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1.
Chem Commun (Camb) ; 55(61): 9015-9018, 2019 Aug 07.
Artigo em Inglês | MEDLINE | ID: mdl-31290867
2.
Anal Chim Acta ; 1078: 182-188, 2019 Oct 31.
Artigo em Inglês | MEDLINE | ID: mdl-31358218

RESUMO

Early detection of toxic proteases in food matrices plays a major role in preventing the occurrence of diseases as well as outbreaks. However, on-site detection of proteases, for instance, botulinum, anthrax and cholera in food matrices remains challenging due to their extremely low lethal dose levels. Here, we report a lateral flow assay (LFA) in a dipstick format for on-site visual detection of proteases in food matrices. The light chain of BoNT serotype A (BoNT/A LC) is used as a model system for validation of the proposed assay using magnetic beads conjugated to a synthetic peptide that provide a specific cleavage site for BoNT/A LC. Magnetic beads serve as both reporters for visual detection and as facilitators for sample clean-up, owing to the efficient magnetic separation protocol adopted. Digestion of the peptide substrate by BoNT/A LC for 5 h followed by the dipstick assay yields a reduction in color intensity of the test line on the dipstick compared to the control line obtained using an un-cleaved peptide substrate. Concentration dependent responses for the assay in carrot juice were obtained with a limit of detection (LOD) of 1 nM/2.5 nM (with/without amplification), also supported by RGB (ΔE) analysis, indicating the potential of the proposed methodology for on-site assaying of proteases in food matrices. Unlike typical affinity-based assays that yield a collective response for the active and inactive forms of the proteases, the proposed functional LFA targets only the active form, thereby enabling a more precise analysis for preventing potential false-positives. The proposed approach could be extended for detection of BoNT serotypes and other proteases in food matrices, upon utilizing appropriate substrates with specific cleavage sites.


Assuntos
Bioensaio/métodos , Toxinas Botulínicas Tipo A/análise , Sucos de Frutas e Vegetais/análise , Sequência de Aminoácidos , Anticorpos/imunologia , Toxinas Botulínicas Tipo A/química , Daucus carota/química , Limite de Detecção , Fenômenos Magnéticos , Peptídeos/química , Polietilenoglicóis/química , Estudo de Prova de Conceito , Estreptavidina/química
3.
Chem Commun (Camb) ; 55(58): 8386-8389, 2019 Jul 25.
Artigo em Inglês | MEDLINE | ID: mdl-31231732

RESUMO

A highly sensitive triple-amplification assay for the detection of microRNA (miRNA) let-7a is reported in this work. The assay relies on the formation of magnetic two-dimensional DNA/Fe3O4 nanosheet networks initiated by the target miRNA-associated hybridization chain reaction. The Fe3O4 nanosheets in the DNA/Fe3O4 networks display peroxidase-like catalytic activity towards a colorimetric reaction, thereby producing a highly sensitive signal for the quantification of let-7a. Under optimal conditions, the assay achieved a detection limit of 13 aM at a signal-to-noise ratio of 3 and a linear calibration plot between 0.05 fM and 12 nM. Successful attempts were made in the quantification of let-7a in serum samples.


Assuntos
Materiais Biomiméticos/química , DNA/química , Óxido Ferroso-Férrico/química , MicroRNAs/sangue , Humanos , Limite de Detecção , Fenômenos Magnéticos , Nanoestruturas/química , Técnicas de Amplificação de Ácido Nucleico/métodos , Hibridização de Ácido Nucleico , Peroxidase/química
4.
Nat Mater ; 18(7): 651, 2019 07.
Artigo em Inglês | MEDLINE | ID: mdl-31217559
5.
Eur Biophys J ; 48(6): 513-521, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31203416

