Development of an endoplasmic reticulum-targeting fluorescent probe for the imaging of superoxide anion in living cells

Superoxide anion (O 2 •− ) is an important reactive oxygen species (ROS), and plays critical roles in biological systems. ER stress has close relation with many metabolic diseases, and could lead to the abnormal production of ROS including O 2 •− . Herein, we present an ER-targeting probe ( ER-Tf ) for the detection of O 2 •− in living cells. The probe ER-Tf used triflate as the response site for O 2 •− , and employed p-methylbenzenesulfonamide as ER-targeting moiety. In response to O 2 •− , the triflate of the probe ER-Tf converted to hydroxyl group, providing strong blue emission under the excitation of ultraviolet light. The probe ER-Tf exhibited high sensitivity and selectivity to O 2 •− . Bioimaging experiments showed that the probe ER-Tf can be applied to detect O 2 •− at ER, and also demonstrated that rotenone could increase the generation of O 2 •− in living cells, while the O 2 •− level at ER showed no remarkable change during ferroptosis.