Described is a method to fabricate a gold/mesoporous silica hybrid nanoparticle. According to the process, a gold nanoparticle can be conjugated onto the surface of a mesoporous silica nanoparticle to yield a photothermal stable theranostic platform, gold/mesoporous silica hybrid nanoparticle. The nanoparticles can be useful for disease detection, treatment, and monitoring.