In order to integrate processes into a microfluidic chipsystems properly, it is important to know its fundamentals and possible difficulties that could occur. To achieve this, we get to know every process and optimize its parameters for its application in the microfluidic chipsystem. As a result of our broad range analytical methods we are able to analyze all processes and can optimize it. As a result of this, we are able to perform several chemical and biological reactions. The latest reactions we dealt with shall be presented on this page.

One major challenge was the integration of photochemical reactions, especially the photochemical synthesis of gold nanoparticles. Since Photochemistry deals with light, which is considered as a clean and traceless reagent, it offers big potential to new strategies for chemical reactions. In combination with microreactors it offers superior advantages as a very good light penetration as well as controllable reactions and high yields due to good mixing in such reactors. Additionally this combination is considered more ecologically friedly because this type of reactions produces less waste and needs less solvents.

The synthesis of nanoparticles gained over the last years enormous attention since it is used in more and more applications. Unfortunately its production in a chemical way lacks of reproducibility. Using photochemistry more parameters are available and a better reproducibility is expected. To synthesize gold nanoparticles in microreactors, we examined a variety of photoinitiators and support agents. Some of these reagents include Michlers ketone or Irgacure 2959 as photoinitiators and e.g. SDS as a supporting agent. The precursor always used in the experiments was auric acid. Synthesizing nanoparticles in a microreactor, we could control nanoparticle properties as size and particle size distribution via control of the flow rate.

Showing the reactors versatility, we applied the photochemical conversion of furanones with addition of 2-propanol and 4,4'-dimethoxybenzophenone (DMBP). Using GC/MS we could show a complete conversion of furanone to its conversion product. This proofed that the microfluidic reactor is powerful to execute photochemical reactions of different kinds.

The usage of immunological reactions offers a broad spectra for the detection of biological molecules. In our group we are using ELISA and immunohistochemistry. With ELISA we are developing an analysis system for mycotoxins in food. Exemplary for this task we are working with the toxins Aflatoxin M1 which could appear in milk Ochratoxin A that could be present in red wine. For optical detection of toxins, we are using gold nanoparticles coupled to antibodies.

Immunohistochemistry is a powerful tool used in pathologies for characterising tumors. To improve the information output of one tumor sample, we are developing a microfluidic system that enables a simultaneous staining of six biomarkers in one tumor sample. To achieve this, an optimization of the process of immunohistochemistry is necessary in order to achieve optimal staining results which includes the choice of staining reagents, their concentration as well as incubation times.