Construction of Bi/phthalocyanine manganese nanocomposite for trimodal imaging directed photodynamic and photothermal therapy mediated by 808 nm light

The current conventional photo-therapeutic agents often show low therapy efficacy because of their single treatment model, the limited penetration depth of excitation light and hypoxia in the tumor microenvironment (TME). Herein, a new type of phthalocyanine manganese (MnPcE4) photosensitizer with strong NIR absorption was designed and fabricated for the first time, and was used to modify pure Bi nanomaterials to obtain an intelligent multifunctional Bi/MnPcE4 nanocomposites. The Mn2+ in the Bi/MnPcE4 nanocomposite could catalyze H2O2 to generate O2, thus helping to overcome TME hypoxia and enhancing the photodynamic therapy (PDT) efficacy. Further, the nanocomposites showed excellent T1-weighted MRI performance. Our novel use of a pure metal Bi core, offers lower toxicity, higher CT imaging performance, and a photothermal therapy (PTT) effect triggered by 808 nm near infrared (NIR) laser. Moreover, in vivo fluorescence imaging (in vivo FL) vividly showed that the nanocomposite rapidly accumulates in tumor sites due to the enhanced permeability and retention (EPR) effect and metabolized in the organs. The presence of Bi enables the use of these nanocomposites as a CT contrast agent, and the Mn content enables them to be used in MRI. This triple imaging ability implies that our nanocomposites have a high potential for use in imaging directed tumor therapy.