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Interface interaction between aromatic molecules and noble metals plays a prominent role in fundamental science and technological applications. However, probing π-metal interactions under ambient conditions remains challenging, as it requires characterization techniques to have high sensitivity and molecular specificity without any restrictions on the sample. Herein, the interactions between polycyclic aromatic hydrocarbon (PAH) molecules and Au nanodimers with a subnanometer gap are investigated by surface-enhanced Raman spectroscopy (SERS). A cleaner and stronger plasmonic field of subnanometer gap Au nanodimer structures was constructed through solvent extraction. High sensitivity and strong π-Au interaction between PAHs and Au nanodimers are observed. Additionally, the density functional theory calculation confirmed the interactions of PAHs physically absorbed on the Au surface; the binding energy and differential charge further theoretically indicated the correlation between the sensitivity and the number of PAH rings, which is consistent with SERS experimental results. This work provides a new method to understand the interactions between aromatic molecules and noble metal surfaces in an ambient environment, also paving the way for designing the interfaces in the fields of catalysis, sensors, and molecular electronics.
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Quantitative measurement is one of the ultimate targets for surface-enhanced Raman spectroscopy (SERS), but it suffers from difficulties in controlling the uniformity of hot spots and placing the target molecules in the hot spot space. Here, a convenient approach of three-phase equilibrium controlling the shrinkage of three-dimensional (3D) hot spot droplets has been demonstrated for the quantitative detection of the anticancer drug 5-fluorouracil (5-FU) in serum using a handheld Raman spectrometer. Droplet shrinkage, triggered by the shaking of aqueous nanoparticle (NP) colloids with immiscible oil chloroform (CHCl3) after the addition of negative ions and acetone, not only brings the nanoparticles in close proximity but can also act as a microreactor to enhance the spatial enrichment capability of the analyte in plasmonic sites and thereby realize simultaneously controlling 3D hot spots and placing target molecules in hot spots. Moreover, the shrinking process of Ag colloid droplets has been investigated using a high-speed camera, an in situ transmission electron microscope (in situ TEM), and a dark-field microscope (DFM), demonstrating the high stability and uniformity of nanoparticles in droplets. The shrunk Ag NP droplets exhibit excellent SERS sensitivity and reproducibility for the quantitative analysis of 5-FU over a large range of 50-1000 ppb. Hence, it is promising for quantitative analysis of complex systems and long-term monitoring of bioreactions.
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Antineoplásicos , Nanopartículas del Metal , Antineoplásicos/farmacología , Coloides , Fluorouracilo , Nanopartículas del Metal/química , Reproducibilidad de los Resultados , Espectrometría Raman/métodosRESUMEN
The aggregation of nanoparticles is the key factor to form hot spots for the flocculation-enhanced Raman spectroscopy (FLERS) method. However, the structure of flocculation is still not clear. It is therefore necessary to explore and analyze the aggregation process of nanoparticles more carefully, so as to realize a better application of FLERS. Here, we report the application of in situ liquid cell transmission electron microscopy (TEM) combined with an in situ high-speed camera to analyze the particle behaviors. The results showed that flocculation can exist stably and the gap between the nanoparticles in the flocculation always remained at 7-9 nm, which ensured the high stability and sensitivity of the FLERS method. We successfully applied FLERS to the in situ noninvasive probing of cupping effect substances. The results indicated the scientific principle behind the traditional Chinese medicine method to some extent, which thus provides a new and effective method for the in situ dynamic monitoring of biological systems.
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Nanopartículas , Espectrometría Raman , Floculación , Microscopía Electrónica de Transmisión , Nanopartículas/químicaRESUMEN
Hybridization chain reaction (HCR) was a significant discovery for the development of nanoscale materials and devices. One key challenge for HCR is the vulnerability to background leakage in the absence of the initiator. Here, we systematically analyze the sources of leakage and refine leak-resistant rule by using molecular thermodynamics and dynamics, biochemical and biophysical methods. Transient melting of DNA hairpin is revealed to be the underlying cause of leakage and that this can be mitigated through careful consideration of the sequence thermodynamics. The transition threshold of the energy barrier is proposed as a testing benchmark of leak-resistance DNA hairpins. The universal design of DNA hairpins is illustrated by the analysis of hsa-miR-21-5p as biomarker when used in conjunction with surface-enhanced Raman spectroscopy. We further extend the strategy for specific signal amplification of miRNA homologs. Significantly, it possibly provides a practical route to improve the accuracy of DNA self-assembly for signal amplification, and that could facilitate the development of sensors for the sensitive detection of interest molecules in biotechnology and clinical medicine.
