Metal–Organic Framework as a Microreactor for in Situ Fabrication of Multifunctional Nanocomposites for Photothermal–Chemotherapy of Tumors in Vivo

Metal–organic frameworks (MOFs) have been applied in chemotherapeutic drug loading for cancer treatment, but challenging for cases with large and malignant lesions. To overcome these difficulties, combinational therapies of chemotherapy and photothermal therapy (PTT) with potentially high selectivity and slight aggressiveness have drawn tremendous attention to treat various tumors. However, current MOF-based nanohybrids with photothermal agents involve tedious synthesis processes and heterogeneous structures. Herein, we employ MIL-53 as a microreactor to grow polypyrrole (PPy) nanoparticles in situ for the fabrication of PPy@MIL-53 nanocomposites. Fe3+ in MIL-53, as an intrinsic oxidizing agent, can oxidize the pyrrole monomer to generate PPy nanoparticles. The prepared PPy@MIL-53 nanocomposites integrate the intrinsic advantages of MOFs with high drug loading ability and magnetic resonance imaging (MRI) capacity, and PPy nanoparticles with outstanding PTT ability and excellent biocompatibility. The versatile PPy@MIL-53 nanocomposites with multiple functions displayed in vitro and in vivo synergism of photothermal–chemotherapy for cancer, potentially MRI-guided. The proposed MOF microreactor-based synthesis strategy shows a promising prospect in the fabrication of diverse multifunctional nanohybrids for tumor theranostics in vivo.