RESUMO

Magnetotactic bacteria are microorganisms that present intracellular chains of magnetic nanoparticles, the magnetosome chain. A challenge in the study of magnetotactic bacteria is the measurement of the magnetic moment associated with the magnetosome chain. Several techniques have been used to estimate the average magnetic moment of a population of magnetotactic bacteria, and others permit the measurement of the magnetic moment of individual bacteria. The U-turn technique allows the measurement of the individual magnetic moment and other parameters associated with the movement and magnetotaxis, such as the velocity and the orientation angle of the trajectory relative to the applied magnetic field. The aim of the present paper is to use the U-turn technique in a population of uncultured magnetotactic cocci to measure the magnetic moment, the volume, orientation angle and velocity for the same individuals. Our results showed that the magnetic moment is distributed in a log-normal distribution, with a mean value of 8.2 × 10-15 Am2 and median of 5.4 × 10-15 Am2. An estimate of the average magnetic moment using the average value of the orientation cosine produces a value similar to the median of the distribution and to the average magnetic moment obtained using transmission electron microscopy. A strong positive correlation is observed between the magnetic moment and the volume. There is no correlation between the magnetic moment and the orientation cosine and between the magnetic moment and the velocity. Those null correlations can be explained by our current understanding of magnetotaxis.


Assuntos
Bactérias , Fenômenos Magnéticos , Movimento
6.
Soft Matter ; 15(27): 5412-5420, 2019 Jul 10.
Artigo em Inglês | MEDLINE | ID: mdl-31241639

RESUMO

Suspensions of magnetic nanoplatelets in isotropic solvents are very interesting examples of ferrofluids. It has been shown that above a certain concentration ΦNI such suspensions form a ferromagnetic nematic phase, which makes this system a unique example of a dipolar fluid. The formation of a nematic phase is driven by anisotropic electrostatic and long-range dipolar magnetic interactions. Here, we present studies of the evolution of short range positional and orientational magnetic order in suspensions with volume fractions below and above ΦNI, using small angle neutron scattering (SANS). The results show that in the absence of an external magnetic field, short range positional and orientational order already exist at relatively low volume fractions. Polarized SANS revealed that the contribution of ferromagnetic ordering to the formation of the nematic phase is significant. The ferromagnetic correlations can be qualitatively explained by a simple model, which takes into account anisotropic screened electrostatic and dipolar magnetic interactions.


Assuntos
Nanopartículas de Magnetita/química , Simulação por Computador , Campos Magnéticos , Fenômenos Magnéticos , Imãs/química , Tamanho da Partícula
7.
Talanta ; 201: 266-270, 2019 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-31122422

RESUMO

Magnetic cellulose nanoparticles (MCNPs) were used for the first time as sorbents for stir bar-sorptive dispersive microextraction (SBSDME). The main experimental parameters involved in the SBSDME process that affect extraction (i.e. amount of MCNPs, ionic strength, pH, extraction and back-extraction time) were investigated. The method was applied to the determination of nine polychlorinated biphenyls (PCBs) in fruit juice samples by gas chromatography-mass spectrometry (GC-MS). Under the optimized conditions, a good linearity was obtained in a concentration range of 10-1000 ng mL-1 with determination coefficients over 0.9945. Limits of detection and quantification for all target PCBs were in the range 2.1-54 ng L-1 and 7.0-180 ng L-1, respectively. Intra-day precision ranged from 1.7% to 8.8% and inter-day precision from 3.4% to 9.3% RSD. The enrichment factors of the analytes were from 74.6 to 98.2. The MCNPs can be reused up to 5 times. The method was applied to commercial orange and pineapple juices (n = 5), where concentrations were below the limits of detection. Recoveries from 70.4 to 108.0% were obtained by applying the method for the analysis of spiked fruit juice samples at 1 and 2 ng mL-1 concentration levels. The use of cellulose makes this approach environmentally friendly and the magnetism of the resulting sorbent in conjunction with SBSDME provides ease of handling and saving of time.


Assuntos
Celulose/química , Contaminação de Alimentos/análise , Sucos de Frutas e Vegetais/análise , Nanopartículas/química , Bifenilos Policlorados/análise , Microextração em Fase Sólida/métodos , Adsorção , Ananas/química , Citrus sinensis/química , Concentração de Íons de Hidrogênio , Compostos de Ferro/química , Limite de Detecção , Fenômenos Magnéticos , Fatores de Tempo
8.
Talanta ; 201: 286-294, 2019 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-31122425

