The preparation of a new capped silica mesoporous material, Rh-Azo-S, for on-command delivery applications in the presence of target enzymes is described. The material consists of nanometric mesoporous MCM-41-like supports loaded with Rhodamine B and capped with an azopyridine derivative. The material was designed to show ¿zero delivery¿ and to display a cargo release in the presence of reductases and esterases, which are usually present in the colon, mainly due to intestinal microflora. The opening and cargo release of Rh-Azo-S in vitro studies were assessed and seen to occur in the presence of these enzymes, whereas no delivery was noted in the presence of pepsine. Moreover, Rh-Azo-S nanoparticles were used to study controlled Rhodamine¿B dye delivery in intracellular media. HeLa cells were employed for testing the ¿non¿-toxicity of nanoparticles. Moreover, delivery of the dye in these cells, through internalization and enzyme-mediated gate opening, was confirmed by confocal microscopy. Furthermore, the nanoparticles capped with the Azo group and loaded with a cytotoxic camptothecin (CPT) were also prepared (solid CPT-Azo-S) and used as delivery nanodevices in HeLa cells. When this solid was employed, the cell viability decreased significantly due to internalization of the nanoparticles and delivery of the cytotoxic agent. ; Spanish Government (projects MAT2009-14564-C04, MAT2012-38429-C04-01, CTQ2007-64735-AR07 and SAF2010-15512) ; Generalitat Valenciana (projects PROMETEO/2009/016 and /2010/ 005) ; Ministerio de Ciencia e Innovacion ; Generalitat Valenciana ; Mas Font, N.; Agostini ., A.; Mondragón Martínez, L.; Bernardos Bau, A.; Sancenón Galarza, F.; Marcos Martínez, MD.; Martínez Mañez, R. (2012). Enzyme-Responsive Silica Mesoporous Supports Capped with Azopyridinium Salts for Controlled Delivery Applications. Chemistry - A European Journal. 19(4):1346-1356. doi:10.1002/chem.201202740. ; Senia ; 1346 ; 1356 ; 19 ; 4