NIR organic dyes based on phenazine-cyanine for photoacoustic imaging-guided photothermal therapy

As non-invasive diagnosis and therapy methods, photoacoustic (PA) imaging and photothermal therapy (PTT) have attracted extensive attention. Herein, two new acceptor-donor-acceptor near-infrared organic phenazine-cyanine dyes PH-1 and PH-2 were reported for photoacoustic imaging-guided photodynamic therapy. In the strong donor phenazine molecule, the electron-withdrawing indole salt unit was introduced for absorption to the near-infrared region. To improve water solubility, the two organic dyes were assembled with human serum albumin (HSA) to form nanoparticles of appropriate sizes, i.e., PH-1@HSA and PH-2@HSA, which showed excellent stability in both weakly acidic and weakly basic environments. Moreover, the results showed that PH-1@HSA and PH-2@HSA nanoparticles can effectively transform luminous energy to thermal energy in vitro and in vivo, and they can be utilized for PA imaging. Importantly, PH-1@HSA can accumulate in mice subcutaneous tumors by enhanced permeability and retention (EPR) and damage cancer tissues effectively.