Localized surface plasmon resonance-based DNA detection in solution using gold-decorated superparamagnetic Fe3O4 nanocomposite.

In the field of nucleic acid-based biosensor technology, DNA-conjugated nanocomposites have attracted much attention due to their unique properties and multimodal applicability. However, quantitative estimation of sequence-specific oligonucleotide in a simpler way is still a challenge. Precise positioning of DNA probes over the surface of the nanocomposite can overcome problems such as steric hindrance of the surface-bound molecules to enable further sensing as well as nonspecific folding of the DNA molecule over the surface of the gold (Au) nanolayer. Considering such objectives, we have developed glutathionated Fe3O4@Au core/shell nanocomposite, fabricated with DNA molecules and applied for sensing complementary oligo spectrophotometrically, using the localized surface plasmon resonance (LSPR) properties of the synthesized nanocomposite. When hybridization experiments were performed with 10 to 100 fM complementary DNA and DNA-conjugated nanocomposite, a strong linear relationship was observed between DNA concentration and surface plasmon resonance (SPR). Discrimination even at the single-base level was also observed when further experiments were performed with complementary DNA, but with a sequential decrease of bases from the single level to the fifth level.