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ADN/química , Secuencias Invertidas Repetidas , MicroARNs/química , Hibridación de Ácido Nucleico/métodos , Emparejamiento Base , Benchmarking , ADN/genética , ADN/metabolismo , Exosomas/química , Humanos , MicroARNs/genética , MicroARNs/metabolismo , Simulación de Dinámica Molecular , Conformación de Ácido Nucleico , Desnaturalización de Ácido Nucleico , Espectrometría Raman , Termodinámica , Neoplasias de la Vejiga Urinaria/química , Neoplasias de la Vejiga Urinaria/orinaRESUMEN
Retinal ganglion cells (RGCs) apoptosis and their axon degeneration are pivotal features in glaucoma. Previous studies suggest that the process of RGCs soma degeneration is distinct from axon degeneration and that both of them lead to vision loss but separately. However, since a normal visual function relies on the integrity of axon, synapse and soma in the retina, a comprehensive understanding of the changes of these neuron components in glaucoma is desired. Therefore, in an acute ocular hypertension (AOH) model in mice, we systematically evaluated retinal neuron soma, axon and synapse alteration at certain time points. We found that ocular hypertension led to a progressive apoptosis of retinal neural cells which proceeded from peripheral to central retina in the wholemount, meanwhile, started in the ganglion cell layer (GCL) and spread to the inner nuclear layer (INL) and then the outer nuclear layer (ONL) as time went on. The type of apoptotic cells was identified as RGCs in GCL, amacrine cells in INL and cone photoreceptor cells in ONL. Axon degeneration was observed at the same time as soma degenerated and also progressed from peripheral to central retina. More interestingly, accumulation of neurofilament in the soma caused by axon transport failure was detected synchronously. We also found that presynaptic and postsynaptic vesicle proteins were downregulated. Taken together, these data support a view that retinal neuronal apoptosis happens not only in RGCs, but also other neurons in laminar layers. Axon damage and synapse loss occur synchronously with soma loss in AOH. The combination of these three parameters might facilitate a systematic evaluation of the disease progression and treatment strategies in glaucoma.
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Apoptosis , Axones/patología , Modelos Animales de Enfermedad , Degeneración Nerviosa/patología , Hipertensión Ocular/patología , Células Ganglionares de la Retina/patología , Sinapsis/patología , Enfermedad Aguda , Células Amacrinas/patología , Animales , Western Blotting , Femenino , Técnica del Anticuerpo Fluorescente , Etiquetado Corte-Fin in Situ , Presión Intraocular , Ratones , Ratones Endogámicos C57BL , Células Fotorreceptoras Retinianas Conos/patologíaRESUMEN
Development of analytical methods allowing sensitive detection of neurotransmitters in various biofluids is vital. However, limitations of these methods include interference of impurities and stringent requirements concerning sample purity. In the current work, we developed a strategy for the rapid and sensitive analysis of dopamine (DA) in various biofluids with a smart surface-enhanced Raman spectroscopy (SERS) probe composed of magnetite Fe3O4 and Au nanoparticles (Fe3O4/Au NPs). Besides the simple and quick separation of DA from the specimen, Fe3O4 not only enabled a specific chemical interaction with DA molecules, but also acted as a SERS substrate capable of electromagnetically enhancing the Raman signal of DA. Therefore, the Fe3O4/Au NP composite with its coexisting electric-field effect and charger transfer (CT) enhancement was found to be beneficial for capturing the target molecules in biological environments and then enhancing the DA sensitivity. To understand the strong binding interaction between Fe3O4/Au and DA, X-ray photoelectron spectroscopy (XPS) was carried out, specifically to illuminate the chemical adsorption or possible CT complex. Moreover, a rapid purification strategy for further separating DA from serum was developed, and thus a high nanometer-level sensitivity was achieved. In addition, the feasibility of using Fe3O4/Au combined with the developed purification method was also verified using various tissue homogenates spiked with DA molecules. Such a nanocomposite can offer the possibility of efficiently separating DA from the complex specimen and then providing the sensitive detection of DA for various tissues. Accordingly, the smart SERS Fe3O4/Au nanocomposite probe, with its advantages of simple pre-treatment and synergetic enhanced mechanisms, shows great promise for the rapid and sensitive detection of DA in complicated specimens.
