondrial imaging

Hypochlorite serves as a significant antimicrobial agent in the human immune system, and its detection is of great importance. Herein, a novel near-infrared BODIPY-based ClO^- fluorescent probe (NCS-BOD-OCH₃) was designed and synthesized. The emission bands of NCS-BOD-OCH₃ concentrated at 595 nm and 665 nm. Since the electron withdrawing group 1,3,4-oxadiazole was formed after the desulfurization reaction, the fluorescence intensity of NCS-BOD-OCH₃ decreased significantly in THF/H₂O (v/v, 1 : 1, buffered with 10 mM PBS pH = 7.4), which is visible to the naked eye with an obvious color change. NCS-BOD-OCH₃ can realize the two-photon up-converted fluorescence emission. The low detection limit was calculated from the titration results, with the figure for NCS-BOD-OCH₃/ClO^- being 1.15 × 10^-6 M. The result of living cell imaging experiment demonstrated that NCS-BOD-OCH₃ can successfully detect ClO^- in living cells and can serve as a NIR mitochondrial imaging agent. It is an excellent platform for developing NIR ClO^- fluorescent probes.