Process and device for the screening of molecules with regard to their individual binding behaviour towards at least one given ligand

A device for screening molecular libraries based on the binding of fluorescent ligands to library constituents, the device comprising an inverse fluorescence microscope and a moving stage for holding a substrate together with plated-out objects and a first light source for exciting a first fluorescence at a first wavelength and a second light source for exciting a second fluorescence at a second wavelength, the second wavelength being different than the first, wherein,

• a) a CCD camera measuring the total image or stepwise partial images of the substrate for the identification of a first local fluorescence-intensity of the plated-out objects emitted in response to excitation by said first light source, and
• a second fluorescence intensity of said plated-out objects in suspension emitted in response to excitation by said second light source, which CCD camera connected to an image calculator for comparing identified fluoresncence intensities to the predetermined selection criteria such that
• (i) the first fluorescence intensity is above a threshold value, S1, and
• (ii) the quotient of the first and second fluorescence intensities is above a threshold value S2, and
• to select one or more of the plated-out objects of the substrate having fluorescence intensities that satisfy the predetermined criteria of (i) and (ii), and
• for recording the position on the substrate of said selected objects and ascribing to the selected objects location coordinates that have been determined from pixel coordinates in the image measured by the CCD camera
• and storage of said selected objects' fluorescent image information and their location coordinates;
• b) a separation actuator for the transfer of the selected objects is arranged above the moving stage;
• c) and the image calculator controls the positioning of the moving stage relative to the separation actuator.