Surface-Enhanced Raman Scattering Detection of DNAs Derived from Virus Genomes Using Au-Coated Paramagnetic Nanoparticles

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.

Surface-enhanced Raman spectroscopy at single-molecule scale and its implications in biology

“…Due to the advantages of the microfluidic system in SERS, immunoassays for protein detection have been developed based on microfluidics by SERS [76,77]. By using a magnetic pull-down system, proteins and DNA from viruses were detected effectively and such a system was very beneficial for SM or single-particle SERS study [78,79]. Most recently, with the development of optical tools and electron microscopy, super optical resolution imaging and STEM imaging have also contributed to SM-SERS development.…”

Magnetic and noble metal nanocomposites for separation and optical detection of biological species

“…In a clinical setting such magnetic 'pre-concentration' could also be used to isolate the modified particles from background medium. 110 Herein, an overview is presented of the application of nanoalloys (Au-Ag and magnetic plasmonic) in SERS for biodiagnostics and sensing with selected approaches from recent literature. Core@shell structures.…”

Multiplexing the Raman Way

“…This feature saves on the need for the enzymes required for amplification in PCR assays. Of further importance is the high sensitivity of the technology, with a limit of detection in the nanomolar range, as Dr. Wilson and Dr. Johnson demonstrated in a SERS immunoassay they designed to detect West Nile virus and Rift Valley fever virus (1 ).…”