RESUMO

Herein, high performance peroxidase-like activity of zinc and cobalt bi-metal metal-organic framework (ZnCo MOF) is reported and applied for the sensitive measurement of atropine. ZnCo MOF was synthesized by the reaction of 2-methylimidazole with Zn and Co (II) cations in aqueous media. The colorimetric and fluorometric experiments were applied to investigate the catalytic activity of obtained MOF, using o-phenylenediamine (OPD) and terephthalic acid (TA) peroxidase substrates, respectively. The results demonstrated the more efficient mimetic behavior of ZnCo MOF compared with common Zn or Co MOFs. Besides, it was found that atropine hindered the catalytic action of ZnCo MOF and this effect was intensified by increasing the atropine concentration. So, it was considered to design a sensitive analytical assay for atropine detection. To assure a high specific recognition, molecularly imprinted polymer (MIP)-based extraction using magnetic graphene oxide supports was applied to extract atropine before its determination. The combination between the high specific extraction and great catalytic activity of ZnCo MOF led to the ultrasensitive and reliable determination of atropine. The best linear range of calibration graph was achieved using fluorometric detection system for 0.1-45 ng mL-1 atropine concentrations, and detection limit (3Sb/m) was 27 pg mL-1. The relative standard deviations (RSD %) for the determination of 1, and 10 ng mL-1 atropine (n = 5) were 2.13% and 3.08%, respectively. The explained fluorometric assay was examined for the measurement of atropine in biological fluids (Recoveries were in the range of 95.90-103.57%), and the results were validated by an official method.


Assuntos
Atropina/sangue , Colorimetria/métodos , Grafite/química , Estruturas Metalorgânicas/química , Extração em Fase Sólida/métodos , Espectrometria de Fluorescência/métodos , Adulto , Materiais Biomiméticos/síntese química , Materiais Biomiméticos/química , Cobalto/química , Humanos , Limite de Detecção , Fenômenos Magnéticos , Masculino , Estruturas Metalorgânicas/síntese química , Pessoa de Meia-Idade , Impressão Molecular , Peroxidase/química , Porosidade , Zinco/química
9.
Talanta ; 201: 388-396, 2019 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-31122439

RESUMO

Ascorbic acid (AA) is an essential vitamin and plays an irreplaceable role in humans' daily life. Therefore, it is of profound significance to develop effective strategies for AA sensing. Herein, a novel bi-functional sensing strategy was developed by using carbon dots (CDs) and MnO2 nanosheet as the fluorometric/magnetic signal source. When AA was absence, the fluorescence of CDs was quenched by MnO2 nanosheet due to the inner filter effect. Neither the fluorescence nor magnetic signal of the nanoprobe can be detected. In the presence of AA, a redox reaction occurred between MnO2 nanosheet and AA resulting in the generation of magnetic resonance imaging (MRI) response Mn2+ and decomposing of MnO2 nanosheet structure, thus leading to the recovery of CDs fluorescence. The detection limit of the AA was determined to be 2.89 µM with a linear range of 0-80 µM in fluorescence mode, and detection limit of 0.776 µM with a linear range of 0-80 µM in MRI mode when used transverse relaxation rate as signal. Furthermore, the developed fluorometric/magnetic bi-functional nanoprobe showed good biocompatibility, high response rate, high selectivity towards AA and could be used to analyses AA in real samples. Moreover, in vivo imaging of AA in mice was achieved in magnetic mode. The fluorometric/magnetic bi-function sensor for AA detection was introduced, which provided a novel strategy for sensor design based on CDs.


Assuntos
Ácido Ascórbico/análise , Corantes Fluorescentes/química , Imagem por Ressonância Magnética/métodos , Compostos de Manganês/química , Óxidos/química , Pontos Quânticos/química , Espectrometria de Fluorescência/métodos , Animais , Ácido Ascórbico/química , Ácido Ascórbico/metabolismo , Fluorescência , Corantes Fluorescentes/toxicidade , Limite de Detecção , Fenômenos Magnéticos , Masculino , Camundongos Endogâmicos BALB C , Oxirredução , Óxidos/toxicidade , Pontos Quânticos/toxicidade
10.
Talanta ; 201: 441-449, 2019 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-31122447

