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1.
Artigo em Chinês | MEDLINE | ID: mdl-31495121

RESUMO

Objective: To establish a method for determination of lead and istope ratios in the blood by ISIS-ICP-MS. Methods: After wet digestion, the blood sample was on-line addition of thallium as internal standard and analyzed by ISIS-ICP-MS. Results: The limit of detection was 0.03 µg/L and the lower limit of quantification was 0.08 µg/L. The detection concentration was 0.45 µg/L and the minimum quantitative concentration was 1.49 µg/L. The relative standard deviations (RSD) were 0.3%~1.7%. The recovery was between 91.0% and 103.4%. The precision of the major lead isotope ratios was better than 0.3%. The calibrated isotope ratios of the standard liquid are close to the certificate. Conclusion: The method has a low detection limit, good precision and high accuracy, it is feasible for determination of lead concentration and isotope ratios in the bloune.


Assuntos
Chumbo/sangue , Espectrometria de Massas , Humanos , Isótopos/sangue , Limite de Detecção , Análise Espectral
2.
Fa Yi Xue Za Zhi ; 35(4): 419-422, 2019 Aug.
Artigo em Inglês, Chinês | MEDLINE | ID: mdl-31532149

RESUMO

Abstract: Objective To develop a high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method for the determination of the content of 4-fluoromethamphetamine (4-FMA) in rat plasma, and to provide a methodological basis for the study of the toxicokinetics of 4-FMA in rats. Methods Rat plasma samples were added into internal standard methamphetamine (MA). Its proteins were precipitated with methanol and then separated with Poroshell 120 EC-C18 chromatographic column. A 0.1% formic acid aqueous solution and a 0.1% formic acid acetonitrile solution were used as the mobile phase at the flow rate of 0.4 mL/min. Electrospray ionization source was used for detection in the multiple reaction monitoring (MRM) mode. Results The linear relationship was good when the mass concentration of 4-FMA in plasma samples was in the range of 5-1 000 ng/mL (r>0.999). The limit of detection (LOD) was 3 ng/mL and the limit of quantification (LOQ) was 5 ng/mL. The accuracy was expressed as relative error (RE), and in the range of ±5%, the intra-day precision and inter-day precision (relative standard deviation, RSD) less than 9%, and the extraction recovery rate was more than 90%. The analysis and detection of plasma samples were completed within 2.5 min. Conclusion This study developed a HPLC-MS/MS method for the determination of 4-FMA in rat plasma samples. This method is accurate, rapid, simple and sensitive and can be applied to the study of toxicokinetics of 4-FMA.


Assuntos
Cromatografia Líquida de Alta Pressão , Metanfetamina/sangue , Espectrometria de Massas em Tandem , Animais , Limite de Detecção , Metanfetamina/análogos & derivados , Ratos , Reprodutibilidade dos Testes , Toxicocinética
3.
J Agric Food Chem ; 67(38): 10800-10812, 2019 Sep 25.
Artigo em Inglês | MEDLINE | ID: mdl-31490681

RESUMO

In this work, a highly efficient pesticide residue screening and quantification method was established using ultrahigh-performance liquid chromatography-tandem quadrupole time-of-flight mass spectrometry based on in-source fragmentation. Over 400 pesticides were tested, among which 96 pesticides displayed in-source fragmentation. A novel concept of in-source fragment fraction was proposed to evaluate the extent of in-source fragmentation, which was found to be chemical structure- and source parameter-dependent. A high-resolution MS/MS library containing 403 pesticides and 126 fragments was created and was applied for library searching of pesticide residues in vegetables and fruits. The introduction of in-source fragments effectively circumvented misannotation and occurrence of false negatives. The quantification ability for the fragments was validated in terms of recovery, linearity, and limit of quantification and its superiority to the parent pesticides was established. Finally, the proposed method was applied for the analysis of real samples and proficiency test samples, and false negative results were successfully avoided in the analysis.


Assuntos
Cromatografia Líquida de Alta Pressão/métodos , Frutas/química , Resíduos de Praguicidas/química , Espectrometria de Massas em Tandem/métodos , Verduras/química , Contaminação de Alimentos/análise , Limite de Detecção
4.
J Agric Food Chem ; 67(38): 10791-10799, 2019 Sep 25.
Artigo em Inglês | MEDLINE | ID: mdl-31497956

RESUMO

Very weak signals of fragment ions of nosiheptide could be observed using liquid chromatography-tandem mass spectrometry. The preparation of 4-hydroxymethyl-3-methyl-1H-indole-2-carboxylic acid (HMIA), a specific fragment of nosiheptide, by alkaline hydrolysis is described. HMIA showed a good mass spectrometric signal in negative electrospray ionization mode. In the new method, the nosiheptide residue in muscle tissue was hydrolyzed with sodium hydroxide aqueous solution; this was followed by cleanup using mixed mode cartridges. Identification and quantification of nosiheptide were carried out by analyzing HMIA in hydrolysate of muscles. Nosiheptide showed a good linear relationship (r > 0.996) in the calibration range of 2-500 µg/kg, and a low limit of quantification of 2 µg/kg was obtained in swine, chicken, and fish muscles. Recoveries of nosiheptide from spiked muscle samples were 85-108% with relative standard deviations less than 10%. The proposed method was successfully applied for the detection of the nosiheptide residue in medicated animal tissues samples.


Assuntos
Antibacterianos/química , Cromatografia Líquida de Alta Pressão/métodos , Resíduos de Drogas/química , Contaminação de Alimentos/análise , Carne/análise , Espectrometria de Massas em Tandem/métodos , Álcalis/química , Animais , Galinhas , Peixes , Hidrólise , Limite de Detecção , Músculos/química , Suínos , Tiazóis/química
5.
Chem Commun (Camb) ; 55(66): 9857-9860, 2019 Aug 25.
Artigo em Inglês | MEDLINE | ID: mdl-31364637

RESUMO

A novel fluorescent sensing platform for telomerase activity assay was developed by coupling a three-dimensional (3D) DNA walker with the MnO2 nanosheet-upconversion nanoparticle (UCNPs) complex-based fluorescence resonance energy-transfer (FRET) system.


Assuntos
Técnicas Biossensoriais/métodos , DNA/química , Transferência Ressonante de Energia de Fluorescência/instrumentação , Compostos de Manganês/química , Nanoestruturas/química , Óxidos/química , Telomerase/metabolismo , Limite de Detecção
7.
Chem Commun (Camb) ; 55(67): 10019-10022, 2019 Aug 28.
Artigo em Inglês | MEDLINE | ID: mdl-31378803

RESUMO

We report a facile hydrothermal method to synthesize a novel mesoporous graphitic carbon nitride (MCN)@NiCo2O4 nanocomposite, which can be used as a solid phase microextraction coating for high efficiency extraction and preconcentration of trace polychlorinated biphenyls and polycyclic aromatic hydrocarbons in human serum samples.


Assuntos
Poluentes Ambientais/sangue , Nanocompostos/química , Nitrilos/química , Bifenilos Policlorados/sangue , Hidrocarbonetos Policíclicos Aromáticos/sangue , Cobalto/química , Humanos , Limite de Detecção , Níquel/química , Microextração em Fase Sólida/instrumentação , Microextração em Fase Sólida/métodos
8.
Chem Commun (Camb) ; 55(69): 10312-10315, 2019 Aug 22.
Artigo em Inglês | MEDLINE | ID: mdl-31397446

RESUMO

Herein, we report a novel magnet-mediated antibody-boronate sandwich-typed assay (ABSTA) strategy for the ultrasensitive, specific, rapid, and enzyme-free detection of glycoproteins in complex samples. The proposed ABSTA method exhibited ultrahigh sensitivity for HCG with a detection limit of 0.19 mIU mL-1, which is approximately 40-fold lower than that of conventional sandwich enzyme immunoassay.


Assuntos
Anticorpos Imobilizados/química , Ácidos Borônicos/química , Gonadotropina Coriônica/sangue , Corantes Fluorescentes/química , Imãs/química , Anticorpos Monoclonais/química , Gonadotropina Coriônica/análise , Fluorescência , Humanos , Imunoensaio/métodos , Limite de Detecção
10.
J Cosmet Sci ; 70(4): 167-180, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31441771

