Roche NimbleGen manufactures custom, high-density DNA arrays based on its proprietary Maskless Array Synthesizer (MAS) technology. The MAS system is a bench top, solid-state, high-density DNA array fabrication instrument comprised of a maskless light projector, a reaction chamber, a personal computer, and a DNA synthesizer. Roche NimbleGen builds its arrays using photo-mediated synthesis chemistry with its MAS system.
At the heart of the system is a Digital Micromirror Device (DMD), similar to Texas Instruments' Digital Light Processor (DLP employing a solid-state array of miniature aluminum mirrors to pattern 786,000 to 4.2 million individual pixels of light. The DMD creates "virtual masks" that replace the physical chromium masks used in traditional arrays.
These "virtual masks" reflect the desired pattern of UV light with individually addressable aluminum mirrors controlled by the computer. The DMD controls the pattern of UV light projected on the microscope slide in the reaction chamber, which is coupled to the DNA synthesizer. The UV light selectively cleaves a UV-labile protecting group at the precise location where the next nucleotide will be coupled. The patterns are coordinated with the DNA synthesis chemistry in a parallel, combinatorial manner such that 385,000 to 2.1 million unique probe features are synthesized in a single array.
The synthesis of microarrays using NimbleGen MAS technology is very similar to traditional oligonucleotide synthesis with some important exceptions. Unlike conventional oligo synthesis, arrays are synthesized on glass slides rather than controlled pore glass supports. Another key difference is that the deprotection steps are performed by photodeprotection rather than by acid deprotection. The illustration here depicts digital micromirrors reflecting a pattern of UV light, which deprotects the nascent oligonucleotide and allows addition of the next base.
