Precise and Long-Term Tracking of Mitochondria in Neurons using a Bioconjugatable and Photostable AIE Luminogen

Tracking mitochondrial movement in neurons is an attractive research field as dysregulation of mitochondrial motion is associated with multiple neurological diseases. To attain the precise trajectory of a single mitochondrion and achieve long-term imaging of mitochondria in neurons, specific and photostable fluorescent probes with a long emission lifetime are required. Existing mitochondrial targeting fluorescent dyes suffer from poor photostability, high toxicity, “always-on” behavior, and aggregation-caused quenching effect, which limit their use in studying mitochondria in neurons. To overcome these challenges, we designed and synthesized an aggregation-induced emission (AIE)-active luminogen, TPAP-C5-yne, which consists of an activated alkyne terminus for bioconjugation with amines, and a cationic pyridinium moiety to selectively target mitochondria. For the first time using TPAP-C5-yne, we successfully tracked and analyzed the motion of a single mitochondrion in live primary hippocampal neurons accurately using real-time fluorescence images acquired by a sensitive EMCCD camera. In addition, long-term imaging of mitochondria in live neurons for a week is achieved by TPAP-C5-yne, which was not feasible with a commercially available mitochondrial targeting probe before.