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1.
Biosens Bioelectron ; 169: 112604, 2020 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-32980805

RESUMO

Virus severely endangers human life and health, and the detection of viruses is essential for the prevention and treatment of associated diseases. Metal-organic framework (MOF), a novel hybrid porous material which is bridged by the metal clusters and organic linkers, has become a promising biosensor platform for virus detection due to its outstanding properties including high surface area, adjustable pore size, easy modification, etc. However, the MOF-based sensing platforms for virus detection are rarely summarized. This review systematically divided the detection platforms into nucleic acid and immunological (antigen and antibody) detection, and the underlying sensing mechanisms were interpreted. The nucleic acid sensing was discussed based on the properties of MOF (such as metal ion, functional group, geometry structure, size, porosity, stability, etc.), revealing the relationship between the sensing performance and properties of MOF. Moreover, antibodies sensing based on the fluorescence detection and antigens sensing based on molecular imprinting or electrochemical immunoassay were highlighted. Furthermore, the remaining challenges and future development of MOF for virus detection were further discussed and proposed. This review will provide valuable references for the construction of sophisticated sensing platform for the detection of viruses, especially the 2019 coronavirus.


Assuntos
Técnicas Biossensoriais/métodos , Estruturas Metalorgânicas/química , Viroses/virologia , Vírus/isolamento & purificação , Animais , Anticorpos Antivirais/análise , Antígenos Virais/análise , Técnicas Biossensoriais/instrumentação , Técnicas Eletroquímicas/instrumentação , Técnicas Eletroquímicas/métodos , Humanos , Imunoensaio/instrumentação , Imunoensaio/métodos , Modelos Moleculares , Impressão Molecular/instrumentação , Impressão Molecular/métodos , Ácidos Nucleicos/análise , Espectrometria de Fluorescência/instrumentação , Espectrometria de Fluorescência/métodos , Viroses/diagnóstico
2.
Ecotoxicol Environ Saf ; 204: 111129, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32805505

RESUMO

Anaerobic digestate has been widely used for agricultural activities as an organic fertilizer product. Dissolved organic matter (DOM) derived from anaerobic digestate plays a key role in the speciation, bioavailability and ultimate fate of metals that is related to agriculture and food safety as well as the soil environment. Hence, the binding properties of Cu, Pb and Zn with digestate DOM are investigated using two-dimensional correlation spectroscopy (2D-COS) in combination with ultraviolet absorption, synchronous fluorescence spectra (SFS) and Fourier transform infrared (FTIR) spectroscopy. The 2D absorption COS shows that the DOM at 200 nm is most susceptive with the addition of Pb, followed by Zn and Cu. The log-transformed absorption spectra can also obtain more valuable signals than that from conventional absorption spectra. The 2D-SFS-COS indicates that protein-like peak is more sensitive to the variation of the concentration of metal ions, and fulvic-like substances can preferentially interact with the three heavy metals (HMs). The 2D-FTIR-COS reveals that Cu(II) and Zn(II) ions can be bonded preferentially to the N-H of secondary amide (II), and phenolic OH groups shows a favorable binding with Pb(II). Humic-like peaks with Cu(II) and Zn(II) obtains relatively higher log KM values than fulvic- and protein-like substances. However, the proportion of initial fluorescence (f) for DOM-Cu(II) and DOM-Zn(II) decreased with an increase in wavelength. Protein-like materials have more fluorescent substances that can combine with Cu(II) and Zn(II). This study provides a guide for understanding the geochemical behavior of metal ions in agricultural soils when anaerobic digestate is applied as an organic fertilizer product.


