Your browser doesn't support javascript.
Mostrar: 20 | 50 | 100
Resultados 1 - 10 de 10
Filtrar
Mais filtros










Base de dados
Intervalo de ano de publicação
1.
Artigo em Inglês | MEDLINE | ID: mdl-31912582

RESUMO

Sulfur is not normally considered a light-emitting material, even though there have been reports of a dim luminescence of this compound in the blue-to-green spectral region. Now, it is shown how to make red-emissive sulfur by a two-step oxidation approach using elemental sulfur and Na2 S as starting materials, with a high photoluminescence quantum yield of 7.2 %. Polysulfide is formed first and is partially transformed into Na2 S2 O3 in the first step, and then turns back to elemental S in the second step. The elevated temperature and relatively oxygen-deficient environment during the second step transforms Na2 S2 O3 into Na2 SO3 incorporated with oxygen vacancies, thus resulting in the formation of a solid-state powder consisting of elemental S embedded in Na2 SO3 . It shows aggregation-induced emission properties, attributed to the influence of oxygen vacancies on the emission dynamics of sulfur by providing additional lower energy states that facilitate the radiative relaxation of excitons.

2.
Mikrochim Acta ; 187(1): 38, 2019 12 10.
Artigo em Inglês | MEDLINE | ID: mdl-31823079

RESUMO

Luminescent copper nanoclusters (Cu NCs) are chosen to functionalize Ti3C2Tx MXene flakes to form a new kind of nanohybrid. It was applied to the determination of glutathione (GSH) via photoluminescence (PL). The Cu NCs and MXene flakes are in close contact, and the blue PL of the Cu NCs (with excitation/emission peaks at 380/425 nm) is quenched. The addition of GSH triggers the separation of the nanohybrid. This results in the recovery of PL. GSH also promotes the PL of Cu NCs via host-guest interactions. Thus, target recognition, corresponding signal output and further magnification are accomplished in a single step. Under optimum conditions, the nanohybrid can detect GSH in the 5.0 to 100 µM concentration range and with a 3.0 µM detection limit. The assay is very specific and shows high selectivity towards metal ions, small biomolecules, amino acids, and thiol containing molecules. Graphical abstractLuminescent copper nanoclusters are used to functionalize Ti3C2Tx MXene flakes, forming a nanohybrid, which is applied to detect glutathione. Target recognition, signal output and magnification are accomplished in a single step, resulting in high selectivity.

3.
Chem Commun (Camb) ; 55(86): 13004-13007, 2019 Oct 24.
Artigo em Inglês | MEDLINE | ID: mdl-31608907

RESUMO

An ultrasonication-promoted strategy was proposed to synthesize luminescent S-dots, which reduced the synthesis time from the commonly used 5 days to several hours. The as-synthesized S-dots show a high photostability and low cytotoxicity, and are then successfully applied for cellular imaging.


Assuntos
Pontos Quânticos/química , Enxofre/química , Linhagem Celular , Sobrevivência Celular/efeitos dos fármacos , Humanos , Microscopia Confocal , Polietilenoglicóis/química , Pontos Quânticos/toxicidade , Sonicação
4.
ACS Appl Mater Interfaces ; 11(6): 6561-6567, 2019 Feb 13.
Artigo em Inglês | MEDLINE | ID: mdl-30656937

RESUMO

Visually observable pH-responsive luminescent materials are developed by integrating the properties of aggregation-induced emission enhancement of Cu nanoclusters (NCs) and the Ca2+-triggered gelatin of alginate. Sodium alginate, CaCO3 nanoparticles, and Cu NCs are dispersed in aqueous solution, which is in a transparent fluid state, showing weak photoluminescence (PL). The introduced H+ can react with the CaCO3 nanoparticles to produce free Ca2+, which can cross-link the alginate chains into gel networks. Meanwhile, a dramatic increase in the PL intensity of Cu NCs and a blue shift in the PL peak appeared, assigned to the Ca2+-induced enhancement and gelatin-induced enhancement, respectively. Their potential application as a sensor for glucose is also demonstrated based on the principle that glucose oxidase can recognize glucose and produce H+, which further triggers the above-mentioned two-stage enhancement. A linear relationship between the PL intensity and the concentration of glucose in the range of 0.1-2.0 mM is obtained, with the limit of detection calculated as 3.2 × 10-5 M.


