Inorganic nanoparticles for optical bioimaging

The tremendous progress in the synthesis of different inorganic nanoparticles with pretailored size, shape, structural, compositional, and surface properties has significantly raised their potential applications in biomedicine. Optically active inorganic nanoparticles are those that, based on inorganic materials, can produce fluorescence or scattered light under suitable optical excitation. These outgoing radiations can be conveniently used for bioimaging purposes. In this work, the different types of optically active inorganic nanoparticles that are being used for optical bioimaging are reviewed in detail. Special attention is paid to fluorescent and inorganic persistent luminescence nanoparticles and how their different excitation mechanisms (no-photon, one-photon, or multiphoton excited fluorescence) and working spectral ranges can be conveniently applied for in vitro and in vivo high-contrast optical bioimaging.