Functional mesoporous nanoparticles have recently attracted substantial attention in view of their great potential for targeted drug delivery and controlled release. For such demanding applications, it is desirable that the mesoporous particles be equipped with internal functionality for controlled host-guest interactions, a release system for the switchable release of the guest based on external stimuli, as well as targeting ligands for the required type of cell. We have developed a novel strategy to obtain control over the spatial localization of molecular functionality in such nanoparticles. This is achieved via synthesis of multiple core-shell colloidal mesoporous silica (CMS) nanoparticles having different molecular functionalities in the inner surface and on the outer particle shell. We show that active enzymes can be stabilized in such mesoporous nanoparticles using concepts of click-chemistry. In recent work, we have demonstrated a number of switchable release mechanisms based on changes in pH, redox potential, or activated by light. Our core-shell nanoparticles were also used for the successful release of bioactive molecules such as cell toxins into living cells. Microscopic studies shed light on the detailed entry and release mechanisms of these particles in living cells. This collaborative work is being performed with several LMU research groups in chemistry, physics and pharmacy.