Michael Mertig
Bionanotechnology and structure formation
Previous and current research
Our laboratory is interested in biomimetic materials synthesis, bionanotechnology and high-resolution microscopy. We explore basic principles of biological structure formation and try to apply them in an engineering context for the controlled in-vitro fabrication of structures which do not exist as such in nature, e.g., DNA nanotubes or metallic nanowires fabricated by template-directed metal deposition onto double-stranded DNA. Besides DNA, biological systems which have been successfully investigated with respect to their application as basic building blocks for the bottom-up assembly of predefined artificial nanostructures, involve different structural proteins (collagen, microtubule, regular bacterial surface layer proteins) and motor proteins. The scientific scope of our work can be divided into three main areas:
Biomolecular Templating
By addressing fundamental issues of both nanometer fabrication and supramolecular engineering, biomolecular templating has demonstrated the capability to build up thoroughly predefined inorganic nanostructures by taking advantage of the unique self-assembly capabilities of biomolecules and of their well-defined structural, physical and chemical properties. In particular, the precise control of the nucleation and growth of metal cluster on biomolecular templates has led to hybrid metal-organic nanostructures with extremely high structural densities and novel material properties.
Structural and physical properties of biomolecular and hybrid structures
Precise knowledge about structure and morphology of the used biomolecular templates is an important issue of our work. We use fluorescence, scanning probe and electron microscopy in combinations with advanced image processing methods to elucidate native protein and artificial DNA structures.
One particular focus of our work is the study of relevant physical properties of both the used biomolecular templates and the resulting hybrid structures, including low-temperature transport properties of DNA-templated metallic nanowires. Very recently, the electronic structure of the occupied and unoccupied states of a bacterial surface protein layer was measured by photoemission and NEXAFS spectroscopy.
DNA construction
The ability to synthesize DNA with arbitrary base sequence permits to program their intra- and intermolecular associations, and thus to build up artificially engineered supramolecular structures and networks. We explore fundamental principles for a DNA-based fabrication of wires and networks that constitute the basics for the construction of future nanoelectronic circuits. One central issue of this research is to develop reliable methods for the site-specific implementation of individual DNA molecules into microfabricated contact arrays by making use of the unique molecular recognition properties of DNA and the action of motor proteins.

AFM image of an artificially designed DNA junction
Future prospects and goals
• Bottom-up strategies for the synthesis of advanced nanostructures.• Nanoelectronics.
• Electrical and mechanical properties of biomolecules.
• Electrical and SPR sensor principles for biological detection.
• Microfluidics.
About
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Selected publications
Aichmayer, B., Mertig, M., Kirchner, A., Paris, O., Fratzl, P. (2006): Small-angle scattering of S-layer metallization. Advanced Materials 18: 915-919.
Dinu, C.Z., Opitz, J., Pompe, W., Howard, J., Mertig, M., Diez, S. (2006): Parallel manipulation of bifunctional DNA molecules on structured surfaces using kinesin-driven microtubules. Small 2: 1090-1098.
Vyalikh, D.V., Kirchner, A., Danzenbächer, S., Dedkov, Y.S., Kade, A., Mertig, M., Molodtsov, S.L. (2005): Photoemission and NEXAFS studies of the bacterial surface protein layer of Bacillus sphaericus NCTC 9602, Journal of Physical Chemistry B 109: 18620-18627.
Wahl, R. Engelhardt, H., Pompe, W., Mertig, M. (2005): Multivariate statistical analysis of two-dimensional metal cluster arrays grown in vitro on a bacterial surface layer. Chemistry of Materials 17: 1887-1894.
Mertig, M., Colombi Ciacchi, L., Seidel, R., Pompe, W., De Vita, A. (2002): DNA as a selective metallization template. Nano Letters 2: 841-845.
