Micropatterned agarose gels for stamping arrays of proteins and gradients of proteins

We describe a method for repetitive and rapid formation of planar microarrays and gradients of proteins using patterned agarose stamps. It demonstrates: (i) micropatterning of agarose gels with feature sizes as small as 2 μm; (ii) inking of posts (diameter 50–1000 μm) on patterned agarose stamps with one or multiple (here, eight) proteins and repetitive stamping of patterns (>100 times in the case of one protein) and arrays (20 times in the case of eight proteins) without the need for intermediate re‐inking; (iii) transferring spots of proteins with good homogeneity in surface coverage to glass slides; (iv) applying this technique to surface‐based immunoassays; (v) stamping that requires only sub‐nanomolar amounts of protein (typically ∼3 μg in ∼0.6 μL of solution); (vi) stamping without the need for drying of the proteins, as opposed to stamping with stamps made of poly(dimethylsiloxane); and (vii) patterning gradients of proteins by allowing two proteins to diffuse toward each other in an agarose stamp, followed by printing the protein gradients onto a surface.