RESUMO

A worldwide outbreak of skin cancer, related to ultraviolet (UV) radiations, was reported. Therefore, primary prevention programs were initiated. Application of sunscreens is one of the most efficient ways of protection; however, their efficiency and safety have remained a challenging issue. So, it seems necessary to consider the potential side effects for limiting the use and amount of sunscreens. In this study, an high performance liquid chromatography (HPLC) system equipped with a UV-visible detector has been used. For separation, an Agilent C18 column was used (Agilent Technologies, Santa Clara, CA). This method was applied for quantitative determination of nine UV filters in commercial sunscreen products which were widely used in Iran. Fifty samples of Iranian and imported sunscreen products were analyzed. The detection limit was determined to be 0.439-1.481 µg/ml, and the quantization limit was determined to be 1.330-4.490 µg/ml. Also, in this study, chemometric methods were used to investigate the differences between Iranian and other countries' sunscreen brands. It was observed that despite the amount of UV filters in Iranian sunscreens, which was in the allowed range, there were some differences between Iranian and other countries' sunscreens. The proposed HPLC method allows efficient and simultaneous analysis of UV filters and is suitable as a quality control assay for commercial sunscreen products.


Assuntos
Protetores Solares/química , Raios Ultravioleta , Cromatografia Líquida de Alta Pressão , Irã (Geográfico) , Limite de Detecção
11.
Vet Parasitol ; 273: 17-23, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31442888

RESUMO

The protozoan parasite Tritrichomonas foetus may cause severe diarrhea in cats all over the world. In order to evaluate the methodology in coprological molecular diagnosis of feline tritrichomonosis, we compared previously published ("old") and newly developed ("novel") loop-mediated isothermal amplification (LAMP) (targeted to the T. foetus ß-tubulin and the elf1α 1 gene, respectively) as well as an old conventional and an old and novel real-time PCR (all targeted to overlapping regions of T. foetus rDNA) assays regarding their diagnostic sensitivities and specificities. Here, the novel real-time PCR yielded the best methodical performance in that a sensitivity with a detection limit of <0.1 trophozoites (corresponding to ca.<0.13 trophozoites per mg feces) and a maximal specificity for diagnosis of Tritrichomonas spp. was achieved. The other test systems exhibited either an approximately 10-times lower sensitivity (<1 trophozoite corresponding to ca.<1.3 trophozoites per mg feces) (conventional PCR and both LAMP assays) or a lower specificity (old real-time PCR). Conversely, the diagnostic performance assessed with clinical fecal samples from cats demonstrated identical sensitivities (8 of 20 samples tested were positive) for the novel PCR and both LAMP assays. Diagnostic sensitivities were significantly higher than those found for the old real-time (5 positive samples) and conventional PCR (6 positive samples), respectively. Accordingly, our data suggested the novel PCR and both LAMP assays to be well suited molecular tools for direct (i.e. without including an in vitro cultivation step) coprological diagnosis of tritrichomonosis in cats. Interestingly, relative high (novel LAMP, 7 positive samples) to at least moderate (old LAMP, 6 positive samples and 1 sample with equivocal score) diagnostic sensitivities were also achieved by testing clinical samples upon simple visual inspection of colorimetric changes during the LAMP amplification reactions. Accordingly, both LAMP assays may serve as practical molecular tools to perform epidemiological studies on feline (and bovine as well as porcine) tritrichomonosis under simple laboratory conditions.


Assuntos
Doenças do Gato/diagnóstico , Técnicas de Amplificação de Ácido Nucleico/veterinária , Reação em Cadeia da Polimerase/veterinária , Infecções Protozoárias em Animais/diagnóstico , Tritrichomonas foetus , Animais , Doenças do Gato/parasitologia , Gatos , Fezes/parasitologia , Limite de Detecção , Técnicas de Amplificação de Ácido Nucleico/normas , Reação em Cadeia da Polimerase/normas , Sensibilidade e Especificidade
12.
J Enzyme Inhib Med Chem ; 34(1): 1474-1480, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31414611

RESUMO

The discovery of allosteric modulators is a multi-disciplinary approach, which is time- and cost-intensive. High-throughput screening combined with novel computational tools can reduce these factors. Thus, we developed an enzyme activity assay, which can be included in the drug discovery work-flow subsequent to the in-silico library screening. While the in-silico screening yields in the identification of potential allosteric modulators, the developed in-vitro assay allows for the characterisation of them. Candida rugosa lipase (CRL), a glyceride hydrolysing enzyme, has been selected for the pilot development. The assay conditions were adjusted to CRL's properties including pH, temperature and substrate specificity for two different substrates. The optimised assay conditions were validated and were used to characterise Tropolone, which was identified as an allosteric modulator. In conclusion, the assay is a reliable, reproducible, and robust tool, which can be streamlined with in-silico screening and incorporated in an automated high-throughput screening workflow.