RESUMO

Heparin is a highly sulfated polysaccharide, applied in clinic for treatment of thrombotic diseases. The biological activity is closely related to its molecular structure e.g. compositions of disaccharides and oligosaccharides units. The classical method to isolate the oligosaccharides after depolymerization by heparinases or nitrous acid I s by size exclusion chromatography which is a time-consuming process. In this study, we explored the possibility for rapid separation of oligosaccharides using a novel polymer material. The magnetic thermoresponsive molecularly imprinted polymers (MIPs) were synthesized using heparin disaccharide as a template, AEM, NIPAAm, and AAm as functional monomer, and MBAA as crosslinker by surface radical polymerization in an aqueous media. Incubation of the MIP with hepairn oligosaccharides demonstrated specific binding to the template molecule. This binding to the targeted molecule was affected by reaction temperature with regard to binding capacity and specificity. The recognition specificity and selectivity can be modulated by varying the compositions of multi-functional monomers. The pseudo-second-order kinetic model and Langmuir isotherm model provide the best fit to the equilibrium adsorption of heparin disaccharides by MIPs. The results suggest that the new material can be used for rapid separation of di- and tetra-saccharides of heparin, which can also be adapted to the applications for isolation of oligosaccharides from other polysaccharides, e.g. heparan sulfate and chondoriting sulfate.


Assuntos
Resinas Acrílicas/química , Heparina/química , Oligossacarídeos/química , Resinas Acrílicas/síntese química , Adsorção , Ácido Cítrico/química , Cinética , Fenômenos Magnéticos , Nanopartículas de Magnetita/química , Impressão Molecular , Polimerização , Temperatura Ambiente
11.
Talanta ; 200: 279-287, 2019 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-31036185

RESUMO

Plants are well-recognized sources of inhibitors for α-glucosidase - a key target enzyme for management of type 2 diabetes. Recently, two advanced bioactivity-profiling techniques, i.e., ligand fishing and high-resolution inhibition profiling, have shown great promises for accelerating identification of α-glucosidase inhibitors from complex plant extracts. Non-specific affinities and non-specific inhibitions are major sources of false positive hits from ligand fishing and high-resolution inhibition profiling, respectively. In an attempt to minimize such false positive hits, we describe a new screening approach based on ligand fishing and high-resolution inhibition profiling for detection of high-affinity ligands and assessment of inhibitory activity, respectively. The complementary nature of ligand fishing and high-resolution inhibition profiling was explored to identify α-glucosidase inhibitory ligands from a complex mixture, and proof-of-concept was demonstrated with crude ethyl acetate extract of Ginkgo biloba. In addition to magnetic beads with a 3-carbon aliphatic linker, α-glucosidase was immobilized on magnetic beads with a 21-carbon aliphatic linker; and the two different types of magnetic beads were compared for their hydrolytic activity and fishing efficiency.


Assuntos
Biflavonoides/farmacologia , Inibidores de Glicosídeo Hidrolases/farmacologia , Extratos Vegetais/farmacologia , alfa-Glucosidases/metabolismo , Biflavonoides/química , Biflavonoides/isolamento & purificação , Avaliação Pré-Clínica de Medicamentos , Ginkgo biloba/química , Inibidores de Glicosídeo Hidrolases/química , Inibidores de Glicosídeo Hidrolases/isolamento & purificação , Ligantes , Fenômenos Magnéticos , Estrutura Molecular , Extratos Vegetais/química , Extratos Vegetais/isolamento & purificação , Saccharomyces cerevisiae/enzimologia , Relação Estrutura-Atividade
12.
Phys Chem Chem Phys ; 21(21): 10908-10913, 2019 Jun 07.
Artigo em Inglês | MEDLINE | ID: mdl-31080970

RESUMO

We estimate the time- and temperature-evolution of spin energy levels in a metallopeptide by combining molecular dynamics with crystal field analysis. Fluctuations of tens of cm-1 for spin energy levels at fs times gradually average out at longer times. We confirm that local vibrations are key in spin dynamics.


