Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 71
Filtrar
Mais filtros










Base de dados
Intervalo de ano de publicação
1.
J Phys Chem Lett ; 13(14): 3261-3268, 2022 Apr 14.
Artigo em Inglês | MEDLINE | ID: mdl-35389224

RESUMO

Bandgap engineering is an efficient strategy for controlling the physical properties of semiconductor materials. For flexible two-dimensional (2D) materials, strain provides a nondestructive and adjustable method for bandgap adjustment. Here, we propose that, in 2D materials with out-of-plane ferroelectricity, the antibonding nature of the valence band maximum and conduction band minimum and polarized charge distribution induced by ferroelectricity give rise to giant changes of the bandgap under curvature strain field. This hypothesis was proven by scanning tunneling microscopy/spectroscopy measurements on monolayer α-In2Se3 that revealed that the bandgap of α-In2Se3 increases significantly due to bending. Both experiments and theoretical calculations indicated that the bandgap increases monotonically with the degree of bending of the α-In2Se3 layer. Our work suggests that bending is an effective method for tuning the gaps of 2D ferroelectric materials, providing a new platform for bandgap engineering under the combination of ferroelectricity and strain field.

2.
ChemSusChem ; 15(12): e202200280, 2022 Jun 22.
Artigo em Inglês | MEDLINE | ID: mdl-35384321

RESUMO

Searching for highly-efficient electrocatalysts for water splitting has been greatly endowed due to the huge demand for green energy sources. Two-dimensional (2D) materials are widely explored for the purpose because of their unique physical and chemical properties, abundant active sites, and easy fabrication. Here, we present a new family of 2D M4 B6 X6 (2D Boridenes) and investigate their physical and chemical properties for their potential applications into electrocatalysis based on first-principles calculations. We demonstrate that 2D M4 B6 X6 (M=Cr, Mo, and W; X=O and F) are dynamically, thermodynamically, and mechanically stable, and show intriguing electronic and catalytic properties. Importantly, we find that M4 B6 O6 are intrinsically active for oxygen evolution reaction (OER). Our results demonstrate that: (1) the adsorbate-escape mechanism dominates the OER process with a low overpotential of 0.652 V on Cr4 B6 O6 ; (2) the partial surface-oxidization can improve the catalytic performance of M4 B6 F6 dramatically; and (3) the surface reconstruction greatly affects the OER performance of M4 B6 X6 . Our findings illustrate that the surface reconstruction is critical to the OER activity, which may provide a new strategy on the design of 2D materials for electrocatalysis and offer theoretical insight into the catalytic mechanism.

3.
J Am Chem Soc ; 144(9): 3949-3956, 2022 Mar 09.
Artigo em Inglês | MEDLINE | ID: mdl-35200018

RESUMO

Intertwisted bilayers of two-dimensional (2D) materials can host low-energy flat bands, which offer opportunity to investigate many intriguing physics associated with strong electron correlations. In the existing systems, ultra-flat bands only emerge at very small twist angles less than a few degrees, which poses a challenge for experimental studies and practical applications. Here, we propose a new design principle to achieve low-energy ultra-flat bands with increased twist angles. The key condition is to have a 2D semiconducting material with a large energy difference of band edges controlled by stacking. We show that the interlayer interaction leads to defect-like states under twisting, which forms a flat band in the semiconducting band gap with dispersion strongly suppressed by the large energy barriers in the moiré superlattice even for large twist angles. We explicitly demonstrate our idea in bilayer α-In2Se3 and bilayer InSe. For bilayer α-In2Se3, we show that a twist angle of ∼13.2° is sufficient to achieve the band flatness comparable to that of twist bilayer graphene at the magic angle ∼1.1°. In addition, the appearance of ultra-flat bands here is not sensitive to the twist angle as in bilayer graphene, and it can be further controlled by external gate fields. Our finding provides a new route to achieve ultra-flat bands other than reducing the twist angles and paves the way toward engineering such flat bands in a large family of 2D materials.

