Alleviating hypoxia by integrating MnO with metal-organic frameworks coated upconversion nanocomposites for enhanced photodynamic therapy .

Photodynamic therapy (PDT) requires the participation of abundant oxygen while the hypoxic tumor microenvironment limits the efficacy of PDT. Here, upconversion luminescent nanocomposites coated with metal-organic frameworks (MOFs) were synthesized and modified with MnO (named UMMnP) to alleviate hypoxia of the tumor microenvironment. Under 980 nm light irradiation, the upconversion nanoparticles (UCNPs) achieve upconversion emission to excite porphyrin MOFs, which then transfer energy to oxygen to produce singlet oxygen for PDT. At the same time, the MnO in the UMMnP nanocomposites can catalyze the generation of O from HO, which could increase singlet oxygen production in a hypoxic environment, thus enhancing the PDT effect. The HeLa cell viability assay shows that the UMMnP nanocomposites possess good biocompatibility, while after irradiation with 980 nm light, the cell viability decreases dramatically, demonstrating efficient PDT. Furthermore, the nanocomposites can be successfully applied for upconversion luminescence imaging . Thus, this work provides a promising application of bioimaging and enhanced photodynamic therapy by alleviating hypoxia in tumor treatment.