Raman Scattering Applications Research Articles

3D SERS substrate using silver nanoparticles decorated ZnO nanorods on silicon micropyramids hybrid heterostructure

3D hybrid heterostructure have been fabricated using Ag Nanoparticles decorated ZnO nanorods over textured Silicon Micropyramid for Surface Enhanced Raman Scattering (SERS) applications. Silicon texturing was performed using facile Alkaline texturing route followed by the growth of ZnO nanorods (ZnONR) array on the micropyramids over which, the Ag nanoparticles (AgNPs) were decorated. The phase and the surface of the heterostructure was studied by XRD and Field Emission Scanning Electron Microscope (FESEM), respectively. The SERS performance of the 3D heterostructure was evaluated using Rhodamine 6G (R6G) at various concentrations with a detection limit of 0.1 pM. The superior properties of SiMP/ZnONR/AgNP over ZnONR/AgND heterostructure has also been presented to understand the effect of the 3D pyramidal substrate for superior SERS performance. The recovery of the prepared heterostructure has also been demonstrated by photocatalytic degradation of Rhodamine 6G and Methylene Blue. Our work demonstrates a facile synthesis of 3D SERS heterostructure and sheds light on its superior SERS properties paving ways for wide range of applications in bio-sensors, detection of harmful chemicals, food adulterations, narcotic detection and many more.

Reusable Wrinkled Nanoporous Silver Film Fabricated by Plasma Treatment for Surface-Enhanced Raman Scattering Applications.

A nanoporous silver film (npAgF), a promising structure for surface-enhanced Raman spectroscopy (SERS), can be fabricated by using successive O2 and Ar plasma treatments on a planar silver film. The common dealloying method for producing an npAgF involves annealing at high temperatures to produce an alloy film, as well as harsh etching using corrosive chemicals. By contrast, the plasma-based method can be applied directly to various functional substrates to produce more sophisticated npAgF structures. Herein, we report a facile fabrication method for a wrinkled npAgF (w-npAgF) for SERS applications using a thermally contractible polystyrene substrate. The w-npAgF had 3D wrinkles of the nanoporous structure and showed approximately 8 times higher SERS enhancement than did the flat npAgF. Moreover, the w-npAgF could be reused for multiple SERS measurements of different molecules by mild O2 and Ar plasma treatments after each use, in which the O2 plasma effectively removed the adsorbed organic molecules and the Ar plasma reduced silver oxide to pristine silver for subsequent SERS measurements. The wrinkled nanoporous structure was maintained after multiple mild plasma treatments for reuse. The simplicity of plasma-based fabrication and high sensitivity of w-npAgFs are promising features for the green production of low-cost and reusable 3D SERS substrates.

Self-Assembly of Silver Nanowire Films for Surface-Enhanced Raman Scattering Applications.

The development of SERS detection technology is challenged by the difficulty in obtaining SERS active substrates that are easily prepared, highly sensitive, and reliable. Many high-quality hotspot structures exist in aligned Ag nanowires (NWs) arrays. This study used a simple self-assembly method with a liquid surface to prepare a highly aligned AgNW array film to form a sensitive and reliable SERS substrate. To estimate the signal reproducibility of the AgNW substrate, the RSD of SERS intensity of 1.0 × 10-10 M Rhodamine 6G (R6G) in an aqueous solution at 1364 cm-1 was calculated to be as low as 4.7%. The detection ability of the AgNW substrate was close to the single molecule level, and even the R6G signal of 1.0 × 10-16 M R6G could be detected with a resonance enhancement factor (EF) as high as 6.12 × 1011 under 532 nm laser excitation. The EF without the resonance effect was 2.35 × 106 using 633 nm laser excitation. FDTD simulations have confirmed that the uniform distribution of hot spots inside the aligned AgNW substrate amplifies the SERS signal.

Dual Function of 4-Aminothiophene in Surface-Enhanced Raman Scattering Application as an Internal Standard and Adsorbent for Controlling Au Nanocrystal Morphology.

