Two-Photon-Triggered Drug Delivery via Fluorescent Nanovalves

Mesoporous silica nanoparticles (MSN) are functionalized in the walls with an original fluorophore with a high two‐photon absorption cross‐section. The pores of the MSN filled with anticancer drug are blocked with a pseudo‐rotaxane constituted by an azobenzene stalk and a β‐cyclodextrin moiety. After incubation of the nanosystem with MCF‐7 breast cancer cells, two‐photon irradiation at low power is used to image the cells. At high power, cancer cell killing is observed due to the two‐photon‐triggered opening of the pores through FRET and the release of the anticancer drug from the MSN.