Research into lanthanide-doped organic-inorganic hybrid materials emerged in the 1990s with the development of interesting materials for optics: high efficiency and stable solid-state lasers, new fiber amplifiers and sensors, devices with upconversion, fast photochromic and non-linear responses, etc. Their interest relies on the possibility of combining properties of sol-gel host materials (shaping, tunable refractive index and mechanical properties, corrosion protection, specific adhesion, etc.) and the well-known luminescence of lanthanide ions (Ln). The fast development of photonic hybrids allowed the commercial exploitation of products with new or enhanced characteristics (megajoule pulsed Nd-YAG laser, protective coatings of glasses, screens or glasswares). However, recently, Ln-hybrid nanocomposites have found new applications in bio-sensors, bio-analytics and even clinical imaging diagnostics. These applications make use of the fluorescence properties of lanthanides that make luminescent hybrids ideal candidates for time-resolved fluoroimmunoassays, DNA hybridation assays, fluorescence imaging microscopy, or in vivo imaging. As a consequence, the goal of this review is twofold: (i) as a reminder of some general considerations that must be taken into account to design new optically active Ln-doped nanocomposites whatever the application field, and (ii) to show the most important advances achieved in the past years in different areas, paying special attention to bio-medical applications.

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Silica glasses containing both ZnS quantum dots (QDs) and luminescent lanthanide ions are attractive candidates to develop new lighting displays, sensor devices or laser emitters. This work reports an easy sol-gel method to prepare Eu 3+ -doped and Eu 3+ ,Mn 2+ -codoped ZnS nanocrystals dispersed in a transparent silica matrix. Semiconductor nanocrystals with an average size of 5-6 nm and exhibiting both cubic and hexagonal phases were obtained at low temperature. The luminescent interactions between ZnS QDs, Eu 3+ and Mn 2+ ions provided materials with different optical responses but also gave information about the organization of the different species in the nanocomposite. Indeed, Eu ions were found to be both dispersed within the silica and located at the surface of the nanochalcogenide, the latter providing a ZnS / Eu 3+ energy transfer. Incorporation of Mn 2+ into the ZnS lattice induced the appearance of defect states that enhance the blue luminescence of the nanocomposite. These results underline the sensitivity of optical processes to the nature and organization of the active species, which is of vital importance for the design of photonic materials.

Registro de acceso restringido Este recurso no está disponible en acceso abierto por política de la editorial. No obstante, se puede acceder al texto completo desde la Universitat Jaume I o si el usuario cuenta con suscripción. Registre d'accés restringit Aquest recurs no està disponible en accés obert per política de l'editorial. No obstant això, es pot accedir al text complet des de la Universitat Jaume I o si l'usuari compta amb subscripció. Restricted access item This item isn't open access because of publisher's policy. The full--text version is only available from Jaume I University or if the user has a running suscription to the publisher's contents.

The use of electrospray ionization mass spectrometry (ESI-MS) in parallel with 29 Si and 1 H NMR to elucidate the aqueous speciation and temporal evolution of the organosilane methyldiethoxysilane (MDES) through hydrolysis and condensation processes is reported here. A suitable methodological approach for the monitoring of the oligomerization of MDES under different pH conditions has been developed revealing details on the particular oligomerization mechanism of this organosilane.