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Dopamina/sangre , Oro/química , Nanopartículas de Magnetita/química , Nanocompuestos/química , Adsorción , Humanos , Espectrometría Raman/métodos , Resonancia por Plasmón de Superficie/métodosRESUMEN
A rapid and accurate method for the sensitive detection of illegal drug additives including atenolol (ATN), metformin hydrochloride (MET), and phenformin hydrochloride (PHE) in health products using solvent microextraction (SME) combined with surface-enhanced Raman spectroscopy (SERS) was developed. Various illegal drug additives in different health products were separated via microextraction and then detected in situ using a portable Raman spectrometer with Ag colloids acting as SERS-active substrates. The effects of experimental parameters on the detection sensitivity and producibility were evaluated, and the applications of illegal additives spiked into samples were systematically investigated with SME-SERS. It was demonstrated that the mixture of CH3OH and CHCl3 (v/v = 1 : 4) as the extractant was suitable for the rapid microextraction separation of illegal drug additives and also induced the distribution of the Ag colloids (2 M) on the CHCl3 surface. More importantly, CH3OH can carry the drug molecules to enter into the inter-particles of the Ag colloids in this process, and then significantly improve the detection sensitivity of illegal drug additives. Furthermore, the high-throughput and real-time detection of illegal drug additives spiked into health products with SME-SERS in multi-well 96 plates were achieved with the level of 0.1 µg mg-1. The results reveal that this rapid and convenient method could be used for the effective separation and sensitive detection of illegal additives in complex specimen.
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Atenolol/análisis , Hipoglucemiantes/análisis , Microextracción en Fase Líquida/métodos , Metformina/análisis , Fenformina/análisis , Espectrometría Raman/métodos , Cloroformo/química , Coloides/química , Contaminación de Medicamentos , Límite de Detección , Nanopartículas del Metal/química , Metanol/química , Reproducibilidad de los Resultados , Plata/química , Solventes/químicaRESUMEN
The development of sensitive and rapid methods for analysis and detection of small molecules is highly desirable for medical diagnostics and therapeutics. We report an acupuncture needle functionalized with gold nanoparticles (Au NPs) and a macrocyclic amine (MA) Raman tag as the platform to realize the sensitive detection of adenosine triphosphate (ATP) by surface-enhanced Raman spectroscopy (SERS). The assembled Au NPs with abundant hot spots on the surface of the needle avoids the aggregation of Au NPs and results in a good signal response. Moreover, there is strong combination between ATP and MA through electrostatic adsorption, hydrogen-bonding interactions, and π-π stacking, and as a consequence, this functionalized needle can be used as a SERS platform for detection of ATP (25 nM) through a decrease of the Raman signal of MA resulting from the high chemical affinity of ATP for MA. Specially, the Au NP/MA-functionalized needle is conveniently used to monitor ATP (100 nM) added to serum, and demonstrates great promise in the study and detection of ATP in a complex sample, laying the foundation for SERS applications in complex acupuncture specimens with fast response and simple operation. Graphical abstract.
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Acupuntura/instrumentación , Adenosina Trifosfato/sangre , Agujas , Espectrometría Raman/métodos , Oro/química , Indicadores y Reactivos/química , Límite de Detección , Nanopartículas del Metal/químicaRESUMEN
Surface enhanced Raman spectroscopy (SERS) is a powerful spectroscopic technique with unique vibrational fingerprints, making it an ideal candidate for in situ multiphase detection. However, it is a great challenge to determine how to guide the SERS sensor to target molecules of interest in multiphase heterogeneous samples with minimal disturbance. Here, we present a portable ultrasensitive and highly repeatable SERS sensor for in situ multiphase detection. The sensor is composed of commercial Ag acupuncture needle and PVP-Au nanoparticles (Au NPs). The PVP on the Au NPs can adsorb and induce the Au NPs into a highly uniform array on the surface of the Ag needle because of its adhesiveness and steric nature. The Au NPs-Ag Needle system (Au-AgN) holds a huge SERS effect, which is enabled by the multiple plasmonic couplings from particle-film and interparticle. The PVP, as the amphiphilic polymer, promotes the target molecules to adsorb on surface of the Au-AgN whether in the oil phase or in the water phase. In this work, the Au-AgN sensor was directly inserted into the multiphase system with the laser in situ detection, and SERS detection at different spots of the Au-AgN sensor provided Raman signal of targets molecule in the different phase. In situ multiphase detection can minimize the disturbance of sampling and provide more accurate information. The facile fabrication and amphiphilic functionalization make Au-AgN sensor as generalized SERS detection platform for on-site testing of aqueous samples, organic samples, even the multiphase heterogeneous samples.