Assuntos
Substâncias Húmicas/análise , Esterco/microbiologia , Metais Pesados/química , Anaerobiose , Animais , Galinhas , Fertilizantes , Fluorescência , Solo/química , Espectrometria de Fluorescência/métodos , Espectroscopia de Infravermelho com Transformada de Fourier/métodos
3.
Chemosphere ; 259: 127396, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32645596

RESUMO

The performance of the UV/H2O2 advanced oxidation process (AOP) is dependent on water quality parameters, including the UV absorbance coefficient at 254 nm and hydroxyl radical (•OH) water background demand (scavenging factor, s-1). The •OH scavenging factor represents the •OH scavenging rate of the background substances in the water matrix, and it is known to be one of the key parameters to predict the performance of the UV/H2O2 process. The •OH scavenging factor has been determined experimentally by using a probe compound such as pCBA and rhodamine B. The experimental method has been validated to accurately predict the micropollutants removal in the UV/H2O2 process, but there is a need for an easier and simple method of determining the OH scavenging factor. We evaluated the alternative method to analyze the •OH scavenging factor using fluorescence excitation-emission matrix and parallel factor analysis (F-EEM/PARAFAC). The correlation between •OH scavenging factor and the spectroscopic characteristics and structure of different organic matter types was evaluated. Organic matter was characterized using a fluorescence excitation-emission matrix, parallel factor analysis, and liquid chromatography-organic carbon detection. Second-order reaction rates of humic acid sodium salt, sodium alginate, Suwannee River humic acid and bovine serum albumin were calculated as 1.30 × 108 M-1 s-1, 1.39 × 108 M-1 s-1, 1.03 × 108 M-1 s-1, and 3.17 × 107 M-1 s-1, respectively. Results of PARAFAC analysis, the ratio of humic and fulvic fluorescence component 2 to terrestrial humic-like fluorescence component 1 (C2/C1), and •OH scavenging factor showed high linearity. A predictive model, which combines with the F-EEM/PARAFAC method, predicted the optimal UV and H2O2 dose to achieve target compound removal.


Assuntos
Poluentes Químicos da Água/química , Purificação da Água/métodos , Análise Fatorial , Fluorescência , Substâncias Húmicas/análise , Peróxido de Hidrogênio/análise , Radical Hidroxila/química , Oxirredução , Rios/química , Espectrometria de Fluorescência/métodos , Água/análise , Poluentes Químicos da Água/análise , Qualidade da Água
4.
Artigo em Inglês | MEDLINE | ID: mdl-32515655

RESUMO

To understand the effect of 17α-ethinylestradiol (EE2) on the conformation changes of bovine serum albumin (BSA), the binding mechanisms of EE2 with BSA were investigated by fluorescence spectroscopy, time-resolved fluorescence spectroscopy, synchronous fluorescence spectroscopy, three-dimensional fluorescence spectroscopy, UV-visible spectroscopy, circular dichroism (CD) spectroscopy and molecular docking. The quenching constants, binding constants, the number of binding sites, thermodynamic parameters, binding distance and the secondary structure changes of BSA were determined. The results of fluorescence quenching experiment suggested that the fluorescence quenching of BSA by EE was due to the formation of complex through static quenching, which was also confirmed by time-resolved fluorescence measurements. The thermodynamic parameters indicated that the binding of EE2 to BSA was driven mainly by van der Waals forces and hydrogen bonding. The conformation alterations of BSA upon EE2 binding were studied by UV-vis spectroscopy and CD spectroscopy. The results of site marker competitive experiments and molecular docking showed that the binding sites of EE2 were mainly located within site I in the subdomain IIA of BSA.


Assuntos
Dicroísmo Circular/métodos , Poluentes Ambientais/química , Etinilestradiol/química , Soroalbumina Bovina/química , Espectrometria de Fluorescência/métodos , Espectrofotometria Ultravioleta/métodos , Animais , Sítios de Ligação , Bovinos , Simulação de Acoplamento Molecular , Ligação Proteica , Conformação Proteica , Termodinâmica
5.
PLoS One ; 15(6): e0233844, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32492068

