2 research outputs found
DNAzyme-Based Plasmonic Nanomachine for Ultrasensitive Selective Surface-Enhanced Raman Scattering Detection of Lead Ions via a Particle-on-a-Film Hot Spot Construction
We
propose a highly sensitive and selective surface-enhanced Raman
scattering (SERS) method for determining lead ions based on a DNAzyme-linked
plasmonic nanomachine. A metallic nanoparticle-on-a-film structure
was built through a rigid double-stranded bridge linker composed of
a DNAzyme and its substrate. This DNAzyme could be activated by lead
ions and catalyze a fracture action of the substrate. Thus, the double
chain structure of DNA would turn into a flexible single strand, making
the metal nanoparticles that connected to the terminal of DNAzyme
fall to the surface of the metal film. Hereby, a narrow gap close
to 2 nm generated between metal nanoparticles and the metal film,
exhibiting a similar effect of a “hot spot” and remarkably
enhancing the signal of randomly dispersed Raman-active molecules
on the surface of metal film. By measuring the improvement of SERS
intensity of the Raman-active molecules, we realized the lowest detection
concentration of Pb<sup>2+</sup> ions to 1.0 nM. This SERS analytical
method is highly selective and can be extended universally to other
targets via the accurate programming of corresponding DNA sequences
Waveguide-Enhanced Surface Plasmons for Ultrasensitive SERS Detection
We
design an ultrasensitive surface-enhanced Raman scattering (SERS)
substrate based on waveguide-enhanced surface plasmons (SPs). An optical
waveguide was exploited to concentrate and restrict the electromagnetic
(EM) energy of the incident light, and Ag nanoparticles that were
assembled on the waveguide surface were used to enhance the EM field
further by means of SP resonance. The enhancement factor (EF) of the
incident EM field can reach 10<sup>3</sup> on the two sides of nanoparticles,
and a 10<sup>8</sup>–10<sup>12</sup> EF of SERS is expected.
This waveguide-assisted isolated nanoparticle substrate can reach
a comparable SERS enhancement capability to that of gap-type SERS
hot spots. In addition, this SERS substrate is applicable to the SERS
detection of large molecules (biomacromolecules etc.), which cannot
be placed in traditional gap-type hot spots