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1.
Science ; 367(6482): 1151-1156, 2020 03 06.
Artigo em Inglês | MEDLINE | ID: mdl-32139547

RESUMO

The regulation of messenger RNA levels in mammalian cells can be achieved by the modulation of synthesis and degradation rates. Metabolic RNA-labeling experiments in bulk have quantified these rates using relatively homogeneous cell populations. However, to determine these rates during complex dynamical processes, for instance during cellular differentiation, single-cell resolution is required. Therefore, we developed a method that simultaneously quantifies metabolically labeled and preexisting unlabeled transcripts in thousands of individual cells. We determined synthesis and degradation rates during the cell cycle and during differentiation of intestinal stem cells, revealing major regulatory strategies. These strategies have distinct consequences for controlling the dynamic range and precision of gene expression. These findings advance our understanding of how individual cells in heterogeneous populations shape their gene expression dynamics.


Assuntos
Estabilidade de RNA , RNA Mensageiro/metabolismo , Análise de Sequência de RNA/métodos , Análise de Célula Única/métodos , Transcrição Genética , Animais , Humanos , Indicadores e Reagentes/química , Células K562 , Camundongos , Uridina/análogos & derivados
2.
Anal Bioanal Chem ; 412(2): 299-309, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31814048

RESUMO

Oligonucleotide drugs represent an emerging area in the pharmaceutical industry. Solid-phase synthesis generates many structurally closely related impurities, making efficient separation systems for purification and analysis a key challenge during pharmaceutical drug development. To increase the fundamental understanding of the important preparative separation step, mass-overloaded injections of a fully phosphorothioated 16mer, i.e., deoxythymidine oligonucleotide, were performed on a C18 and a phenyl column. The narrowest elution profiles were obtained using the phenyl column, and the 16mer could be collected with high purity and yield on both columns. The most likely contribution to the successful purification was the quantifiable displacement of the early-eluting shortmers on both columns. In addition, the phenyl column displayed better separation of later-eluting impurities, such as the 17mer impurity. The mass-overloaded injections resulted in classical Langmuirian elution profiles on all columns, provided the concentration of the ion-pairing reagent in the eluent was sufficiently high. Two additional column chemistries, C4 and C8, were also investigated in terms of their selectivity and elution profile characteristics for the separation of 5-20mers fully phosphorothioated deoxythymidine oligonucleotides. When using triethylamine as ion-pairing reagent to separate phosphorothioated oligonucleotides, we observed peak broadening caused by the partial separation of diastereomers, predominantly seen on the C4 and C18 columns. When using the ion-pair reagent tributylamine, to suppress diastereomer separation, the greatest selectivity was found using the phenyl column followed by C18. The present results will be useful when designing and optimizing efficient preparative separations of synthetic oligonucleotides.


Assuntos
Indicadores e Reagentes/química , Oligonucleotídeos Fosforotioatos/análise , Oligonucleotídeos Fosforotioatos/isolamento & purificação , Cromatografia Líquida de Alta Pressão/métodos , Cromatografia de Fase Reversa/métodos
3.
Chemistry ; 26(12): 2705-2712, 2020 Feb 26.
Artigo em Inglês | MEDLINE | ID: mdl-31851392

RESUMO

Trityl radicals (TAMs) have recently appeared as an alternative source of spin labels for measuring long distances in biological systems. Finland trityl radical (FTAM) served as the basis for this new generation of spin labels, but FTAM is rather lipophilic and susceptible to self-aggregation, noncovalent binding with lipophilic sites of proteins, and noncovalent docking at the termini of duplex DNA. In this paper the very hydrophilic OX063 TAM with very low toxicity and little tendency for aggregation is used as the basis for a spin label. Human serum albumin (HSA) labeled with OX063 has an intense narrow line typical of TAM radicals in solution, whereas HSA labeled with FTAM shows broad lines and extensive aggregation. In pulse EPR measurements, the measured phase memory time TM for HSA labeled with OX063 is 6.3 µs at 50 K, the longest yet obtained with a TAM-based spin label. The lowered lipophilicity also decreases side products in the labeling reaction.


