Bead-based single protein micro-array 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 micro-arrays. We generate positively charged surface micro-patterns on a glass substrate and use them as template for adsorbing negatively-charged carboxylated beads. The template for bead adsorption is generated by patterning an aminosilane layer using conventional lift-off technique. The –COOH moiety which is present on the patterned bead 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 withstand agitated rinse in de-ionized water. We also show here that the same method can be extended for bead patterning within sealed microfluidic channels.