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A facile method to fabricate a novel 3D porous silicon/gold architecture for surface enhanced Raman scattering
摘要： Si-based surface enhanced Raman scattering (SERS) sensing technology is a powerful tool for the detection of various chemical and biological species. Further improvement of the simplicity, stability, sensitivity, and low cost of Si-based SERS platforms is still in great demand for real applications. In this study, the facile fabrication of three-dimensional (3D) porous Si/Au SERS platform with attractive SERS performances was reported. The developed method relied on laser-induced dendrite-like microstructure on the surface of Al-Si cast alloy followed by dealloying Al from the laser treated surface, leaving a 3D dendrite-like porous Si substrate. By sputtering, the substrate was coated with Au film to form 3D porous Si/Au SERS platform. Such 3D porous Si/Au SERS platform had high SERS sensitivity that enabled ultralow concentration detection of R6G molecules down to 10-15 M with enhancement factor in the range of 1011 to 1012. The relative standard deviation of 6.2% was obtained from 15 random SERS spectrum, indicating superior reproducibility of the as-fabricated 3D porous Si/Au SERS platform.
关键词： laser,porous Si/Au,SERS,dealloying
更新于2025-11-28 14:24:20
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Fabrication of gold-silver core-shell nanoparticles for performing as ultrabright SERS-nanotags inside human ovarian cancer cells
摘要： This paper presents the fabrication and characterization of new gold-silver core-shell nanoparticles labeled with para-mercaptobenzoic acid (4MBA) molecules and demonstrates their use as SERS-nanotags with ultra-bright traceability inside cells and ability to convey spectrally-coded information about the intracellular pH by means of Surface-Enhanced Raman Spectroscopy (SERS). Unlike to previous reported studies, our fabrication procedure includes in the first step the synthesis of chitosan-coated gold nanoparticles as a seed material with subsequent growing of a silver shell. The bimetallic core-shell structure is revealed by transmission electron microscopy (TEM), high-angle annular dark field scanning transmission electron microscopy (HAADF-STEM), energy-dispersive X-ray elemental mapping (EDX) and the presence of two interacting localized surface plasmon resonance (LSPR) modes in UV-Vis extinction spectrum. The high SERS activity and sensitivity of as fabricated 4MBA-chit-Au-AgNPs nano-constructs to different pH in solution is investigated under 532 and 633 nm laser lines excitation. Next, in view of future studies in cancer diagnosis, the in vitro antiproliferative effects of SERS-nanotags against human ovarian adenocarcinoma cells (NIH:OVCAR-3) are evaluated. The capacity to operate as bright SERS nanotags with precise localization at a single cell level as well as intracellular pH indicators is clearly demonstrated by performing cell imaging under scanning confocal Raman microscopy.
关键词： core-shell nanoparticles,pH sensors,ovarian cancer cells,chitosan,SERS tags
更新于2025-11-21 11:24:58
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Template growth of Au/Ag nanocomposites on phosphorene for sensitive SERS detection of pesticides
摘要： We report template growth and dense packing of noble metallic nanoparticles on few-layer phosphorene for sensitive SERS detection. Phosphorene obtained by electrochemical exfoliation serves as both the template and reductant in the fabrication of noble metallic nanoparticles which are dispersed on phosphorene without aggregation or pile-up. The BP/Ag/Au and BP/Au/Ag nanocomposites with a nanogap structure exhibit excellent SERS sensitivity and reproducibility with respect to Rhodamine 6G (R6G). The BP/Au/Ag nanocomposite is further utilized as the SERS substrate for the detection of two fungicides, thiabendazole and thiram, and detection limits of 10-7 and 10-8 M are achieved. Template growth of Au/Ag nanocomposites is demonstrated to be a green strategy for the fabrication of SERS substrates and has large potential in applications such as pesticide detection.
关键词： template growth,nanocomposites,phosphorene,SERS
更新于2025-11-21 11:01:37
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Rapid and fingerprinted monitoring of pesticide methyl parathion on the surface of fruits/leaves as well as in surface water enabled by gold nanorods based casting-and-sensing SERS platform
摘要： An effective, simple and portable gold nanorod (Au NR) based casting-and-sensing surface enhanced Raman scattering (SERS) platform was developed for rapid and fingerprinted detection of pesticide methyl parathion. Monodispersed Au NRs with an average length of 60 nm and an aspect ratio of ca. 3 were synthesized through a seed mediated method and then systematically characterized. After a proof-of-concept detection for methyl parathion in DI water and on solid surface, the sensing platform was further applied to real samples (lake water, orange, apple and plant leave) contaminated with methyl parathion. The results show that the sensitivity of the SERS sensor for methyl parathion was satisfactory for real application, with detection limits of 1 μM in spiked lake water and 110-440 ng/cm2 on the surface of various fruits and plant leaves. This study indicates that the developed casting-and-sensing SERS sensor shows great promise to secure agricultural, food and environmental safety.
关键词： lake water,fruits and leaves,Au NRs,methyl parathion,SERS
更新于2025-11-19 16:56:42
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Evaluation of 3D gold nanodendrite layers obtained by templated galvanic displacement reactions for SERS sensing and heterogeneous catalysis
摘要： Dense layers of overlapping three-dimensional (3D) gold nanodendrites characterized by high specific surfaces as well as by abundance of sharp edges and vertices creating high densities of SERS hotspots are promising substrates for SERS-based sensing and catalysis. We have evaluated to what extent structural features of 3D gold nanodendrite layers can be optimized by the initiation of 3D gold nanodendrite growth at gold particles rationally positioned on silicon wafers. For this purpose, galvanic displacement reactions yielding 3D gold nanodendrites were guided by hexagonal arrays of parent gold particles with a lattice constant of 1.5 μm obtained by solid-state dewetting of gold on topographically patterned silicon wafers. Initiation of the growth of dendritic features at the edges of the gold particles resulted in the formation of 3D gold nanodendrites while limitation of dendritic growth to the substrate plane was prevented. The regular arrangement of the parent gold particles supported the formation of dense layers of overlapping 3D gold nanodendrites that were sufficiently homogeneous within the resolution limits of Raman microscopy. Consequently, SERS mapping experiments revealed a reasonable degree of uniformity. The proposed preparation algorithm comprises only bottom-up process steps that can be carried out without the use of costly instrumentation.
关键词： heterogeneous catalysis,galvanic displacement reactions,3D gold nanodendrites,SERS sensing,solid-state dewetting
更新于2025-11-19 16:56:35
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Ultrathin and Isotropic Metal Sulfide Wrapping on Plasmonic Metal Nanoparticles for SERS-based Detection of Trace Heavy Metal Ions.
摘要： A facile and general strategy is presented for homogenous and ultrathin metal sulfide-wrapping on plasmonic metal (PM) nanoparticles (NPs) based on a thiourea-induced isotropic shell growth. This strategy is typically implemented just via adding the thiourea into pre-formed PM colloidal solutions containing target metal ions. The validity of this strategy is demonstrated by taking the wrapped NPs with Au core and CuS shell or Au@CuS NPs as an example. They are successfully fabricated via adding the thiourea and Cu2+ solutions into pre-formed Au NP colloidal solution. The CuS shell layer is highly homogenous (<10% in relative standard deviation of shell thickness), regardless of the NPs’ shape or curvature. The shell thickness can be controlled from tens down to 0.5 nm just by the addition amounts of the shell precursors. The formation of the shell layer on the Au NPs can be attributed to the alternative deposition of Cu2+ and S2- ions on the thiourea-modified surface of Au NPs in the solution, which induces the isotropic shell growth. Further, this strategy is of good universality. Many other sulfide-wrapped PM NPs, such as Ag@CuS, Au@PtS2, Au@HgS, Ag@Ag2S NPs and Ag@CuS nanorods have been successfully obtained with homogeneous and ultrathin shells. Importantly, such ultrathin sulfide-wrapped PM NPs can be used for SERS-based detection of trace heavy metal ions with strong anti-interference via ion exchange process between the metal sulfide shell and heavy metal ions. This study provides a simple and controllable route for wrapping the homogenous and ultrathin sulfide layers on the PM NPs, and such wrapped NPs have good practical applications in the SERS-based detection of trace heavy metal ions.
