Tunable Hollow Bimetallic MnFe Prussian Blue Analogue as the Targeted pH-Responsive Delivery System for Anticancer...

Owning to the improved ability of selectivity and penetration toward cancer cells, drug delivery systems (DDSs) play essential roles in chemotherapy for solid tumors. Herein, a series of bimetallic MnFe Prussian blue analogues (PBAs) with a tunable nanostructure was prepared by using sodium citrate (SC) as a structure regulator (represented by MnFe-PBA-SC). An advanced targeted drug delivery system was obtained by adding folic acid (FA) to the preparation system of MnFe-PBA-SC nanospheres (denoted as MnFe-PBA-SC-FA). The shape of pure MnFe PBA was changed from a typical nanocube to a hollow nanosphere when adding SC, leading to the formation of the core-shell nanospheres of the MnFe-PBA-SC-FA composite. The hollow nanostructures and intrinsic cavities in PBA can carry large amounts of doxorubicin (DOX), showing a high loading efficiency of MnFe-PBA-SC_1.0-FA (91.8%), which was higher than that in MnFe-PBA-SC_0.5 (63.2%). Additionally, the series of MnFe-PBAs showed pH-responsive drug release behaviors. A cell viability assay illustrated no remarkable cytotoxicity of MnFe-PBA-SC-FA against human breast cancer cells, Michigan Cancer Foundation-7 (MCF-7) cells, for 24 h. Confocal laser scanning showed that the MnFe-PBA-SC_1.0-FA/DOX system significantly entered FA receptor-expressing MCF-7 cells in vitro and in vivo, while an increased DOX release was observed in the cytoplasm of the MCF-7 cells. In consequence, this novel anticancer delivery system based on bimetallic PBAs can be potentially applied to drug delivery.