4.
ACS Appl Mater Interfaces ; 13(50): 60200-60208, 2021 Dec 22.
Artigo em Inglês | MEDLINE | ID: mdl-34883018

RESUMO

Magnetic tunnel junctions (MTJs), ferroelectric/antiferroelectric tunnel junctions (FTJs/AFTJs), and multiferroic tunnel junctions (MFTJs) have recently attracted significant interest for technological applications of nanoscale memory devices. Until now, most of them are based on perovskite oxide heterostructures with a relatively high resistance-area (RA) product and low resistance difference unfavorable for practical applications. The recent discovery of the two-dimensional (2D) van der Waals (vdW) ferroelectric (FE) and magnetic materials has opened a new route to realize tunnel junctions with high performance and atomic-scale dimensions. Here, using first-principles calculations, we propose a new type of 2D tunnel junction: an antiferroelectric magnetic tunnel junction (AFMTJ), which inherits the features of both MTJ and AFTJ. This AFMTJ is composed of monolayer CuInP2S6 (CIPS) sandwiched between 2D magnetic electrodes of CrSe2. The AFTJ with nonmagnetic electrodes of TiSe2 on both sides of CIPS and the asymmetric AFTJ with both CrSe2 and TiSe2 electrodes are also investigated. Based on quantum-mechanical modeling of the electronic transport, sizeable tunneling electroresistance effects and multiple nonvolatile resistance states are demonstrated. More importantly, a remarkably low RA product (less than 0.1 Ω·µm2) makes the proposed vdW AFMTJs superior to the conventional MFTJs in terms of their promising nonvolatile memory applications. Our calculations provide new guidance for the experiment and application of nanoscale memory devices.

5.
J Agric Food Chem ; 69(43): 12828-12836, 2021 Nov 03.
Artigo em Inglês | MEDLINE | ID: mdl-34694123

RESUMO

Foodborne pathogens can cause illnesses. Existing tools for detecting foodborne pathogens are typically time-consuming or require complex protocols. Here, we report an assay to directly analyze pathogenic genes based on CRISPR-Cas12. This new test, termed proximal DNA probe-based CRISPR-Cas12 (PPCas12), facilitates the detection of foodborne pathogens without amplification steps. The elimination of the nucleic acid amplification process dramatically reduced the processing time, complexity, and costs in the analysis of foodborne pathogens. The substitution of the frequently used dually labeled DNA reporter with a proximal DNA probe in the PPCas12 assay led to a 4-fold sensitivity enhancement. PPCas12 offered a limit of detection of 619 colony-forming units in the detection of Salmonella enterica (S. enterica) without the nucleic acid amplification process. The specific recognition of genes via PPCas12 allowed distinguishing S. enterica from other foodborne pathogens. The PPCas12 assay was applied in the screening of S. enterica contamination on fresh eggs with high precision. Hence, the new PPCas12 assay will be a valuable tool for on-site monitoring of foodborne pathogens.


Assuntos
Doenças Transmitidas por Alimentos , Salmonella enterica , Sistemas CRISPR-Cas , Sondas de DNA , Microbiologia de Alimentos , Humanos , Técnicas de Amplificação de Ácido Nucleico , Salmonella enterica/genética
6.
Nanomicro Lett ; 13(1): 195, 2021 Sep 14.
Artigo em Inglês | MEDLINE | ID: mdl-34523042

RESUMO

Magnesium metal anode holds great potentials toward future high energy and safe rechargeable magnesium battery technology due to its divalent redox and dendrite-free nature. Electrolytes based on Lewis acid chemistry enable the reversible Mg plating/stripping, while they fail to match most cathode materials toward high-voltage magnesium batteries. Herein, reversible Mg plating/stripping is achieved in conventional carbonate electrolytes enabled by the cooperative solvation/surface engineering. Strongly electronegative Cl from the MgCl2 additive of electrolyte impairs the Mg…O = C interaction to reduce the Mg2+ desolvation barrier for accelerated redox kinetics, while the Mg2+-conducting polymer coating on the Mg surface ensures the facile Mg2+ migration and the effective isolation of electrolytes. As a result, reversible plating and stripping of Mg is demonstrated with a low overpotential of 0.7 V up to 2000 cycles. Moreover, benefitting from the wide electrochemical window of carbonate electrolytes, high-voltage (> 2.0 V) rechargeable magnesium batteries are achieved through assembling the electrode couple of Mg metal anode and Prussian blue-based cathodes. The present work provides a cooperative engineering strategy to promote the application of magnesium anode in carbonate electrolytes toward high energy rechargeable batteries.

