Silica nanoparticles doped with either organic or inorganic
luminescent dyes have been developed for ultra-sensitive
sensors. The large number of dye molecules confined in a
single silica particle guarantees huge improvement in sensitivity.
Moreover, the silica matrix protects the dye molecules
from the external environment, largely suppressing photobleaching
and photodegradation. The outstanding photostability
makes dye-doped silica nanoparticles especially
advantageous for applications that require high intensity or
prolonged excitations (Yan et al., 2007). The rich silica chemistry
(e.g., silane chemistry) also helps future surface modification
and conjugation.