A novel NIR fluorescent probe to image HNO during ferroptosis.

BACKGROUND

As an important reactive nitrogen species (RNS), HNO has been identified as an essential signaling molecule in many physiological processes. Ferroptosis produces a large amount of reactive oxygen species and reactive nitrogen species. However, the detailed mechanism of HNO during process of ferroptosis is rarely reported, especially in the near-infrared range. So, we designed a new near-infrared (NIR) HNO fluorescent probe X-1 based on a tricyanofuran (TCF) derivative and then applied it in ferroptosis imaging. The TCF derivative was chosen as the NIR fluorophore and 2-(diphenylphosphino)benzoate was used as the recognition group.

RESULTS

In this paper, a novel NIR HNO fluorescent probe X-1 based on tricyanofuran (TCF) derivatives was synthesized using the Staudinger linkage reaction. X-1 exhibited high selectivity for HNO in the near-infrared region (λem = 660 nm). When the recognition group undergoes the Staudinger linkage reaction with HNO, the NIR fluorescence emission increased significantly with the enhancement of the ICT effect. The response mechanism of X-1 to HNO was verified by high-resolution mass spectrometry (HRMS). Probe X-1 has the advantages of fast response (5 min), low detection limit, a large Stokes shift (120 nm) and strong anti-interference ability for HNO recognition. CCK-8 staining result indicates that the probe X-1 has good biocompatibility and little toxic effect on the cells. The probe was successfully applied to imaging the exogenous and endogenous HNO in living cells.

SIGNIFICANCE: In the near-infrared range, HNO was discovered as a mediator of cellular signaling molecules, increasing in concentration during the process of ferroptosis. Furthermore, using this probe, it was further verified that sorafenib, a commonly used drug for cancer treatment, exerts its therapeutic effect by inducing ferroptosis in cancer cells, leading to cell death.