DNA-Driven Two-Layer Core-Satellite Gold Nanostructures for Ultrasensitive MicroRNA Detection in Living Cells.

It is a significant challenge to achieve controllable self-assembly of superstructures for biological applications in living cells. Here, a two-layer core-satellite assembly is driven by a Y-DNA, which is designed with three nucleotide chains that hybridized through complementary sequences. The two-layer core-satellite nanostructure (C30 S5 S10 NS) is constructed using 30 nm gold nanoparticles (Au NPs) as the core, 5 nm Au NPs as the first satellite layer, and 10 nm Au NPs as the second satellite layer, resulting in a very strong circular dichroism (CD) and surface-enhanced Raman scattering. After optimization, the yield is up to 85%, and produces a g-factor of 0.16 × 10-2 . The hybridization of the target microRNA (miRNA) with the molecular probe causes a significant drop in the CD and Raman signals, and this phenomenon is used to detect the miRNA in living cells. The CD signal has a good linear range of 0.011-20.94 amol ngRNA -1 and a limit of detection (LOD) of 0.0051 amol ngRNA -1 , while Raman signal with the range of 0.052-34.98 amol ngRNA -1 and an LOD of 2.81 × 10-2 amol ngRNA -1 . This innovative dual-signal method can be used to quantify biomolecules in living cells, opening the way for ultrasensitive, highly accurate, and reliable diagnoses of clinical diseases.