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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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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
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Electrochemical SERS for in situ Monitoring the Redox States of PEDOT and Its Potential Application in Oxidant Detection
摘要： In response to recent developments for applying conducting polymers on various biomedical applications, the development of characterization techniques for evaluating the states of conducting polymers in liquids is beneficial to the applications of these materials. In this study, we propose a platform using electrochemical surface-enhanced Raman scattering (EC-SERS) technology, which allows a direct measurement of the redox states of conducing polymers in liquids. A thiophene-based conducting polymer, hydroxymethyl poly(3,4-ethylenedioxythiophene) or poly(EDOT-OH), was used to demonstrate this concept. Poly(EDOT-OH) films were coated on Au nanoparticle-coated ITO glass as SERS-active substrates. Taking the advantage of Raman enhancement, we are able to in situ and clearly monitor the redox behavior of poly(EDOT-OH) in aqueous solutions. The Raman peak intensity decreases as the poly(EDOT-OH) film is oxidized. Furthermore, we demonstrated our idea to utilize this phenomenon as the sensing mechanism for oxidant detection. The Raman intensity of conducting polymers reduces faster when oxidants exist and we obtain a quantitative analysis for the detection of oxidants. Moreover, the oxidized poly(EDOT-OH) films can be reused for detection of oxidants simply by applying a reduction potential to activate the poly(EDOT-OH) films. The film stability was also confirmed and the detection of two other oxidants, namely ammonium persulfate and iron chloride, were also demonstrated. The results show different SERS spectra of poly(EDOT-OH) films oxidized by using different oxidants. Besides, the oxidized films can be easily recovered simply by applying a cathodic potential, which allows repeating usage and makes it possible for continuous monitoring applications. To the best of our knowledge, this is the first time to apply PEDOT’s Raman feature for detection purpose.
关键词： oxidant detection,electrochemical surface-enhanced Raman scattering,spectroelectrochemistry,conducting polymers,redox behavior
更新于2025-09-04 15:30:14
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Designing surface-enhanced Raman scattering (SERS) platforms beyond hotspot engineering: emerging opportunities in analyte manipulations and hybrid materials
摘要： Surface-enhanced Raman scattering (SERS) is a molecule-specific spectroscopic technique with diverse applications in (bio)chemistry, clinical diagnosis and toxin sensing. While hotspot engineering has expedited SERS development, it is still challenging to detect molecules with no specific affinity to plasmonic surfaces. With the aim of improving detection performances, we venture beyond hotspot engineering in this tutorial review and focus on emerging material design strategies to capture and confine analytes near SERS-active surfaces as well as various promising hybrid SERS platforms. We outline five major approaches to enhance SERS performance: (1) enlarging Raman scattering cross-sections of non-resonant molecules via chemical coupling reactions; (2) targeted chemical capturing of analytes through surface-grafted agents to localize them on plasmonic surfaces; (3) physically confining liquid analytes on non-wetting SERS-active surfaces and (4) confining gaseous analytes using porous materials over SERS hotspots; (5) synergizing conventional metal-based SERS platforms with functional materials such as graphene, semiconducting materials, and piezoelectric polymers. These approaches can be integrated with engineered hotspots as a multifaceted strategy to further boost SERS sensitivities that are unachievable using hotspot engineering alone. Finally, we highlight current challenges in this research area and suggest new research directions towards efficient SERS designs critical for real-world applications.
关键词： non-wetting surfaces,porous materials,Surface-enhanced Raman scattering,SERS,plasmonic surfaces,chemical coupling,hotspot engineering,semiconductors,piezoelectric polymers,analyte manipulation,hybrid materials,graphene
更新于2025-09-04 15:30:14
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Metal-organic frameworks as SERS substrates with high tailorability
摘要： Surface enhanced Raman scattering (SERS) is a widely used analytical technique for detecting trace-level molecules based on an indispensable SERS substrate. SERS substrates with high tailorability are assumed to be attractive and desirable for SERS detection, because the substrates match the need for the selective detection of different species. Nevertheless, the rational design of such SERS substrates is rather challenging for both noble-metal and semiconductor substrates. Herein, expanding beyond conventional SERS substrates, we demonstrate that metal-organic framework (MOF) materials can serve as a type of SERS substrate with molecular selectivity, which are rarely realized for SERS detection without any special pretreatment. A salient structural characteristic of MOF-based SERS substrates benefiting the SERS selectivity is their high tailorability. By controlling the metal centers, organic ligands, and framework topologies of our MOF-based SERS substrates, we show that the electronic band structures of MOF-based SERS substrate can be purposively manipulated to match those of the target analytes, thus resulting in different detectable species. Going further, the SERS enhancement factors (EFs) of the MOF-based SERS substrates can be greatly enhanced to as high as 106 with a low detection limit of 10-8 M by pore-structure optimization and surface modification, which is comparable to the EFs of noble metals without “hot spots” and recently-reported semiconductors. This selective enhancement is interpreted as being due to the controllable combination of several resonances, such as the charge-transfer, interband and molecule resonances, together with the ground-state charge-transfer interactions. Our study opens a new venue for the development of SERS substrates with high-design flexibility, which is especially important for selective SERS detection towards specific analytes.
关键词： Surface enhanced Raman scattering (SERS),tailorability,charge-transfer,molecular selectivity,interband and molecule resonances,enhancement factors (EFs),metal-organic framework (MOF),ground-state charge-transfer interactions,SERS substrates
更新于2025-09-04 15:30:14