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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
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Silver nanoparticles with reduced graphene oxide for surface-enhanced vibrational spectroscopy of DNA constituents
摘要： Composite of silver nanoparticles with reduced graphene oxide flakes is proposed for surface enhanced vibrational spectroscopy, particularly for detection of adenine and thymine as constituents of deoxyribonucleic acid. Composite was formed by original method implying simultaneous reduction of silver ions and graphene oxide by discharge plasma at the gas–liquid interface. Combination of nanosized silver with reduced graphene oxide provided greater enhancement of Raman light scattering and infrared light absorption in comparison with separately used components. Addition of the composite to water solutions of adenine and thymine allowed detection of these analytes at micromolar concentrations. Composite of nano-silver with reduced graphene oxide can be prospective for surface enhanced spectroscopy as an alternative to the expensive lithographically prepared noble metal substrates.
关键词： Adenine,Surface Enhanced InfraRed Absorption (SEIRA),Thymine,Reduced graphene oxide,Discharge plasma,Silver nanoparticles,Surface Enhanced Raman Scattering (SERS)
更新于2025-09-23 15:23:52
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Au@Cu Nanoarrays with Uniform Long-Range Ordered Structure: Synthesis and SERS Applications
摘要： The nanostructures with uniform long-range ordered structure are of crucial importance for performance standardization of high-quality surface-enhanced Raman scattering (SERS) spectra. In this paper, we described the fabrication and SERS properties of Au decorated Cu (Au@Cu) nanoarrays. The Cu nanoarrays with uniform long-range ordered structure were first synthesized by in-situ electrochemistry assembly on insulated substrate. The Cu nanoarrays can reach a size of centimeters with strictly periodic nano-microstructure, which is beneficial for the production and performance standardization of SERS substrates. Then Au nanoparticals were decorated on the Cu nanoarrays by galvanic reaction without any capping agent. The obtained Au@Cu nanoarrays exhibit excellent SERS activity for 4-Mercaptopyridine, and the sensitivity limit is as low as 10?8 M. Therefore, this facile route provides a useful platform for the fabrication of SERS substrates based on nano ordered arrays.
关键词： Au nanoparticles,Cu nanoarrays,surface decoration,surface-enhanced Raman scattering (SERS)
更新于2025-09-23 15:23:52
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Silver Nanostructures on Graphene Oxide as the Substrate for Surface-Enhanced Raman Scattering (SERS)
摘要： Nanosized surface-enhanced Raman scattering (SERS) substrates fabricated by the controlled growth of metal nanostructures on water-dispersed two-dimensional nanomaterials can open a new avenue for SERS analysis of liquid samples in biological fields. In this work, regular and uniform Ag nanostructures were grown on the surface of graphene oxide (GO) through a microwave-assisted hydrothermal method. Polyamidoamine (PAMAM) dendrimers were assembled on the surface of GO to form GO/PAMAM templates for growing Ag nanostructures, which are primarily comprised of Ag dimers and trimers. The prepared Ag/GO nanocomposites are highly dispersed and stable in aqueous solution and may be used as substrates for enhanced Raman detection of rhodamine 6 G (R6G) in aqueous solution. This special substrate provides high-performance SERS and suppresses R6G fluorescence in aqueous solution and is promising as a nanosized material for the enhanced Raman detection of liquid samples in biological diagnostics.
关键词： graphene oxide (GO),Surface-enhanced Raman scattering (SERS),polyamidoamine (PAMAM) dendrimers,transmission electron microscopy (TEM),Fourier transform infrared (FTIR) spectroscopy,rhodamine 6G (R6G)
更新于2025-09-23 15:23:52
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Determination of Saxitoxin by Aptamer-Based Surface-Enhanced Raman Scattering
摘要： Saxitoxin is one of the most harmful paralytic shellfish toxins due to its high toxicity and adverse effects on the environment and human health. Aptasensors provide simple detection procedures because they have the advantages of chemical stability, easy synthesis and modification, and high convenience in signal transformation. Surface-enhanced Raman scattering (SERS) is an analytical technique that amplifies the analytical signals of molecules at extremely low concentrations, or even at the single molecule level, when the analyte is very close to rough metal surfaces or nanostructures. In this study, an SERS aptasensor is reported for the determination of saxitoxin for the first time. The optimized saxitoxin aptamer (M-30f) was modified on gold nanoparticles and served as the recognition element. Crystal violet was used as the Raman reporter without chemical bounding. The analytical principles of the aptasensor are that saxitoxin destabilized the conformations of the aptamer at high temperature conditions and altered the binding of crystal violet on the gold nanoparticles. In the presence of saxitoxin, the conformation of aptamer containing the G-quadruplex that selectively bound crystal violet unfolded to a large extent and hence the crystal violet molecules were released from gold nanoparticles with a reduced SERS signal. The effects of the gold nanoparticle size, the amount of DNA, aptamer density, sodium chloride concentration, and operation temperature upon the SERS determination were optimized. The resulting simple SERS aptasensor was developed with a satisfactory limit of detection (11.7 nM) and selectivity. The application for the analysis of real shellfish samples with simple procedures demonstrates that this SERS aptasensor is promising for on-site applications.
