Biomedical subjects

Michael Mertig

Publications and source records attributed to Michael Mertig.

4 recordsLinked to original sources

PubMed2006

Parallel manipulation of bifunctional DNA molecules on structured surfaces using kinesin-driven microtubules.

We have developed a technique to manipulate bifunctional DNA molecules: One end is thiolated to bind to a patterned gold surface and the other end is biotinylated to bind to a microtubule gliding over a kinesin-coated surface. We found that DNA molecules can be stretched and overstretched between the gold pads and the motile microtubules, and that they can form dynamic networks. This serves as a proof-of-principle that biological machineries can be used in vitro to accomplish the parallel formation of structured DNA templates that will have applications in biophysics and nanoelectronics.

Bacteriophage lambda↗

PubMed2006

Growing one-dimensional metallic nanowires by dielectrophoresis.

We report an electrical-field-controlled growth process for the directed bottom-up assembly of one-dimensional palladium nanowires between microfabricated electrodes. The wires, grown from an aqueous palladium salt solution by dielectrophoresis, have a thickness of only 5-10 nm and a length of up to several micrometers. The growth process depends largely on both the strength of the applied ac field and the concentration of the metal salt solution. The conditions for optimum growth are evaluated. Room-temperature current-voltage measurements show ohmic behavior and indicate electromigration effects at higher voltages. Low-temperature transport measurements reveal localization effects with a characteristic resistance minimum at 20 K. The temperature dependence below the minimum shows the wires to be one dimensional in their electron-transport properties. The investigated growth method is capable of building complex circuit patterns for future nanoelectronics.

Electric Conductivity↗

PubMed2005

Photoemission and near-edge X-ray absorption fine structure studies of the bacterial surface protein layer of Bacillus sphaericus NCTC 9602.

The electronic structure of the regular, two-dimensional bacterial surface protein layer of Bacillus sphaericus NCTC 9602 has been examined by photoemission (PE) and near-edge X-ray absorption fine structure (NEXAFS) spectroscopy. Both the O 1s and the N 1s core-level PE spectra show a single structure, whereas the C 1s core-level spectrum appears manifold, suggesting similar chemical states for each oxygen atom and also for each nitrogen atom, while carbon atoms exhibit a range of chemical environments in the different functional groups of the amino acids. This result is supported by the element-specific NEXAFS spectra of the unoccupied valence electronic states, which exhibit a series of characteristic NEXAFS peaks that can be assigned to particular molecular orbitals of the amino acids by applying a phenomenological building-block model. The relative contributions of the C-O, C-N, and C-C bond originating signals into the C 1s PE spectrum are in good agreement with the number ratios of the corresponding bonds calculated from the known primary structure of the bacterial surface protein. First interpretation of the PE spectrum of the occupied valence states is achieved on the basis of electronic density-of-states calculations performed for small peptides. It was found that mainly the pi clouds of the aromatic rings contribute to both the lowest unoccupied and the highest occupied molecular orbitals.

Amino Acids↗

PubMed2004

Electronic structure of regular bacterial surface layers.

We report photoemission and near-edge x-ray absorption fine structure measurements of the occupied and unoccupied valence electronic states of the regular surface layer of Bacillus sphaericus, which is widely used as the protein template for the fabrication of metallic nanostructures. The two-dimensional protein crystal shows a semiconductorlike behavior with a gap value of approximately 3.0 eV and the Fermi energy close to the bottom of the lowest unoccupied molecular orbital. We anticipate that these results will open up new possibilities for the electric addressability of biotemplated low-dimensional hybrid structures.

Bacillus↗