Assuntos
Metaloproteínas/química , Simulação de Dinâmica Molecular , Termodinâmica , Fenômenos Magnéticos , Fatores de Tempo , Vibração
13.
Nat Commun ; 10(1): 2159, 2019 05 14.
Artigo em Inglês | MEDLINE | ID: mdl-31089141

RESUMO

Accurate DNA replication is tightly regulated in eukaryotes to ensure genome stability during cell division and is performed by the multi-protein replisome. At the core an AAA+ hetero-hexameric complex, Mcm2-7, together with GINS and Cdc45 form the active replicative helicase Cdc45/Mcm2-7/GINS (CMG). It is not clear how this replicative ring helicase translocates on, and unwinds, DNA. We measure real-time dynamics of purified recombinant Drosophila melanogaster CMG unwinding DNA with single-molecule magnetic tweezers. Our data demonstrates that CMG exhibits a biased random walk, not the expected unidirectional motion. Through building a kinetic model we find CMG may enter up to three paused states rather than unwinding, and should these be prevented, in vivo fork rates would be recovered in vitro. We propose a mechanism in which CMG couples ATP hydrolysis to unwinding by acting as a lazy Brownian ratchet, thus providing quantitative understanding of the central process in eukaryotic DNA replication.


Assuntos
DNA Helicases/metabolismo , Replicação do DNA , Proteínas de Drosophila/metabolismo , Modelos Moleculares , DNA Helicases/isolamento & purificação , Proteínas de Drosophila/isolamento & purificação , Fenômenos Magnéticos , Pinças Ópticas , Proteínas Recombinantes/isolamento & purificação , Proteínas Recombinantes/metabolismo , Imagem Individual de Molécula/métodos
14.
Molecules ; 24(9)2019 May 03.
Artigo em Inglês | MEDLINE | ID: mdl-31058870

RESUMO

Large-size, superparamagnetic, and highly magnetic Fe3O4@PDA core-shell submicrosphere-supported nano-palladium catalysts were prepared in this study. Dopamine was encapsulated on the surface of Fe3O4 particles via self-polymerization and then protonated to positively charge the microspheres. PdCl42- was dispersed on the surface of the microspheres by positive and negative charge attraction and then reduced to nano-palladium. With air as oxidant, the catalyst can successfully catalyze the dehydrogenation of benzyl alcohols to produce the corresponding aldehydes at 120 °C.


Assuntos
Aldeídos/síntese química , Álcoois Benzílicos/química , Dopamina/química , Óxido Ferroso-Férrico/química , Paládio/química , Aldeídos/química , Catálise , Hidrogenação , Fenômenos Magnéticos , Nanopartículas de Magnetita/química , Microscopia Eletrônica de Transmissão , Oxirredução , Tamanho da Partícula
15.
Environ Sci Pollut Res Int ; 26(19): 19189-19206, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31069657

RESUMO

A rapid synthetic technique is investigated for magnetic nanoparticles (Co1-yCuyFe2-xCexO4 (x = 0, y = 0), (x = 0.05, y = 0), (x = 0, y = 0.5), and (x = 0.05, y = 0.5)). The structure, morphology, optical and magnetic performance of prepared nanoparticles are analyzed by powder XRD, XPS, FT-IR, SEM-EDAX, TEM, DRS, and VSM. The photocatalytic activity of the synthesized nanoparticles for the removal of the Congo red (CR) dye and bisphenol A (BPA) from aqueous solution is examined by UV-visible spectrometer. Research indicates that the co-doping of Cu2+ and Ce3+ showed marked effect on the structural, optical, magnetic, and photocatalytic properties of the CoFe2O4 nanoparticles. DRS showed that the Co0.5Cu0.5Fe1.95Ce0.05O4 nanoparticles have lower band gap energy (0.78 eV) than other synthesized compounds. High removal percentage of CR and BPA (99.09% and 99.33%) was observed within 30 min and 180 min under visible and UV-light illumination respectively using Co0.5Cu0.5Fe1.95Ce0.05O4. The corresponding photocatalytic degradation kinetics and mechanism are analyzed.


Assuntos
Cério/química , Cobalto/química , Cobre/química , Compostos Férricos/química , Nanopartículas/química , Compostos Benzidrílicos/análise , Catálise , Vermelho Congo/análise , Cinética , Fenômenos Magnéticos , Fenóis/análise , Fotoquímica , Propriedades de Superfície , Poluentes Químicos da Água/análise
16.
Carbohydr Polym ; 216: 107-112, 2019 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-31047046

