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.