Ratiometric Imaging of Cysteine Level Changes in Endoplasmic Reticulum during H2O2-Induced Redox Imbalance.

Cysteine (Cys) is an important mediator to regulate the redox state of endoplasmic reticulum (ER), and its level is closely related with many ER stress induced serious diseases. Herein, we present an ER-specific fluorescent probe for the ratiometric imaging of cellular Cys for the first time. The probe exhibited desirable selectivity and sensitivity to Cys. Biological imaging experiments demonstrated that the probe possessed an ER-targeting property, showed ratiometric response to Cys in ER, and could be applied for the ratiometric imaging of Cys level changes during H2O2-induced redox imbalance in living cells.