Ralf Bischoff

Noncontact charge measurement of moving microparticles contacting dielectric surfaces

In this study examples for a noncontact procedure that allow the description of instant electric charging of moving microparticles that contact dielectric surfaces, for instance, of a flow hose are presented. The described principle is based on the measurement of induced currents in grounded metal wire probes, as moving particles pass close to the probe. The feasibility of the approach was tested with laser printer toner particles of a given size for different basic particle flow and charging conditions. An analytic description for the induced currents was developed and compared to observed effects in order to interpret the results qualitatively. The implementation of the presented procedure can be applied to transparent and nontransparent particle containers and flow lines of complex geometry which can be composed from the presented basic flow stream configurations.

Peptide arrays with a chip.

Today, lithographic methods enable combinatorial synthesis of >50,000 oligonucleotides per cm(2), an advance that has revolutionized the whole field of genomics. A similar development is expected for the field of proteomics, provided that affordable, very high-density peptide arrays are available. However, peptide arrays lag behind oligonucleotide arrays. This is mainly due to the monomer-by-monomer repeated consecutive coupling of 20 different amino acids associated with lithography, which adds up to an excessive number of coupling cycles. A combinatorial synthesis based on electrically charged solid amino acid particles resolves this problem. A computer chip consecutively addresses the different charged particles to a solid support, where, when completed, the whole layer of solid amino acid particles is melted at once. This frees hitherto immobilized amino acids to couple all 20 different amino acids in one single coupling reaction to the support. The method should allow for the translation of entire genomes into a set of overlapping peptides to be used in proteome research.

Funktionelles Protease-Profiling als neue onkologische Diagnosestrategie

Proteases play an important role in different biological processes including cell differentiation, inflammation, haemostasis, angiogenesis, apoptosis and malignant disease. Specifically, proteases are well known factors that promote local progression and metastasis of solid tumours. Tumour-associated protease activity in serum specimens of cancer patients can be monitored using synthetic reporter peptides and this hopefully might facilitate diagnosis and improve prognosis of malignant disease.

Image Processing Quality Analysis for Particle Based Peptide Array Production on a Microchip

Highly complex microarray systems based on combinatorial synthesis techniques are in wide-spread use in biological, medical and pharmaceutical research Chee et al. (1996); Cretich et al. (2006); Debouck & Goodfellow (1999). Two prominent examples are micro arrays for the artificial synthesis of arbitrary DNA sequences out of nucleic acids Heller (2002) and peptide synthesis out of amino acids Beyer et al. (2007); Templin et al. (2003). In the case of DNA arrays, these experiments mostly focus on gene identification or gene expression profiling to determine the effects of single genes on cellular evolution. Peptide arrays aim at understanding interactions of peptides with other molecules. As sequences in proteins, peptides are involved in the regularisation of biological activity.

Characterization of Proteins Involved in Mammalian Mitosis

Our interest in the molecular mechanisms of mitosis includes aspects of the mechanochemistry and fidelity of chromosome distribution, and the control of ontogeny which, in addition to differentiation, requires specific timing and positioning of cell divisions to generate the pattern of some 1014 cells of a mammal from a single fertilized egg and to compensate for cell losses.