Highly Sensitive Magnetic-SERS Dual-Function Silica Nanoprobes for Effective On-Site Organic Chemical Detection

Abstract

We report magnetic silver nanoshells (M-AgNSs) that have both magnetic and SERS properties for SERS-based detection. The M-AgNSs are composed of hundreds of Fe3O4 nanoparticles for rapid accumulation and bumpy silver shell for sensitive SERS detection by near-infrared laser excitation. The intensity of the SERS signal from the M-AgNSs was strong enough to provide single particle-level detection. We obtained much stronger SERS signal intensity from the aggregated M-AgNSs than from the non-aggregated AgNSs. 4-Fluorothiophenol was detected at concentrations as low as 1 nM, which corresponds to 0.16 ppb. The limit of detection for tetramethylthiuram disulfide was 10 μM, which corresponds to 3 ppm. The M-AgNSs can be used to detect trace amounts of organic molecules using a portable Raman system.

Multilayer Ag-Embedded Silica Nanostructure as a Surface-Enhanced Raman Scattering-Based Chemical Sensor with Dual-Function Internal Standards

“…NPs as a SERS substrate have been developed in several directions: by using various kinds of metals such as noble and transition metals, adjusting the size of metals, changing particles’ shapes such as nanocubes, nanorods, nanowires, nanorings, and nanocrescents, and by arranging metal NPs as dimer, trimer, and aggregates, and by fusion of metals such as alloys. − Among the various nanomaterials exhibiting SERS enhancement, Ag NP-embedded silica nanospheres have sufficient SERS signals to be detectable by only one single particle because of the hotspot structure. , These nanostructures, capable of effectively emitting and retaining the SERS signal, enable high sensitivity to target molecules for polycyclic aromatic hydrocarbons, flavonoids and the like. ,,− Also, these easy-to-synthesize template-based nanostructures produced uniform signals and could be scaled up. Moreover, the application of the ligand and shell to the structure showed sensor stability and long-term stability …”

Recent Advances in Surface-Enhanced Raman Scattering Magnetic Plasmonic Particles for Bioapplications

“…Assembly MPPs are MPPs combined with non-metals, such as polyethylenimine (PEI) [ 34 , 35 , 36 , 37 ], SiO 2 [ 38 , 39 , 40 ], graphene oxide [ 32 , 41 , 42 , 43 ], and poly(N-isopropylacrylamide) (pNIPAM) [ 44 ]. PEI is a hydrophilic macromolecule from the primary amine group; therefore, it is introduced as an interlayer to significantly improve the dispersion and adsorption of negatively charged Au NPs [ 36 , 37 ].…”

Mono-6-Deoxy-6-Aminopropylamino-β-Cyclodextrin on Ag-Embedded SiO2 Nanoparticle as a Selectively Capturing Ligand to Flavonoids

“…Ag-embedded silica nanostructures also produced a highly reproducible SERS signals and could be scaled up [21]. As a result, highly sensitive detection of polycyclic aromatic hydrocarbons (PAHs), flavonoids, and the like was successfully developed [23,24,25,26,27]. Subsequently, β -CD dimer was attached on the surface of Ag-embedded SiO 2 NPs to develop the detection of PAHs in our group.…”