Assuntos
Lipase/metabolismo , Miniaturização , Regulação Alostérica , Candida/enzimologia , Cristalografia por Raios X , Estabilidade Enzimática , Ensaios de Triagem em Larga Escala , Concentração de Íons de Hidrogênio , Técnicas In Vitro , Cinética , Limite de Detecção , Lipase/química , Reprodutibilidade dos Testes , Especificidade por Substrato , Temperatura Ambiente
13.
Chem Commun (Camb) ; 55(71): 10603-10606, 2019 Aug 29.
Artigo em Inglês | MEDLINE | ID: mdl-31424058

RESUMO

A truly ratiometric homogeneous electrochemical biosensor has been developed for sensitive miRNA detection based on the unique diffusion/intercalation properties of electroactive dyes without the need for electrode modification or materials preparation.


Assuntos
Técnicas Biossensoriais/métodos , Corantes/química , Técnicas Eletroquímicas/métodos , Substâncias Intercalantes/química , MicroRNAs/análise , DNA/química , Eletrodos , Exodesoxirribonucleases/química , Compostos Ferrosos/química , Limite de Detecção , Metalocenos/química , Azul de Metileno/química , Oxirredução
14.
Chem Commun (Camb) ; 55(71): 10615-10618, 2019 Aug 29.
Artigo em Inglês | MEDLINE | ID: mdl-31428753

RESUMO

A programmable molecular beacon (MB) with a good discrimination capability for mature and precursor microRNAs was loaded onto the surface of Mo2C quantum dots (QDs) for accurate detection of intracellular mature microRNAs.


Assuntos
Corantes Fluorescentes/química , MicroRNAs/análise , Molibdênio/química , Pontos Quânticos/química , Animais , Técnicas Biossensoriais/métodos , Linhagem Celular Tumoral , Humanos , Limite de Detecção , Camundongos , Imagem Óptica/métodos , Precursores de RNA/análise , Propriedades de Superfície
15.
Phys Chem Chem Phys ; 21(35): 19083-19091, 2019 Sep 21.
Artigo em Inglês | MEDLINE | ID: mdl-31432839

RESUMO

The development of new techniques or instruments for detecting and accurately measuring biomarker concentrations in living organisms is essential for early diagnosis of diseases, and for tracking the effectiveness of treatments. In chronic diseases, such as asthma, precise phenotyping can help predict the response of patients to treatments and reduce the risk of complications. Fractional exhaled nitric oxide (FeNO) is a positive biomarker for eosinophilic asthma in humans, and it can be directly detected in the respiratory tract, at very low and volatile concentrations, which makes real-time measurement a challenge. This work describes the first-principles design and characterization of a molecular- and back-gated electronic field-effect transistor device for the detection and measurement of ultra-low FeNO concentrations (pM-nM) from a person' s exhaled breath, as a cost-efficient alternative to the slower and more expensive techniques based on off-line sputum characterization via mass spectrometry. The proposed device uses a partially oxidized phosphorene semiconducting channel material for FeNO detection, allowing nM L-1 concentration measurements of this analyte in an array configuration with an effective sensing surface area of 8.775 µm2, which results in a predicted limit of detection (LOD) of 19 nM L-1. In spite of the limited stability of phosphorene in oxygen-rich and humid environments, the proposed device would be practical for mobile applications with disposable sensors.


Assuntos
Biomarcadores/análise , Testes Respiratórios/instrumentação , Testes Respiratórios/métodos , Óxido Nítrico/análise , Asma/diagnóstico , Expiração , Humanos , Limite de Detecção
16.
Phys Chem Chem Phys ; 21(35): 19288-19297, 2019 Sep 21.
Artigo em Inglês | MEDLINE | ID: mdl-31451821