The sensitivity and quantitative accuracy of surface-enhanced Raman scattering (SERS) are the main factors that restrict its application. Here, novel Au nanoscale convex polyhedrons (Au NCPs) were designed and fabricated to solve these problems via an embedded standard, including eight pods and six small protrusions. Spherical Au seeds regrew into different sizes of Au NCPs with a face-centered cubic structure. This morphology is due to the dual mechanism of the 4-aminothiophene (4-ATP) molecule that serves as an internal standard and a surface ligand regulator combined with the regulatory role of hexadecyl trimethyl ammonium chloride. The results show that Au NCPs were enclosed by high-index {12 9 1} facets, which greatly improved the local plasma resonance and reduced the lowest SERS detectable concentration of pyrene in standard seawater to 0.5 nM. An effective reference was produced by embedding 4-ATP with a relative standard deviation value less than 2.97% (in the same batch) and 3.92% (between different batches). Our research offers a new strategy for morphological regulation of metal nanocrystals, which is useful for the preparation of highly sensitive SERS substrates and trace analysis.

Optimization Temperature Programming of Microwave-Assisted Synthesis ZnO Nanoneedle Arrays for Optical and Surface-Enhanced Raman Scattering Applications.

This study used a rapid and simple microwave-assisted synthesis method to grow ZnO nanoneedle arrays on the silicon substrate with the ZnO seed layer. The effects of reaction temperature and time on the lengths of ZnO nanoneedle arrays were investigated. The appropriate temperature programming step can grow the longer ZnO nanoneedle arrays at the same reaction time (25 min), which is 2.08 times higher than without the temperature programming step. The geometry of the ZnO nanoneedle arrays features a gradual decrease from the Si substrate to the surface, which provides an excellent progressive refractive index between Si and air, resulting in excellent antireflection properties over an extensive wavelength range. In addition, the ZnO nanoneedle arrays exhibit a suitable structure for uniform deposition of Ag nanoparticles, which can provide three-dimensional hot spots and surface active sites, resulting in higher surface-enhanced Raman scattering (SERS) enhancement, high uniformity, high reusability, and low detection limit for R6G molecule. The ZnO/Ag nanoneedle arrays can also reveal a superior SERS-active substrate detecting amoxicillin (10-8 M). These results are promising for applying the SERS technique for rapid low-concentration determination in different fields.

Synthesis and deposition of Silver nanostructures on the silica microsphere by laser-assisted photochemical method for SERS applications

