Chemical modular system
As in a modular system, the researchers placed various molecular layers, one above the other, on the germanium crystal. First, they produced hydroxyl groups on the germanium surface, each consisting of an oxygen atom and a hydrogen atom. The product is referred to as activated germanium. The next layer was formed by a new kind of triethoxysilanes, a hydrocarbon compound, which the RUB team produced itself. The researchers anchored one end of the triethoxysilanes covalently to the germanium, i.e. via an electron-pair bond. They converted the other end into a protein trap. All the proteins that carry a particular adapter, the His-tag, can be attached to this. "There are already a lot of proteins available with this universal adapter" Carsten Ktting says.
Modifying the germanium surface in a controlled manner
Using Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy (XPS), the researchers kept track of what happened when stacking the different layers on the germanium crystal. Together with Prof. Dr. Martin Muhler and Bastian Mei from the Laboratory of Industrial Chemistry, the biophysicists were able to accurately determine the atomic composition of the layers with the XPS. Proteins can also be observed on surfaces using other techniques, such as surface plasmon resonance. "With surface plasmon resonance, the gradual modification of the surface is carried out blindly," Jonas Schartner says. "We've observed each modification step live and thus have very good control over the process."
Functional test for the new process successful
A test confirmed that the newly created surface serves its purpose. The researchers equipped the germanium crystal with the switch protein Ras, which plays an important role in carcinogenesis. There they allowed it to interact with a second molecule that switches Ras on
|Contact: Dr. Carsten Ktting|