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- 2016 (2) (entfernen)
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- Energy transfer (1)
- Europium complex (1)
- Luminescent glasses and glazes (1)
- Nanoclay hybrids (1)
- Nile Red (1)
- Polarity probe (1)
- Protein corona (1)
- Rare earth phosphors (1)
Efficient Near UV excited materials (350<λ<400 nm) responding with green line emission are sparse in comparison to higher energy UV excited emitters (λ<350 nm), while corresponding red line emitters are more abundant, albeit typically also restricted to excitation wavelengths below 400 nm. This situation is disadvantageous for several important actual and potential applications. Among these, excitation with high power UV-LEDs and laser diodes are of particular interest. Here we present results on green emitting YBO3:Ce, Tb, which can be excited with 370–380 nm radiation at quantum efficiencies of up to 60% and decay times in excess of 2 ms. Moreover, as powderous phosphors typically require stable matrices to be hosted in, we investigated low melting, lead- and fluoride-free glasses for their capability to accommodate the phosphor and yet retain its optical properties. In these, we even observed an increase of the quantum efficiencies of up to 70% at decay times approaching 3 ms. Finally, we characterized the thermal quenching behavior, which showed a clear advantage of the phosphors in glassy matrices.
Hydrophobic guest molecules like organic dyes and metalion complexes can be introduced into aqueous media via adsorption onto inorganic nanoclay host materials such as nm-sized laponite. Dispersions of these organicinorganic hybrid materials show several advantageous properties like minimum light scattering due to their small size in the nanometer regime, ease of modification, low cost, low toxicity, and long-term stability, making them perfect candidates as signaling units and optically active materials in photonics and biotechnology. In this study, we summarize first findings on the easy-to-make, but chemically and optically fairly complex behavior of nanoclay hybrids for biotechnological applications. The latter includes the preparation of nanomaterials, which are colloidally stable in buffers and in the presence of biomolecules like proteins, and methods to control their surface chemistry. For this purpose, we used two red emitting fluorophores, the small organic dye Nile Red and the rare earth complex Eu(ttfa)3(topo)2, and evaluated the interaction of the red nanoclay hybrids with two model proteins, bovine serum albumin and β-lactoglobulin. We were able to monitor the formation of the protein corona around these hybrids using absorption and luminescence spectroscopy.