Fig. 1.

Building blocks, photolithographic synthesis and orthogonal processing for multi-patterning nucleic acid photolithography. a High-level schematic depiction and molecular detail of representative elements of classes of nucleic acid building blocks available for photolithographic synthesis. These elements include essentially all biogenic nucleic acids (canonical and non-canonical DNA and RNA nucleotides), structural modifiers including branching and spacing monomers, fluorescent and functionalizing modifiers, and engineered xenobiotic nucleic acid (XNA) monomers with modified sugars, bases or backbones. b Massively parallel surface synthesis is performed using maskless photolithography mediated by patterned light from a digital micromirror device to selectively remove the photolabile protecting group present on each monomer. c Surface synthesis results in dense arrays including hundreds of thousands to millions of unique sequences at defined positions. d Multi-level patterning includes multiple orthogonal surface modifications: patterned surface biopolymers synthesis with free choice of monomer chemistry, further modification with additional photochemistry, and final modifications with a variety of nucleic acid processing enzymes ranging from DNA and RNA polymerases to nucleases such as uracil-DNA glycosylase and RNase HII