The homogeneous distribution of nano-metallic structures on the surface-enhanced Raman (SERS) substrates plays an important factor for high-sensitive Raman scattering measurement. In this paper, we present a low-cost laser-assisted photochemical method for making a SERS probe based on silver nanostructures, which are one-timely synthesized nano-silver structures, homogeneously deposited on silica microsphere surfaces. Achieved SERS-activity substrates with a homogeneous distribution of Ag-nanostructures are verified by a mapping technique on the surface of Ag-coated microsphere for the detection of low concentration of Rhodamine 6G in aqueous solutions in a range of 10-4-10-9M. The obtained results show that a SERS microsphere probe has a good repetition of SERS-activity in any space of sensing area, and large potential for application in a biochemical sensing technique. Full Text: PDF ReferencesY. Chen et al., "Interfacial reactions in lithium batteries", J. Phys. D: Appl. Phys. 50, 02510 (2017). CrossRef T.B. Pham, H. Bui, H.T. Le, V.H. Pham, "Characteristics of the Fiber Laser Sensor System Based on Etched-Bragg Grating Sensing Probe for Determination of the Low Nitrate Concentration in Water", Sensors 17, 0007 (2017). CrossRef X. Wang, O.S. Wolfbeis, "Fiber-Optic Chemical Sensors and Biosensors (2013–2015)", Anal. Chem. 88, 203 (2016). CrossRef R. Wang, K. Kim, N. Choi, X. Wang, J. Lee, J.H. Joen, G. Rhie, J. Choo, "Highly sensitive detection of high-risk bacterial pathogens using SERS-based lateral flow assay strips", Sens. Actuators B-Chem. 270, 72 (2018). CrossRef H. Zhang et al., "Determination of Pesticides by Surface-Enhanced Raman Spectroscopy on Gold-Nanoparticle-Modified Polymethacrylate", Anal. Let. 49, 2268 (2016). CrossRef L. Chen, H. Yan, X. Xue, D. Jiang, Y. Cai, D. Liang, Y.M. Jung, X.X. Han, B. Zhao, "Surface-Enhanced Raman Scattering (SERS) Active Gold Nanoparticles Decorated on a Porous Polymer Filter", Appl. Spectrosc. 71, 1543 (2017). CrossRef A. Matikainen, T. Nuutinen, P. Vahimaa, S. Honkanen, "A solution to the fabrication and tarnishing problems of surface-enhanced Raman spectroscopy (SERS) fiber probes", Sci. Rep. 5, 8320 (2015). CrossRef J. Zhang, S. Chen, T. Gong, X. Zhang, Y. Zhu, "Tapered Fiber Probe Modified by Ag Nanoparticles for SERS Detection", Plasm. 11, 743 (2016). CrossRef W. Xu et al., "A Dual-Butterfly Structure Gyroscope", Sensors 17, 467 (2017). CrossRef K. Setoura, S. Ito, M. Yamada, H. Yamauchi, H. Miyasaka, "Fabrication of silver nanoparticles from silver salt aqueous solution at water-glass interface by visible CW laser irradiation without reducing reagents", J. Photochem. Photobio. A: Chem. 344, 168 (2017). CrossRef K. Liu, Y. Bai, L. Zhang, Z. Yang, Q. Fan, H. Zheng, Y. Yin, C. Gao, "Porous Au–Ag Nanospheres with High-Density and Highly Accessible Hotspots for SERS Analysis", Nano Lett. 16, 3675 (2016). CrossRef Z. Huang, X. Lei, Y. Liu, Z. Wang, X. Wang, Z. Wang, Q. Mao, G. Meng, "Tapered Optical Fiber Probe Assembled with Plasmonic Nanostructures for Surface-Enhanced Raman Scattering Application", ACS Appl. Mater. Interfaces 7, 17247 (2015). CrossRef

Understanding the Role of Metal-Organic Frameworks in Surface-Enhanced Raman Scattering Application.

Metal-organic frameworks (MOFs), built from organic linkers and metal ions/clusters, have emerged as highly promising materials for wide applications. Combining highly porous crystalline MOFs with the surface-enhanced Raman scattering (SERS) technique can achieve unprecedented advantages of high selectivity, high sensitivity, and expedience in analysis and detection. In this critical review, the aim is to present a comprehensive review of recent advances in understanding of the roles of MOFs in MOF-SERS systems, particularly their structure-to-property correlation. Key examples are selected from representative literature to illustrate critical concepts and the MOF-based property-dependent applications are particularly emphasized. Finally, the barriers, future trends, and prospects for further advances in MOF-SERS platforms are also discussed.

Facile In Situ Photochemical Synthesis of Silver Nanoaggregates for Surface-Enhanced Raman Scattering Applications.

Recently, photochemical synthesis has attracted wide interest on in situ preparing the surface-enhanced Raman scattering (SERS) substrate with excellent performance, especially in a compact space and microfluidic channel. Herein, a facile, green and cost-effective approach to in situ photochemically synthesize silver nanoaggregates is demonstrated for SERS applications. By adjusting the photo-irradiation conditions, the morphologies and sizes of the silver nanoaggregates can be deliberately tailored. The synthesized silver nanoaggregates-based substrates exhibit a highly sensitive and reproducible SERS activity with a low detection limit of 10−8 M for 4-Aminothiophenol detection and relative standard deviation of 12.3%, paving an efficient and promising route for in situ SERS-based rapid detection in the environmental monitoring and food quality control.

