MRI Enhancement and Tumor Targeted Drug Delivery Using Zn²⁺-Doped Fe₃O₄ Core/Mesoporous Silica Shell Nanocomposites

Developing of multifunctional nanoplateforms for simultaneous accurate cancer detection and target therapy is essential in cancer treatment. Herein, we present a facile synthesis of DOX/MNPs-FA nanocomposites for high-performance MRI and tumor-targeted drug delivery. In such core–shell structured DOX/MNPs-FA nanocomposite, the high magnetism of iron oxide core can be tuned and achieved by controlling the Zn²⁺ dopant amount, making them suitable as excellent contrasts in T₂-weighted MR imaging. The outer porous silica shell with large pores about 5.4 nm in diameter possesses high surface area and pore volume. Anticancer drug (DOX molecules) can be stored in the large pore channels and is triggered to be released under acidic condition (pH 4–6). Importantly, the presence of folic acid on the surface of DOX/MNPs-FA allows the targeted delivery of the DOX to tumor cells, and therefore improves tumor chemotherapy efficiency. Our in vitro studies also demonstrated that DOX/MNPs-FA could be efficiently internalized into HeLa cells via the folate receptor-mediated endocytosis, and generate a greater cytotoxicity toward cancer cells compared to free DOX and DOX/MNPs. Therefore, these DOX/MNPs-FA multifunctional nanocomposites have great potential applications for simultaneous tumor diagnosis and targeted chemotherapy.