Hybrid Mesoporous-Microporous Nanocarriers for Overcoming Multidrug Resistance by Sequential Drug Delivery

Combination chemotherapy with a modulator and a chemotherapeutic drug has become one of the most promising strategies for the treatment of multidrug resistance (MDR) in cancer therapy. However, the development of nanocarriers with a high payload and sequential release of therapeutic agents poses a significant challenge. In this work, we report a type of hybrid nanocarriers prepared by polydopamine (PDA) mediated integration of the mesoporous MSN core and the microporous zeolite imidazolate frameworks-8 (ZIF-8) shell. The nanocarriers exploit storage capacities for drugs based on the high porosity and molecular sieving capabilities of ZIF-8 for sequential drug release. Particularly, large amounts of an anticancer drug (DOX, 607 μg mg^-1) and a MDR inhibitor curcumin (CUR, 778 μg mg^-1) were sequentially loaded in the mesoporous core via π-π stacking interactions mediated by PDA and in the microporous shell via the encapsulation during ZIF-8 growth. The sustained release of DOX was observed to follow earlier and faster release of CUR by acid-sensitive dissolution of the ZIF-8 shell. Furthermore, the nanoparticles showed good biocompatibility and effective cellular uptake in in vitro evaluations using drug-resistant MCF-7/ADR cancer cells. More importantly, the preferentially released CUR inhibited the drug efflux function of the membrane P-glycoprotein (P-gp), which subsequently facilitated the nuclear transportation of DOX released from the PDA-MSN core, and, in turn, the synergistic effects on killing MDR cancer cells. The hybrid mesoporous-microporous nanocarrier holds great promise for combination chemotherapy applications on the basis of sequential drug release.