Assuntos
Alginatos/química , Cobre/química , Glucose/análise , Medições Luminescentes/métodos , Nanopartículas Metálicas/química , Aminoácidos/química , Dopamina/química , Géis/química , Glucose/metabolismo , Glucose Oxidase/metabolismo , Concentração de Íons de Hidrogênio
5.
Dalton Trans ; 46(41): 14251-14255, 2017 Oct 24.
Artigo em Inglês | MEDLINE | ID: mdl-28991296

RESUMO

A new strategy for the synthesis of luminescent copper nanoclusters (Cu NCs), by virtue of the reduction of Cu2+ using ascorbic acid and the protection of polyvinylpyrrolidone at 75 °C, was reported. Blue emitting Cu NCs with photoluminescence (PL) quantum yield of 12% and high stability up to at least 1 month were obtained. Moreover, the PL of Cu NCs showed a reversible response to temperature, and a linear relationship between PL intensity and temperature even after 10 cycles of repeated heating and cooling process was obtained, indicating great potential application in thermal sensors.

6.
Talanta ; 158: 322-329, 2016 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-27343612

RESUMO

Highly bioaccumulated polycyclic aromatic hydrocarbons (PAHs) have cause health concerns because of their carcinogenic properties. PAHs could migrate to food from contaminated food contact materials. In this study, a hyphenated technique combining surface enhanced Raman spectroscopy (SERS) with surface microextraction was developed for in-situ on site screening of PAHs on food contact materials. Methanol and 1-propanethiol-modified silver nanoparticles (PTH-Ag NPs) were used to perform the in-situ microextraction and detection of PAHs, respectively. The SERS spectra can be obtained by a portable Raman spectrometer. The vibration of the C-C bond of PTH at 1030cm(-1) was chosen as an internal standard peak. The PTH-Ag NPs showed high uniformity with an RSD of 2.96%. A plot of the normalized SERS intensity against fluoranthene concentration showed a linear relationship (R(2)=0.98). The detection limit could reach 0.27ngcm(-2). The in-situ microextraction-SERS hyphenated technique for the detection of three PAHs at five food contact materials was demonstrated. The method can be also applied to detect PAH mixtures. This in-situ microextraction-SERS hyphenated method demonstrated its ability to rapidly screen PAHs on contaminated food contact materials free from complex sample pretreatment.


Assuntos
Utensílios de Alimentação e Culinária , Embalagem de Alimentos , Nanopartículas Metálicas/química , Hidrocarbonetos Policíclicos Aromáticos/análise , Prata/química , Compostos de Sulfidrila/química , Contaminação de Alimentos , Metanol/química , Hidrocarbonetos Policíclicos Aromáticos/química , Análise Espectral Raman/métodos
7.
Anal Chim Acta ; 923: 66-73, 2016 Jun 07.
Artigo em Inglês | MEDLINE | ID: mdl-27155303

RESUMO

Solid phase microextraction-surface enhanced Raman spectroscopy (SPME-SERS), combining the pretreatment and determination functions, has been successfully used in environmental analysis. In this work, Au-coated ZnO nanorods were fabricated on stainless steel fiber as a self-cleaning SERS-active SPME fiber. The ZnO nanorods grown on stainless steel fiber were prepared via a simple hydrothermal approach. Then the obtained nanostructures were decorated with Au nanoparticles through ion-sputtering at room temperature. The obtained SERS-active SPME fiber is a reproducible sensitivity sensor. Taking p-aminothiophenol as the probe molecule, the RSD value of the SERS-active SPME fiber was 8.9%, indicating the fiber owned good uniformity. The qualitative and quantitative detection of crystal violet and malachite green was also achieved. The log-log plot of SERS intensity to crystal violet and malachite green concentration showed a good linear relationship. Meanwhile, this SERS-active SPME fiber can achieve self-cleaning owning to the excellent photocatalytic performance of ZnO nanorods. Crystal violet was still successfully detected even after five cycles, which indicated the high reproducibility of this SERS-active SPME fiber.

