Sensitive and Label-Free SERS Detection of Single-Stranded DNA Assisted by Silver Nanoparticles and Gold-Coated Magnetic Nanoparticles

Abstract

An efficient surface-enhanced Raman scattering (SERS) method combined with DNA ligation is demonstrated in this proof-of-concept study for the detection of the single-strand DNA associated with BRAF V600E mutation. Gold-coated magnetic nanoparticles with 6-mercaptopyridine-3-carboxylic acid (MPCA) as internal reference attached on the surface (MNP@SiO2@Au-MPCA) and silver nanoparticles with Raman reporter 4-mercaptobenzonic acid (4-MBA) on the surface (Ag@4-MBA) are used as the SERS substrates. Rationally designed DNA probes are conjugated to these two types of nanoparticles, respectively. The single-stranded DNA containing the BRAF V600E mutation is the target analyte, which would act as the substrate for MNP@SiO2@Au-MPCA and Ag@4-MBA to be linked together through ligation. After multiple cycles of DNA ligation, more Ag@4-MBA are brought to the surface of MNP@SiO2@Au-MPCA. The resulting nanoparticles are easily isolated by a magnet rapidly from the mixture and redispersed in aqueous solution for homogeneous SERS measurement. The detection sensitivity is improved by the enhancement of the SERS peaks of 4-MBA between the plasmonic nanoparticles, and the detection quantification is improved by the use of internal reference, MPCA, for signal normalization. The intensity ratio of 4-MBA/MPCA increases linearly in the 1–100 fmol range of the matched DNA (BRAF mutation). Different ratios of matched DNA in the background of a large number of the single-base mismatched DNA (BRAF normal) are used to mimic real samples, and the intensity ratios of 4-MBA/MPCA are linear in the 0.02–1% range of matched DNA/mismatched DNA. The high sensitivity and specificity of the method demonstrate its potential for clinical use.

Hybrid Nanoparticles Based on Cobalt Ferrite and Gold: Preparation and Characterization

“…As discussed above, in this paper, 10-15 nm magnetic nanoparticles of cobalt ferrite, decorated with 2 nm gold nanoclusters, were obtained. It is worth noting that the nanomaterials decorated with gold are of interest for catalytic applications [4,5,[20][21][22][23][24][25][26]70,71]. The gold-decorated nanoparticles were synthesized by Félix et al [22], using polyethyleneiminetreated Fe 3 O 4 as magnetic cores and sodium borohydride as a reducing agent; they were also synthesized by Silvestri et al [5], using CoFe 2 O 4 and 2,3-meso-dimercapto succinic acid as a bifunctional organic ligand.…”

“…Such a hybrid catalyst material has higher efficiency and lower cost due to the larger Au surface area, compared with gold NPs. It is also worth noting that it is possible to separate the catalyst using an external magnetic field [4,5,[20][21][22][23][24][25][26]. The catalytic properties of gold-coated magnetic nanoparticles can be varied by the type of coating (thick shell or decoration with nanoclusters) and the morphology and size of gold nanoparticles on the surface.…”

New Trends in Nanoarchitectured SERS Substrates: Nanospaces, 2D Materials, and Organic Heterostructures

“…Bimetallic plasmonic systems, especially those with core–shell NPs, have been developed as their hybrid nature is highly appealing for SERS sensing, [ 34 ] photocatalyst, [ 35 ] and biomedicine applications. [ 36 ] Manipulating the magnetic properties enables a controllable shift of plasmon resonance; avoids degradation of the core materials; and during SERS, the analyte can be easily separated from the complex system and the plasmonic NPs can be recycled [ 37 ] (Table 1).…”

Hybrid Nanoparticles Based on Cobalt Ferrite and Gold: Preparation and Characterization

“…Gold is one of the most effective coating materials to protect magnetic nanoparticles and increase their biocompatibility. Additionally, the optical and catalytic properties of gold-coated magnetic nanoparticles can be varied by the type of coating (thick shell or decoration with nanoclusters) and the morphology and size of gold nanoparticles on the surface [20][21][22].…”