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A high-resolution study of in situ surface-enhanced Raman scattering nanotag behavior in biological systems
摘要： The colloidal stability of surface-enhanced Raman scattering (SERS) nanotags (Raman reporter-conjugated plasmonic nanoparticles) significantly affects the accuracy and reproducibility of SERS measurements, particularly in biological systems. Limited understanding of SERS nanotag stability may partly hamper the translation of SERS nanotags from the laboratory to their use in the clinic. In this contribution, we utilized differential centrifugal sedimentation (DCS), a reliable and straightforward technique to comprehensively analyze the colloidal stability of SERS nanotags in biological systems. Compared with other particle characterization techniques, DCS has been shown to have a unique advantage for high-resolution and high-throughput polydisperse particle characterization. DCS data revealed that the universal aggregation prevention practice of coating SERS nanotags with silica or bovine serum albumin layers did not sufficiently stabilize them in common measurement environments (e.g., 1× PBS). Combined DCS and SERS measurements established a strong correlation between the degrees of nanotag aggregation and signal intensities, further reinforcing the necessity of characterizing SERS nanotag stability for every condition in which they are used. We also found that increasing the protein thickness by the inclusion of extra protein components in the detection environments and antibody functionalization can improve the stability of SERS nanotags. We believe that this study can provide guidelines on appropriate measurement techniques and particle design considerations to assess and improve SERS nanotag stability in complex biological systems.
关键词： surface-enhanced Raman scattering (SERS),plasmonic nanoparticles,differential centrifugal sedimentation (DCS),SERS nanotags,colloidal stability
更新于2025-09-10 09:29:36
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Fluorescence-SERS dual-signal probes for pH sensing in live cells
摘要： The activity of many cells is closely related to the pH of their internal environment, and the increase of intracellular pH value is a common feature of many drug-resistant tumors. The intracellular pH needs to be determined as the research basis when studying the intracellular transport protein and ion concentration changes. Nanomaterials are now widely used as the effective imaging and drug delivery vehicles, but it remains to be studied as a sensor for intracellular environment. Based on this, we have constructed a nanoprobe with fluorescence and surface-enhanced Raman scattering (SERS) dual-signal for sensing intracellular pH. The principle of this strategy is to construct fluorescence-SERS dual-signal nanoprobes by modifying pH-responsive fluorescent probes and SERS reporter molecules on the surface of gold nanorods (AuNRs) with the core-shell structure. The fluorescence-SERS dual response of the nanoprobe to pH can be achieved by investigating the fluorescence and SERS spectra of nanoprobes at different pH. Moreover, by incubating the nanoprobes into different cells, different double-signal response results can be obtained, thereby achieving intracellular pH sensing. The nanoprobe has dual responsiveness to fluorescence and SERS, which makes up for many of the deficiencies of single-signal probes, and realizes high sensitivity, accuracy and stability of intracellular pH detection. It is expected to be widely applied in the fields of medicine, chemistry and biology.
关键词： Dual-signal,Intracellular pH,Fluorescence,Surface-enhanced Raman scattering,Nanoprobe
更新于2025-09-10 09:29:36
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Quantitative Determination of Urine Glucose: Combination of Laminar Flow in Microfluidic Chip with SERS Probe Technique
摘要： A surface-enhanced Raman scattering(SERS) sensing approach for urine glucose was developed based on the laminar flow technology in a cross-type microfluidic chip with SERS probes, 4-mercaptophenylboronic acid (MPBA) functionalized Ag nanoparticles. MPBA as the glucose receptor can identify and bind up with glucose at a molar ratio of 2:1, which can cause the aggregation of SERS probes at a certain position of the chip channel and further enhance the SERS signal of MPBA significantly. Thus, the quantitative SERS detection of glucose was achieved indirectly. No sample pretreatment and separation were needed in this method since the SERS detection was achieved in the gradient diffusion and molecular recognition processes between urine glucose and SERS probe in the laminar flow, which simplified the sample treatment procedures, saved detection time and made it feasible for clinic applications. This method shows a good linear relationship within human body’s normal physiological range and has high sensitivity and selectivity. The lowest detection concentration can reach 1.0 mg/dL.
关键词： Urine glucose,4-Mercaptophenylboronic acid,Microfluidic chip,Surface-enhanced Raman scattering(SERS)
更新于2025-09-10 09:29:36
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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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Morphology Effect on SERS Activity of Embedded Silver Nanostructures
摘要： Embedded silver nanostructures with different shapes and sizes are grown in Si substrates by chemical vapor deposition (CVD) method. Systematic study of their surface-enhanced Raman properties is performed. Influence of shape, size, and coverage of the nanoparticles on the average enhancement factors is calculated with the help of standard analyte molecules viz. crystal violet and Rhodamine 6G to optimize the substrates for future sensing applications.
