Synthesis of DNA oligonucleotides in mesoporous silicon

In-situ oligonucleotide synthesis through an 8-base sequence is demonstrated within 30 rim silicon mesopores utilizing sequential phosphoramidite reactions. Stepwise attachment of each base is confirmed by monitoring the porous silicon effective refractive index via a waveguide resonance angle. A linear increase in the effective refractive index is observed after the addition of each base, and the detection of oligonucleotides containing only a single thymine is possible. It is estimated that 50% of the available internal pore surface is occupied by the 8-base oligonucleotides, which is a substantially greater coverage than obtained by using traditional methods of direct attachment of presynthesized DNA oligonucleotides. The greater surface coverage by DNA probes will enable more effective biosensing devices. (C) 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim