In recent years,the newly emerging area of in vitro and in vivo diagnosis, analysis, and measurements inside intact biologic systems (e.g., tissues, blood, and singlecells), with the use of nanoparticle devices, has attracted considerable attention. Some of the typical applications in this area may include (1) dyedoped nanospheres as nanosensors for intracellular measurements(2) magnetic nanoparticles for di-agnostic magnetic resonance imaging and (3)nanospheres coated with biodegradable materials as injectable blood-persistent systems for the controlled release of drugs, site-specific drug delivery, and medical imaging.