Pesticides in vegetables, antibiotics in meat, expired goods – frequent scandals in the food industry are making consumers more and more critical. That’s why the Heinz Nixdorf Chair for Medical Electronics at the Technical University in Munich has been researching test systems for many years now, which are making it possible to accurately analyze the effects of medications, pesticides in foods, and other environmental toxins. As a result of this research, experts at the Steinbeis Transfer Center for Cell Chip Technology have developed a miniature mobile device for use in frontline applications in the field.
The research was based on monitoring cell activity: Observing the reactions of a specially selected cell organism to specific substances, researchers can draw conclusions about the potential reactions of other organisms such as the human body. The cells continually integrate various physical and chemical signals from the environment in order to “calculate” the suitable reaction. This behavior manifests itself in the decision of cell division or cell death, in the activation of certain metabolic pathways, or the production and release of proteins. As part of the project, these micro-physiological parameters of sensitive cell cultures where recorded when the cells came into contact with environmental toxins – in and outside of the lab. These parameters were recorded through so-called automated agent testing in which cell signals are registered and analyzed through sensor chips.
The Steinbeis Transfer Center for Cell Chip Technology developed a mobile device for this process of identifying active agents that affect cells. This was intended to meet the requirement of finding a fast-track method which could be applied outside of the lab. A chip is inserted into the device which is then coupled to a fluidics system that periodically supplies the cells with fresh substances. Its specially designed bioelectronic microsensors and the selection of a suitable organotypic “target” cell culture can then precisely record the in-vitro toxicity of substances. The practical testing device measures changes in the metabolic activity of the cells before, during, and after the test substances have been applied. Under certain conditions, this toxicity can be used as an indication of the effects it would have on the human organism. First trials of the method investigated the effect of commonly available fungicides on the vitality of yeast cells.
The process has already proven itself in practice. The prepared physical data and processed digital data are immediately sent to an online database. After the measured data has been analyzed, the user receives direct feedback regarding, for example, the toxicological evaluation of the substance.
The biosensor chip used in this “biohybrid system” has been named a cellristorR, analogous to a transistor, since it controls biological signals in the cell and the electrical current in the electronic component. The sensor chip contains the physical sensors used to capture the signals of the living organism. A life support system ensures that an in-vivo type micro-environment is achieved for the tested cells. The device construction is highly complex, functioning as a systems platform with a host of integrated mechanical, microfluid, and electronic components as well as microsensors. One of the greatest challenges the project faced was how to integrate everything into a single, functional system; that is, the precise coordination of all system components to meet the goal of real-time monitoring in exceptionally sensitive cells. Another difficult issue related to environmental analysis relates to the appropriate extraction of ingredients from raw test materials and their transfer to a suitable culture medium.
The biosensor system, which is based on using living cells as signal exchangers, poses an interesting alternative to existing measuring devices used in environmental monitoring. It can also be used to complement such devices. The low operating costs and ability to tap into a mobile signal network offer researchers a lot of flexibility when analyzing the effects of environmental toxins. Automatically analyzing and evaluating measurements make it possible to quickly identify environmental hazards or the occurrence of specific pollutants in water. Using living organisms also allows for targeted reactions to any kind of toxin, which can generally only be achieved through sophisticated chemical processes.
Prof. Dr. Bernhard Wolf
Steinbeis Transfer Center for Cell Chip Technology (München)
Karolin Herzog
Heinz Nixdorf-Chair for Medical Electronics at the TU Munich
herzog.ka@tum.de