Ferroptosis Accompanied by •OH Generation and Cytoplasmic Viscosity Increase Revealed via Dual-Functional Fluorescence Probe

Ferroptosis, a new form of regulated cell death, results from the iron-dependent accumulation of lipid peroxides that are associated with reactive oxygen species. However, it remains unclear how hydroxyl radical ( • OH) and cellular microenvironments such as viscosity alter in this process. Herein, we characterize for the first time the changing behavior of • OH and cytoplasmic viscosity during ferroptosis using a dual-functional fluorescence probe (H–V) that is designed via the molecular rotor strategy and the unique aromatic hydroxylation of • OH. Probe H–V shows completely separate spectral responses to • OH and viscosity with high sensitivity and selectivity, thereby achieving the detection of • OH and viscosity in two independent channels without spectral cross-interference. With the probe we find that ferroptosis is accompanied by significant • OH generation and cytoplasmic viscosity increase. Most notably, the raised • OH comprises the majority of the total reactive oxygen species in ferroptosis. H–V is biocompatible, ready to prepare, and may be expected to be used in the study of viscosity and • OH detection in more biosystems.