High brightness red emitting polymer beads for immunoassays: Comparison between trifluoroacetylacetonates of Europium.

Efficiently luminescing spherical polymer particles (beads) in the nanoscale regime of up to approximately 250 nm have become very valuable tools in bioanalytical assays. Eu- complexes imbedded in polymethacrylate and polystyrene in particular proved to be extraordinarily useful in sensitive immunochemical and multi-analyte assays, and histo- and cytochemistry. Their obvious advantages derive from both, the possibility to realize very high ratios of emitter complexes to target molecules, and the intrinsically long decay times of the Eu-complexes, which allows an almost complete discrimination against bothersome autofluorescence via time-gated measuring techniques; the narrow line emission in conjunction with large apparent Stokes shifts are additional benefits with regard to spectral separation of excitation and emission with optical filters.

Design and Mechanism of Rare-Earth Singlet Oxygen Sensing: An Experimental and Quantum Chemical Approach.

The sensitive detection of singlet oxygen (O) is one key issue in various photochemical analyses, reactions, and processes; it is indispensable for designing catalysts for photodynamic therapies. Corresponding fluorescence-based organic O monitor luminophores may be equipped with rare-earth complexes with several intrinsic advantages. The design of the necessary ligands being a tedious, time-consuming effort, often involving empirical guesswork, we decided to support our experimental work with quantum chemical calculations.

The microbial threat: Can rare earths help?

Despite an ever increasing demand for reliable and cheap methods in the detection and quantification of microbes, surprisingly few investigations have explored or utilized the luminescence of rare earths in the microbial context, neither in conventional, that is, plating and microscopic imaging techniques, nor in advanced methods like fluorescence flow cytometry. We have thus investigated the potential of some rare earth complexes and hybrid materials for microbiological analysis. We found fairly simple procedures for internal staining (dyes inside the bacterial cell) and external staining (dyes on the cell surface).

Monitoring of nanoclay-protein adsorption isotherms via fluorescence techniques.

The investigation of nanoparticles and their interaction with bio-macromolecules have become an important issue; the widely discussed protein corona around nanoparticles and their biological fate in general have drawn particular attention. Here, we focus on nanoclay dispersions and the use of solvatochromic fluorescent dyes (Dansyl and Coumarin 153) for monitoring the interaction with two model proteins, bovine serum albumin and β-lactoglobulin. On one hand, these dyes are poorly emissive in water, but experience a boost in their fluorescence when adsorbed into the hydrophobic domains of proteins.

Patterning of Nanoclays on Positively Charged Self-Assembled Monolayers via Micromolding in Capillaries.

Nanoclays are nanomaterials with versatile adsorptive properties. This contribution describes the generation of micropatterns of a nanoclay ("laponite") on ammonium-terminated, self-assembled monolayers (SAMs) on glass and silicon. Microstructured immobilization of the laponite was performed using micromolding in capillaries (MIMIC).

Selective Inactivation of Resistant Gram-Positive Pathogens with a Light-Driven Hybrid Nanomaterial.

Herein, we present a straightforward strategy to disperse highly insoluble photosensitizers in aqueous environments, without major synthetic efforts and keeping their photosensitizing abilities unaffected. A layered nanoclay was employed to adsorb and to solubilize a highly efficient yet hydrophobic Si(IV) phthalocyaninate in water. The aggregation of the photoactive dye was correlated with its photophysical properties, particularly with the ability to produce highly cytotoxic singlet oxygen.

Photophysical efficiency-boost of aqueous aluminium phthalocyanine by hybrid formation with nano-clays.

Novel organic-inorganic hybrid materials comprising nanoscaled layered silicates and native aluminium hydroxide phthalocyanine (Al(OH)Pc) allowed for the first time the exploitation of their unique photophysical properties in aqueous ambience. In particular, we were able to observe the efficient emission of Al(OH)Pc-nanoclay hybrids and generation of singlet oxygen in aqueous solution.

Laponite blue: dissolving the insoluble.

The neutral organic dye indigo forms an inorganic-organic hybrid material with nanoclays (see picture; blue circles on disks symbolizing indigo, spheres indicating liberated cations) and can thus be transferred into aqueous solution. Solids recovered from these solutions resemble the ancient Maya Blue pigment. The method can also be applied to other hydrophobic species and may open the gate for novel solution chemistry, including photonic and catalytic applications.