Endoplasmic Reticulum-Directed Ratiometric Fluorescent Probe for Quantitive Detection of Basal H₂O₂

The endoplasmic reticulum (ER) has a central role in the fine-tuning of environmental and internal stimuli. We herein report a ratiometric fluorescent probe, α-Naph, capable of determining basal H₂O₂ in the ER. The probe specifically responds to H₂O₂. The limit of detection of the probe is as low as 38 nM, making it a feasible sensor to image intracellular basal H₂O₂. In addition, utilizing its ratiometric property, we are able to measure the concentration of H₂O₂ in the ER quantitatively, eliminating the error caused by the probe concentration and environment. The intracellular concentration of H₂O₂ in the ER is calculated to be 0.692 μM under normal conditions and 1.26 μM under the stimulation of phorbol myristate acetate.