Fabrication of Silver Nano-Dendrites on Optical Fibre Core by Laser-Induced Method for Surface-Enhanced Raman Scattering Applications.

In this work, we present a novel fabrication method for making the surface-enhanced Raman scattering (SERS) probe based on silver (Ag) nano-dendrites which are grown and deposited on the end of multi-mode fibre core by a simple and low-cost laser-induced technique. The morphology of the Ag-nanoparticles (AgNPs) could be controlled by the experimental conditions such as laser power, illumination time, and concentration of the reaction solution. The morphology and chemical composition of SERS fibre probes are characterized by high-resolution scanning electron microscope (HR-SEM) and Energy dispersive X-ray spectroscopy (EDX), respectively. These results confirmed how the Ag nanostructures morphology is modified as a function of illumination time of laser irradiation, and the growth and deposition of Ag nanostructures occur only in the main laser-irradiated part on the end of multi-mode fibre core. The achieved SERS-activity substrates on the fibre probes are testing with the detection of low concentration of Rhodamine 6G aqueous solutions in the range of 10-5-10-10 M. This study shows that SERS activity coupled with Ag nano-dendrites substrate on the fibre probe has the best enhancement factor of 1.93×107 for Rhodamine 6G due to the creation of many of hot-spots for amplifying Raman signals by Ag nano-dendrite structures, which is a promising candidate with low-cost SERS probe of chemical compact optical fibre sensors for direct, rapid, real-time and non-destructive detection of chemical compounds in liquid environment.

Self-Assembly of Faceted Gold Nanocrystals for Surface-Enhanced Raman Scattering Application

In this work, self-assembly monolayers of faceted gold nanocrystals were employed as surface-enhanced Raman scattering (SERS) substrates for the examination of facet-dependent SERS performance. In ...

Synthesis of Graphene-based Materials for Surface-Enhanced Raman Scattering Applications

Synthesis of Graphene-based Materials for Surface-Enhanced Raman Scattering Applications

Silver Nanoparticles Added Polymer Film Prepared by Electrochemical Route for Surface Enhanced Raman Scattering Applications

A simple method for the fabrication of stable and highly active surface enhanced Raman scattering (SERS) substrate by exploiting the optical properties of the silver nanoparticles (AgNPs) and organizational characteristics of the polymer is presented. Homogeneous distribution of AgNPs is achieved with the usage of poly (4,7-di-2,3-dihydrothieno [3,4-b] [1,4] dioxin-5-yl-2,1,3 benzoselena diazole) (PESeE) film coated on the indium tin oxide glass (ITO) surface. The obtained structure ensured the emergence of a large number of hot spots where the localization of electromagnetic energy can result in enhancement of the Raman signal. The effect of the PESeE film thickness, the density of AgNPs added to the polymer film, and the concentration of silver ion solution on the morphology of the substrate and the enhancement of the SERS signal was revealed by using field emission scanning electron microscopy (FE-SEM) and SERS measurements. Enhancement power, homogeneity, and stability of the PESeE-AgNPs substrate were also investigated with measurement of the Raman probe. Spot-to-spot and batch-to-batch reproducibilities of the prepared substrate were calculated as 8.4%, and 10.2% (RSD %) respectively. Due to these properties, PESeE-AgNPs SERS substrate can be a good candidate for the detection and sensor application of various biological and chemical analytes.

NIR-Active Plasmonic Gold Nanocapsules Synthesized Using Thermally Induced Seed Twinning for Surface-Enhanced Raman Scattering Applications.

