Controlled intracellular release of doxorubicin in multidrug-resistant cancer cells by tuning the shell-pore sizes of mesoporous silica nanoparticles.

In this work, hollow mesoporous silica nanoparticles (HMSNs) with three pore sizes were manufactured to control the drug release rate, and the biological roles of these HMSNs were evaluated in multidrug-resistant (MDR) cancer cells. As novel pore-size-controllable inorganic materials, HMSNs showed negligible cytotoxicity and efficient cellular uptake toward drug-sensitive MCF-7 and drug-resistant MCF-7/ADR cells. Doxorubicin (DOX)-loaded HMSNs (DMSNs) not only demonstrated effective drug loading and a pH-responsive drug release character but also exhibited pore-size-dependent and sustained drug release performance in both in vitro and intracellular drug release experiments. In addition, DMSNs exhibited pore-size-dependent anticancer activity against MCF-7/ADR cells. DMSNs with larger pore size could mediate more cellular uptake of DOX and faster intracellular drug release, which led to more intracellular drug accumulation and stronger MDR-reversal effects. The MDR-overcoming mechanism could be due to the efficient cellular uptake, P-gp inhibition, and ATP depletion. These results demonstrate that HMSNs could be a very promising drug delivery system for pore-size-controllable drug release and cancer MDR reversion.