关键词： Plasmonic metal nanoparticles,Trace heavy metal ions,Ultrathin sulfide wrapping,Thiourea-induced isotropic shell growth,SERS-based detection
更新于2025-11-14 17:04:02
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Sensitive surface-enhanced Raman scattering detection of atrazine based on aggregation of silver nanoparticles modified carbon dots
摘要： The development of precise detection methods with simply operation for pesticides in various environmental samples is a particular challenge. Here a highly sensitive surface-enhanced Raman scattering (SERS) approach for the selective detection of trace atrazine was proposed with R6G as a Raman reporter, which was adsorbed on silver nanoparticles modified carbon dots. The latter were prepared by the reduction of Ag+ by carbon dots. In the presence of atrazine, the aggregation of the modified carbon dots due to the interaction between silver nanoparticles and atrazine led to great enhancement of the SERS signal of R6G. Under optimal assay conditions, the limit of quantification was estimated to be 10 nM, which matched with the standard for drinking water quality of China and WHO defined limit. A good linear response to atrazine was found in the concentration range of 10-1000 nM with the relative standard deviations between 1.8% and 5.6%. The determination of atrazine in real water samples was also carried out to confirm the practicability of the proposed method, which showed the recoveries from 95% to 117.5%. The target induced aggregation for enhancing the signal offered great potential for sensitive on-site detection of atrazine in environments.
关键词： Silver nanoparticles,Pesticides,SERS detection,Target induced aggregation,Atrazine,Carbon dots
更新于2025-11-14 17:03:37
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A flexible surface-enhanced Raman substrates based on cellulose photonic crystal/Ag-nanoparticles composite
摘要： Surface-enhanced Raman scattering (SERS) significantly increases Raman scattering intensity. SERS usually uses rough-surface nano-metal materials such as gold, silver and copper as a substrate [1]. It has been widely used in surface science, analytical science and other fields [2-4]. According to the preparation method, SERS substrates can be divided into three categories: (1) solid phase substrates with fixed metal nanoparticles [5, 6]; (2) metal nanostructures prepared by nanoimprinting [7, 8]; (3) metal nanostructures prepared by template method [9-11]. Conventional SERS substrates, such as roughened surfaces of noble metals, are difficult to control and the SERS effect is unstable due to the random distribution of nanostructures. The microstructure of the nanometer regular pattern, which is processed by etching and electron beam deposition, is limited by the high cost of the instrument, the complicated production process, the difficulty to make large area and the subsequent modification of the surface. The SERS substrate prepared by a template of nanospheres array has a good controllability and reproducibility. By assembling nanospheres with different sizes to prepare the templates of different thicknesses, 2D metal films with different spacing can be obtained. The preparation of SERS substrate based on nanospheres array is simple and has low cost, easy regulation and high reproducibility. Protective agent and surfactant are not required in the preparation, meanwhile, the obtained substrate is relatively pure. PhCs are periodic structures which can be generated by a controllable self-assembly method of the spherical colloidal particles [12-15]. Light propagated inside PhCs follows Bragg's law of diffraction [16-19]. The characteristics of PhCs strongly depend on the spatial structure. Because of its cost-efficiency and easy preparation, PhC has attracted significant attentions in the application of optical sensors, optical switches [20, 21] and display devices [22-26]. The regular periodical structures can also be used as template to prepare other structural functional materials [27]. A lot of researches on the preparation and application of PhCs have been carried out in our recent work [28, 29]. Based on the special capture effect of PhC optical bandgap, the plasma effect of silver nanoparticles and the enrichment of cellulose matrix on analytes in organic solvents, we designed a combination of three properties for enhancing Raman scattering. Design concept is as follows: a PhC array which bandgap matches the incident light is used as a template, filled with a cellulose matrix that is easily degraded, and modified with silver nanoparticles. Based on the above design, a novel surface-enhanced Raman