Litchi-like Fe3O4@Fe-MOF capped with HAp gatekeepers for pH-triggered drug release and anticancer effect.

A novel litchi-like porous composite composed of a magnetic core, a tunable metal-organic framework (MOF) shell and a pH-sensitive hydroxyapatite (HAp) gatekeeper was successfully fabricated in this work. The anticancer drug doxorubicin (DOX) was effectively loaded on the Fe₃O₄@Fe-MOF@HAp nanocomposite with a loading capacity of 75.38 mg g^-1. The nanocomposite had a saturation magnetization of 34 emu g^-1 and thus possessed magnetic targeting function. In addition, the HAp gate, which had favorable biocompatibility and pH response characteristics, could be used to control the release of loaded DOX from the Fe₃O₄@Fe-MOF@HAp nanocomposite microspheres in a simulated acidic tumor cell environment, effectively killing tumor cells and reducing the toxic side effects to normal tissue. The smart design presented in this study, which incorporates a tunable shell and gate-controlled architecture, allows the sensitive release of drugs for efficient antitumor activity.