Certain diseases present themselves as a complex molecular scenario. In these diseases, of which the most important examples are cancer and autoimmune diseases, a single treatment, e.g. a drug, only works under strict conditions. Therefore, the disease must be characterized by so-called markers. These can be small molecules, proteins or other features that represent the biochemical state of the disease. Today, complex diseases are treated by diagnosing the disease, characterizing the conditions and then applying appropriate treatments. In the future, these three steps will be performed simultaneously by molecular computers. Molecular computers are sets of molecules that are designed to interact with each other and with target molecules so that they can be used to determine whether a molecule is present or not (e.g. a cancer marker) and then trigger a further response, the treatment, but only if the right markers are present. In other words, the diagnosis, characterization and treatment of complex diseases is done all at once. There are many types of chemical systems that can be used to build molecular computers. In this project, we explored aptamer displacement reactions. Aptamers are short DNA sequences that can bind specifically to a molecule or protein, the target. In the displacement reaction, another DNA molecule is bound to the aptamer, which is released when the target binds the aptamer. In this case, the released molecule acts as a signal that can trigger further reactions. Aptamer displacement reactions are complex, but form the basis for future drugs that can be used to diagnose and treat patients with complex diseases.