Assuntos
Indicadores e Reagentes/química , Mesilatos/química , Albumina Sérica Humana/química , Compostos de Sulfidrila/química , Espectroscopia de Ressonância de Spin Eletrônica , Interações Hidrofóbicas e Hidrofílicas , Estrutura Molecular , Marcadores de Spin , Relação Estrutura-Atividade , Temperatura Ambiente
4.
Chem Commun (Camb) ; 56(5): 723-726, 2020 Jan 16.
Artigo em Inglês | MEDLINE | ID: mdl-31840690

RESUMO

A new prosthetic group is reported for 18F-labelling of peptides and proteins based on the chemoselective ligation of potassium acyltrifluoroborates (KATs) and hydroxylamines without any detectable 18F/19F isotope exchange at the acyltrifluoroborate moiety. The new building block is appended via a common amide bond at room temperature with no need for protecting groups which enables an effective orthogonal 18F-radiolabelling.


Assuntos
Boratos/química , Radioisótopos de Flúor/química , Marcação por Isótopo/métodos , Peptídeos/química , Proteínas/química , Piridinas/química , Animais , Indicadores e Reagentes/química , Masculino , Camundongos Endogâmicos C57BL , Peptídeos/metabolismo , Tomografia por Emissão de Pósitrons/métodos , Proteínas/metabolismo , Compostos Radiofarmacêuticos/química , Temperatura Ambiente
5.
Talanta ; 206: 120219, 2020 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-31514888

RESUMO

A new method to determine the total titratable acidity of orange, lemon and passion fruit, based on a spot test obtained from digital images and using anthocyanins as the biodegradable indicator, is presented for the first time. The colorimetric reactions were carried out by acid-base titration on a microscale, employing anthocyanin with a microplate for spot test purposes, with detection by digital imaging. To obtain highly precise data, a chamber based on a diffuser was developed to control the illumination supplied by the light emitting diodes, and coupled to a smartphone to acquire adequate digital images. High precision was obtained with a relative standard deviation of 0.758% for n = 95. The RGB values were extracted from the digital images and used as analytical signals, the values being correlated with the micro-volume of the titrant and used to construct the titration curves and obtain the first and second derivatives, respectively. For comparative purposes, the official AOAC (Association of Official Analytical Chemists) and MAPA (Ministry of Agriculture, Livestock and Food Supply of Brazil) methods were used and the results compared by applying the paired t-test at the 95% confidence level (n = 3). No difference was found between the values and the relative errors were less than 2.8%. The micro-titrimetric method was fast, uses anthocyanins as the natural indicator, is practical, and permits a reduction of 922 times or 99.9% of the volume required in a conventional titration. It is therefore ideal for routine analyses leading to a reduction in the waste generated, according to the principles of green chemistry.


Assuntos
Citrus sinensis/química , Frutas/química , Passiflora/química , Antocianinas/química , Colorimetria/instrumentação , Colorimetria/métodos , Química Verde/métodos , Concentração de Íons de Hidrogênio , Indicadores e Reagentes/química , Phaseolus/química , Smartphone , Titulometria/instrumentação , Titulometria/métodos
6.
Org Biomol Chem ; 17(47): 10097-10102, 2019 12 04.
Artigo em Inglês | MEDLINE | ID: mdl-31754683

RESUMO

New open-chain and water-soluble hypervalent iodine reagents were synthesized and used for the transfer of fluoroalkyl groups to sulfur atoms of cysteine and cysteine-containing peptides under biocompatible conditions. Some of the reagents displayed excellent reactivity despite their limited stability in aqueous media. In reactions with a short cysteine-containing peptide, in addition to the expected S-fluoroalkylated product, a range of side-products were obtained. The amount of side-products depended on the conditions used (type of reagent, concentration, and pH). With highly activated hypervalent iodine reagents, a new reactive mode was observed - reaction with disulfides to form fluoroalkyl thiols.


