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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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An ultrasensitive luteolin sensor based on MOFs derived CuCo coated nitrogen-doped porous carbon polyhedron
摘要： Designing high-efficiency electrocatalysts for luteolin detection is essential and vital in biological and medical field. Herein, CuCo coated nitrogen-enriched porous carbon polyhedron (CuCo@NPCP) materials are fabricated as a highly sensitive electrochemical luteolin sensor by simple and mild approach. As characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, N2 adsorption-desorption isotherms and electrochemical methods, CuCo@NPCP materials possess high specific surface area, 3D porous framework, amounts of available active sites, which all contribute to the adsorption and catalysis for luteolin. Meanwhile, vast mesoporous structure of CuCo@NPCP further affords more mass transport channels and enhances the mass transfer capacity. Thanks to above-mentioned characteristics, optimal Cu1Co3@NPCP presents superior analytical performance: a wide linear range from 0.2 nM to 2.5 μM, a ultrahigh sensitivity of 134.57 μA μM-1 surpassing to other reported catalysts previously, a low detection limit of 0.08 nM, as well as satisfactory selectivity, reproducibility, and long-term stability. This work offers an attractive catalyst derived from MOFs for constructing effective luteolin sensors.
关键词： Luteolin sensor,Metal-organic framework derivatives,Ultrahigh sensitivity,Trace detection
更新于2025-09-23 15:21:01
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Ultrathin Hexagonal PbO Nanosheets Induced by Laser Ablation in Water for Chemically Trapping Surface-Enhanced Raman Spectroscopy Chips and Detection of Trace Gaseous H <sub/>2</sub> S
摘要： Lead oxide (PbO) nanosheets are of significance in design of functional devices. However, facile, green and fast fabrication of ultrathin and homogenous PbO nanosheets with chemically clean surface is still desirable. Herein, a simple and chemically clean route is developed for fabricating such nanosheets via laser ablation of a lead target in water for a short time and then ambient ageing. The obtained PbO nanosheets are (002)-oriented with microsize in planar dimension and ca. 15 nm in thickness. They are mostly hexagonal in shape. Experimental observations of the morphological evolution have revealed that the formation of such PbO nanosheets can be attributed to two processes: (i) laser ablation-induced formation of ultrafine Pb and PbO nanoparticles (NPs); (ii) PbO NPs’ aggregation and their oriented connection growth. Importantly, a composite surface enhanced Raman spectroscopy (SERS) chip is designed and fabricated, by covering a PbO nanosheets’ monolayer on a Au NPs’ film. Such composite SERS chip can be used for the fast and trace detection of gaseous H2S, in which the PbO nanosheets can effectively chemically trap H2S molecules, demonstrating a new application of these PbO nanosheets. The response of this chip to H2S can be detected within 10s and the detection limit is below 1 ppb. Also, this PbO nanosheet-based chip is reusable by heating after use. This study not only deepens understanding the NPs-based formation mechanism of nanosheets, but also provides the renewable SERS-chips for the highly efficient detection of trace gaseous H2S.
关键词： Ultrathin hexagonal PbO nanosheets,Chemically trapping-SERS chip,Trace detection of gaseous H2S,Reusable performance,Laser ablation in water
更新于2025-09-23 15:19:57
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Ag@Fe <sub/>3</sub> O <sub/>4</sub> Core–Shell Surface-Enhanced Raman Scattering Probe for Trace Arsenate Detection
摘要： Developing an effective and reliable method for trace arsenic (As) detection is a prerequisite for improving the safety of drinking water. In this paper, we designed and prepared Ag@Fe3O4 core–shell nanoparticles (NPs), which were then used as Surface-Enhanced Raman Scattering (SERS) probe for trace arsenate (As(V)) detection. The Ag@Fe3O4 core–shell NPs were prepared by in situ growth of Fe3O4 NPs on the surface of AgNPs, which can effectively combine the strong adsorption ability of Fe3O4 nanoshells to As(V) with high SERS activity of Ag nanocores to decrease the detection limit. By use of Ag@Fe3O4 core–shell NPs for As(V) detection, the detection limit can be as low as 10 (cid:2)g/L, and a good linear relationship between the SERS intensity of As(V) and their concentrations in the range from 10 to 500 (cid:2)g/L was achieved. Furthermore, Ag@Fe3O4 core–shell NPs could be regenerated through desorption of As(V) from Fe3O4 nanoshells in NaOH solution, and then used for recyclic SERS detection. Therefore, it has been demonstrated for the ?rst time that multifunctional Ag@Fe3O4 core–shell SERS probe could be applied to realize the highly sensitive and reversible detection of As(V).
关键词： Drinking Water,Core–Shell,Fe3O4,Heavy Metals,Trace Detection
更新于2025-09-04 15:30:14