An endoplasmic reticulum-selective ratiometric fluorescent probe for imaging a copper pool.

Hydrazide-linked naphthalimides undergo copper ion-selective hydrolysis with concomitant ratiometric fluorescence change. In addition, probe 1 is biocompatible and mainly localized to the endoplasmic reticulum ( ER) in live HeLa cells. It thus can be used for imaging copper accumulation in the ER of live cells, as implied in copper-overloaded situations.