Assuntos
Hidrocarbonetos Fluorados/química , Hidrocarbonetos Fluorados/síntese química , Indicadores e Reagentes/química , Indicadores e Reagentes/síntese química , Iodo/química , Compostos de Sulfidrila/química , Água/química , Alquilação , Estrutura Molecular , Solubilidade
7.
Curr Protoc Nucleic Acid Chem ; 79(1): e100, 2019 12.
Artigo em Inglês | MEDLINE | ID: mdl-31756051

RESUMO

This article describes a simple, reliable, efficient, and general method for the synthesis of 7-methylguanosine nucleotides such as 7-methylguanosine 5'-O-monophosphate (m7 GMP), 7-methylguanosine 5'-O-diphosphate (m7 GDP), 7-methyl-2'-deoxyguanosine 5'-O-triphosphate (m7 2'dGTP), and 7-methylguanosine 5'-O-triphosphate (m7 GTP) starting from the corresponding guanosine nucleotide is described. The present protocol involves methylation reaction of guanosine nucleotide using dimethyl sulfate as a methylating agent and water as a solvent at room temperature to provide the corresponding 7-methylguanosine nucleotide in good yields with high purity (>99.5%). It is noteworthy that the present methylation reaction proceeds smoothly under aqueous conditions that is highly regioselective to afford exclusive 7-methylguanosine nucleotide. © 2019 by John Wiley & Sons, Inc. Basic Protocol: Synthesis of 7-methylguanosine nucleotides.


Assuntos
Guanosina Difosfato/análogos & derivados , Análogos de Capuz de RNA/síntese química , Guanosina Difosfato/síntese química , Guanosina Difosfato/química , Indicadores e Reagentes/química , Metilação , Análogos de Capuz de RNA/química , Solventes/química , Ésteres do Ácido Sulfúrico/química
8.
Anal Chim Acta ; 1079: 139-145, 2019 Nov 04.
Artigo em Inglês | MEDLINE | ID: mdl-31387704

RESUMO

A short G-rich sequence with three G-tracts can form a G-triplex (G3), a recently identified noncanonical DNA structure. Until now, very limited functional study and application of G3 is reported. Herein, we integrated G3 with isothermal exponential amplification reaction (EXPAR) for achieving simple and sensitive biosensing strategy. In this strategy, the cascade EXPAR cycles produces larger numbers of short G-rich sequences, which self-assemble into G3 structure and then bind hemin to form G3/hemin DNAzyme. This G3/hemin DNAzyme-based EXPAR strategy could detect as low as 4.7 fM target DNA with colorimetric detection, and the sensitivity of G3/hemin DNAzyme-based EXPAR strategy was much higher than that of the conventional G-quadruplex/hemin DNAzyme-based EXPAR strategy. We explored the reason for higher sensitivity of G3/hemin DNAzyme-based EXPAR strategy. The experimental results demonstrated that G3/hemin DNAzyme is an ideal signal generator for EXPAR-based biosensing platform. This work opens a new avenue to develop effective signal amplification strategy for ultrasensitive biosensing. This work is also helpful for a deeper understanding of G3 structure and the future application of G3.


Assuntos
Técnicas Biossensoriais/métodos , Colorimetria/métodos , DNA Catalítico/química , DNA Viral/análise , DNA/química , Hemina/química , Pareamento Incorreto de Bases , Benzotiazóis/química , DNA/genética , DNA Catalítico/genética , DNA Viral/genética , HIV/genética , Peróxido de Hidrogênio/química , Indicadores e Reagentes/química , Limite de Detecção , Técnicas de Amplificação de Ácido Nucleico/métodos , Conformação de Ácido Nucleico , Hibridização de Ácido Nucleico , Ácidos Sulfônicos/química
9.
Talanta ; 205: 120146, 2019 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-31450401

RESUMO

We developed a highly sensitive and accurate differential method for analyzing chiral and achiral carboxylic acids in Japanese commercial beers, using ultra high-performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UHPLC-Q-TOF-MS), based on chiral derivatization combining three isotopic chiral reagents: 12C-DMT-3(S)-Apy, 13C2-DMT-3(S)-Apy, and d6-DMT-3(S)-Apy. By combining these reaction solutions and analyzing the resulting mixture, simultaneous comparative analyses of the three samples could be achieved while offsetting the matrix effects on the samples. Using this approach, it was possible to differentiate the beers according to the type (draft, low-malt, and non-alcoholic), manufacturer, and storage conditions (temperature and storage period), based on the concentrations of carboxylic acids in the beers. Furthermore, we identified α-ketoglutaric acid as a new marker for determining the storage condition of Japanese beers. The proposed method would provide insights into the identification of markers in various fields, such as in biological samples, as well as food and beverages.