7.
ACS Sens ; 6(9): 3295-3302, 2021 09 24.
Artigo em Inglês | MEDLINE | ID: mdl-34516103

RESUMO

Foodborne pathogen infection is a key issue of food safety. Herein, we developed a label-free assay for Salmonella enterica (S. enterica) detection based on the G-quadruplex-probing CRISPR-Cas12 system (termed G-CRISPR-Cas), allowing highly sensitive detection of S. enterica and investigation of their colonization in chickens. The introduction of the G-quadruplex probe serving as the substrate of Cas 12a realized a label-free analysis for foodborne pathogens. Due to the amplification process induced by loop-mediated isothermal amplification (LAMP), G-CRISPR-Cas assay can detect S. enterica as low as 20 CFU. Specificity for pathogenic gene detection was guaranteed by the dual recognition process via LAMP primers and Cas 12a-guided RNA binding. The G-CRISPR-Cas assay was applied to explore S. enterica colonization in the intestinal tract and organs of chickens and showed the risk of S. enterica infection outside of the intestinal tract. The G-CRISPR-Cas assay is promising for on-site diagnosis of the infection or contamination of foodborne pathogens outside the laboratories, such as abattoirs and markets.


Assuntos
Sistemas CRISPR-Cas , Galinhas , Animais , Técnicas de Diagnóstico Molecular , Técnicas de Amplificação de Ácido Nucleico
8.
Front Physiol ; 12: 716173, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34421658

RESUMO

Digital subtraction angiography (DSA) is a fluoroscopic technique used extensively in interventional radiology for visualizing blood vessels. It has also been used to evaluate blood perfusion. However, the perfusion obtained in previous techniques was extracted from signal intensity rather than by the transport of contrast material (CM) through blood flow. The main aim of this study is to evaluate the morphological effects on the hemodynamics and the CM concentration in the middle cerebral artery (MCA) stenosis. We proposed a quantitative parameter, i.e., contrast material remaining time (CMRT), to describe the variation in the transport of CM over time. Computational fluid dynamics simulations were performed on both reconstructive synthetic and patient-derived models. In the synthetic models, we evaluated the variation of flow patterns and the transport of CM with different degrees of stenosis and the location of the lesion. It was found that an increase in the degree of stenosis (from 30 to 80%) resulted in a significant increase in CMRT at the anterior cerebral artery (ACA) outlet (p = 0.0238) and a significant decrease in CMRT at the MCA outlet (p = 0.012). The patient-derived models were reconstructed from the pre- and post-interventional DSA images of a patient with MCA stenosis. Both blood flow velocity and CMRT increased at the ACA outlet but decreased at the MCA outlet. The perfusion analysis demonstrated that the perfusion function was improved after interventional surgery. In conclusion, changes in stenotic degree at MCA may lead to apparent differences in the hemodynamic distribution and the transport of CM. CMRT could be a quantitative indicator to evaluate the changes in blood perfusion after the intervention for MCA stenosis.

9.
J Agric Food Chem ; 69(29): 8065-8080, 2021 Jul 28.
Artigo em Inglês | MEDLINE | ID: mdl-34269568

RESUMO

Sodium salt is a pivotal ingredient in traditional fermented foods, but its excessive consumption adversely affects human health, product quality, and production efficiency. Therefore, reducing sodium salt content in traditional fermented foods and developing low-sodium fermented foods have attracted increasing attention. Given the essential role of sodium salt in the safety and quality of fermented foods, appropriate approaches should be applied in the production of low-sodium fermented foods. In this review, the challenges of sodium reduction in traditional fermented foods are presented, including the possible growth of pathogenic bacteria, the formation of hazardous chemicals, flavor deficiency, and texture deterioration. Physical, chemical, and biological strategies are also discussed. This review provides references for improving the quality and safety of low-sodium fermented foods.


