The present invention concerns compositions, apparatus and methods of use of recognition complexes, comprising biological sensors operably linked to an organic semiconductor. Multiple recognition complexes can be associated into a recognition complex system. The recognition complex system is of use to identify analytes, to separate biological sensors that bind to a target analyte from those that do not, to separate analytes that bind to a specific biological sensor from those that do not, and to prepare biological sensors with a high affinity for a particular analyte. The recognition complex system may be attached to a variety of surfaces, such as a chip, a flow cell, magnetic beads or non-magnetic beads. The biological sensor may be used for screening of, for example, a phage library, combinatorial chemistry library, plant tissue extract or animal tissue extract for inhibitors, activators or binding factors of bioactive molecules.
 The invention described herein was made with Government support under contracts F41622-96-D-008 and F41824-00-D-700 awarded by the Department of the Air Force and Department of Energy contract number DE-AC06-76RL01830. The Federal Government has a nonexclusive, nontransferable, irrevocable, paid-up license to practice or have practiced for or on behalf of the United States the subject invention.