pH-Responsive Polymer-Stabilized ZIF-8 Nanocomposites for Fluorescence and Magnetic Resonance Dual-Modal Imaging-Guided Chemo-/Photodynamic Combinational Cancer Therapy

A multifunctional diagnosis and treatment integration platform is crucial in cancer treatments. Here, we show that by integrating Gd-doped silicon nanoparticles (Si–Gd NPs), chlorine e6 (Ce6), doxorubicin (DOX), zeolitic imidazolate framework-8 (ZIF-8), poly(2-(diethylamino)ethyl methacrylate) polymers (HOOC-PDMAEMA-SH), and folic acid–poly(ethylene glycol)–maleimide (MaL–PEG–FA) into one single nanoplatform by a self-assembly method, novel multifunctional MOFs (named FZIF-8/DOX–PD–FA) are synthesized with great biocompatibility and tumor targeting as well as pH responsiveness and no drug leakage for drug delivery. In the design, Si–Gd NPs and Ce6 embedded in the nanocomposites are used for magnetic resonance and fluorescence dual-modal imaging, respectively. DOX loaded by the FZIF-8/DOX–PD–FA porous structure is used for chemotherapy, while Ce6 is excited by near-infrared radiation (NIR) for photodynamic therapy. In addition, the pH-responsive ability of HOOC-PDMAEMA-SH to effectively prevent drug leakage is demonstrated by drug release studies in vitro. From the results of confocal microscopy imaging in vitro and fluorescence/magnetic resonance imaging in vivo, FZIF-8/DOX–PD–FA showed a targeting effect on MCF-7 cancer cells. More importantly, the results of treatment experiments on tumor-bearing mice showed that the tumor volume of the FZIF-8/DOX–PD–FA + NIR group is decreased the most compared to the original volume. Owing to the unique dual-modal imaging capability and excellent chemo-/photodynamic combinational cancer therapy effect, the present hybrid nanocarrier provides a new research platform for a new generation of theranostic nanoparticles.