Assuntos
Bactérias , Fermentação , Humanos , Sódio , Paladar
10.
Nanoscale ; 13(26): 11552-11560, 2021 Jul 08.
Artigo em Inglês | MEDLINE | ID: mdl-34190296

RESUMO

Impurity doping has been widely applied in nanomaterial synthesis for modulating the crystallographic phase, morphology, and size of nanocrystalline materials, but mostly by altering thermodynamic equilibria of final products. Here, we report the use of lanthanide dopants to manipulate the growing kinetics of halide perovskite nanocrystals to enable the preparation of highly anisotropic two-dimensional (2D) CsPbBr3-based nanoplatelets with precisely controlled thickness. We demonstrate that the incorporation of trivalent lanthanides increases the energy barrier in growing three-monolayer (3 ML) CsPbBr3 from a 2 ML intermediate. It enables the growth of thermodynamically unfavorable 2 ML CsPbBr3 products through kinetic control. This finding provides a novel approach for dimensional control of perovskite nanocrystals with strong quantum confinement. It offers opportunities to generate deep-blue emitting (at 430 nm) CsPbBr3:Lu3+ nanoplatelets with good structural- and photo-stabilities potentially useful for many applications including light-emitting, lasers, and photocatalysis.

11.
Int J Food Microbiol ; 351: 109262, 2021 Aug 02.
Artigo em Inglês | MEDLINE | ID: mdl-34090033

RESUMO

Chinese horse bean-chili-paste (CHCP), a fermented condiment in China, is traditionally manufactured through naturally spontaneous semi-solid fermentation procedures without intentionally inoculated microorganisms. The aim of this study was to investigate the effect on microbiota and quality variations during CHCP fermentation by inoculation of selected autochthonous microorganisms Bacillus amyloliquefaciens and Candida versatilis. The results showed that relative abundance of Bacillus in the samples inoculated with B. amyloliquefaciens were increased from about 0.6% to almost 25%, and the batches bio-augmented with C. versatilis exhibited clearly 0.7 Lg copies/g higher biomass than that of the other samples. By bio-augmentation, six enzyme activities, namely acid protease, leucine aminopeptidase, α-amylase, cellulose, ß-glucosidase and esterase, were considerably enhanced. As a result, inoculation of these two strains exhibited significant effect on the volatile profiles of CHCP. B. amyloliquefaciens herein was found to contribute mainly to the accumulation of acids, sulfur-containing compounds and pyrazines, whereas C. versatilis was considerably associated with the formation of alcohols, esters and phenols. This study proved that combination of B. amyloliquefaciens and C. versatilis could obtain more extensive aroma profiles, especially for the enrichment of miso-like and fruity flavors, which could provide a guideline for the tailored control of CHCP fermentation process.


Assuntos
Bacillus amyloliquefaciens/metabolismo , Aromatizantes/metabolismo , Microbiota , Saccharomycetales/metabolismo , Vicia faba/microbiologia , China , Condimentos/análise , Condimentos/microbiologia , Fermentação , Aromatizantes/análise , Odorantes/análise , Compostos Orgânicos Voláteis/análise , Compostos Orgânicos Voláteis/metabolismo
12.
Nature ; 593(7857): 56-60, 2021 05.
Artigo em Inglês | MEDLINE | ID: mdl-33953409

