Silica nanoparticles, produced by the sol–gel process that uses silicon alkoxides as starting materials,have received much attention for many years because of their practical importance in a variety of fields.In recent years, the newly emerging area of in vitro andin vivo diagnosis, analysis, and measurements inside intact biologic systems (e.g., tissues, blood, and single
cells), with the use of nanoparticle devices, has attracted considerable attention.Some of the typical applications in this area may
include