A D-π-A conjugated probe with dual responses to bisulfite and microenvironmental viscosity/polarity for imaging ferroptosis in neural cells.

Ferroptosis is a form of programmed cell death characterized by lipid peroxidation and changes in the cellular microenvironment (such as increased viscosity and decreased polarity). Currently, there are still relatively few fluorescent probes capable of simultaneously responding to both bisulfite levels and microenvironmental changes. To address this, we designed and synthesized a fluorescent probe with a D-π-A conjugated structure. Based on the intramolecular charge transfer (ICT) mechanism, this probe exhibits dual responsiveness to bisulfite and the microenvironment (viscosity/polarity) and is used for ferroptosis imaging in neural cells. Spectroscopic studies indicate that bisulfite selectively adds to the probe's conjugated double bond, blocking the ICT process and inducing a significant fluorescence enhancement in the green fluorescence channel. The probe exhibits high sensitivity and selectivity, with a detection limit for HSO₃- as low as 0.31 μM. Regarding microenvironmental responsiveness, the probe's fluorescence intensity significantly increases with rising viscosity or decreasing polarity. Further studies revealed that during ferroptosis, comprehensive changes in the cellular microenvironment lead to fluorescence enhancement in both the green and red fluorescence channels. Based on this dual-channel simultaneous response, the probe has been successfully applied to imaging studies of neuronal ferroptosis, effectively distinguishing ferroptotic cells from normal cells. This study provides a simple and effective molecular tool for the detection of bisulfite and the visualization of the dynamic microenvironment of ferroptosis in the nervous system.