Assuntos
Cerveja/análise , Ácidos Carboxílicos/análise , Cromatografia Líquida de Alta Pressão/métodos , Análise de Alimentos/métodos , Limite de Detecção , Espectrometria de Massas/métodos , Ácidos Carboxílicos/química , Temperatura Alta , Indicadores e Reagentes/química , Estereoisomerismo
10.
J Drugs Dermatol ; 18(8): 798-802, 2019 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-31424710

RESUMO

Cutaneous fungal infections account for millions of office visits per year, yet their varied presentations often lead to misdiagnosis. If dermatology clinics are Clinical Laboratory Improvement Amendment (CLIA) certified, direct microscopy with potassium hydroxide or other stains can be used to inexpensively and rapidly diagnose fungal infections. In this survey, we examined dermatologists' perceptions of fungal preparations and CLIA certification to identify barriers that prevent the use of these bedside diagnostics. The response rate was 13% (n=308, based on the number of emails opened). When a cutaneous fungal infection is suspected, 20.94% rarely/never and 19.86% sometimes perform fungal preparations, often because they think clinical diagnosis is adequate or that preparations take too long. 21.32% reported not having CLIA certification, most frequently because the process requires too much work, or they do not know how to apply. Of providers with CLIA certification, over 25% thought it was difficult to obtain. Our results demonstrate that numerous barriers prevent the common use of fungal preparations, including the perception that clinical diagnosis is sufficient and the lack of required CLIA certification. These barriers emphasize the need for additional education about cutaneous fungal infections and use of bedside diagnostics. Additionally, policy-based interventions are necessary to ease the process of CLIA certification.


Assuntos
Dermatomicoses/diagnóstico , Fungos/isolamento & purificação , Indicadores e Reagentes/química , Adulto , Idoso , Dermatologistas/estatística & dados numéricos , Dermatologia/métodos , Dermatologia/estatística & dados numéricos , Dermatomicoses/microbiologia , Dermatomicoses/patologia , Diagnóstico Diferencial , Feminino , Humanos , Hidróxidos/química , Masculino , Técnicas Microbiológicas/métodos , Técnicas Microbiológicas/estatística & dados numéricos , Microscopia , Pessoa de Meia-Idade , Visita a Consultório Médico/estatística & dados numéricos , Compostos de Potássio/química , Padrões de Prática Médica/estatística & dados numéricos , Pele/microbiologia , Pele/patologia , Inquéritos e Questionários/estatística & dados numéricos
12.
Bioanalysis ; 11(12): 1129-1138, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-31319683

RESUMO

The 12th GCC Closed Forum was held in Philadelphia, PA, USA, on 9 April 2018. Representatives from international bioanalytical Contract Research Organizations were in attendance in order to discuss scientific and regulatory issues specific to bioanalysis. The issues discussed at the meeting included: critical reagents; oligonucleotides; certificates of analysis; method transfer; high resolution mass spectrometry; flow cytometry; recent regulatory findings and case studies involving stability and nonclinical immunogenicity. Conclusions and consensus from discussions of these topics are included in this article.


Assuntos
Certificação , Técnicas de Química Analítica , Citometria de Fluxo , Espectrometria de Massas , Oligonucleotídeos/análise , Controle Social Formal , Sociedades Científicas , Indicadores e Reagentes/química
13.
J Pharm Biomed Anal ; 175: 112765, 2019 Oct 25.
Artigo em Inglês | MEDLINE | ID: mdl-31349211

RESUMO

The objective of present work was to develop rapid, sensitive, selective, accurate and precise RP-HPLC method for analysis of Efavirenz from combination anti-HIV drug (Efavirenz-Enfuvirtide) incorporated into polymer-lipid hybrid nanoparticles (PLN). Chromatographic separation of Efavirenz was performed on Waters Spherisorb® 5 µm ODS (C18) column (4.6 x 250 mm) with acetonitrile and 10 mM phosphate buffer pH 6.8 (70:30, v/v) as mobile phase. The UV detection wavelength was 246 nm. The method was found to be linear between the concentration range of 500-20000 ng/ml with 160 ng/ml and 480 ng/ml as limit of detection and limit of quantitation respectively. Heteroscedasticity of calibration curve responses was minimized using weighted least square regression analysis. The method was found to be specific for analysis of Efavirenz in presence of Enfuvirtide (a fusion inhibitor peptide), formulation excipients and release media, accurate (average recovery rate: 99.9 ±â€¯9.39%) and precise (%RSD < 2%). The validated RP-HPLC method could be effectively utilized to determine % entrapment efficiency (%EE), % drug loading (%DL), % cumulative drug release and drug content of Efavirenz from Efavirenz-Enfuvirtide co-loaded PLN.


