Oligonucleotide contact printing. 10 μL oligonucleotide solutions containing 3 μM DNA diluted in DNase-free water were deposited onto micro-patterned polydimethylsiloxane stamps and incubated for 8 min. Concurrently, glass slides wrapped with the target polyethylene substrate were oxygen plasma-treated for 3 mins. Subsequently, the stamps were briefly rinsed in phosphate buffered saline and deionized water. Following momentary drying under nitrogen flow, the stamps were placed onto the oxygen plasma-treated polyethylene substrates and weighed down with 500 g of mass. After 2 mins, the stamps were removed.