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Exfoliation of graphite as flexible SERS substrate with high dye adsorption capacity for Rhodamine 6G
摘要： Adsorption is one of the most important processes in wastewater treatment, especially for dye removal. In addition to adsorption, there must be a vigilant technique, such as Surface Enhanced Raman spectroscopy (SERS), for detection of low concentration of dye molecules to detect water foiling. Herein, we report a simple, low cost, rapid and e?cient technique for the production of exfoliated graphite (EG) under microwave irradiation at 800 W in 1 min, as excellent adsorption material for Rhodamine 6G (R6G) dye. The e?ect of adsorption process parameters such as pH, contact time, isotherm models (Langmuir and Freundlich) and kinetic models (pseudo-?rst and pseudo-second-order) on dye removal under aqueous solutions, were investigated. The maximum adsorption capacity for R6G dye is 212.72 ( ± 5.3) mg/g. Meanwhile compressing of EG, into a ?exible graphite sheet (FGS) demonstrates responsive SERS for R6G molecules up to detection limit of 10?7 mol/L. However, with silver nanoparticle incorporation, the detection limit increases up to 10?12 mol/L. Performance of ?exible sheet checked over a month by rubbing sheet through paper and cloth doesn’t have any impact on the synthesis of exfoliated graphite. Aging factor of the sheet also shows reproducible SERS spectra after a month. These are the highest reported values till today, for adsorption of R6G dye on Exfoliated graphite, with reasonable SERS detection.
关键词： Microwave irradiation,Flexible graphite sheet,Exfoliated graphite,SERS,Adsorption
更新于2025-09-23 15:22:29
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A novel bi-functional SiO2@TiO2/CDs nanocomposite with yolk-shell structure as both efficient SERS substrate and photocatalyst
摘要： A novel multi-functional yolk-shell SiO2@TiO2/CDs(y-STCs) nanocomposite with interesting structure of SiO2 cores, porous TiO2 shell, and cavities was synthesized by using a simple method. The experimental results indicate that the yolk-shell structure and modification of carbon dots (CDs) play important roles in the enhancement of SERS signals and photocatalytic performance. The y-STCs nanocomposite used as the SERS substrate showed excellent efficiency and reproducibility for the detection of rhodamine 6G (R6G). The detection limit of R6G was shown to be as low as 6 × 10?8 M. Furthermore, the fabricated y-STCs nanocomposite utilized as the photocatalytst for the degradation of dinitraphenols (DNP) can greatly shorten reaction time to 120 min compared with previous studies, and the DNP degradation rate could reach 96% under simulated sunlight irradiation. The y-STCs nanospheres also possessed excellent cycle stability for the photocatalytic degradation of DNP. Thus, the bi-functional y-STCs nanocomposite may have potential applications in the detection and photocatalytic degradation of organic pollutants.
关键词： SiO2@TiO2/CDs nanocomposite,Yolk-shell structure,SERS detection,Photocatalytic activity
更新于2025-09-23 15:22:29
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Surface-enhanced Raman scattering method for the identification of methicillin-resistant Staphylococcus aureus using positively charged silver nanoparticles
摘要： The article describes a SERS-based method for diagnosis of bacterial infections. Positively charged silver nanoparticles (AgNPs+) were employed for identification of methicillin-resistant Staphylococcus aureus (MRSA). It is found that AgNPs+ undergo self-assembly on the surface of bacteria via electrostatic aggregation. The assembled AgNPs+ are excellent SERS substrates. To prove the capability of SERS to differentiate between S. aureus and other microorganisms, six standard strains including S. aureus 29213, S. aureus 25923, C. albicans, B. cereus, E. coli, and P. aeruginosa were tested. To further demonstrate its applicability for the identification of MRSA in clinical samples, 52 methicillin-sensitive S. aureus (MSSA) isolates and 215 MRSA isolates were detected by SERS. The total measurement time (include incubation) is 45 min when using a 3 μL sample. The method gives a strongly enhanced Raman signal (at 730 cm?1 and 1325 cm?1) with good reproducibility and repeatability. It was successfully applied to the discrimination of the six strain microorganisms. The typical Raman peaks of S. aureus at 730, 1154, 1325, and 1457 cm?1 were observed, which were assigned to the bacterial cell wall components (730 cm?1- adenine, glycosidic ring mode, 1154 cm?1- unsaturated fatty acid, 1325 cm?1- adenine, polyadenine, and 1457 cm?1 for -COO- stretching). S. aureus was completely separated from other species by partial least squares discriminant analysis (PLS-DA). Moreover, 52 MSSA isolates and 215 MRSA isolates from clinical samples were identified by PLS-DA. The accuracy was almost 100% when compared to the standard broth microdilution method. A classification based on latent structure discriminant analysis provided spectral variability directly. Conceivably, the method offers a potent tool for the identification of bacteria and antibiotics resistance, and for studies on antibiotic-resistance in general.
