A New Highly Selective and Sensitive Assay for Fluorescence Imaging of . OH in Living Cells: Effectively Avoiding the Interference of Peroxynitrite

A new nonredox fluorescent probe to realize the imaging of hydroxyl radicals ( . OH) in living cells was designed and synthesized. The structure comprised the fluorescent dye boron dipyrromethene (BDP) and a 2,2,6,6‐tetramethyl‐1‐piperidinoxyl (TEMPO) unit. This probe could rapidly respond to . OH with a detection limit of 18 p M , and it possessed superior photostability and pH insensitivity. Other reactive oxygen species (ROS) and relevant intracellular components did not interfere. In particular, the important problem of ONOO − interference was efficiently avoided. An MTT assay proved that the probe was not very cytotoxic. The probe could penetrate into intact cell membranes to selectively detect intracellular . OH without causing cellular damage in living mice macrophages, normal human liver cells. and human hepatoma cells. These advantageous characteristics make the fluorescent probe potentially useful as a new candidate to detect . OH in broad biosystems.