Microchips are used in the combinatorial synthesis of peptide arrays by means of amino acid microparticle deposition. The surface of custom‐built microchips can be equipped with an amino‐modified poly(ethylene glycol)methacrylate (PEGMA) graft polymer coating, which permits high loading of functional groups and resists nonspecific protein adsorption. Specific microparticles that are addressed to the polymer‐coated microchip surface in a well defined pattern release preactivated amino acids upon melting, and thus allow combinatorial synthesis of high‐complexity peptide arrays directly on the chip surface.
Currently, arrays with densities of up to 40,000 custom peptide synthesis spots/cmcan be generated in this way, with a minimum of coupling cycles required for full combinatorial synthesis. Without using any additional blocking agent, specific peptide recognition has been verified by background‐free immunostaining on the chip‐based array. This unit describes microchip surface modification, combinatorial peptide array synthesis on the chip, and a typical immunoassay employing the resulting high‐density custom peptide synthesis arrays.
. By sandwiching a glass plate having pierced holes between two channel-etched glass surfaces, we made a glass chip in which channels in upper and bottom plates can cross without contacting each other (two-level crossing). To check the 3-D channel network, combinatorial amide syntheses by mixing two acid chlorides with two amines were carried out.