DNA stabilization and hybridization detection on porous silicon surface by EIS and total reflection FT-IR spectroscopy

Electrochemically etched porous silicon (PSi) is formed and employed as a substrate for the entrapment of oligonucleotides and the subsequent development of stable DNA biosensors. The controlled potential anodic etching of p-type silicon wafers is optimized in order to obtain a surface layer with pore diameters which are close to those of the adsorbed DNA helix. The stabilization and hybridization of DNA inside the PSi layer is confirmed using ATR-FTIR. Moreover hybridization is verified by the large and reproducible impedance changes at the interface layer. The developed PSi DNA sensor paves the way for the label-free detection of oligonucleotide sequences in DNA microarrays and microfabricated PSi field-effect sensors.