A salt-assisted acid etching strategy for hollow mesoporous silica/organosilica for pH-responsive drug and gene co-delivery

A salt-assisted acid etching (SAAE) strategy has been developed to construct rattle/hollow mesoporous silica/organosilica nanovehicles (R/HMSVs or R/HMOVs), which settles the drawbacks of traditional silica etching approaches, such as undesirable by-products, by alkaline etching and strong corrosion of the HF etching process. The hollow structure and phenylene-bridged framework of HMOVs were found to be responsible for the high cargo-loading capacity and pH-responsive drug releasing behavior, respectively, based on the special cargo-framework interaction. Especially, the molecularly organic-inorganic hybrid HMOVs have been, for the first time, successfully engineered to concurrently deliver anticancer drugs and P-gp-associated shRNA molecules for enhancing the intracellular drug concentrations and reversing the multidrug resistance (MDR) of cancer cells. On the basis of this special SAAE strategy, a wide range of mesoporous silica-based hollow nanostructures are anticipated to be synthesized to satisfy the strict requirements in various nano-catalytic and biomedical applications.