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Oro/química , Nanopartículas del Metal/química , Agujas , Povidona/química , Espectrometría Raman/instrumentación , Terapia por Acupuntura/instrumentación , Adsorción , Técnicas Biosensibles/instrumentación , Humanos , Plata/química , Propiedades de Superficie , Tensoactivos/químicaRESUMEN
Surface-enhanced resonance Raman scattering (SERRS) is not realized for most molecules of interest. Here, we developed a new SERRS platform for the fast and sensitive detection of 2,4,6-trinitrotoluene (TNT), a molecule with low Raman cross section. A cationic surfactant, cetylpyridinium chloride (CPC) was modified on the surface of silver sols (CP-capped Ag). CPC not only acts as the surface-seeking species to trap sulfite-sulfonated TNT, but also undergoes complexation with it, resulting in the presence of two charge-transfer bands at 467 and 530 nm, respectively. This chromophore absorbs the visible light that matches with the incident laser and plasmon resonance of Ag sols by the use of a 532.06 nm laser, and offered large resonance Raman enhancement. This SERRS platform evidenced a fast and accurate detection of TNT with a detection limit of 5×10(-11) M under a low laser power (200 µW) and a short integration time (3 s). The CP-capped Ag also provides remarkable sensitivity and reliable repeatability. This study provides a facile and reliable method for TNT detection and a viable idea for the SERS detection of various non-resonant molecules.
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Background: Retinal ganglion cells (RGCs) axon loss at the site of optic nerve head (ONH) is long believed as the common pathology in glaucoma since different types of glaucoma possessing different characteristic of intraocular pressure, and this damage was only detected at the later stage. Methods: To address these disputes and detect early initiating events underlying RGCs, we firstly detected somatic or axonal change and compared their difference in acute and chronic phase of primary angle-closed glaucoma (PACG) patient using optical coherence tomography (OCT), then an axonal-enriched cytoskeletal protein neurofilament heavy chain and its phosphoforms (NF-H, pNF-H) were utilized to reveal spatio-temporal undetectable damage insulted by acute and chronic ocular hypertension (AOH, COH) in two well characterized glaucoma mice models. Results: In clinic, we detected nonhomogeneous changes such as ONH and soma of RGCs presenting edema in acute phase but atrophy in chronic one by OCT. In AOH animal models, an increase expression of NF-H especially its phosphorylation modification was observed as early as 4 h before RGCs loss, which presented as somatic accumulation in the peripheral retina and at the sites of ONH. In contrast, in microbeads induced COH model, NF-H and pNF-H reduced significantly, these changes firstly occurred as NF-H or pNF-H disconnection at ONH and optic nerve after 2 weeks when the intraocular pressure reaching the peak; Meanwhile, we detected aqueous humor pNF-H elevation after AOH and slight reduction in the COH. Conclusion: Together, our data supports that early alteration of NF-H and its phosphoforms would reveal undetectable subcellular damage consisting of peripheral somatic neurofilament compaction, impaired axonal transport and distal axonal disorganization of cytoskeleton beyond the ONH, and identifies two distinct axonal degeneration which were Wallerian combination with retrograde degeneration in acute PACG and retrograde degeneration in the chronic one.
