MnO2-coated porous Pt@CeO2 core-shell nanostructures for photoacoustic imaging-guided tri-modal cancer therapy.

We describe the synthesis of MnO2-coated porous Pt@CeO2 core-shell nanostructures (Pt@CeO2@MnO2) as a new theranostic nano-platform. The porous Pt cores endow the core-shell nanostructures with high photothermal conversion efficiency (80%) in the near-infrared region, allowing for photothermal therapy (PTT) and photoacoustic imaging (PA) of tumors. The combination of the Pt core and porous CeO2 interlayer enhances the separation of photo-generated electrons and holes, which is beneficial for the generation of singlet oxygen. With the porous structures of the cores and interlayers, the Pt@CeO2@MnO2 nanostructures are further loaded with an anti-cancer drug (doxorubicin, DOX). The degradation of the MnO2 shell in the tumor microenvironment (TME) can generate O2 for enhanced photodynamic therapy (PDT) and simultaneously trigger DOX release. PA imaging shows good accumulation and retention of DOX-loaded Pt@CeO2@MnO2 in tumors, which guides precise laser irradiation to initiate combined PTT and PDT. The synergistic PTT/PDT/chemotherapy demonstrated by DOX-loaded Pt@CeO2@MnO2 yields remarkable therapeutic outcomes in vitro and in vivo. Taken together, our DOX-loaded Pt@CeO2@MnO2 provides a new avenue for designing high-performance nano-platforms for imaging and therapeutics.