Dr. Bernd Grohe - Current Research and Collaboration

Research interests:

• Polyelectrolyte-controlled mineralization processes (e.g. biomineralization) and their chemical and biochemical perspectives
• Polyelectrolyte mediated nucleation and growth of mineralizing systems and biominerals
• Inhibited nucleation and crystal growth by polyelectrolytes
• Polyelectrolyte – crystal - interactions and their molecular features involved in these processes
• Biofunctional interfaces
• Biocompatibility

Current Research:

In collaboration with Dr. K. A. Rogers (UWO , Anatomy & Cell Biology), we have developed a method to non-invasively investigate in-situ nucleating and growing crystals. The basis of this technique is the combination of confocal microscopy and the use of interference phenomena appearing in thin films. This technique, the so-called Scanning Confocal Interference Microscopy (SCIM), has been shown to resolve objects separated by 30-100 nm, depending on the wavelength of the laser used.		Twinned calcium oxalate monohydrate (COM). Note the macrosteps on {100} faces.
In a further project with Dr. K. A. Rogers we study the selectivity of adsorbing polyelectrolytes to faces and edges of crystals. For these investigations we label polyelectrolytes with a fluorescent dye and separately image the fluorescence and a crystal via confocal microscopy. Both images can be superimposed and analyzed with respect to the local distribution and intensity of fluorescence.		OPN (green) adsorption to a calcium oxalate monohydrate crystal (red).
In collaboration with Dr. Silvia Mittler (Physics & Astronomy, UWO), we mimic the biomineralization of bone growth by means of a bonesialo protein mediated crystallization of hydroxyapatite on collagen. The latter is templated on self-assembled monolayers containing terminated thiols adsorbed on gold.		Templated collagen on a gold/thiol substrate. Scale bar: 15 μm; optical microscopy, darkfield image.
In urine, crystallization and aggregation is affected by a large variety of proteins and other compounds, in healthy as well as in diseased individuals. In cooperation with J. Denstedt (Department of Surgery, UWO), M. Karttunen (Applied Math, UWO), and E. S. SØrensen (Department of Molecular Biology, University of Aarhus, Denmark), we study the ability of osteopontin (OPN), a phosphorylated glycoprotein found in bone, kidney and milk, to inhibit crystallization processes and pathological mineralization such as kidney stone formation.		Osteopontin (OPN). One of the major proteins investigated in our group.