scattering substrate made by Ag-nanoparticles modified flexible cellulose photonic crystal film was firstly prepared. We synthesized an Ag-nanoparticles modified PhCs methylcellulose film (Ag-PHC-MCF) and carboxymethyl cellulose film (Ag-PHC-CMCF) SERS flexible substrates using the PhCs as templates. The innovative combination of metal nanoparticles and the ordered PhCs cellulose film (PHCCF) effectively avoided the aggregation of metal nanoparticles, as a result, the hot spots of the metal nanoparticles were distributed around the pores to ensure the uniform adsorption of the target analytes and uniform Raman signals on a large area. Through the excellent enrichment of cellulose film with pore structures, the targets in the organic solvent were captured on the cellulose film, so the Raman detection signals of the analyte were enhanced with the contact probability between the targets and the hot spots of metal nanoparticles increasing. At the same time, the light scattered on the PHCCF was enhanced significantly because of the trapping effect of PhC. Based on the original combination of the enrichment of porous methylcellulose, the plasmon resonance of Ag and the bandgap of photonic crystal, the composite film has a significant enhancement of the Raman signals. Simultaneously, due to its good degradability, it also has outstanding advantages in environmental protection. Meanwhile, it is easy to be carried and preserved because of its flexibility and light texture, which has great superiorities in transportation and storage.Therefore, it is of great significance in industrial pollutant detection or national defense safety monitoring.
关键词： SERS,cellulose films,photonic crystal,plasmonic responses
更新于2025-11-14 15:27:09
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Plasmonic MoO2 nanospheres assembled on graphene oxide for highly sensitive SERS detection of organic pollutants
摘要： The molybdenum oxide and graphene oxide (MoO2/GO) nanocomposite has been fabricated via simple hydrothermal assisted synthesis using Mo and MoO3 as precursors. The MoO2 nanospheres with porous hollow structure are assembled onto GO nanosheets. Profiting from the plasmonic effects of MoO2 and synergistic effect of MoO2 and GO, this hybrid nanomaterial exhibits significantly enhanced surface enhanced Raman scattering (SERS) activity for organic pollutants. The detection limit for rhodamine 6G (R6G) is 1.0 × 10?9 M, and the maximum enhancement factor (EF) reaches up to 1.05 × 107, which is the best among the semiconductor-based SERS materials. For practical application, the MoO2/GO SERS substrates are also applied to detect Methylene blue (MB) in river water, and the detection limit (1.0 × 10?8 M) can be acquired. Pyrene is also chosen as probe molecule, and quantitative determination is achieved with detection limit of 1.0 × 10?7 M. These demonstrate the well feasibility for multi-molecule detection. Furthermore, the nanocomposite displays high stability, reproducible stability, and acid and alkali resistance.
关键词： Organic pollutants,Plasmonic effect,SERS,Graphene oxide,Detection,MoO2
更新于2025-11-14 15:27:09
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Magnetic SERS Composite Nanoparticles for Microfluidic Oil Reservoir Tracer Detection and Nanoprobe Applications
摘要： Composite magnetic nanoparticles are designed and synthesized with different morphologies as surface-enhanced Raman scattering (SERS) substrates or SERS-active particles. Through the incorporation of a magnetic functionality we provide a means to concentrate SERS-active nanoparticles in a low-volume microfluidic channel where the detected entity is now either a flowing analyte (e.g. tracer or chemical) or SERS-active particles contained in a target reservoir fluid. This collection strategy allows for detection using small amounts of material and can be optimized to provide selectivity for trace-level materials detection at the wellsite. We also demonstrate low-concentration detection of dye molecules used for reservoir tracer materials by optimizing the fluid flow rate and the intensity of the magnetic field. Thus, we developed an efficient magnetic SERS microfluidic detection platform for in situ monitoring trace level of analyte molecules. The integration of SERS with microfluidic systems also can extends the application of Raman detection in bio-medical research and microreactor monitoring where low volumes of expensive samples make traditional detection methods ineffective or cost prohibitive.
关键词： surface-enhanced Raman scattering,SERS nanoprobes,magnetic SERS,SERS substrate,nanoparticle,microfluidics
更新于2025-09-23 15:23:52