Assuntos
Benzoxazinas/química , Enfuvirtida/química , Lipídeos/química , Nanopartículas/química , Polímeros/química , Calibragem , Cromatografia Líquida de Alta Pressão/métodos , Cromatografia de Fase Reversa/métodos , Excipientes/química , Indicadores e Reagentes/química , Limite de Detecção , Reprodutibilidade dos Testes
14.
Talanta ; 204: 415-423, 2019 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-31357314

RESUMO

A cyclic-organophosphate, specifically 2-chloro-5,5-dimethyl-1,3,2-dioxaphosphorinane-2-oxide, was used to derivatise the hydroxyl group at the C3 position of selected steroid hormones to analyse the derivatives using UPLC-MS/MS (ultra-performance liquid chromatography-tandem mass spectrometry). Reactions were performed in an anhydrous pyridine environment in the presence of AlCl3 at 50 °C. The developed reaction is suitable for analytical chemistry applications and was validated by analysis of selected contraceptive drugs. The sensitivity of the method depends on hormone tested and the limit of detection ranges from 130 pg/mL for ß-estradiol to 240 pg/mL for estriol. The estimated efficiency of derivatisation reactions varies in the range from 77.5 to 95.7%, and depends upon the hormone undergoing derivatisation. The method's recovery rate for the lowest concentration tested (800 pg/mL) is 88.1-96.3%. The method exhibits linearity in the 390 pg/mL to 2.5 µg/mL range, with R2 = 0.997. The developed steroid hormone derivatisation reaction was validated experimentally using UHPLC-QTOF-MS (ultra-high performance liquid chromatography quadrupole time of flight mass spectrometry) and NMR (nuclear magnetic resonance) spectroscopy. These studies show that the developed derivatisation reaction provides a precise and repeatable determination of selected steroid hormones in contraceptive drugs. At n = 10, CV (Coefficient of Variation) did not exceed 7%, which is a very good result compared with other analytical methods.


Assuntos
Congêneres do Estradiol/análise , Indicadores e Reagentes/química , Organofosfatos/química , Esteroides/análise , Cromatografia Líquida de Alta Pressão/métodos , Congêneres do Estradiol/química , Limite de Detecção , Fosforilação , Esteroides/química , Espectrometria de Massas em Tandem/métodos
15.
Talanta ; 204: 833-839, 2019 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-31357372

RESUMO

The peroxidase-like activity of ficin is relatively low, which limits its application. It was found that thiol groups of ficin could inhibit its peroxidase-like activity. So, two procedures, i.e., direct blocking with N-ethylmaleimide (NEM), or using tris (2-carboxyethyl) phosphine hydrochloride (TCEP) to interrupt disulfide bonds then blocking thiol groups with NEM, were applied to block thiol groups of ficin, ficin-NEM (ficin-N) and ficin-TCEP-NEM (ficin-TN) were produced, respectively. The blocking of thiol groups accelerated the peroxidase activity dramatically. The peroxidase catalytic activity of ficin-N and ficin-TN toward the peroxidase substrate 3,3',5,5'-tetramethylbenzidine (TMB) oxidation by H2O2 was about 2.5-fold and 5-fold increase compared with ficin, respectively, which accompanied a color change from colorless to blue and followed classic Michaelis-Menten model. The kinetic parameters indicated that higher affinity of ficin-N (Km = 0.31) and ficin-TN (Km = 0.39) to H2O2 compared with ficin (Km = 0.58), and ficin-TN had the highest Kcat which increased by 6.5 times and 4.5 times for TMB and H2O2, respectively. According to these findings, a colorimetric method with high sensitivity for the detection of biothiols was developed due to sulfhydryl compounds inhibited the peroxidase activity of ficin. Comparing with ficin and ficin-N, ficin-TN had the widest detection range (0.01-16 µM) and the lowest detection limit (3 nM). The practical applications of ficin-TN for biothiol determination in human serum samples have been demonstrated with satisfactory results. Ficin-N and ficin-TN are promising to apply to the bioanalysis.