Hollow and porous core-shell nanostructures with defined interior nanogaps are of great significance in the field of surface-enhanced Raman scattering (SERS) applications because of the presence of intrinsic electromagnetic (EM) hot spots, multipolar resonances, and multiple facets. Further, nanomaterials having extinction in the near-infrared (NIR) region are particularly important for SERS and biomedical applications, and thus it is highly desirable to synthesize NIR-active plasmonic nanostructures. Herein, we report the synthesis of gold nanocapsules having a solid Au bead as core and a thin-porous rod-shaped shell with extinction in both NIR I and NIR II regions. Thermally induced twinned seeds were used for the silver-free synthesis of pentatwinned Au bead, which served as the foundation for the directed growth of Ag nanorods, which was finally converted to Au nanocapsules following galvanic replacement reaction (GRR). Detailed investigation was carried out to understand the effect of thermal treatment duration in the seed morphology and its subsequent growth to anisotropic Au beads. Ag overgrowth on Au beads yielded uniform Au-bead@Ag nanorods whose size can be tuned by varying the Ag precursor. Five different sized Au-bead@Ag nanorods were studied, and they were converted to Au nanocapsules following GRR. We explored the size-dependent SERS activity of the prepared Au nanocapsules along with their comparison with solid pentatwinned Au beads and found that the smallest sized Au nanocapsules were the best SERS performers. Finite-difference time-domain simulation revealed the presence of intense EM hot spots in the smallest sized Au nanocapsule and corroborated the experimental SERS data. Finally, we fabricated a simple flexible cellulose-based SERS substrate by using the smallest sized Au nanocapsules and investigated its SERS sensing ability for the detection of 2-napthalenethiol (2-NT), as a model analyte, and were able to achieve its detection down to 1 fM concentration.

In Situ Synthesis of Silver Nanospheres, Nanocubes, and Nanowires over Boron-Doped Graphene Sheets for Surface-Enhanced Raman Scattering Application and Enzyme-Free Detection of Hydrogen Peroxide.

An effective in situ synthesis strategy is demonstrated for the preparation of silver nanostructures (nanospheres (NSs), nanocubes (NCs), and nanowires (NWs)) on the surface of boron-doped graphene (BG). Further, these functional nanomaterials are employed for the surface-enhanced Raman scattering (SERS) and non-enzymatic electrochemical detection of H2O2. The results confirm the superior performance of BG-Ag nanostructures as SERS platform. Among various geometries of silver nanoparticles studied in this work, we find that the AgNCs over BG (BG-AgNC) present outstanding SERS performance for detecting 4-mercaptobenzoic acid, with a limit of detection of 1.0 × 10-13 M. Furthermore, BG-AgNC exhibits excellent capability to detect melamine as low as 1.0 × 10-9 M. Electrochemical results confirm that the BG-AgNW-based platform exhibits a superior biosensing performance toward H2O2 detection. The enhanced performance is due to the presence of graphene, which improves the conductivity and provides more active sites. The synthesis of doped graphene with metallic nanoparticles described in this work is expected to be a key strategy for the development of an efficient SERS and electrochemical sensor that offers simplicity, cost-effectiveness, long-term stability, and better reproducibility.

Graphene Grown on Ni Foam: Molecular Sensing, Graphene-Enhanced Raman Scattering, and Galvanic Exchange for Surface-Enhanced Raman Scattering Applications

The growth of graphene on an irregular three-dimensional (3D) Ni structure is demonstrated to be an interesting platform for molecular sensing, graphene-enhanced Raman scattering, and surface-enhanced Raman scattering (SERS) applications after galvanic exchange of Ag+ ions. Raman, scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDX), optical images, and diffuse reflectance demonstrate that graphene grows in a multilayer fashion with different stacking configurations. Statistics performed employing Raman show that the as-grown graphene can be classified into two main stacking configurations: AB (or Bernal stacking) and rotated graphene, which are separated by a full width at half-maximum (fwhm) threshold of ∼30 cm–1 corresponding to the 2D Raman band. The rotated stacking senses low concentrations of methylene blue (MB), whereas the AB stacking seems to be much less sensitive upon molecular adsorption. The galvanic exchange of Ag leads to agglomerates preferentially formed on top of gra...

