A near-infrared fluorescent probe based on a novel rectilinearly π-extended rhodamine derivative and its applications
We designed and synthesized a novel near-infrared (NIR) mitochondria-targeted fluorescent probe RQNA for the specific detection of mitochondrial Cu2+ because mitochondria are important reservoir of intracellular copper. For the preparation of this probe, a novel π-extended fluorescent xanthene dye RQN was firstly synthesized via an intramolecular nucleophilic substitution of aromatic hydrogen (SNArH) strategy. Then, the probe RQNA was prepared by the reaction of RQN and hydrazine hydrate, and followed treatment by acetone. RQNA exhibited a selectivity, sensitivity (22 nM), and fast response time (20 s) for the detection of Cu2+ via a specific Cu2+-triggered ring-opening and hydrolysis cascade reaction. RQNA is cell-membrane permeable and mitochondria-targetable, and can be used for monitoring mitochondrial Cu2+ in the living cell.