Dual-Responsive Mechanized Mesoporous Silica Nanoparticles Based on Sulfonatocalixarene Supramolecular Switches

Mesoporous silica nanoparticles (MSNs) have been functionalized with supramolecular switches, composed of cleavable disulfide bond-containing alkylammonium stalks encircled by water-soluble sulfonatocalix[4,6]arenes, to result in smart mechanized MSNs. Cargo can be encased tightly in the nanopores of these mechanized MSNs in their closed state, but are released efficiently either in response to L-glutathione (GSH), by cleaving the disulfide bonds in the stalks, or in response to pH variation, by turning on the calixarene-based supramolecular switches. The higher concentration of GSH in cancer cell cytosol and the relatively lower pH value of cancer cell lysosome can simultaneously activate the mechanized MSNs, enabling them to release the pre-loaded cargo in place. This sufficient use of the different environment of cancer cells and normal healthy cells can enhance the targeting effect of delivery vehicles and effectively lower the side effects of delivered anti-cancer drugs. In vitro cytotoxicity tests suggest good biocompatibility and low toxicity of these newly developed drug-delivery systems.