Scheme 2.

Process flow for surface patterning of biomolecules and bonding. The stamp is first inked with 1 mg/mL BSA-biotin solution (ii), dried with nitrogen and stamped onto a pristine glass slide with finger pressure (iii). The pattern is then incubated with a 5% (wt/v) BSA solution in phosphate-buffered saline (PBS) for 15 minutes for blocking, followed by a droplet of 1 mg/mL streptavidin and then 100 nM biotin-modified Kras-capturing DNA for 1 hour and overnight, respectively. The patterned substrate is then bonded to a PDMS chamber that has either been activated by oxygen plasma, or polymer-grafted and hydrolyzed. After a 4-hour baking step, the Cy5-labeled DNA target oligonucleotides are introduced and DNA capture is observed under fluorescence scanner