关键词： S. aureus,Nanoparticles,Methicillin resistance,Antibiotics,Latent structure discriminant analysis classification (OPLS-DA),SERS,Partial least squares discriminant analysis (PLS-DA),AgNPs,Discriminant analysis,Raman spectroscopy
更新于2025-09-23 15:22:29
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SERS detection of mercury (II)/lead (II): A new class of DNA logic gates
摘要： A conceptually new class of DNA logic gates for Hg2+ and Pb2+ ion simultaneous detection has been constructed based on the activity of DNAzyme dependent on metal ions. For sensitive and specific detection of Hg2+ and Pb2+ ions, we demonstrate a surface-enhanced Raman scattering (SERS)-active platform by employing the oligonucleotide-functionalized and gold coated polystyrene microspheres (PSMPs). In this work, Hg2+ and Pb2+ were used as the input, and the SERS signals were the output. Hg2+ ions were captured by a mismatched T-Hg-T bridge. Pb2+ ions were bound to 8–17DNAzyme to break the cleavage substrate. The limit of detection (LOD) of Hg2+ is 0.1 nmol L?1 and Pb2+ is 1.0 nmol L?1, which is far below the limit of 10.0 ppb (31 nmol L?1) and 10.0 ppm (3.02 × 104 nmol L?1) for drinking water stipulated by the World Health Organization. Additionally, this system has the potential to be ideal candidates for intelligent DNA calculator design applications. Furthermore, the designed strategy could be extended to other multiplex metal ions that can be combined with DNA molecules, and can be applied to many other fields such as environmental detection, toxin detection and liquid analysis.
关键词： SERS,DNA logic gates,Simultaneous detection
更新于2025-09-23 15:22:29
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Invisible-ink-assisted pattern and written surface-enhanced Raman scattering substrates for versatile chem/biosensing platforms
摘要： In recent years, highly sensitive surface-enhanced Raman scattering (SERS) integrated with flexible substrates has drawn increasing attention for label-free detection. In this study, an invisible ink-inspired process was developed for the fabrication of plasmonic Au-based SERS substrates through an on-site redox strategy. Tannic acid (TNA), a common green reagent, was used not only for fabricating various SERS absorbents through a confinement reduction of a Au-TNA complex, but also for supplying an amphiphilic inorganic–organic surface structure for outstanding SERS enhancement at micromolar to nanomolar concentrations for a wide range of compounds. In addition to label-free sensing, this TNA/Au-based SERS substrate provides a versatile analysis platform for studies of chemical and biological reactions. A combination of TNA ink with different metal ions allows for a reliable procedure for the synthesis of a bimetallic AuAg SERS substrate that further enhances the SERS intensity of analyte molecules and extends the lower limit of detection.
关键词： bimetallic AuAg SERS substrate,invisible ink,tannic acid,label-free detection,SERS,plasmonic Au-based SERS substrates,surface-enhanced Raman scattering
更新于2025-09-23 15:21:21
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Evaluation of selected SERS substrates for trace detection of explosive materials using portable Raman systems
摘要： Raman spectroscopy has become an essential analytical technique for field detection and identification of illicit or dangerous materials such as explosives, but its main drawback is low signal intensity. This problem can be circumvented by using surface enhanced Raman spectroscopy (SERS), in which scattering signals increase significantly for analytes adsorbed onto or near nanostructured surfaces of the plasmonic materials. However, despite numerous studies, SERS has still not been widely used in real-world applications. The main goal of the studies describe herein was to investigate the possibility of detection of trace amounts of selected explosive materials on various commercial and non-commercial SERS substrates using portable Raman instruments. Our studies have shown that while portable systems suitable for SERS measurement of trace amounts of explosives are readily available, the problem remains in the selection of reliable and reproducible SERS substrates. Among five investigated SERS substrates only two, Klarite 312 and GaN-pillars allowed for trace analysis of all studied explosive materials. In both cases, detected concentrations of explosives ranged from single to hundreds of μg/cm2 depending on the explosive material and the Raman spectrometer used. Based on our findings, it could be concluded that the best SERS substrates for trace analysis of explosives are substrates with hot spots densely and evenly distributed over a whole active area of SERS substrate.