8.
Analyst ; 140(13): 4668-75, 2015 Jul 07.
Artigo em Inglês | MEDLINE | ID: mdl-25988666

RESUMO

Solid phase microextraction (SPME), a solvent free technique for sample preparation, has been successfully coupled with GC, GC-MS, and HPLC for environmental analysis. In this work, a method combining solid phase microextraction with surface enhanced Raman spectroscopy (SERS) is developed for detection of polycyclic aromatic hydrocarbons (PAHs). Silver nanoparticle aggregates were deposited on the Ag-Cu fibers via layer-by-layer deposition, which were modified with propanethiol (PTH). The SERS-active SPME fiber was immersed in water directly to extract PAHs and then detected using a portable Raman spectrometer. The pronounced valence vibration of the C-C bond at 1030 cm(-1) was chosen as an internal standard peak for the constant concentration of PTH. The RSD values of the stability and the uniformity of the SERS-active SPME fiber are 2.97% and 5.66%, respectively. A log-log plot of the normalized SERS intensity versus fluoranthene concentration showed a linear relationship (R(2) = 0.95). The detection limit was 7.56 × 10(-10) M and the recovery rate of water samples was in the range of 95% to 115%. The method can also be applied to detection of PAH mixtures, and each component of the mixtures can be distinguished by Raman characteristic peaks. The SERS-active SPME fiber could be further confirmed by GC-MS.


Assuntos
Cobre/química , Nanopartículas Metálicas/química , Hidrocarbonetos Policíclicos Aromáticos/análise , Hidrocarbonetos Policíclicos Aromáticos/isolamento & purificação , Prata/química , Microextração em Fase Sólida/métodos , Análise Espectral Raman/métodos
9.
Analyst ; 140(8): 2815-22, 2015 Apr 21.
Artigo em Inglês | MEDLINE | ID: mdl-25730599

RESUMO

Perchlorate, which causes health concerns because of its effects on the thyroid function, is highly soluble and mobile in the environment. In this study, diethyldithiocarbamate (DDTC)-modified silver nanoplates were fabricated on a copper wire to perform the on-site microextraction and detection of perchlorate. This fiber could be inserted into water or soil to extract perchlorate through electrostatic interaction and then can be detected by a portable Raman spectrometer, owing to its surface-enhanced Raman (SERS) activity. A relatively stable vibrational mode (δ(HCH)(CH3), (CH2)) of DDTC at 1273 cm(-1) was used as an internal standard, which was negligibly influenced by the absorption of ClO4(-). The DDTC-modified Ag/Cu fiber showed high uniformity, good reusability and temporal stability under continuous laser radiation each with an RSD lower than 10%. The qualitative and quantitative detection of perchlorate were also realized. A log-log plot of the normalized SERS intensity against perchlorate concentration showed a good linear relationship. The fiber could be also directly inserted into the perchlorate-polluted soil, and the perchlorate could thereby be detected on site. The detection limit in soil reached 0.081 ppm, which was much lower than the EPA-published safety standard. The recovery of the detection was 105% and comparable with the ion chromatography. This hyphenated method of microextraction with direct SERS detection may find potential application for direct pollutant detection free from complex sample pretreatment.

10.
Analyst ; 139(10): 2525-30, 2014 May 21.
Artigo em Inglês | MEDLINE | ID: mdl-24668444

RESUMO

A disordered silver nanowires membrane combining solid-phase extraction (SPE) with surface-enhanced Raman spectroscopy (SERS) was used for the rapid collection and detection of food contaminants. The membrane was fabricated via filtration of the silver nanowires colloid solution, which was prepared by a solvothermal polyol process. Analytes in 5 mL of liquid phase were concentrated in less than 10 s due to their affinity for the silver nanowires on the filter membrane. The membrane combined the advantages of SPE and SERS technology for the analysis of food safety contaminants. The use of the SERS-active extraction membrane eliminated the procedure of elution, which shortened the time of analysis. It has been shown that the as-prepared membrane had good uniformity and high temporal stability under continuous laser irradiation. Qualitative and quantitative detection of phorate and melamine was further performed based on a flow-through method. The characteristic SERS intensity plotted against phorate and melamine concentrations exhibited a good linear relationship over the concentration range of 2.5 to 10 µg mL(-1) (phorate) and 2.5 to 100 µg mL(-1) (melamine).


Assuntos
Nanofios , Prata/química , Análise Espectral Raman/instrumentação , Microscopia Eletrônica de Varredura , Propriedades de Superfície , Difração de Raios X
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA