A versatile tumor-targeted drug-delivery system based on IR808-modified nanoparticles, its co-loading with PTX and R848 and its extraordinary antitumor efficacy.

Nearly all antitumor drugs can benefit greatly from effective tumor-targeted delivery for improved therapeutic efficacy and reduced toxic side effects. However, the vast majority of tumor-targeting ligands can only target specific tumor cells that highly express the corresponding receptors and thus are only applicable to limited tumor types. Heptamethine cyanines with medium cyclohexene and medium Cl atoms, such as IR780 and IR808, have shown an unusual ability to indiscriminately accumulate into virtually all tumor types. In this study, IR808 was conjugated with DSPE-mPEG2000-NH2, and the resultant DSPE-PEG2000-IR808 (DP-IR808) in combination with TPGS successfully encapsulated paclitaxel (PTX) and immunomodulator R848 into nanoparticles with a small particle size of 150.20 nm, negative charge of -16.50 mV, rod-like morphology, and PTX loading content of 31.6%. The obtained DP-IR808@PTX-R848 NPs rapidly accumulated in 4T1 tumors with a tumor/liver fluorescence ratio of 1.71, and it demonstrated a significant photothermal effect and could be directly used for NIR imaging. The DP-IR808@PTX-R848 NPs achieved a high tumor inhibition rate of 94%, a mean survival time of >90 d, and a tumor-free survival percentage of 57%. To the best of our knowledge, this was the first time that nanoparticles were modified with heptamethylcyanine molecules. The nanoparticles system based on DSPE-PEG-IR808, which integrates tumor-targeted drug delivery, in vivo infrared imaging and photothermal therapy, is expected to become a versatile drug-delivery platform for tumor therapy.