Upconverted/downshifted NaLnF4 and metal-organic framework heterostructures boosting NIR-II imaging-guided photodynamic immunotherapy toward tumors

Heterostructures of NaLnF4 and porphyrinic metal-organic frameworks (MOF) have been reported as a promising platform for near-infrared (NIR)-driven photodynamic therapy (PDT), while the energy transfer from NaLnF4 to MOF greatly decreased the upconversion emissions. To develop NaLnF4 and MOF heterostructures with significantly improved PDT and imaging simultaneously is important to track their location to implement therapy accurately. Herein, we constructed Er3+-doped NaLnF4@MOF [email protected] nanoparticles to integrate NIR-driven PDT and NIR-II imaging. NaLnF4 nanoparticles are designed with upconversion and NIR emission simultaneously under a single 980 nm excitation, where the upconversion luminescence (UCL) overlaps well with the absorption of Zr-based porphyrin MOF, enabling efficient energy transfer from NaLnF4 to the MOF shell to generate 1O2. And the NIR luminescence, which gave out under a lower excitation power than that of UCL, could be used to track the location and distribution of the heterostructures via NIR-II imaging. Moreover, antiprogrammed death-ligand 1 (α-PD-L1) immunotherapy was introduced synergistically to improve antitumor immunity efficacy. The combination of NaLnF4@MOF and α-PD-L1 not only inhibited primary tumors but also suppressed distant one, leading to an effective tumor inhibition rate of 95%. This work provides an integrated nanoplatform for boosting NIR-II imaging-guided PDT/immunotherapy efficacy toward tumor treatment.