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Label-free Identification of Trace Microcystin-LR with Surface-Enhanced Raman Scattering Spectra
摘要： The analysis of trace microcystin-LR (MC-LR) plays important roles in environmental fields, especially in monitoring domestic water quality and safety, since it has particularly harmful effect on wild and domestic animals as well as humans at low doses. Herein, we combine confocal Raman spectroscopy with SERS-AG substrate to characterize the “fingerprint” information of MC-LR directly. High sensitivity of SERS-AG substrates was verified by utilizing the probe molecule Rhodamine 6G. Mapping spectra demonstrated good reproducibility of MC-LR identification with label-free surface-enhanced Raman scattering (SERS) strategy. Differences between SERS spectra of MC-LR and R6G, microcystin-RR were evaluated by calculating their scores and loading weights with an unsupervised exploratory principal component analysis method. Then, relationship between Raman intensities and concentrations was preliminary analyzed with SERS spectra of MC-LR and the lowest concentration of MC-LR identification was 10-6 mg.L-1 while using SERS-AG substrate. Thereafter, 68.6% quantitative recovery of 10-3 mg.L-1 MC-LR in tap water samples was obtained by the proposed label-free SERS method. These results showed that confocal Raman spectroscopy with label-free surface-enhanced Raman scattering strategy can handle the identification of trace MC-LR for monitoring water quality and safety worldwide in future.
关键词： principal component analysis,microcystin-LR,surface-enhanced Raman scattering
更新于2025-09-09 09:28:46
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[Springer Series in Optical Sciences] Fano Resonances in Optics and Microwaves Volume 219 (Physics and Applications) || Fano Resonance Generation and Applications in 3D Folding Metamaterials
摘要： The development of nanotechnology has endowed the light-matter interaction with more degrees of freedom, and made the manipulation of optical phenomena more precise and arbitrary. Fano resonance is a type of resonant scattering phenomenon with asymmetric line profile, which was firstly studied in atomic physics and then introduced to photonics and plasmonics. This phenomenon is due to the interference between a discrete bound state and a continuum state, thus a two-body or few-body system is needed to provide different types of states that are necessary in this phenomenon. Artificial metamaterial is a very good candidate to generate Fano resonances because of its designable configuration. In this paper, a new type of structure—3D folding metamaterial—is introduced for Fano resonance generation and application. The structure, fabricated by focused-ion-beam based folding technique, is composed of planar and out-of-plane parts, which are essential for the excitation of the discrete bound states and continuum states. The intensity, frequency and quality factor of the Fano resonances can be modulated by the configuration of the 3D folding structures (shape, size, inclined angle, etc.), thus enlarges its application potential such as index sensing and surface enhanced Raman scattering.
关键词： 3D folding metamaterial,nanotechnology,Fano resonance,surface enhanced Raman scattering,light-matter interaction
更新于2025-09-09 09:28:46
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Surface plasmon resonance, photoluminescence and surface enhanced Raman scattering behaviour of Ag/ZnO, ZnO/Ag and ZnO/Ag/ZnO thin films
摘要： The surface plasmon resonance (SPR) of Ag thin films in ZnO/Ag, Ag/ZnO bilayers and ZnO/Ag/ZnO multilayers produced by vacuum thermal evaporation has been studied. The role of thickness of the individual layers in the range of 5-50 nm was investigated. Detailed studies were carried out by fixing the thickness of the plasmon active layer and varying the dielectric layer thickness and vice versa. These studies reveal that the SPR of Ag is very sensitive to the geometry of the structures and as a consequence it has a strong effect on the photoluminescence (PL) as well as Surface enhanced Raman Scattering (SERS) behaviour. The PL peak of 5 nm thickness pure ZnO films which was centred at around 370 nm, was red shifted at higher thickness of 50 nm. Further, this peak was blue shifted to 324 nm when a 5 nm thickness Ag layer is introduced underneath the ZnO layer. The SERS behaviour of these structures was tested using R6G as the analyte. The enhancement factor for a 5 nm thickness pure Ag film was found to be 5x103. The highest enhancement factor for ZnO/Ag, Ag/ZnO and ZnO/Ag/ZnO trilayer films was found to be 7.4x106, 4.4x105 and 8.9x104, respectively.