关键词： portable Raman spectroscopy,SERS,SERS substrates,trace detection,explosives
更新于2025-09-23 15:21:21
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Formation of the AuNPs GO@MoS2/AuNPs Nanostructures for the SERS Application
摘要： GO nanomeshes and GO@MoS2/AuNPs nanostructures are formed on the flexible 3D Ni foam substrate for the SERS application. Smaller and denser AuNPs “hot spots” are spin-coated on such mesh-like GO@MoS2/AuNPs nanostructures to form AuNPs/GO@MoS2/AuNPs SERS substrates. The branches of GO nanomeshes are used as the homogeneous nanogaps to form the separated denser “hot spots” and absorb the molecules, resulting high electromagnetic (confirmed by the FDTD simulation) and signals enhancement. As low as 10-14 M of the Crystal Violet (CV) and Rhodamine 6G (R6G) are detected. Such flexible foam-like substrate can be used for the in-situ detection on the fish surface by scraping. DNA without label can also be easily detected by spin-coating the mixed AuNPs-DNA solution in our experiment.
关键词： AuNPs GO@MoS2/AuNPs；hybrid nanostructures；homogeneous nanogaps；SERS
更新于2025-09-23 15:21:21
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Controlling surface morphology and sensitivity of granular and porous silver films for surface-enhanced Raman scattering, SERS
摘要： The design of efficient substrates for surface-enhanced Raman spectroscopy (SERS) for large-scale fabrication at low cost is an important issue in further enhancing the use of SERS for routine chemical analysis. Here, we systematically investigate the effect of different radio frequency (rf) plasmas (argon, hydrogen, nitrogen, air and oxygen plasma) as well as combinations of these plasmas on the surface morphology of thin silver films. It was found that different surface structures and different degrees of surface roughness could be obtained by a systematic variation of the plasma type and condition as well as plasma power and treatment time. The differently roughened silver surfaces act as efficient SERS substrates showing greater enhancement factors compared to as prepared, sputtered, but untreated silver films when using rhodamine B as Raman probe molecule. The obtained roughened silver films were fully characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM), X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron (XPS and Auger) and ultraviolet–visible spectroscopy (UV–vis) as well as contact angle measurements. It was found that different morphologies of the roughened Ag films could be obtained under controlled conditions. These silver films show a broad range of tunable SERS enhancement factors ranging from 1.93 × 102 to 2.35 × 105 using rhodamine B as probe molecule. The main factors that control the enhancement are the plasma gas used and the plasma conditions, i.e., pressure, power and treatment time. Altogether this work shows for the first time the effectiveness of a plasma treatment for surface roughening of silver thin films and its profound influence on the interface-controlled SERS enhancement effect. The method can be used for low-cost, large-scale production of SERS substrates.
关键词： plasma treatment,sputtering,surface-enhanced Raman spectroscopy (SERS),silver,surface roughening
更新于2025-09-23 15:21:21
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Flexible and reusable cap-like thin Fe2O3 film for SERS applications
摘要： Cap-like α-Fe2O3 films are fabricated and deposited onto quartz fabric by using radio frequency magnetron sputtering and annealing. The treated fabric sample in this study shows highly sensitive surface-enhanced Raman scattering (SERS) and excellent flexibility, reproducibility and stability. In addition, the sample can be recovered after a washing process with an organic solvent and repeatedly used. The sensitive SERS performance is attributed to chemical enhancement through a charge transfer process. Moreover, the SERS performance is also found to be dependent on the light coupling effect. When the light absorbance rate of the α-Fe2O3 films increases at a wavelength near that of laser light, the film shows excellent sensitivity due to light coupling effect.
关键词： α-Fe2O3,Raman sensor,flexible,quartz fabric,SERS
更新于2025-09-23 15:21:21
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Encyclopedia of Spectroscopy and Spectrometry || Surface-Enhanced Raman Optical Activity (SEROA)
摘要： This review discusses research into the enhancement of the chiroptical spectroscopic technique of Raman optical activity (ROA) through plasmonic resonance effects. The sensitivity of ROA spectroscopy to molecular stereochemistry and conformational dynamics has led to its increasing use in biology and the pharmaceutical sciences. However, the relative weakness of the ROA scattering process, being typically three to five orders of magnitude lower than the parent Raman scattering, has limited its application to conditions of relatively high concentrations and data accumulation times. The potential solution to this limitation in ROA by using the surface plasmon resonances that give rise to surface-enhanced Raman scattering (SERS) in order to boost ROA spectral intensity has been recognized by many researchers. Frustratingly, reliable measurement of this new technique of surface-enhanced Raman optical activity (SEROA) proved challenging to accomplish. A previous review by Abdali and Blanch presented the challenges involved in attempts to measure SEROA, as well as early results. Since then, significant advances have been made in exploring the SEROA phenomenon, and the time is appropriate for an updated account of this work. In order to provide sufficient background for guiding readers into the underlying principles of, and challenges faced in, measuring SEROA, we begin with an introduction to ROA before progressing on to its plasmonically-enhanced form.
关键词： chiroptical spectroscopy,SEROA,ROA,plasmonic resonance,Surface-Enhanced Raman Optical Activity,Raman Optical Activity,SERS,surface-enhanced Raman scattering
更新于2025-09-23 15:21:21