RESUMO

A simple, convenient and inexpensive method for the preparation of magnetic chitin composite, in which magnetite particles are densely covered with the polysaccharide shell has been developed. Two-step procedure for magnetic chitin preparation includes: (i) adsorption of chitosan onto magnetite particles and (ii) N-selective acetylation of chitosan to produce magnetic chitin. The composite combines the magnetic properties of magnetite and the adsorption properties of chitin. The synthesized magnetic chitin is an efficient adsorbent of ß-d-GlcNAc-specific lectins and lysozyme. The adsorption capacity of magnetic chitin for wheat germ (Triticum vulgaris) and potato (Solanum tuberosum) lectins was in the range of 67-86 mg g-1 of the adsorbent. Magnetic chitin showed the high capacity for enzyme-lysozyme. Synthesized adsorbent is environmentally friendly and recyclable. Magnetic chitin may be used as a promising multi-purpose adsorbent of pollutants of organic or inorganic nature.


Assuntos
Quitina/química , Nanopartículas de Magnetita/química , Muramidase/química , Soroalbumina Bovina/química , Aglutininas do Germe de Trigo/química , Adsorção , Animais , Bovinos , Galinhas , Quitina/síntese química , Química Verde/métodos , Fenômenos Magnéticos , Solanum tuberosum/química , Triticum/química
17.
Carbohydr Polym ; 216: 119-128, 2019 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-31047048

RESUMO

As a kind of potential absorbent, polysaccharide materials are limited due to weak stability, low absorption and recovery rate. Herein, a novel composite adsorbent - the magnetic composite gel beads (CMC/SA/graphene oxide@Fe3O4) were prepared by combining carboxymethyl chitosan (CMC), sodium alginate (SA) with graphene oxide@Fe3O4, and then utilized for the adsorption of Cu2+, Cd2+ and Pb2+ from the wastewater. The physicochemical property of CMC/SA/graphene oxide@Fe3O4 beads were characterized in detail. The CMC/SA/graphene oxide@Fe3O4 magnetic gel beads could separate easily from the wastewater and showed a higher stability due to the addition of graphene oxide@Fe3O4. The adsorption experiments show that the adsorption of Cu2+, Cd2+ and Pb2+ on the magnetic gel bead was well fitted with pseudo-second-order model and Langmuir isotherm model, and the maximum adsorption capacity of Cu2+, Cd2+ and Pb2+ reached 55.96, 86.28 and 189.04 mg/g, respectively. Moreover, the magnetic gel beads had selective adsorption toward Pb2+. In addition, the magnetic gel beads still obtained 90% of the adsorption rates after five cycles, and showed good adsorption efficiency in the simulated real environment. This work proves that the CMC/SA/graphene oxide@Fe3O4 magnetic gel beads as the adsorbents have promising potential in wastewater treatment.


Assuntos
Alginatos/química , Quitosana/análogos & derivados , Óxido Ferroso-Férrico/química , Géis/química , Grafite/química , Metais Pesados/química , Adsorção , Cádmio/química , Quitosana/química , Cobre/química , Óxido Ferroso-Férrico/síntese química , Géis/síntese química , Grafite/síntese química , Química Verde/métodos , Substâncias Húmicas , Chumbo/química , Fenômenos Magnéticos , Termodinâmica , Purificação da Água/métodos
18.
Carbohydr Polym ; 216: 54-62, 2019 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-31047082

RESUMO

Biodegradable, antimicrobial, and semiconducting cellulosic composite was synthesized by in-situ polymerization of polyaniline in the presence of cellulose. The cobalt ferrite nanoparticles (CFO-NPs) were added during the polymerization process to acquire this composite magnetic property. The CFO-NPs were prepared by sol-gel method with average particles size less than 50 nm. The nanocomposites were characterized by Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) and energy-dispersive X-ray (EDX). In addition, their magnetic, dielectric constant, dielectric loss, and conductivity behaviors were studied. The magnetization (Ms) and conductivity increased up to 3.7 emu/g and 3.5 × 10-3 S/cm, respectively, with increasing CFO-NPs content. The prepared electromagnetic nanocomposite exhibits highly efficient biodegradability and antimicrobial activity against Escherichia coli, Bacillus subtilis, and Candida albicans. The antimicrobial activity increased with increasing CFO-NPs while the biodegradability decreased.