关键词： surface plasmon resonance,surface enhanced Raman scattering,photoluminescence,Ag-ZnO multilayer films
更新于2025-09-09 09:28:46
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Nickel foam–caged Ag-Au bimetallic nanostructure as a highly rugged and durable SERS substrate
摘要： A three-dimensional nickel foam (NF) caging Ag-Au bimetallic nanostructure (Ag-Au@NF) has been demonstrated as a highly rugged and sensitive surface-enhanced Raman scattering (SERS) substrate. The main concept employed in designing this substrate was the protection of SERS-active nanostructures by holding them within a sturdy frame. For this purpose, NF was readily chosen as a strong porous frame to secure the internal nanostructures owing to its excellent structural strength and ability to easily incorporate analytes due to its porous structure. The next issue was the construction of stable and SERS-e?cient nanostructures within the NF frame. To meet this need, an Ag-Au bimetallic nanostructure was chosen, combining the high SERS e?ciency of Ag and the good surface stability of Au. To fabricate the Ag-Au nanostructure, ?rst a Sn-Ag alloy was constructed on the NF frame by means of electrodeposition (producing Sn-Ag@NF) and then Sn was selectively leached from the alloy by means of free corrosion in NaOH solution (producing Ag@NF). This selective leaching was adopted to make the surface rough to enhance the SERS e?ciency in the ?nal substrate. Finally, Au was incorporated into the Ag@NF by means of a galvanic replacement reaction (producing Ag-Au@NF). The use of Ag-Au@NF enabled identi?cation of rhodamine 6G at concentrations as low as 0.1 nM. The Ag-Au@NF substrates were rugged, showing small Raman signal drops after 100 cycles of sandpaper abrasion or 30 min of sonication. Also, the signal decrease was only 4.26% upon 3 days of exposure to ambient air without special care. Overall, the Ag-Au@NF developed herein shows practical merits for adoption in routine and ?eld SERS analyses.
关键词： Surface enhanced Raman scattering,High durability,Ag-Au nanostructure,Porous structure,Nickel foam
更新于2025-09-09 09:28:46
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Total Aqueous Synthesis of Au@Cu <sub/>2?</sub><i> <sub/>x</sub></i> S Core–Shell Nanoparticles for In Vitro and In Vivo SERS/PA Imaging‐Guided Photothermal Cancer Therapy
摘要： Both accurate tumor navigation and nanostructures with high photothermal (PT) conversion efficiency are important but remain challenging to achieve in current biomedical applications. This study reports an anion exchange-based facile and green approach for synthesizing Au@Cu2?xS core–shell nanoparticles (NPs) in an aqueous system. In addition to the PT effect of the suggested NPs, the surface-enhanced Raman scattering (SERS) is also significantly improved due to the tailored localized surface plasmon resonance coupling between the Au metal core and the Cu2?xS semiconductor shell. Using an epitaxial strategy, Au@Cu2O NPs are first obtained by the in situ reduction of cupric hydroxide on a cresyl violet acetate-coated Au core; then, Au@Cu2?xS NPs are obtained via anion exchange between the S2? and Cu2O shell. Both the Cu/S atomic ratio and the Cu2?xS shell thickness can be adjusted conveniently. Hence, the ideal integration of the plasmonic Au core and Cu2?xS shell into a single unit is conducive not only to highly efficient PT conversion but also to the construction of a SERS-based navigator. This new type of SERS-guided NP, with enhanced photoacoustic signals, is an important candidate for both accurate tumor navigation and nondestructive PT treatment guided in vivo by two modes of optical imaging.
关键词： navigation treatment,photothermal therapy (PTT),Au@Cu2?xS core–shell nanoparticles (NPs),plasmonic enhancement,surface-enhanced Raman scattering (SERS)
更新于2025-09-09 09:28:46
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A Biomedical Surface Enhanced Raman Scattering Substrate: Functionalized Three-Dimensional Porous Membrane Decorated with Silver Nanoparticles
摘要： We fabricated a simple, cheap, and functional surface enhanced Raman scattering substrate for biomedical application. Hotspots between two close silver nanoparticles distributed in the skeleton of a three-dimensional porous membrane, especially in the pores, were formed. The dual poles of micropores in the membrane were discussed. The pores could protect the silver nanoparticles in the pores from being oxidized, which makes the membrane effective for a longer period of time. In addition, Staphylococcus aureus cells could be trapped by the micropores and then the Raman signal became stronger, indicating that the functional surface enhanced Raman scattering substrate is reliable.
关键词： three-dimensional porous membrane,biomedical application,silver nanoparticles,surface enhanced Raman scattering
更新于2025-09-09 09:28:46
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Surface enhanced Raman spectroscopy with methyl-orange on Ag-TiO2 nanocomposites: Experimental and theoretical investigation
摘要： Ag-TiO2 nanocomposites of different Ag nanoparticle (NP) concentrations are experimentally prepared and their UV-vis and surface enhanced Raman scattering characteristics are determined. The enhancement of the Raman signal for the ligand methyl-orange (MO) adsorbed onto the nanocomposite system, is observed. To investigate the influence of changing Ag concentration in this nanocomposite system, molecular dynamics (MD) simulations are conducted with both a fixed as well as varying number of the surfactant MO adsorbed onto the nanocomposite. Density functional theory (DFT) simulations are performed to investigate the conditions for charge transfer from the MO surfactant via the highest occupied molecular orbitals (HOMO), lowest unoccupied molecular orbitals (LUMO) as well as the electrostatic potentials. It is shown that the bonding mode of the surfactant contributes greatly to the observed Raman scattering enhancement.
