Symmetrically Fluorinated D-π-A Structured Cyanine Dye for Highly Efficient NIR-II Imaging-Guided Cancer Phototheranostics.

Near-infrared-II (NIR-II) fluorescence imaging-guided photothermal therapy (PTT) represents a cutting-edge approach for precise tumor diagnosis and treatment, providing real-time therapeutic efficacy evaluation. However, a significant challenge lies in the creation of phototheranostic agents that provide robust imaging and efficient photothermal conversion. To address this, a donor-π-acceptor (D-π-A) structure heptamethine cyanine derivative, IR1116, that confers a strong intramolecular charge transfer effect is developed. To enhance its applicability, IR1116 is formulated with DSPE-PEG to create a water-dispersible NIR-II phototheranostic nanoheater, NP. This nanoheater benefits from the incorporation of an electron-withdrawing group, leading to reduced photooxidation activity and significantly improved photostability. NP exhibits strong NIR-II absorption and fluorescence, peaking at 1004 and 1116 nm, respectively, as well as a photothermal conversion efficiency of 79% under 1064 nm lasers. In vitro and in vivo studies showed the efficacy of NP in tumor imaging via NIR-II fluorescence and its ability to effectively induce tumor cell apoptosis under 1064 nm laser irradiation. These findings underscore the potential of NP in NIR-II fluorescence imaging-guided PTT for tumor treatment, paving the way for further advancements in NIR-II dye development and bioimaging technologies.