Mitochondria-targeted fluorophore: State of the art and future trends

Mitochondria, pivotal organelles responsible for cellular energy production and behavioral regulation, play a crucial role in various diseases, notably cancer. Mitochondria-targeting fluorophores, exhibiting fluorescence within the visible to near-infrared (NIR) spectrum, enables monitoring of morphological variations, functional integrity, and defects in mitochondria. In addition, these fluorophores can detect intact mitochondrial function by detecting important substances in the mitochondrial internal environment. This capability facilitates comprehensive physiological and pathological studies at the cellular level. At the biological level, fluorescence fluorophores within the NIR window (>650 nm) exhibit superior imaging performance compared to those at shorter wavelengths. Mitochondria-targeting fluorophores within the NIR window enable real-time monitoring of mitochondrial changes in vivo, enhancing the precision of pathological studies in patients. Biological tissues have inherently weaker absorption and scattering for the NIR-II window (1000–1700 nm) light and lower autofluorescence, which endows the NIR-II window fluorescence imaging with deeper tissue penetration and superior imaging capabilities. Furthermore, phototherapies targeting mitochondria have emerged as a promising approach for tumor elimination. With the exceptional monitoring capabilities of NIR fluorophore, the entire therapeutic process can be conveniently observed in real-time. This review comprehensively delineates recent advancements in mitochondria-targeting fluorophores. These fluorophores' intricate design and inherent advantages for theranostics are meticulously summarized, underscoring the future prospects within this burgeoning field.