Electrochemically directed synthesis of oligonucleotides for DNA microarray fabrication

We demonstrate a new method for making oligonucleotide microarrays by synthesis in situ. The method uses conventional DNA synthesis chemistry with an electrochemical deblocking step. Acid is delivered to specific regions on a glass slide, thus allowing nucleotide addition only at chosen sites. The acid is produced by electrochemical oxidation controlled by an array of independent microelectrodes. Deblocking is complete in a few seconds, when competing side-product reactions are minimal. We demonstrate the successful synthesis of 17mers and discrimination of single base pair mismatched hybrids. Features generated in this study are 40 μm wide, with sharply defined edges. The synthetic technique may be applicable to fabrication of other molecular arrays.