l‐DNA Duplex Formation as a Bioorthogonal Information Channel in Nucleic Acid‐Based Surface Patterning

Photolithographic in situ synthesis of nucleic acids enables extremely high oligonucleotide sequence density as well as complex surface patterning and combined spatial and molecular information encoding. No longer limited to DNA synthesis, the technique allows for total control of both chemical and Cartesian space organization on surfaces, suggesting that hybridization patterns can be used to encode, display or encrypt informative signals on multiple chemically orthogonal levels. Nevertheless, cross‐hybridization reduces the available sequence space and limits information density. Here we introduce an additional, fully independent information channel in surface patterning with in situ l‐DNA synthesis. The bioorthogonality of mirror‐image DNA duplex formation prevents both cross‐hybridization on chimeric l‐/d‐DNA microarrays and also results in enzymatic orthogonality, such as nuclease‐proof DNA‐based signatures on the surface. We show how chimeric l‐/d‐DNA hybridization can be used to create informative surface patterns including QR codes, highly counterfeiting resistant authenticity watermarks, and concealed messages within high‐density d‐DNA microarrays.