Fabrication and application of copper metal–organic frameworks as nanocarriers for pH-responsive anticancer drug delivery

Copper-based metal−organic frameworks (Cu-MOFs) have been extensively used in delivery of several therapeutics because of their cytocompatibility, favorable degradation and structural flexibility. In this work, we investigated two types of Cu-MOF-based nanocomposites including GO/Cu-TCPP and Fe3O4@Cu3(BTC)2 for loading of doxorubicin (DOX) and pH-sensitive release of the drug in vitro. The Fe3O4@Cu3(BTC)2 is an octahedron network structure, while the GO/Cu-TCPP nanocomposite consists of copper (II)-porphyrin metal–organic framework (Cu-TCPP) crystals embedded between exfoliated graphene oxide (GO) layers. Our studies show that GO/Cu-TCPP has adsorbed more doxorubicin (DOX) (45.7 wt.%) compared to Fe3O4@Cu3(BTC)2 (40.5 wt.%). More drug loading for Cu3(BTC)2 was also obtained than that of Cu-TCPP. For GO/Cu-TCPP at pH 5, 98.9% of DOX released for 60 h and 33.5% of DOX released after 60 h at pH 7.4, while the released amount of DOX from Fe3O4@Cu3(BTC)2 at pH 5 reached 85.5% and 33.5% at pH 7.4 afterward 60 h. The difference between the amount of drug released in two nanocomposites related to drug loading capacity demonstrating the impact nanocomposite structure on the smart MOF construction for pH-responsive behavior in vitro. Based on the results, the GO/Cu-TCPP and Fe3O4@Cu3(BTC)2 nanocomposites possess low toxicity and good biocompatibility, but DOX-loaded GO/Cu-TCPP generate better toxicity to cancer cells compared with Fe3O4@Cu3(BTC)2-DOX.Graphical abstract