BACKGROUND Selective etching of silica nanoparticles allows the formation of mesoporosity, increasing the loading capability of nanoparticles for further drug release applications. By coating such mesoporous silica nanoparticles with biocompatible pH-sensitive polymers, the selectivity of drug delivery systems can be enhanced and adverse side effects can be minimized. So far, selectively etched silica has been scarcely explored for drug encapsulation. RESULTS Spherical particles with sizes ranging from 200 to 500 nm were obtained by the Stober method. Selective etching was performed at two different aging times, leading to the formation of uniform pores with specific surface areas of 115 and 150 m(2) g(-1) for 0 and 14 h of aging respectively. X-ray analysis demonstrated the formation of ordered materials, while the hydrodynamic sizes were around 300 nm. cis-Diamminedichloroplatinum(II) was encapsulated in etched silica nanoparticles and coated with chitosan, and the drug was released at pH 5. In vitro evaluation of the nanoparticles was performed in U-373 cells, reaching around 40% of cell death. CONCLUSION Selective etching of nanoparticles allowed the obtaining of homogeneous coated hybrid nanoparticles and an efficient pH-sensitive drug delivery hybrid system for the release of chemotherapeutic agent with enhanced activity against U-373 human glioblastoma cells. (c) 2019 Society of Chemical Industry