Surface-Enhanced Raman
Scattering Detection of DNAs
Derived from Virus Genomes Using Au-Coated Paramagnetic Nanoparticles
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Abstract
A magnetic capture-based, surface-enhanced Raman scattering
(SERS)
assay for DNA detection has been developed which utilizes Au-coated
paramagnetic nanoparticles (Au@PMPs) as both a SERS substrate and
effective bioseparation reagent for the selective removal of target
DNAs from solution. Hybridization reactions contained two target DNAs,
sequence complementary reporter probes conjugated with spectrally
distinct Raman dyes distinct for each target, and Au@PMPs conjugated
with sequence complementary capture probes. In this case, target DNAs
were derived from the RNA genomes of the Rift Valley Fever virus (RVFV)
or West Nile virus (WNV). The hybridization reactions were incubated
for a short period and then concentrated within the focus beam of
an interrogating laser by magnetic pull-down. The attendant SERS response
of each individually captured DNA provided a limit of detection sensitivity
in the range 20–100 nM. X-ray diffraction and UV–vis
analysis validated both the desired surface plasmon resonance properties
and bimetallic composition of synthesized Au@PMPs, and UV–vis
spectroscopy confirmed conjugation of the Raman dye compounds malachite
green (MG) and erythrosin B (EB) with the RVFV and WNV reporter probes,
respectively. Finally, hybridization reactions assembled for multiplexed
detection of both targets yielded mixed MG/EB spectra and clearly
differentiated peaks which facilitate the quantitative detection of
each DNA target. On the basis of the simple design of a single-particle
DNA detection assay, the opportunity is provided to develop magnetic
capture-based SERS assays that are easily assembled and adapted for
high-level multiplex detection using low-cost Raman instrumentation