A relatively facile and adjustable approach was investigated to synthesize mesoporous silica nanoparticles (MSNs) with a thin controllable solid silica-cap (sSiO(2)) outer layer that prevented unwanted degradation for controlled drug release because the sSiO(2) turned out to degrade gradually. Ibuprofen (IBU) and calcium ions were loaded to evaluate the efficiency of this system. This sSiO(2)-capped degradation strategy for controlled release could easily be extended to other pH- or temperature-responsive MSN systems and applications.