RESUMO

This paper reports a facile, fast, and cost-effective method for the synthesis of three-dimensional (3D) porous AgNPs/Cu composites as SERS substrates for the super-sensitive and quantitative detection of food organic contaminations. Due to the 3D porous hotspot architecture and the strong plasmonic coupling between Ag and Cu, the porous AgNPs/Cu substrate achieves ultrasensitive detection of multiple analytes as low as 10-11 M (crystal violet, CV), 10-9 M (malachite green, MG), 10-11 M (acephate), and 10-9 M (thiram) even with a portable Raman device. Moreover, this 3D solid substrate has good signal uniformity (RSD < 11%) and superior stability (<14% signal loss), allowing for practical SERS detections. Importantly, by simply wiping the real sample surface using the substrate, it successfully detects CV and MG residues on crayfish, and the limit of detection (LOD) of CV and MG is determined to be 1.14 × 10-9 M and 0.94 × 10-7 M, respectively. Further, the substrate can also be applied to detect acephate on eggplant with a LOD of 1.41 × 10-9 M and thiram on an apple surface with a LOD of 1.04 × 10-7 M. Note that all these SERS detections on real samples have a broad dynamic concentration range and a good linear dependence. As a "proof of concept", multi-component detection on a real sample has also been demonstrated. This 3D solid substrate possesses excellent detection sensitivity, diversity, and accuracy, which allows rapid and reliable determination of toxic substances in foods.


Assuntos
Técnicas de Química Analítica/métodos , Análise de Alimentos/métodos , Contaminação de Alimentos/análise , Praguicidas/análise , Análise Espectral Raman , Animais , Técnicas de Química Analítica/economia , Cobre/química , Limite de Detecção , Nanopartículas Metálicas/química , Reprodutibilidade dos Testes , Prata/química
17.
Chem Commun (Camb) ; 55(70): 10380-10383, 2019 Aug 27.
Artigo em Inglês | MEDLINE | ID: mdl-31397448

RESUMO

A strategy for the photoelectrochemical detection of miRNA with ultra-low background noise was developed using tungsten diselenide-cysteine-dopamine (WSe2/Cys/DA) as a nanoprobe coupled with mismatched catalytic hairpin assembly target recycling. A superior detection limit of 3.3 aM toward miRNA-221 was achieved.


Assuntos
Cisteína/química , Dopamina/química , Técnicas Eletroquímicas/métodos , MicroRNAs/análise , Sondas Moleculares/química , Nanoestruturas , Processos Fotoquímicos , Selênio/química , Tungstênio/química , Técnicas Biossensoriais , Catálise , Humanos , Limite de Detecção , MicroRNAs/sangue , Estudo de Prova de Conceito
18.
Chem Commun (Camb) ; 55(70): 10404-10407, 2019 Aug 27.
Artigo em Inglês | MEDLINE | ID: mdl-31402361

RESUMO

We established an efficient method for single-cell miRNA analysis by droplet microfluidics, which has high sensitivity of single molecule detection and high throughput. Single-cell analysis of multiple miRNAs in various cells shows that miRNA expression is closely related to cancer type. CTC analysis shows that the method is applicable for rare cell analysis.


Assuntos
Sequenciamento de Nucleotídeos em Larga Escala/métodos , MicroRNAs/genética , Neoplasias/genética , Análise de Célula Única , Linhagem Celular Tumoral , Fluorescência , Humanos , Limite de Detecção
19.
Chem Commun (Camb) ; 55(70): 10424-10427, 2019 Aug 27.
Artigo em Inglês | MEDLINE | ID: mdl-31407744

RESUMO

The development of sensitive and reliable fluorescent probes for the early diagnosis of Alzheimer's disease (AD) is highly challenging and plays an important role in achieving effective treatments. Herein, we designed and synthesized an indole-based fluorophore for TTR in human plasma, an important hallmark of AD pathogenesis. This robust and simple fluorescent method allows quantification of TTR in the complex biological matrix.


Assuntos
Doença de Alzheimer/diagnóstico , Corantes Fluorescentes/química , Pré-Albumina/metabolismo , Doença de Alzheimer/sangue , Peptídeos beta-Amiloides/metabolismo , Humanos , Limite de Detecção , Espectrometria de Fluorescência
20.
Chem Commun (Camb) ; 55(70): 10444-10447, 2019 Aug 27.
Artigo em Inglês | MEDLINE | ID: mdl-31410430

RESUMO

A new series of 2D catalytic materials whose inorganic surfaces are fully covered with pre-designed "promoter" groups are reported. One of them showed excellent biomimetic catalytic activity and provided the lowest detection limit to glucose among the reported 2D materials and their composite materials.


Assuntos
Biomimética , Calcogênios/química , Metais/química , Catálise , Limite de Detecção , Microscopia de Força Atômica , Microscopia Eletrônica de Transmissão , Espectroscopia Fotoeletrônica , Difração de Pó
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