A phosphorescent iridium probe for sensing polarity in the endoplasmic reticulum and in vivo.

The polarity of a cell is the feedback of a series of complex mechanisms that establish and maintain functionality of particular domains. Many cellular processes involved in the spatial arrangement and protein composition such as differentiation, localized membrane growth, activation of the immune response, directional cell migration, and vectorial transport of molecules across cell layers may lead to changes and development of polarity. In this work, a phosphorescent iridium complex was reported for sensitively probing environmental and cellular polarity. This probe exclusively targeted the endoplasmic reticulum (ER) and successfully in situ tracked polarity variations during ER stress in living cells. Importantly, the blood of diabetic mice in the presence of this probe appears to have distinguished phosphorescence compared with the blood of normal mice, indicating that the probe probably monitors blood polarity in diabetes.