Spatially reinforced Au nano-cavities as a reaction nano-reservoir for trace analysis of DNA hybridization

Spatially reinforced Au nano-cavities (SR-nAu) with reduced tip-to-tip displacement create strongly localized surface plasmon resonance by Raman scattering. Within SR-nAu, the nano-cavity structure with high aspect ratio was optimized as the nano-reservoir for the distinction of DNA hybridization responses from specific DNA sequences of Avian influenza virus. In the nano-reservoir, the suspended or immobilized probe, its complementary and noncomplementary target sequences were characterized at very low concentration through enhanced Raman spectra. The presence of Raman shift at 738 cm ^-1, the characteristic breathing mode of thymine, and the change of relative peaks intensity at 1603 and 1554 cm^-1 before and after hybridization were particularly taken as the major indications to validate the match or mismatch state of DNA sequences. Through a labeling-free means, and from the evidence provided by specific complementary and noncomplementary DNA sequences, the recognition capability of nano-reservoir can be down to subnano-molar concentration (10^-10 M).