(190e) DNA Microarrays Formed by Microquill Guided Attachment to Chemically Synthesized Oligonucleotide Surfaces

DNA microarrays have become an important tool for studies of gene expression, single nucleotide polymorphisms, and comparative genomics. These immobilized patterns of DNA strands on support have been prepared by a variety of methods, differing in their ease of preparation, their specificities, and sensitivities. A frequently employed in-house approach is the spotting of gene-specific PCR products onto a poly-L-lysine coated microscopic slides. This method electrostatically fixes the DNA strands to the surface, albeit by multiple points along the DNA sequence. End-immobilized DNA sequences have instead been fabricated by light-directed combinatorial chemical synthesis and by inkjet printing technology, both requiring highly specialized equipment for their construction. We have developed an alternative method for preparing DNA microarrays, taking advantages of both oligonucleotide synthesis chemistry and conventional spotting methods for their in-house preparation. With the former method, a covalently bound single-stranded oligonucleotide sequence is formed one base unit at a time, by a fully selectable and programmable process. This sequence is designed to be specific toward a complementary sequence that is attached to an end region of oligos that are patterned onto the surface using a microprinting technique. The talk will describe key features of this approach: the synthesis of single stranded DNA sequences on glass substrates; the specificity of these surface DNAs toward the binding to complementary DNA and their rejection of non-complementary sequences, their use in generating microarray patterns that exhibit selectivity in DNA binding, and the quantitation of binding preferences by fluorescence methods. Relevant timescales of each steps and process integration will be discussed.