Assuntos
Compostos de Anilina/farmacologia , Celulose/farmacologia , Cobalto/farmacologia , Compostos Férricos/farmacologia , Nanocompostos/química , Nanopartículas/química , Compostos de Anilina/síntese química , Compostos de Anilina/química , Antibacterianos/síntese química , Antibacterianos/química , Antibacterianos/farmacologia , Antifúngicos/síntese química , Antifúngicos/química , Antifúngicos/farmacologia , Bacillus subtilis/efeitos dos fármacos , Plásticos Biodegradáveis/síntese química , Plásticos Biodegradáveis/química , Plásticos Biodegradáveis/farmacologia , Candida albicans/efeitos dos fármacos , Celulose/análogos & derivados , Celulose/síntese química , Cobalto/química , Condutividade Elétrica , Escherichia coli/efeitos dos fármacos , Compostos Férricos/síntese química , Compostos Férricos/química , Fenômenos Magnéticos , Tamanho da Partícula
19.
Talanta ; 200: 443-449, 2019 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-31036207

RESUMO

Highly selective and efficient extraction of endogenous peptides from complex biological systems plays an important role in proteomics. In this study, an ordered mesoporous magnetic material (denoted as CZIF) with micron size (1 µm) was facilely synthesized by direct pyrolyzing ZIF-67 under N2 atmosphere for efficient and selective enrichment of endogenous peptides. The CZIF keeps the morphology of the original ZIF-67 crystal with enlarged pore size of 3.67 nm and a specific surface area of 156.58 m2/g, and shows weak magnetism (18 emu/g). The loading buffer and eluting buffer were optimized to improve the sensitivity and selectivity of the CZIF. Benefiting from the highly graphitization of the CZIF, the limit detection of BSA digest as low as 0.2 fmol/µL was achieved, showing good enrichment sensitivity for peptides. The uniform mesoporous help to achieve high selectivity by excluding proteins (BSA tryptic digest/BSA = 1:1000). The CZIF can be repeatedly used (n ≥ 5) without further treatment. Moreover, 402 endogenous peptides were enriched from human serum by CZIF, which indicated that CZIF was a promising candidate for the extraction of endogenous peptides from complex biologicals.


Assuntos
Carbono/química , Estruturas Metalorgânicas/química , Peptídeos/sangue , Humanos , Fenômenos Magnéticos , Tamanho da Partícula , Porosidade , Propriedades de Superfície
20.
Talanta ; 199: 212-219, 2019 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-30952249

RESUMO

A simple, rapid and sensitive method based on in situ derivatization combined with magnetic ionic liquid (MIL)-dispersive liquid-liquid microextraction (DLLME) was developed for the determination of biogenic amines (BAs). Six BAs (tryptamine, phenylethylamine, histamine, tyramine, spermidine, and spermine) were in situ derivatized with dansyl chloride (DNS-Cl), extracted by MIL-DLLME, and then chromatographed by high-performance liquid chromatography with ultraviolet detection (HPLC-UV). This MIL trihexyltetradecylphosphonium tetrachlorocobalt (II) [P6,6,6,14+]2[CoCl42-] was explored as the extraction solvent with the advantages of magnetic susceptibility, hydrophobicity and mobile phase compatibility. Furthermore, the MIL was designed to reduce hydrolysis in aqueous solvent as well as decrease absorbance when submitted to HPLC. In order to obtain optimized extraction efficiency, the MIL mass, the volume of derivatizing agent, the type and volume of disperser, the derivatizing and extraction time, and pH of sample solution were investigated. The proposed method was successfully applied for the analysis of wine and fish samples, and the recoveries of analytes achieved were in the range of 93.2-103.1% and 94.5-102.3%, respectively. The limits of detection/quantification for wine and fish samples were in the range of 1.3-3.9/4.1-9.9 µg/L and 1.2-3.8/3.9-9.6 µg/kg, respectively. Additionally, good reproducibility with relative standard deviations lower than 4.9% (n = 5) was obtained for the analysis of wine and fish samples. The in situ DNS-Cl derivatization and MIL-DLLME method was an efficient, rapid, environmental friendly microextraction approach for the determination of BAs in foodstuffs.


Assuntos
Aminas Biogênicas/análise , Análise de Alimentos , Contaminação de Alimentos/análise , Líquidos Iônicos/química , Microextração em Fase Líquida , Fenômenos Magnéticos , Interações Hidrofóbicas e Hidrofílicas
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