关键词： HOMO-LUMO,Surface Enhanced Raman Scattering,density functional theory,molecular dynamics,Ag-TiO2 nanocomposite,electrostatic potential
更新于2025-09-09 09:28:46
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Imaging the Optical Fields of Functionalized Silver Nanowires through Molecular TERS
摘要： We image 4-mercaptobenzonitrile-functionalized silver nanowires (~20 nm diameter) through tip-enhanced Raman scattering (TERS). The enhanced local optical field-molecular interactions that govern the recorded hyperspectral TERS images are dissected through hybrid finite-difference time-domain-density functional theory simulations. Our forward simulations illustrate that the recorded spatio-spectral profiles of the chemically functionalized nanowires may be reproduced by accounting for the interaction between orientationally averaged molecular polarizability derivative tensors and enhanced incident/scattered local fields polarized along the tip axis. In effect, we directly map the enhanced optical fields of the nanowire in real space through TERS. The simultaneously recorded atomic force microscopy (AFM) images allow a direct comparison between our attainable spatial resolution in topographic (13 nm) and TERS (5 nm) imaging measurements performed under ambient conditions. Overall, our described protocol enables local electric-field imaging with few nm precision through molecular TERS, and it is therefore generally applicable to a variety of plasmonic nano-structures.
关键词： silver nanowires,TERS,nanoscale imaging,optical fields,tip-enhanced Raman scattering
更新于2025-09-09 09:28:46
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In Situ Creation of Surface-Enhanced Raman Scattering Active Au–AuO <i> <sub/>x</sub></i> Nanostructures through Electrochemical Process for Pigment Detection
摘要： Roughing the metallic surface via oxidation?reduction cycles (ORC) to integrate the surface plasmon resonance and surface-enhanced Raman scattering (SERS) is predominant in developing sensor systems because of the facile preparation and uniform distribution of nanostructures. Herein, we proposed a distinctive ORC process: the forward potential passed through the oxidation of Au and reached the oxygen evolution reaction, and once the potential brie?y remained at the vertex, the various reverse rates were employed to control the reduction state. The created hybrid Au?AuOx possessed electromagnetic and chemical enhancements concurrently, wherein the rough surface provided the strong local electromagnetic ?elds and signi?cant interaction between AuOx and molecule to improve the charge transfer. The synergistic e?ects signi?cantly ampli?ed the intensity of Raman signal with an enhancement factor of 5.5 × 106 under the optimal conditions. Furthermore, the prepared SERS substrate can simultaneously identify and quantify the mixed edible pigments, Brilliant Blue FCF and Indigo Carmine, individually. This result suggested that the development of SERS sensor based on the proposed SERS-activated methodology is feasible and reliable.
关键词： Au?AuOx nanostructures,electrochemical process,surface-enhanced Raman scattering,pigment detection
更新于2025-09-09 09:28:46
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SERS-Based Quantification of PSMA in Tissue Microarrays Allows Effective Stratification of Patients with Prostate Cancer
摘要： Prostate specific membrane antigen (PSMA), a type II membrane protein, is an attractive biomarker that has been validated clinically for the diagnosis of prostate cancer. In this study, we developed surface-enhanced Raman scattering (SERS) nanoprobes for PSMA detection and quantification at the single-cell level on prostate cancer cells. The cells were targeted employing SERS nanoprobes that consisted of gold nanostars functionalized with PSMA aptamer molecules. We were able to quantify picomolar concentrations of soluble PSMA protein and used the resulting calibration curve to estimate the expression of PSMA on the surface of the prostate cancer cell, LNCaP, at the single-cell level. Importantly, we employed these SERS tags to stratify prostate cancer patients by assessing PSMA expression in tissues contained in a prostate tissue microarray. The stratification results clearly correlated PSMA expression to recommended therapy groups, rendering the described method as an effective tool to aid in designing personalized therapeutic protocols. Benchmarking detection sensitivity against immunofluorescence staining and comparing stratification results obtained with the two methods allowed us to validate our novel approach against standard practices. On the basis of these results, we confirm the validity of PSMA as an effective biomarker for prostate cancer patient evaluation and propose SERS-based diagnostic techniques as integrative methods for the assessment of disease stage and the identification of effective therapeutic protocols.
关键词： aptamer,tissue microarray,surface-enhanced Raman scattering,PSMA,Prostate specific membrane antigen,SERS,nanoprobes,prostate cancer,biomarker,gold nanostars
更新于2025-09-04 15:30:14