Recent advances in the mitochondria-targeting small molecule fluorescent probes: from the principal design to biological applications

Monitoring and regulating the functions of mitochondria holds significant research value for disease management. Small molecule fluorescent probes, due to their various advantages including noninvasiveness, superior sensitivity, and real-time feedback, have emerged as powerful tools for studying the structure and function of mitochondria. Until now, numerous fluorescent probes based on various mitochondrial targeting strategies and multiple response mechanisms have been reported. Therefore, we herein summarize the typical response mechanism of the fluorescent probes, including photoinduced electron transfer (PET), Förster resonance energy transfer (FRET), intramolecular charge transfer (ICT), etc. In addition, the strategies for mitochondria-targeting probes, such as triphenylphosphonium, pyridinium, rhodamine derivatives, and indolium derivatives, are also concluded. Specially, the mitochondria-targeting probes developed in recent years are highlighted carefully according to the analytes, including probes responding to enzymes, reactive oxygen species, viscosity, etc. At last, a detailed outlook for designing high-performance small molecule fluorescent probes is provided.