RESUMO

Exciting phenomena may emerge in non-centrosymmetric two-dimensional electronic systems when spin-orbit coupling (SOC)1 interplays dynamically with Coulomb interactions2,3, band topology4,5 and external modulating forces6-8. Here we report synergetic effects between SOC and the Stark effect in centrosymmetric few-layer black arsenic, which manifest as particle-hole asymmetric Rashba valley formation and exotic quantum Hall states that are reversibly controlled by electrostatic gating. The unusual findings are rooted in the puckering square lattice of black arsenic, in which heavy 4p orbitals form a Brillouin zone-centred Γ valley with pz symmetry, coexisting with doubly degenerate D valleys of px origin near the time-reversal-invariant momenta of the X points. When a perpendicular electric field breaks the structure inversion symmetry, strong Rashba SOC is activated for the px bands, which produces spin-valley-flavoured D± valleys paired by time-reversal symmetry, whereas Rashba splitting of the Γ valley is constrained by the pz symmetry. Intriguingly, the giant Stark effect shows the same px-orbital selectiveness, collectively shifting the valence band maximum of the D± Rashba valleys to exceed the Γ Rashba top. Such an orchestrating effect allows us to realize gate-tunable Rashba valley manipulations for two-dimensional hole gases, hallmarked by unconventional even-to-odd transitions in quantum Hall states due to the formation of a flavour-dependent Landau level spectrum. For two-dimensional electron gases, the quantization of the Γ Rashba valley is characterized by peculiar density-dependent transitions in the band topology from trivial parabolic pockets to helical Dirac fermions.

13.
ACS Appl Mater Interfaces ; 13(11): 13517-13523, 2021 Mar 24.
Artigo em Inglês | MEDLINE | ID: mdl-33689259

RESUMO

Ferroelectricity exists in a variety of three- and two-dimensional materials and is of great significance for the development of electronic devices. However, the presence of ferroelectricity in one-dimensional materials is extremely rare. Here, we predict ferroelectricity in one-dimensional SbN and BiN nanowires. Their polarization strengths are 1 order of magnitude higher than ever reported values in one-dimensional structures. Moreover, we find that spontaneous spin polarization can be generated in SbN and BiN nanowires by moderate hole doping. This is the first time the coexistence of both ferroelectricity and ferromagnetism in a one-dimensional system has been reported. Our finding not only broadens the family of one-dimensional ferroelectric materials but also offers a promising platform for novel electronic and spintronic applications.

14.
J Sci Food Agric ; 101(13): 5645-5651, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-33740265

RESUMO

BACKGROUND: Esters are indispensable aroma compounds and contribute significantly to the fruity aromas in fermented condiments. The ester synthesis activity and pathways of Bacillus licheniformis, Candida etchellsii, and Zygosaccharomyces rouxii, isolated from Chinese horse bean chili-paste (CHCP), were investigated. Chemical buffer models containing esterification and alcoholysis systems inoculated with extracellular extracts of these three strains were established. RESULTS: The ester synthesis activity of C. etchellsii was stronger than that of the other two strains. Zygosaccharomyces rouxii could synthesize acetate esters via esterification, whereas the biosynthesis pathways of B. licheniformis and C. etchellsii were esterification and alcoholysis. Esterification exhibited relatively high activity at pH 4, whereas alcoholysis activity improved with an increase in the pH from 4 to 8. Candida etchellsii could synthesize C6 -C8 of acetate esters, and its activity improved with the number of alcohol carbon atoms. These three strains could synthesize C10 -C18 of ethyl esters. Their ethyl ester synthesis activity decreased with the aliphatic acid carbon number. CONCLUSION: Candida etchellsii has the potential to be used in CHCP fermentation to accumulate esters and improve flavor compared with the other two strains. This research is helpful in explaining the mechanism of ester synthesis in fermented condiments. © 2021 Society of Chemical Industry.


Assuntos
Bacillus licheniformis/metabolismo , Candida/metabolismo , Ésteres/metabolismo , Aromatizantes/metabolismo , Saccharomycetales/metabolismo , Vicia faba/microbiologia , China , Condimentos/análise , Condimentos/microbiologia , Esterificação , Ésteres/análise , Fermentação , /microbiologia , Aromatizantes/química , Vicia faba/química , Vicia faba/metabolismo
15.
Nanoscale ; 13(2): 1069-1076, 2021 Jan 14.
Artigo em Inglês | MEDLINE | ID: mdl-33393568

RESUMO

The electrical control of two-dimensional (2D) van der Waals ferromagnets is a step forward for the realization of spintronic devices. However, using this approach for practical applications remains challenging due to its volatile memory. Herein, we adopt an alternative strategy, where the bistable ferroelectric switches (P↑ and P↓) of Sc2CO2 (SCO) assist the ferromagnetic states of Cr2Ge2Te6 (CGT) in order to achieve non-volatile memories. Moreover, MXene SCO, being an aided layer in multiferroic CGT/SCO hetero-structures, also modifies the electronic properties of CGT to half metal by its polarized P↓ state. In contrast, the P↑ state does not change the semiconducting nature of CGT. Hence, non-volatile, electrical-controlled switching of ferromagnetic CGT can be engineered by the two opposite ferroelectric states of single layer SCO. Importantly, the magnetic easy axis of CGT switches from in-plane to out-of-plane when the direction of electric polarization of SCO is altered from P↓ to P↑.