Assuntos
Cisteína/sangue , Ficina/química , Glutationa/sangue , Homocisteína/sangue , Peroxidases/química , Benzidinas/química , Compostos Cromogênicos/química , Colorimetria/métodos , Etilmaleimida/química , Humanos , Peróxido de Hidrogênio/química , Indicadores e Reagentes/química , Cinética , Limite de Detecção , Fosfinas/química
16.
J Pharm Biomed Anal ; 175: 112787, 2019 Oct 25.
Artigo em Inglês | MEDLINE | ID: mdl-31362247

RESUMO

Cordyceps sinensis is a traditional Chinese food. A high-throughput screening and quantitative method based on hydrophilic interaction chromatography coupled to quadrupole/Orbitrap high resolution mass spectrometry has been proposed for the joint measurement of nucleosides and their corresponding nucleotides in thirty-two Cordyceps sinensis samples. A total of thirty-two natural samples from six regions were enrolled. A multiple-step analysis strategy, including features extraction, noise level evaluation, mass shift correction and suspect spectral library spectra searching, was employed to discover, identify and validate the nucleosides and nucleotides. The remaining unknown compounds were identified with the characteristic structural fragments. The on-line dispersive solid-phase extraction system eliminates human-based steps errors and affords superior method reproducibility in the presence of hexafluoro-2-propanol and diethylamine as hydrophilic ion-pairing reagents. In view of the great difference of the quality, this high coverage confirmation strategy is of great reference value to the future quantitative analysis of potential nucleosides and nucleotides. Nucleosides and nucleotides ingredients could be considered as origins and quality assessment index of C. sinensis.


Assuntos
Nucleosídeos/química , Nucleotídeos/química , Cromatografia Líquida de Alta Pressão/métodos , Cordyceps/química , Ensaios de Triagem em Larga Escala/métodos , Interações Hidrofóbicas e Hidrofílicas , Indicadores e Reagentes/química , Limite de Detecção , Propanóis/química , Reprodutibilidade dos Testes , Extração em Fase Sólida/métodos , Espectrometria de Massas em Tandem/métodos
17.
Carbohydr Polym ; 222: 115006, 2019 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-31320067

RESUMO

A novel intelligent film was developed by immobilizing 1%, 3% and 5% black rice bran anthocyanins (BACNs) into oxidized-chitin nanocrystals (O-ChNCs)/ chitosan (CS) matrix. The ultraviolet-visible spectrum of BACNs solutions showed color variations from red to greyish green in a range of pH 2.0-12.0. Fourier transform infrared spectrum and atomic force microscope of the films showed that O-ChNC and BACNs were well dispersed into the CS matrix. Although the incorporation of BACNs decreased the mechanical and barrier properties of the CS/O-ChNCs/BACNs (COB) films, it endowed the COB films with excellent UV-barrier, antioxidant and pH sensitivity character. The results of the application trial showed that the COB films containing 3% of BACNs (COB-3) were able to monitor the spoiling of fish and shrimp by visible color changes. Therefore, the developed COB-3 films could be used as an intelligent food packaging for monitoring animal-based protein food spoilage.


Assuntos
Antocianinas/química , Quitina/química , Quitosana/química , Indicadores e Reagentes/química , Nanopartículas/química , Alimentos Marinhos , Animais , Antocianinas/isolamento & purificação , Antioxidantes/química , Cor , Peixes , Embalagem de Alimentos/métodos , Conservação de Alimentos/métodos , Armazenamento de Alimentos/métodos , Concentração de Íons de Hidrogênio , Membranas Artificiais , Oryza/química , Penaeidae , Resistência à Tração
18.
Carbohydr Polym ; 222: 115030, 2019 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-31320095

RESUMO

A novel intelligent pH-sensing indicator based on bacterial nanocellulose (BC) and black carrot anthocyanins (CA) was developed and characterized to monitor the freshness/spoilage of rainbow trout and common carp fillet during the storage at 4 °C. The indicator displayed wide color differences from red to gray over the 2-11 pH range, which was clearly discerned by the naked eye. The fabricated pH-sensing indicator showed distinguishable color changes during fresh (deep carmine color), best to eat (charm pink color), and spoiled (jelly bean blue and khaki colors) stages of both fish fillets. Moreover, a strong and positive correlation was obtained between the total color differences values of the indicator and bacterial count (R = 0.952 and 0.991) and total volatile basic nitrogen (R = 0.815 and 0.92) in rainbow trout and common carp samples. The results of this work demonstrated a significant correspondence of fish shelf life and color changes of a nanocellulose-based pH-sensing indicator.


