Representation of a novel nano-system for targeted intracellular drug delivery composed by photo-sensitizer-incorporated G4 DNA-capped mesoporous silica nano-particles. This system is composed by a photo-sensitizer (TMPyP4) that upon light irradiation generates ROS, leading to cleavage of G4 DNA ((G4T4G4)2) capping agent and allowing doxorubicin release. The nano-system is internalized via folate receptor-mediated endocytosis. Copyright (2013) Wiley. Used with permission from Chen, C.; Zhou, L.; Geng, J.; Ren, J.; Qu, X. Photo-sensitizer-incorporated quadruplex DNA-gated nano-vechicles for light-triggered, targeted dual drug delivery to cancer cells. Small. John Wiley and Sons, Inc. [63].