The detection of antibodies in a blood sample is a versatile and widely applied method of today's diagnostics ^{1) 2)}. Common methods include ELISA-assays which either rely on the capture of disease antigens by immobilized antibodies (Sandwich and competitive ELISA) or on the direct immobilization of these antigens beforehand³⁾. Both methods require stable conditions for handling and storage of the plates as test reliability is crucially dependent on native-state proteins. To maintain these conditions is already expensive under European standards, but becomes elaborate when working in tropical or arid regions.

Especially in those regions, where hospitals are mostly hard to reach and local medical treatment seldom relies on physicians, it is necessary to reliably distinguish between different illnesses. The treatment of potential epidemic pathogens requires an enormous logistic effort, and differential diagnosis of a less potent pathogen may save thousands of dollars. Thus, it would be beneficial to have a large library of known antigens that is easy and cost-effective to store or to ship, but nonetheless functions as a selective tool in diagnostics.

Our idea of how to deal with this problem is to use the unique properties of DNA as reliable information storage and combine it with cell-free expression in the detection device. The antigens produced directly before diagnosis are not only less prone to denaturation, but are also enriched in the device by a specific surface and detected by a new kind of detection method called iRIf.

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