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In the manual dynamic surface-enhanced Raman spectroscopy (D-SERS) detection process, it is difficult to focus on sample drop due to the constantly changing hotspot and easy judgment method. In this paper, we proposed an automatic focusing method based on long time stable hotspot with aid of optimization of hill-climbing algorithm and achieved on a designed device. First, set up a high temperature accelerating evaporation process to obtain hotspot and then cool to a low temperature rapidly to maintain it. Then, the spectral intensity was used as a focus of feedback signal in optimized hill-climbing algorithm to drive the sample stage to move up and down to adjust the depth of the laser on the samples to realize automatic focusing. As a result, the hotspot can be maintained for 5 min, and the autofocusing result can be achieved within 9 s, while the sensitivity was improved with two orders of magnitude in D-SERS detection of crystal violet (CV) compared with manual focusing.
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A delicate system, that is, in situ photoreduced silver metal nanoparticles (NPs) formed from a combination of Ag(+) complexes with L- or D-cysteine, enables the introduction of chirality. This chirality is essentially programmed by a synergetic interplay between the CO(2)(-) and NH(3)(+) groups on cysteine, rather than the formation of a chiral metal core (see figure).
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Cisteína/análogos & derivados , Cisteína/química , Nanopartículas del Metal/química , Plata/química , Dicroismo Circular , Procesos Fotoquímicos , EstereoisomerismoRESUMEN
Amblyopia is a common eye disease characterized by impaired best-corrected visual acuity. It starts in early childhood and leads to permanent vision reduction if left untreated. Even though many young patients with amblyopia are well treated in clinical practice, the underlying mechanism remains to be elucidated, which limits not only our understanding of this disease but also the therapeutic approach. To investigate the molecular mechanism of amblyopia, primate and rodent models of monocular-deprived amblyopia were created for mRNA screening and confirmation. We obtained 818 differentially expressed genes from the dorsal lateral geniculate nucleus (dLGN) of a primate model of amblyopia. After Gene Ontology and kyoto encyclopedia of genes and genomes (KEGG) enrichment analyses, the main enriched pathways were related to neural development. Interestingly, a particular neurotransmitter pathway, the dopaminergic pathway, was identified. The downregulation of dopamine receptor D1 (DRD1) was confirmed in both monkey and mouse samples. Furthermore, the immunofluorescence staining indicated that DRD1 expression was downregulated in both ventrolateral region of the contralateral dLGN and the dorsomedial region of the ipsilateral dLGN in the mouse model. The regions with downregulated expression of DRD1 were the downstream targets of the visual projection from the amblyopic eye. This study suggested that the downregulation of DRD1 in the LGN may be a cause for amblyopia. This may also be a reason for the failure of some clinical cases of levodopa combined with carbidopa applied to amblyopes.
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Succinylcholine chloride (SCC) is a common poison that threatens human life. At present, there is a lack of research on its on-site rapid detection methods. In this work, the use of gold nanorods as an enhanced substrate based on the high affinity between the quaternary ammonium salt structure can achieve rapid SERS detection of SCC in plasma. The long alkane chain structure of cetyltrimethylammonium bromide (CTAB) and the quaternary ammonium salt structure of SCC have a high molecular affinity, so that the target molecule can show a strong and obvious characteristic signal of SERS. Combined with a simple pretreatment method, acetonitrile is used as a protein precipitation agent to effectively remove matrix interference. The constructed SERS substrate can achieve the sensitive detection of 2 × 10-8 M level of SCC in plasma samples and has high detection reproducibility. The entire pre-processing and testing process can be completed within 7 min, which can be used as an important technical basis for the preliminary identification of on-site SCC-related drug cases. The research results provide an effective solution for the establishment of SCC analysis strategies in complex matrices, and can provide new ideas for solving the problems of difficult identification of common poisons in the field and the lack of rapid detection methods on site.
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Compuestos de Amonio , Nanopartículas del Metal , Preparaciones Farmacéuticas , Oro , Humanos , Reproducibilidad de los Resultados , Espectrometría Raman , SuccinilcolinaRESUMEN
The sensitive detection and identification of toxicants in oily matrices have suffered from difficulty in poisoning incidents, therefore it is necessary to develop the rapid and efficient analytical method to realize the on-site screening and analyzing. In this report, the surface-enhanced Raman spectroscopy (SERS) method was used to detect paraquat and diquat poisons in various oily matrix coupled with solvent extraction. The solvent extraction not only remove interfering impurities of oily substrates, but also can enrich and separate the poisons from oily matrix. It was demonstrated that the ethanol as the extractant was suitable for the rapid separation of poisons such as paraquat (PQ) and diquat (DQ) in oily matrix (soy sauce, pasta sauce, sesame oil, chili oil). Moreover, combined with a handheld Raman spectrometer, the entire detection process was completed within 8 min with the level of 10 ppb PQ and 100 ppb DQ. Furthermore, double-blind experiments verify the reliability of this method. The results demonstrate that this rapid and convenient method could be used for the effective enrichment and sensitive detection of poisons in several oily matrix and has the grate potential application in emergency response and public safety.
