Bead-based protein microarrays realized through electrostatic self-assembly of carboxylated beads

We report here a simple method, based on electrostatic self-assembly, for realizing bead-based single protein microarrays. We generate positively-charged surface micro-patterns on a glass substrate and used them as the template for adsorbing negatively-charged carboxylated beads. The, positively-charged, template for bead adsorption is generated by patterning a aminosilane layer using conventional lift-off technique. The –COOH groups which are present on the patterned beads’ surface is activated using carbodiimide chemistry and then a protein of interest is covalently coupled to the bead surface. The patterned beads bind strongly to the aminosilane patterns and they are able to even withstand agitated rinse in de-ionized water. We also show here that the same method can be extended for bead patterning with in sealed microfluidic channels.