Ionization potentials Ip, electron affinities E.A., and the quantum confinement in CdSe nanocrystals were determined by means of cyclic voltammetry. The results were compared to values obtained from spectroscopic measurements, especially UV/vis absorption and photoluminescence emission spectra. Absolute band gap positions were obtained from the electrochemical measurements and discussed with regard to vacuum level values. The results are in good agreement with theoretical expectations and spectroscopic data.

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Luminescent semiconductor nanocrystals, so called "quantum dots" (QD), have attracted increasing interest for bioanalytical labeling applications in recent years. This review describes the major optical and (bio)chemical features of this class of label, compared with organic dyes. Different conjugation methods are also discussed and the most important recent applications are presented. An overview over the current state-of-the-art is given, as also is an outlook on possibilities and limitations.

W e extend the toolbox of lab procedures in life sciences by development of centrifugal microfluidics for high-level process integration. This is accomplished by implementing novel functional principles for sedimentation, batch-mode mixing, frequencydependent online flow control, and optical read-out, which can be integrated into a process chain. The modular centrifugal setup comprises a microstructured disposable polymer disk as well as a reusable spinning and detection unit. We successfully developed centrifugal microfluidic technologies, which are suitable for sample preparation, process engineering, personalized diagnostics, and hematology, on this platform. (JALA 2005;10:331-41)

We succeeded in labeling tubulin with luminescent CdSe nanorods. The labeled tubulin was still able to self-assemble into microtubules, demonstrating that the protein has remained functional. The comparison with rhodamine-labeled tubulin revealed that whereas the rhodamine bleached completely within the observed time frame, the nanorods did not show any bleaching, which makes it possible to follow the key events of self-assembly at high time resolution. Preparation and derivatization of nanorods are described. Water-soluble, protein-reactive group-containing particles were covalently coupled to tubulin. The conjugate was purified by one cycle of assembly and disassembly and used to induce the formation of fluorescent microtubules. These results suggest that the use of luminescent nanorods should allow continuous confocal monitoring of dynamic biological processes.

Charge transfer mechanisms of several conducting polymers and polymer/CdSe nanocrystal composites (hybrid bulk heterojunction composites) were investigated by means of cyclic voltammetry. Potential application of these composites in hybrid light-emitting diodes was discussed. It was found that charge transfer is observed in most of the composites, used so far, but was relatively slow or incomplete. The PVPy/CdSe nanocrystal composite showed promising results, and is favorable for use in electroluminescent devices.

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