关键词： saxitoxin,paralytic shellfish toxin,surface-enhanced Raman scattering (SERS),Aptamer
更新于2025-09-23 15:23:52
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Ultrasensitive detection of diclofenac in water samples by a novel surface-enhanced Raman scattering (SERS)-based immunochromatographic assay using AgMBA@SiO2-Ab as immunoprobe
摘要： In the last years, surface-enhanced Raman scattering based immunochromatographic assay (SERS-ICA) has been getting great attention and been applied for the detection of different target analytes. In this study, a novel SERS-ICA using AgMBA@SiO2-Ab as an immunoprobe has been developed for rapid, quantitative and ultrasensitive detection of a pharmaceutical diclofenac (DCF) residue in water samples. Ag, Ag@SiO2 and AgMBA@SiO2 nanoparticles (NPs) were synthesized and characterized. The immunoprobe was prepared by sandwiching the Raman reporter mercaptobenzoic acid (MBA) between the core-shell layers and immobilizing the monoclonal antibody (mAb) against DCF on the surface of the Ag@SiO2 NPs. Under optimal conditions, the sensitivity and limit of detection (LOD) of the SERS-ICA for DCF were found to be 9 pg mL-1 and 0.07 pg mL-1, respectively. The detection of the SERS-ICA for DCF was completed within 15 min. AgMBA@SiO2-Ab was stable within four months without significant loss of SERS intensity. The key to success of the SERS-ICA was the employment of the Ag@SiO2 NPs as the SERS substrate, which possessed gorgeous SERS enhancement capability, predominant biocompatibility and excellent stability. This SERS-ICA is potential as an ultrasensitive analytical method in point-of-care testing, clinical diagnosis, food inspecting and environmental monitoring.
关键词： Surface-enhanced Raman scattering (SERS),SERS-ICA,Diclofenac,Ag@SiO2 core-shell nanoparticles,Immunochromatographic assay (ICA)
更新于2025-09-23 15:22:29
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Ordered Array of Metal Particles on Semishell Separated with Ultrathin Oxide: Fabrication and SERS Properties
摘要： Metal particles in gap cavities provide an interesting system to achieve hybrid local surface plasmon modes for local field enhancement. Here, we demonstrate a relatively simple method to fabricate Ag nanoparticles positioned on Ag semishells separated by a thin (~5 nm) dielectric layer. The obtained structure can provide strong local electric field enhancement for surface-enhanced Raman scattering (SERS). The fabrication of the ordered array structure was realized by nanosphere self-assembly, atomic layer deposition, and metal thin-film dewetting. Numerical simulation proved that, compared to the conventional metal semishell arrays, the additional Ag particles introduce extra hot spots particularly in the valley regions between adjacent Ag semishells. As a result, the SERS enhancement factor of the metal semishell-based plasmonic structure could be further improved by an order of magnitude. The developed novel plasmonic structure also shows good potential for application in plasmon-enhanced solar water-splitting devices.
关键词： particle in cavity,nanosphere lithography,surface-enhanced Raman scattering (SERS),surface plasmonic,monolayer self-assembly
更新于2025-09-23 15:22:29
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Growth of Spherical Gold Satellites on the Surface of Au@Ag@SiO <sub/>2</sub> Core–Shell Nanostructures Used for an Ultrasensitive SERS Immunoassay of Alpha-Fetoprotein
摘要： The identification and detection of cancer biomarkers in early stages is an important issue for the therapy of cancer. However, most methods are time-consuming, limited sensing sensitivity and specificity. In this work, we prepared a novel plasmonic multilayered core–shell-satellite nanostructure (Au@Ag@SiO2-AuNP) consisting of an gold nanosphere with silver coating core (Au@Ag), an ultrathin continuous silica (SiO2) shell and high coverage of gold nanospheres (AuNPs) satellites. Au@Ag core is prominent surface enhanced Raman scattering (SERS) platform and the thin SiO2 layer exhibits a long-range plasmon coupling between Au@Ag core to AuNPs satellites further leading to enhanced Raman scattering. Meanwhile, the outer AuNPs satellites have a high biocompatibility and long-term stability. Combining the above advantages, the well-designed metallic nanoassemblies would be a promising candidate for SERS-based applications in biochemistry. For specific detection of alpha-fetoprotein (AFP), we utilized the SERS-active core-shell-satellite nanostructures modified with AFP antibody as immune probes and nitrocellulose membrane (NC) stabilized captured anti-AFP antibodies as solid substrate. To improve the detection performance, we further systematically optimized the parameters, including silver coating thickness of Au@Ag core, the density and size of satellite AuNPs. Under the optimized conditions, AFP could be detected by the SERS-based sandwich immunoassay with an ultralow detection limit of 0.3 fg/mL, and the method exhibited a wide linear response from 1 fg/mL to 1 ng/mL. The limit of detection (LOD) was considerably lower than conventional methods in literature. This work relies on the unique Au@Ag@SiO2-AuNP nanostructures as immune probe develops a new outlook for the application of multilayered nanoassemblies and demonstrates the great potential in early tumor markers detection.