关键词： embedded nanostructures,chemical vapor deposition,silver nanostructures,surface-enhanced Raman scattering
更新于2025-09-09 09:28:46
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A surface-enhanced Raman scattering-based lateral flow immunosensor for colistin in raw milk
摘要： A surface-enhanced Raman scattering (SERS)-based lateral flow immunosensor was created to identify colistin in milk. The Raman reporter 5,5-dithiobis-2-nitrobenzoic acid (DTNB) was used to label gold nanoparticles, and then anti-colistin monoclonal antibody (mAb) was attached. The size of the gold nanoparticles in the SERS nanoprobe was optimized, and the amount of DTNB and mAb, the change in hydrodynamic size, zeta potential, and the surface plasmon resonance band were also monitored in the preparation process. The SERS nanoprobe was then applied to a lateral flow strip followed by Raman signal readout for the quantitative determination of colistin with high sensitivity. The limits of detection of this assay were 0.10 ng/mL for colistin in milk, which was far below the previously reported value that was obtained with the ELISA method and the maximum residue limit set by the European Union. The spiking experiment showed high accuracy for this SERS-based immunosensing assay, with a recovery of 88.1% to 112.7% and satisfactory assay precision with a standard deviation below 15%. Furthermore, this assay also has the advantage of rapidity, with an assay time less than 20 min. Therefore, these results demonstrate that this SERS-based lateral flow immunosensor is promising for use in the rapid monitoring of colistin in milk.
关键词： Surface enhanced Raman scattering,Immunoassay,Sensor,Milk,Colistin
更新于2025-09-09 09:28:46
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Three-Dimensional Hierarchical Reticular Nanostructure of Fulfora candelaria Wing Decorated by Ag Nanoislands as Practical SERS-Active Substrates
摘要： Although surface-enhanced Raman scattering (SERS) technology has been widely explored nowadays in various fields, the fabrication of practical SERS-active substrates with prominent recognition ability for various analyte molecules is still defective. Natural Fulfora candelaria wing (FCW) with three-dimensional (3D) hierarchical reticular nanostructure was selected as a new bioscaffold for rough silver (Ag) nanoislands to be assembled on to prepare a practical SERS substrate (Ag/FCW substrate). By adjusting the sputtering time of metal Ag, the morphology of the substrates could be easily tuned to control the formation and distribution of “hot spots”. Three-dimensional finite-difference time-domain (3D-FDTD) simulation indicated that the excellent SERS performance under optimal morphology was ascribed to the local enhanced electric field in rough Ag surface and effective “hot spot” areas. The SERS measurement results show that the optimal Ag/FCW substrates had high SERS performance in terms of Raman signal sensitivity, reproducibility, uniformity and recognition ability for various analyte molecules. Coupled with flexibility of the biological substrates and the cost effectiveness, the sensitive SERS detection of varied analytes based on Ag/FCW substrates offered great potential for practical applications.
关键词： surface-enhanced Raman scattering,Fulfora candelaria wing,recognition ability,three-dimensional finite-difference time-domain simulation,practicability
更新于2025-09-09 09:28:46
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A simple strategy to improve the sensitivity of probe molecules on SERS substrates
摘要： In this work, we report a simple strategy to improve the detection sensitivity as well as the spectral quality of probe molecules on surface-enhanced Raman scattering (SERS) substrates. On normal SERS substrates, due to the decreased absorption capacity and changes in the molecule orientations, SERS signals disappear when the analyte molecule concentrations reach a limit value. To solve this problem, the molecular template reagent (MTR) technique, a simple strategy based on SERS surface selection rules, is considered. By choosing the best MTR according to different samples, the effect of adjusting the molecular orientations of samples can be studied. In this process, 1-butanethiol, 1-hexanethiol, 1-octanethiol, 1-decanethiol, and 1-dodecanethiol, which are MTRs, are used to adjust the orientations of probe molecules under optimized conditions. The use of the MTR technique indicated that the limit of detection (LOD) of the probe molecules of p-aminobenzenethiol and 4-mercaptobenzoic acid on noble metal substrates showed an increase of one order of magnitude over the LOD of the pure probing molecule systems. Hence, the proposed method introduces a way to detect the molecules with an improved sensitivity at extremely low concentrations. The study corresponds to a proof-of-concept study of MTR-assisted SERS for SERS-based applications in ultrasensitive analyses.
关键词： Surface-enhanced Raman scattering (SERS),Molecular template reagent (MTR),Ultrasensitive analyses,SERS substrates
更新于2025-09-09 09:28:46
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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