Many neurodegenerative diseases have an underlying molecular base that is difficult to study due to the lack of instrumentation with high spatial and temporal resolution. As a solution we present a study on the fabrication of porous silica nanoparticles based on a revised Stöber procedure with the characterization of encapsulated analyte sensitive fluorophores used to measure optically, in vivo and in real time the extracellular concentration of molecules such as O2 or K+.