DNA microarrays based on noncovalent oligonucleotide attachment and hybridization in two dimensions

Short oligonucleotide probes have been linked to a solid support by simple electrostatic adsorption onto a positively charged surface film. Attachment was obtained by microfluidic application of unmodified oligonucleotides in distilled water onto amino-silanized glass. It has been demonstrated that an extremely stable monolayer of oligonucleotide is obtained by this method , at a density of about 10(11) molecules/mm(2), which approaches the limit expected for a two-dimensional closest-packed array. Application of oligonu cleotide by adsorption is followed by capping with acetic anhydride in the vapor phase, and then capping with succinic anhydride in solution to form a surface with weak negative charge. The capping method has been successfull y employed for microarray fabrication and for the analysis of single nucleo tide polymorphisms in the k-ras gene. The data reveal that, subsequent to c apping, the adsorptive association of oligonucleotide to the surface yields a probe layer which is capable of single nucleotide base mismatch discrimi nation and high apparent binding affinity. (C) 2001 Academic Press.