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Venenos , Espectrometría Raman , Diquat , Etanol , Paraquat , Venenos/análisis , Reproducibilidad de los ResultadosRESUMEN
Platelet-derived growth factor C (PDGF-C) is a member of the PDGF/VEGF (vascular endothelial growth factor) family, which includes proteins that are well known for their mitogenic effects on multiple cell types. Glycosylation is one of the most important forms of posttranslational modification that has a significant impact on secreted and membrane proteins. Glycosylation has many well-characterized roles in facilitating protein processing and contributes to appropriate folding, conformation, distribution, and stability of proteins that are synthesized intracellularly in the endoplasmic reticulum (ER) and Golgi apparatus. Although the general process and functions of glycosylation are well documented, there are most likely others yet to be discovered, as the glycosylation of many potential substrates has not been characterized. In this study, we report that the PDGF-C protein is glycosylated at three sites, including Asn25, Asn55, and Asn254. However, we found that mutations at any of these sites do not affect the protein expression or secretion. Similarly, disruption of PDGF-C glycosylation had no impact on its progression through the ER and Golgi apparatus. However, the introduction of a mutation at Asn254 (N254 A) prevents the activation of full-length PDGF-C and its capacity for signaling via the PDGF receptor. Our findings reveal that glycosylation affects PDGF-C activation rather than the protein synthesis or processing. This study characterizes a crucial modification of the PDGF-C protein, and may shed new light on the process and function of glycosylation.
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Trinitrotoluene (TNT) is a primary component in chemical explosives, making them a common focus in public safety detection. However, it is very difficult to achieve selective and sensitive detection of the TNT molecule in practical application. In the present study, a simple surface enhanced Raman scattering (SERS) sensing based on monoethanolamine (MEA) - modified gold nanoparticles (Au NPs) was expanded for high selectivity and sensitive detecting of TNT in an envelope, luggage, lake water, and clothing through a quickly sampling and detection process. The monoethanolamine molecule based on Meisenheimer complex lights up ultra-high Raman scattering of a nonresonant molecule on the superficial coat of gold nanoparticles. Using this detection sensor, a molecular bridge can be established to selectively detect trinitrotoluene with a detection limit of 21.47 pM. We were able to rapidly identification trinitrotoluene molecule with a powerful selective over the familiar interfering substances nitrophenol, picric acid, 2,4-dinitrophenol, and 2,4-dinitrotoluene. The outcome in this work supply an efficient solution to the test of trinitrotoluene and to establishing a SERS sensor analytical strategy. The studies have demonstrated that the MEA-Au NPs based SERS sensing can be potentially used in field detection the trace amount of chemical explosives for public security.
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In this paper, we developed cysteamine-modified surface-enhanced Raman scattering (SERS) substrate for detecting detect trace amount of acidic pigment that shows weak affinity with gold nanoparticles (Au NPs). To realize sensitive and reproducible detection of pigment with weak affinity, the SERS substrate was prepared by attaching cysteamine (CA) to the Au NPs, the acidic pigment molecule could rapidly reached to the surface of Au NPs because of the formation of multihydrogen-bond and electrostatic interaction between the pigment and CA molecule. The proposed method allowed us to detect five kinds of acidic pigment with a limit of 1.0â¯ppm, which is below the strictest safety limit. Compared with the previous methods, the advantages of the present substrate were its simple substrate preparation, high reproducibility and good universality. Furthermore, the reliable and enough accurate results had been obtained by using of the proposed substrates in the assay of trace pigment in real samples.
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A novel long-period and high-stability 3D hotspot matrix was constructed with the assistance of glycerol based on our previous study on the dynamic-SERS approach in the water system: it could increase efficient hotspot duration from few seconds to twenty minutes and strongly improve sensitivity and reproducibility for SERS detection.