Integrated Nanostructure–Semiconductor Molecular Complexes as Tools for THz Spectral Studies of DNA

The study of the THz spectral properties of DNA is facilitated by the use of integrated nanostructure-biomolecule structures since they provide: 1) a means of monitoring correlations in DNA THz spectra with molecular conformation; 2) a means of identifying specific DNA molecules in samples being characterized via THz signatures; and 3) a means of single-molecule detection. Specifically, molecular beacons, based on single strands of DNA, are used as hybridization probes that can potentially detect single nucleotide polymorphisms. This technique combines the use of semiconductor quantum dots (QDs) that fluoresce and the gold nanoparticles as a quencher moiety. This QD-oligonucleotide complex can recognize and pair with its complementary DNA strand. This high affinity of DNA oligonucleotides for its complementary strand has been used to form a simple semiconductor probe for ultra sensitive DNA detection. MicroRaman (¿Raman) signatures of DNA self-assembled on a variety of substrates will be discussed in terms of the THz spectra of DNA. This study will highlight the fabrication of the substrates, AFM and Raman analyses of these DNA-functionalized substrates and the use of these substrates to understand THz spectra of DNA under a variety of conditions, as well as the photoluminescence spectra of the DNA-nanoparticle complexes to study the molecular conformation changes and study of single polynucleotide polymorphism.