RESUMO

The hydrophobicity of nanoparticles (NPs) is a key property determining environmental fate, biological partitioning and toxicity. However, methods to characterize surface hydrophobicity are not uniformly applied to NPs and cannot quantify surface changes in complex environments. Existing methods designed to evaluate the hydrophobicity of bulk solids, chemicals, and proteins have significant limitations when applied to NPs. In this study, we modified and evaluated two methods to determine the hydrophobicity of NPs, hydrophobic interaction chromatography (HIC) and dye adsorption, and compared them to the standard octanol-water partitioning protocol for chemicals. Gold, copper oxide, silica, and amine-functionalized silica NPs were used to evaluate methods based on their applicability to NPs that agglomerate and have surface coatings. The octanol water partitioning and HIC methods both measured Au NPs as hydrophilic, but despite having a small size and stable suspension, NPs could not be fully recovered from the HIC column. For the dye adsorption method, hydrophobic (Rose Bengal) and hydrophilic (Nile Blue) dyes were adsorbed to the NP surface, and linear isotherm parameters were used as a metric for hydrophobicity. CuO was determined to be slightly hydrophilic, while SiO2 was hydrophilic and Ami-SiO2 was hydrophobic. The advantages and limitations of each method are discussed, and the dye adsorption method is recommended as the most suitable for application across broad classes of nanomaterials. The dye assay method was further used to measure changes in the surface hydrophobicity of TiO2 NPs after being suspended in natural water collected from the Alsea Rivers watershed in Oregon. TiO2 NPs adsorbed Rose Bengal when suspended in ultrapure water, but adsorbed Nile Blue after being incubated in natural water samples, demonstrating a shift from hydrophobic to hydrophilic properties on the outer surface. The dye adsorption method can be applied to characterize surface hydrophobicity of NPs and quantify environmental transformations, potentially improving environmental fate models.


Assuntos
Cromatografia/métodos , Corantes Fluorescentes/química , Interações Hidrofóbicas e Hidrofílicas , Nanopartículas/química , Oxazinas/química , Rosa Bengala/química , Espectrometria de Fluorescência/métodos , Adsorção , Cobre/química , Ouro/química , Dióxido de Silício/química , Propriedades de Superfície
6.
PLoS One ; 15(6): e0234849, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32555627

RESUMO

Fluorescent proteins that modulate their emission intensities when protonated serve as excellent probes of the cytosolic pH. Since the total fluorescence output fluctuates significantly due to variations in the fluorophore levels in cells, eliminating the dependence of the signal on protein concentration is crucial. This is typically accomplished with the aid of ratiometric fluorescent proteins such as pHluorin. However, pHluorin is excited by blue light, which can complicate pH measurements by adversely impacting bacterial physiology. Here, we characterized the response of intensity-based, pH-sensitive fluorescent proteins that excite at longer wavelengths where the blue light effect is diminished. The pH-response was interpreted in terms of an analytical model that assumed two emission states for each fluorophore: a low intensity protonated state and a high intensity deprotonated state. The model suggested a scaling to eliminate the dependence of the signal on the expression levels as well as on the illumination and photon-detection settings. Experiments successfully confirmed the scaling predictions. Thus, the internal pH can be readily determined with intensity-based fluorophores with appropriate calibrations irrespective of the fluorophore concentration and the signal acquisition setup. The framework developed in this work improves the robustness of intensity-based fluorophores for internal pH measurements in E. coli, potentially extending their applications.


Assuntos
Proteínas de Bactérias/metabolismo , Fluorescência , Proteínas de Fluorescência Verde/metabolismo , Concentração de Íons de Hidrogênio , Proteínas Luminescentes/metabolismo , Escherichia coli/metabolismo , Espectrometria de Fluorescência/métodos
7.
Food Chem ; 326: 126935, 2020 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-32447160

RESUMO

Carbon dots (CDs) have been a new class of fascinating carbon-based fluorescent nanomaterials. In the present work, new N-doped CDs with highly crystalline graphite structures are prepared from renewable precursors, chitosan and tartaric acid, and are well characterized. The prepared CDs are applied as a biocompatible fluorescent sensor for the sequential detection of Fe3+ and AA. Among various transition metal ions, Fe3+ can selectively quench the fluorescence of CDs. Upon the further addition of AA, the quenched fluorescence of CDs is then restored as Fe3+ is reduced to Fe2+ by AA, which can be utilized for the fluorescent determination of AA. A good linear relationship in the range of 0-150 µM of AA concentration is established with a low detection limit of 0.02 µM. Moreover, the practical applications of this fluorescent sensing method in measurement of AA in food samples are successfully realized with satisfactory results.