Assuntos
Antocianinas/química , Celulose/química , Daucus carota/química , Indicadores e Reagentes/química , Nanofibras/química , Alimentos Marinhos , Acetobacteraceae/química , Animais , Carpas/microbiologia , Microbiologia de Alimentos , Embalagem de Alimentos/métodos , Conservação de Alimentos/métodos , Armazenamento de Alimentos/métodos , Concentração de Íons de Hidrogênio , Membranas Artificiais , Oncorhynchus mykiss/microbiologia
19.
Molecules ; 24(12)2019 Jun 21.
Artigo em Inglês | MEDLINE | ID: mdl-31234296

RESUMO

A cross-coupling reaction of allylic aryl ethers with arylmagnesium reagents was investigated using ß-aminoketonato- and ß-diketiminato-based pincer-type nickel(II) complexes as catalysts. An ß-aminoketonato nickel(II) complex bearing a diphenylphosphino group as a third donor effectively catalyzed the reaction to afford the target cross-coupled products, allylbenzene derivatives, in high yield. The regioselective reaction of a variety of substituted cinnamyl ethers proceeded to give the corresponding linear products. In contrast, α- and γ-alkyl substituted allylic ethers afforded a mixture of the linear and branched products. These results indicated that the coupling reaction proceeded via a π-allyl nickel intermediate.


Assuntos
Catálise , Éteres/química , Magnésio/química , Indicadores e Reagentes/química , Estrutura Molecular , Níquel/química , Estereoisomerismo
20.
Anal Chim Acta ; 1076: 55-63, 2019 Oct 17.
Artigo em Inglês | MEDLINE | ID: mdl-31203964

RESUMO

In this work, an implantable and minimally invasive micro-aptasensor for adenosine monitoring in vivo, based on flexible integrated electrodes, was developed. Firstly the sensor was made by the modification of a needle-type electrode with reduced graphene oxide and gold nanoclusters (rGO-AuNCs) using two-step electrodeposition. Secondly Sulfhydryl-terminated capture probe (ssDNA1) was immobilized on rGO-AuNCs modified electrode surface by self-assembly, and then it was hybridized with adenosine aptamer (ssDNA2). Lastly methylene blue (MB) as an electrochemical indicator was adsorbed on the aptamer through specific interaction of MB with guanine base. The peak current of MB decreased linearly with increasing adenosine concentration due to the formation of aptamer-adenosine complex and displacement of the aptamer from the modified electrode surface. The sensor showed a low detection limit of 0.1 nM with signal-to-noise ratio equal to 3 as well as a wide linear response range (0.1 nM-1 mM) in vitro. Also, a high selectivity was demonstrated for adenosine in relation to uridine, guanosine, and cytidine. Experiments in vivo demonstrated fast responses for a range of adenosine concentrations. This work demonstrates a promising path for implantable devices for the determination of biomolecules in vivo, thus allowing for health tests, detection of infectious diseases, and other medical conditions.


Assuntos
Adenosina/análise , Aptâmeros de Nucleotídeos/química , DNA/química , Animais , Aptâmeros de Nucleotídeos/genética , Técnicas Biossensoriais/instrumentação , Técnicas Biossensoriais/métodos , DNA/genética , Sondas de DNA/química , Sondas de DNA/genética , Técnicas Eletroquímicas/instrumentação , Técnicas Eletroquímicas/métodos , Eletrodos , Ouro/química , Grafite/química , Indicadores e Reagentes/química , Limite de Detecção , Masculino , Nanopartículas Metálicas/química , Azul de Metileno/química , Hibridização de Ácido Nucleico , Ratos Wistar
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