关键词： surface enhanced Raman scattering (SERS),Au-Ag bimetallic nanospheres,alpha-fetoprotein,core-shell-satellite nanostructure,gold nanospheres
更新于2025-09-23 15:22:29
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Photonic Crystal Enhanced SERS Detection of Analytes Separated by Ultrathin Layer Chromatography Using a Diatom Frustule Monolayer
摘要： Diatoms are single-celled algae that biologically fabricate nanostructured silica shells with ordered pore arrays called frustules that resemble a 2D photonic crystal. A monolayer of Pinnularia frustules isolated from cell culture is deposited on a glass substrate and then conformally coated with silver nanoparticles (AgNPs) to serve as a nanostructured thin film for ultrathin layer chromatography (UTLC). Malachite green and Nile red are resolved in toluene mobile phase and the separated analytes are profiled micro-Raman spectroscopy, where plasmonic AgNPs provide surface-enhanced Raman scattering (SERS). The AgNP-diatom frustule monolayer improves SERS detection of malachite green by an average factor of 1.8 ± 0.1 over the plasmonic AgNP layer on glass. Analysis of hot spots on the AgNP-diatom frustule monolayer reveals that nearly 20% of the SERS active area intensifies the SERS signal at least tenfold over the SERS signal for AgNP on glass. Diatom-SERS enhancement is attributed to guided-mode resonances of the Raman laser source, which in turn further enhances the localized surface plasmonic resonance from AgNPs. Overall, the AgNP-diatom frustule monolayer thin film is a new functional material that uniquely enables separation of analytes by UTLC, quantitative SERS detection of separated analytes, and photonic enhancement of the SERS signals.
关键词： ultrathin layer chromatography,Raman,diatoms,surface-enhanced Raman scattering (SERS),photonic crystals
更新于2025-09-23 15:21:01
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Optically controlled hybrid metamaterial of plasmonic spiky gold inbuilt graphene sheets for bimodal imaging guided multimodal therapy
摘要： The development of multifunctional molecular diagnostic platforms for concordant visualization and treatment of diseases with high sensitivity and resolution has recently become a crucial strategy in cancer management. Thus, engineering functional metamaterials with high therapeutic and imaging capabilities to elucidate diseases from morphological behaviors to physiological mechanisms is an unmet need in the current scenario. Here, we report the design of a unique hybrid plasmonic nanoarchitecture, for targeted multiple photo-therapies of breast cancer by simultaneous real time monitoring through fluorescence and surface enhanced Raman scattering (SERS) techniques. The nanoframework consists of plasmonic gold-graphene hybrids tethered with folic acid ligated chitosan modified photosensitizer (PpIX) to afford target specific localized photothermal and photodynamic therapy. The hybrid vehicle also served as an excellent nanocarrier for efficient loading and stimuli responsive release of the chemotherapeutic drug doxorubicin (DOX) to enhance the therapeutic efficacy, thereby forming a trimodal nanomedicine against cancer. The cytotoxic effects induced by the cumulative action of triplet therapeutic tools were visualized through both fluorescence and SERS imaging channels. Moreover, it also generated synchronized therapeutic effects resulting in the effective regression of tumor volume without propagating any toxic effect to other organs of the animals. Taken together, by virtue of strong light-matter interactions, our nanoprobe showed enhanced photoadsorption which facilitate the amplified light reactive therapeutic and imaging efficacies along with targeted and enhanced chemotherapy, both in vitro and in vivo, which may offer a promising outcome in clinical research.
关键词： surface enhanced Raman scattering (SERS),hybrid plasmonic nanoarchitecture,breast cancer,trimodal nanomedicine,fluorescence,doxorubicin (DOX),photothermal and photodynamic therapy,multifunctional molecular diagnostic platforms
更新于2025-09-23 15:19:57