16.
J Sci Food Agric ; 101(6): 2371-2379, 2021 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-33009832

RESUMO

BACKGROUND: Chinese horsebean-chili-paste (CHCP) is a traditional fermented condiment in China, known as 'the soul of Sichuan cuisine'. The horsebean-to-meju phase in its preparation is important for CHCP production and contributes significantly to its taste and odor. In this study, a comprehensive flavor compound profiling analysis of the naturally brewed horsebean meju (NBHM) and the temperature-controlled brewed horsebean meju (TCBHM) was performed with two-dimensional gas chromatography time-of-flight mass spectrometry (GC × GC-TOFMS), and the analysis of physicochemical characteristics and free amino acids. Their aroma-active components and characteristic flavor compounds were evaluated. The flavor compounds responsible for differentiating NBHM and TCBHM were also determined based on the Fisher ratio and principal component analysis. RESULTS: The pH and the reducing sugar and amino-acid nitrogen content of NBHM were 5.38, 64.43, and 5.76 g kg-1 , respectively, whereas those of TCBHM were 5.13, 29.20, and 7.43 g kg-1 . A total of 356 volatiles were identified from 2571 compounds, and 257 volatile compounds were identified in NBHM compared to 322 volatiles in TCBHM. These two horsebean mejus (HMs) exhibited a similar proportion profile for 30 aroma-active compounds. Benzoic acid ethyl ester, 4-ethyl-2-methoxy-phenol and argnine were determined to be characteristic flavor components for NBHM, while 1-(2-furanyl)-ethanone, 2,6-dimethyl-pyrazine, threonine, valine and tyrosine were specific to TCBHM. CONCLUSION: Temperature-controlled brewed horsebean meju possessed better physicochemical and flavor characteristics than NBHM. The temperature-controlled brewing technique in CHCP production can be used as a promising alternative to the traditional natural brewing method. © 2020 Society of Chemical Industry.


Assuntos
Manipulação de Alimentos/métodos , Vicia faba/química , China , Condimentos/análise , Fermentação , Aromatizantes/química , Cromatografia Gasosa-Espectrometria de Massas , Humanos , Odorantes/análise , Sementes/química , Paladar , Temperatura
17.
J Agric Food Chem ; 69(1): 397-403, 2021 Jan 13.
Artigo em Inglês | MEDLINE | ID: mdl-33351608

RESUMO

The effect of gallic acid (GA) on the redox state of hemoglobin (Hb) and the structural mechanism upon the Hb-GA interaction were investigated. Results indicated that GA exhibited antioxidant and pro-oxidant effects on Hb, which depended on its concentration and the redox state of Hb. The antioxidant capacity of GA contributed to the inhibition of free iron release from Hb. GA could bind to the central cavity of Hb and interacted with the heme moiety through direct hydrophobic contacts as indicated by docking analysis, but GA did not disrupt the heme structure. Conversely, GA increased the compactness of the Hb molecule and might narrow the crevice around the heme pocket, which contributed to the inhibition of Hb autoxidation and the free iron release. Results provided significant insights into the interaction of GA with redox-active Hb, which is beneficial to the application of GA in relative meat and blood products.