Optical Field Enhancement in Au Nanoparticle-Decorated Nanorod Arrays Prepared by Femtosecond Laser and Their Tunable Surface-Enhanced Raman Scattering Applications.

Various Au nanostructures have been demonstrated to have an enhanced local electric field around them because of surface plasmons. Herein, we propose a novel method for fabricating Au nanoparticle-decorated nanorod (NPDN) arrays through femtosecond laser irradiation combined with Au coating and annealing. The nanorod cavities strongly confined light and produced an enhanced optical field in response to Au nanoparticles (NPs) introduction. The nanogap and diameter of the fabricated Au NPs significantly affected the surface-enhanced Raman scattering (SERS) performance and could be simultaneously tuned with thickness-controllable Au films and substrate morphologies. The resulting Au NPDN substrate was observed to have efficient "hot spots" for tunable SERS applications. We experimentally determined that the enhancement factor of the Au NPDN substrate reached up to 8.3 × 107 at optimal parameters. Moreover, the Au NPDN substrate showed superior chemical stability, with the greatest intensity deviation of 3.2% on exposure to air for 2 months. This work provides a promising method to fabricate tunable plasmonic surfaces for highly sensitive, reproducible, and chemically stable SERS applications.

Synthesis and Characterization of New Sr3(BO3)2 Crystal for Stimulated Raman Scattering Applications

A new kind of borate crystalline material Sr3(BO3)2 with a similar calcite type structure was designed and synthesized by solid state reaction method, moreover, the single crystal growth was attempted with traditional Czochralski pulling method. Crystal phase of Sr3(BO3)2 was investigated by using X-Ray powder diffraction (XRPD) at room temperature and found similar to Ca3(BO3)2 crystal with space group of R-3c. The phase stability was studied by means of thermogravimetric differential thermal analysis (TG/DTA) and high temperature XRPD up to 1350 °C, where an obvious endothermic peak was observed in DTA curve around 1250 °C, and weak splits of diffraction peaks were found at temperatures above 1250 °C, indicating the existence of structure transformation for Sr3(BO3)2 crystal. Raman properties were studied experimentally and theoretically by using density functional perturbation theory, though the strongest frequency shift of Sr3(BO3)2 crystal (900 cm−1) was comparable to that of Ca3(BO3)2 (927 cm−1), the line width of the strongest Raman peak obtained for Sr3(BO3)2 (5.72 cm−1) was much lower than Ca3(BO3)2 (7.01 cm−1), indicating a larger Raman gain for Sr3(BO3)2 crystal, which would be favorable for stimulated Raman scattering application.

Electrochemical Fabrication of Silver Dendrites as an Excellent Platform for Surface Enhanced Raman Scattering Application

Electrochemical Fabrication of Silver Dendrites as an Excellent Platform for Surface Enhanced Raman Scattering Application

Hollow Gold Nanoprism as Highly Efficient “Single” Nanotransducer for Surface-Enhanced Raman Scattering Applications

In this Article, we report the optical properties of anisotropic hollow nanostructure, hollow gold nanoprism (HGN, an equilateral triangular gold nanoprism with a circular cavity) and its application as a highly active “nonaggregated” surface-enhanced Raman scattering (SERS) substrate. Small colloidal HGNs are prepared using sacrificial galvanic replacement method. Our study reveals that HGNs are highly stable nanostructure in solution and robust against salt or ligand induced aggregation. We find that the LSPR spectra of the HGNs can be tuned by controlling their aspect ratios. Excellent SERS were detected from the J-aggregates of pseudoisocyanine dye, adsorbed on the HGN surface. Interestingly, strong SERS is obtained without the need of any aggregation of the nanoparticles. Numerical simulations reveal that a single HGN can not only harvest large local electromagnetic fields but also offer large sensing volume due to efficient plasmon hybridization, due to the presence of the cavity. This large sensing...

Review of Surface Enhanced Raman Scattering Applications in Forensic Science.

Review of Surface Enhanced Raman Scattering Applications in Forensic Science.