Safe-IS

After organ transplantation, the correct dose of immunosuppressants must be determined for each patient. However, the therapeutic window of these drugs between toxic side effects and too low a dosage with the risk that the body rejects the organ is very narrow. Since some metabolites of the drugs can also have an immunosuppressive effect, the "correct" dose varies greatly from patient to patient. Therefore the adjustment of a certain drug concentration is not effective for all patients. It would be much better to determine the effectiveness of immunosuppressants in the blood of each patient individually. Studies of the signalling pathway have shown that the efficacy correlates with the formation of a complex of certain endogenous proteins with the immunosuppressant or its metabolites.
Therefore, a microfluidic system is being developed that measures the concentration of these complexes quickly and automatically. With this diagnosis, the therapy with immunosuppressants can be specifically adapted for each patient.
The microfluidic chip uses electrochemical sensors to measure the concentration of immunosuppressive complexes of immunosuppressive drugs with the body's own proteins in a small sample volume. Short diffusion paths in the microstructures allow short reaction times and therefore provide fast measurement results.
In this complex formation assay, the proteins from a patient's blood sample react with immunosuppressants or their metabolites specifically to the immunosuppressive complex. Thus, antibodies whose insufficient specificity in immunoassays leads to higher error rates can be completely dispensed with.
A table-top device controls both the fluidic assay sequence and the electrochemical measurement. In addition, in each channel of the sensor chip the position of the liquid front and any air bubbles are detected by measuring the electrical impedance along the channel. The sensor chip is electrically and fluidically connected in the device via specially developed plug contacts. Collection chambers in the chip collect any liquids contaminated with the patient sample, so that the device can be used several times without cross-contamination, while the chip is discarded after the measurement. The complexation assay and the measurement are performed automatically by the computer. This lab-on-a-chip system enables therapeutic monitoring of the efficacy of immunosuppressants (drug monitoring) in the point-of-care environment so that the appropriate dose can be determined for each patient.