Assuntos
Ácido Gálico/química , Hemoglobinas/química , Hemoglobinas/metabolismo , Animais , Antioxidantes/química , Ácido Gálico/metabolismo , Heme/química , Heme/metabolismo , Carne/análise , Músculos/química , Músculos/metabolismo , Oxirredução , Conformação Proteica em alfa-Hélice , Suínos
18.
Anal Chim Acta ; 1132: 28-35, 2020 Oct 02.
Artigo em Inglês | MEDLINE | ID: mdl-32980108

RESUMO

Staphylococcus aureus (S. aureus) causes serious food-borne diseases, and tools able to directly profile intact S. aureus would greatly facilitate food safety and public health. Herein, we proposed a biosensing platform for culture-independent and separation-free profiling S. aureus, thus allow us to directly detect intact S. aureus in complex samples. The binding protection effect of aptamer-cell complex was introduced to construct the aptasensor, and it allowed to eliminate the optimization of aptamer probe sequences. The proposed aptasensor, terms enzymatic cleavage aptasensor could achieve a sensitive (a detection limit of 64 CFU/mL) and broad-concentration quantification (dynamic range 102-107 CFU/mL) of S. aureus. Furthermore, it could specifically identify intact S. aureus in complex samples, and the quantifying of S. aureus was achieved in tap water, milk and porker with high precision. Therefore, enzymatic cleavage aptasensor could be a good candidate for on-site biosensing platform of S. aureus, as well as other pathogens by replacing the aptamer sequences.


Assuntos
Aptâmeros de Nucleotídeos , Técnicas Biossensoriais , Infecções Estafilocócicas , Animais , Limite de Detecção , Staphylococcus aureus , Água
19.
J Colloid Interface Sci ; 574: 251-259, 2020 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-32330751

RESUMO

Surface sulfation has shown to be an effective way in modifying the acidity and oxygen mobility of metal oxide catalysts. Both of the properties were crucial in the catalytic elimination of chlorinated organics from industrial source of emission. Herein, sulfation of a dry-mixed NiO/CeO2 catalyst was conducted. The catalyst was subsequently utilized for eliminating chlorobenzene (CB) under a simulated realistic condition. A range of analytical techniques, including XRD, XPS, in situ DRIFT and NH3-DRIFT were employed to elucidate the sulfation effect on the physiochemical property and reaction activity of NiO/CeO2. Enhanced Lewis acidity and enriched surface oxygen vacancies originating from the interaction of sulfates and metal ions were observed, which led to improved conversion efficiency and COx (CO + CO2) selectivity in CB oxidation. In particular, qualitative analyses of reaction byproducts in the off-gas indicated that sulfation modification did not cause severe electrophilic chlorination of NiO/CeO2, and resulted in limited production of polychlorinated byproducts and less secondary pollution of the catalyst.

20.
J Agric Food Chem ; 68(8): 2554-2561, 2020 Feb 26.
Artigo em Inglês | MEDLINE | ID: mdl-32027503

RESUMO

Excessive use of antibiotics in aquatic products is a serious problem for food safety and human health, and on-site detection of antibiotics is highly demanded. Herein, we proposed multivalence aptamer probes, allowing sensitive, label-free, and homogeneous detection of antibiotics in different aquatic products. Compared to commonly used aptamers, multivalence aptamer probes can provide multiple binding sites and a higher affinity for target molecules, and the iterative binding on different binding sites contributes to an amplified recognition effect, sharply increasing the response and sensitivity of aptamer probes. The 2-valence aptamer probes conferred a limit of detection of 0.097 nM for kanamycin detection, where it is estimated that their sensitivity is enhanced 12 times compared to 1-valence aptamer probes. Meanwhile, multivalence aptamer probes allowed us to specifically identify kanamycin among other antibiotics. It could detect kanamycin residual in aquatic products including river eel and puffer fish, as well as tap water with high precision. A multivalence design strategy of aptamer probes would significantly improve the detection performance of aptamers, facilitating the translation of aptamer for food safety control.


Assuntos
Antibacterianos/análise , Aptâmeros de Nucleotídeos/química , Técnicas Biossensoriais/métodos , Resíduos de Drogas/análise , Alimentos Marinhos/análise , Animais , Aptâmeros de Nucleotídeos/síntese química , Aquicultura , Técnicas Biossensoriais/instrumentação , Peixes/crescimento & desenvolvimento , Contaminação de Alimentos/análise , Água Doce/análise , Canamicina/análise , Limite de Detecção , Poluentes Químicos da Água/análise
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...