Research advances in the applications of mitochondria‐targeted cyanine dyes in imaging

Abstract Near‐infrared (NIR) fluorescence imaging, a novel non‐invasive diagnostic tool, plays a pivotal role in the imaging and monitoring of solid tumors. As core fluorescent probes, NIR fluorescent dyes are widely utilized in biological imaging, primarily due to their capacity to mitigate tissue autofluorescence interference—an attribute that notably enhances the signal‐to‐noise ratio (SNR) and detection selectivity. Mitochondria are indispensable for a spectrum of biological processes, and their dysfunction is closely associated with the metastatic potential and drug resistance of tumor cells; this renders mitochondria‐targeted cyanine dyes highly valuable for research. The functionalization of cyanine dyes can be achieved through three key strategies: (1) introducing active groups into the parent core structure; (2) constructing novel dyes tailored for in vivo imaging and histological analyses; (3) exploring combinations with biological materials. These approaches can significantly modulate the intrinsic properties of cyanine dyes, thereby endowing them with diverse fluorescence imaging functionalities. Recent studies have demonstrated that such modified mitochondria‐targeting cyanine dyes have been successfully applied in the detection of pH fluctuations, metal ions, and oxidative damage, as well as in the targeted imaging of tumor cells. This review summarizes the latest research progress of these probes in the field of biological imaging over recent years.