Fabrication of a pH/Redox-Triggered Mesoporous Silica-Based Nanoparticle with Microfluidics for Anticancer Drugs Doxorubicin and Paclitaxel Codelivery.

A pH/redox-triggered mesoporous silica nanoparticle (MSN)-based nanoplatform has been fabricated for doxorubicin/paclitaxel (DOX/PTX) codelivery. In this drug-delivery system (DDS), PTX is covalently attached to the surface of DOX loaded MSN via a linker with disulfide bond. By directly attaching PTX to MSN, we can significantly enhance the PTX́s loading degree and achieve the optimum drug loading ratio to DOX, therefore, to generate the best synergistical effect. More importantly, PTX and the linker act as a redox-sensitive "gate" to precisely control the release profile of DOX and PTX. Subsequently, polystyrenesulfonate (PSS) is electrostatically coated to DOX loaded MSN-PTX in microfluidics to achieve acidic pH responsive, because the free amino group on MSN surface has a protonation state at acidic pH, and the electrostatic interaction will be destroyed at pH 5. In addition, PSS can also neutralize the surface zeta potential, thus reduce the nonspecific endocytosis of healthy cells. By evaluating cell viability in cancer cell BT549 and healthy breast cell MCF-10A, we observed that the nanoparticles can selectively release DOX and PTX and eliminate cancer cells, while they will have negligible effect on the healthy breast cells, due to the acidic and redox microenvironment in cancer cells. Overall, we have developed a nanoplatform for precise DOX/PTX combination therapy with high selectivity between cancer cells and healthy cells.