Assay devices for combinatorial libraries

An apparatus suitable for conducting an assay for a combinatorial library, wherein the apparatus comprises:

• a block;
• a plurality of wells disposed on a top surface of the block, wherein said plurality comprises at least 10,000 wells within the block, each well in said plurality comprising:
• a cylindrical opening defined by a side wall, the side wall having circular cross sections at any position along the side wall, the cylindrical opening penetrating partly into the block;
• a floor, wherein said floor comprises a hydrophilic target capturing element adherent thereto and impeding movement of a target when added to said well, the hydrophilic target capturing element comprising a film;
• and
• a hydrophilic coating on the side wall;
• and
• a hydrophobic layer disposed on the top surface of the block and between each well, the hydrophobic layer configured to restrict spill-over of an aqueous solution between wells,
• wherein minimum distances from edges of each of the wells to edges of the respective one or more nearest neighboring wells in said plurality of wells are from about 10 microns (μm) to about 50 μm, and
• wherein each of the wells has a well diameter from about 30 μm to about 250 μm and a well depth from about 30 μm to about 400 μm.