A Highly Photostable Hyperbranched Polyglycerol‐Based NIR Fluorescence Nanoplatform for Mitochondria‐Specific Cell Imaging

Considering the critical role of mitochondria in the life and death of cells, non‐invasive long‐term tracking of mitochondria has attracted considerable interest. However, a high‐performance mitochondria‐specific labeling probe with high photostability is still lacking. Herein a highly photostable hyperbranched polyglycerol (hPG)‐based near‐infrared (NIR) quantum dots (QDs) nanoplatform is reported for mitochondria‐specific cell imaging. Comprising NIR Zn‐Cu‐In‐S/ZnS QDs as extremely photostable fluorescent labels and alkyl chain (C 12 )/triphenylphosphonium (TPP)‐functionalized hPG derivatives as protective shell, the tailored QDs@hPG‐C 12 /TPP nanoprobe with a hydrodynamic diameter of about 65 nm exhibits NIR fluorescence, excellent biocompatibility, good stability, and mitochondria‐targeted ability. Cell uptake experiments demonstrate that QDs@hPG‐C 12 /TPP displays a significantly enhanced uptake in HeLa cells compared to nontargeted QDs@hPG‐C 12 . Further co‐localization study indicates that the probe selectively targets mitochondria. Importantly, compared with commercial deep‐red mitochondria dyes, QDs@hPG‐C 12 /TPP possesses superior photostability under continuous laser irradiation, indicating great potential for long‐term mitochondria labeling and tracking. Moreover, drug‐loaded QDs@hPG‐C 12 /TPP display an enhanced tumor cell killing efficacy compared to nontargeted drugs. This work could open the door to the construction of organelle‐targeted multifunctional nanoplatforms for precise diagnosis and high‐efficient tumor therapy.