Multidrug resistance (MDR) greatly impedes the therapeutic efficacy of chemotherapeutic agents. Overexpression of ATP-binding cassette (ABC) transporters, such as P-gp, on the surface of tumor cells is a major mechanism in MDR. In this study, we fabricated manganese dioxide (MnO)/doxorubicin (DOX)-loaded albumin nanoparticles (BMDN) for magnetic resonance imaging and reversing MDR in resistant tumor. BMDN facilitated the delivery of DOX into MDR tumor cells through their MDR reversal effects including enhanced cellular uptake, reduced drug efflux, and decreased hypoxic tumor microenvironment. BMDN also acted as an effective MRI contrast agent, thereby causing good in vitro and in vivo T-weighted imaging.

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Background The natural compound curcumin (Cur) can regulate growth inhibition and apoptosis in various cancer cell lines, although its clinical applications are restricted by extreme water insolubility and instability. To overcome these hurdles, we fabricated a Cur-coordinated reactive oxygen species (ROS)-responsive nanoparticle using the interaction between boronic acid and Cur. Materials and methods We synthesized a highly biocompatible 4-(hydroxymethyl) phenylboronic acid (HPBA)-modified poly(ethylene glycol) (PEG)-grafted poly(acrylic acid) polymer (PPH) and fabricated a Cur-coordinated ROS-responsive nanoparticle (denoted by PPHC) based on the interaction between boronic acid and Cur. The mean diameter of the Cur-coordinated PPHC nanoparticle was 163.8 nm and its zeta potential was −0.31 mV. The Cur-coordinated PPHC nanoparticle improved Cur stability in physiological environment and could timely release Cur in response to hydrogen peroxide (H 2 O 2 ). PPHC nanoparticles demonstrated potent antiproliferative effect in vitro in A549 cancer cells. Furthermore, the viability of cells treated with PPHC nanoparticles was significantly increased in the presence of N -acetyl-cysteine (NAC), which blocks Cur release through ROS inhibition. Simultaneously, the ROS level measured in A549 cells after incubation with PPHC nanoparticles exhibited an obvious downregulation, which further proved that ROS depression indeed influenced the therapeutic effect of Cur in PPHC nanoparticles. Moreover, pretreatment with phosphate-buffered saline (PBS) significantly impaired the cytotoxic effect of Cur in A549 cells in vitro while causing less damage to the activity of Cur in PPHC nanoparticle. Conclusion The Cur-coordinated nanoparticles developed in this study improved Cur stability, which could further release Cur in a ROS-dependent manner in cancer cells.