Assuntos
Ácido Ascórbico/análise , Carbono/química , Compostos Férricos/análise , Nanoestruturas/análise , Espectrometria de Fluorescência/métodos , Fluorescência , Limite de Detecção , Nitrogênio/química , Pontos Quânticos/química , Espectrometria de Fluorescência/instrumentação
8.
Nucleic Acids Res ; 48(12): e67, 2020 07 09.
Artigo em Inglês | MEDLINE | ID: mdl-32421771

RESUMO

We designed and engineered a dye production cassette encoding a heterologous pathway, including human tyrosine hydroxylase and Amanita muscaria 4,5-DOPA dioxygenase, for the biosynthesis of the betaxanthin family of plant and fungal pigments in mammalian cells. The system does not impair cell viability, and can be used as a non-protein reporter system to directly visualize the dynamics of gene expression by profiling absorbance or fluorescence in the supernatant of cell cultures, as well as for fluorescence labeling of individual cells. Pigment profiling can also be multiplexed with reporter proteins such as mCherry or the human model glycoprotein SEAP (secreted alkaline phosphatase). Furthermore, absorbance measurement with a smartphone camera using standard application software enables inexpensive, low-tech reporter quantification.


Assuntos
Proteínas Fúngicas/metabolismo , Genes Reporter , Oxigenases/metabolismo , Ácidos Picolínicos/metabolismo , Análise de Célula Única/métodos , Absorção de Radiação , Animais , Células CHO , Cricetinae , Cricetulus , Proteínas Fúngicas/genética , Células HEK293 , Humanos , Microscopia de Fluorescência/métodos , Oxigenases/genética , Ácidos Picolínicos/efeitos da radiação , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Espectrometria de Fluorescência/métodos , Tirosina 3-Mono-Oxigenase/genética , Tirosina 3-Mono-Oxigenase/metabolismo , Raios Ultravioleta
9.
Yakugaku Zasshi ; 140(5): 739-750, 2020.
Artigo em Japonês | MEDLINE | ID: mdl-32378678

RESUMO

To prevent the abuse of new psychoactive substances (NPS), a total of 2372 substances and two plants are controlled as "Designated Substances" in Japan as of September 2019. Although the distribution of these substances has decreased for the past three years, newly-emerged NPS are still being found. In this study, we detected four lysergic acid diethylamide (LSD) derivatives as designer drugs from four paper sheet products, which were obtained from 2014 to 2017 in Japan. The compounds were identified as 4-Acetyl-N,N-diethyl-7-methyl-4,6,6a,7,8,9-hexahydroindolo[4,3-fg]quinoline-9-carboxamide (ALD-52), N,N,7-triethyl-4,6,6a,7,8,9-hexahydroindolo[4,3-fg]quinoline-9-carboxamide (ETH-LAD), 7-Allyl-N,N-diethyl-4,6,6a,7,8,9-hexahydroindolo[4,3-fg]quinoline-9-carboxamide (AL-LAD), N,N-diethyl-7-methyl-4-propionyl-4,6,6a,7,8,9-hexahydroindolo[4,3-fg]quinoline-9-carboxamide (1P-LSD), by GC-MS, LC-MS, LC-Q-TOF-MS and NMR analyses. Further, we studied the extraction methods of LSD derivatives from paper sheet, and the analytical conditions of GC-MS, LC-MS and LC-FL(fluorescence). Among LSD derivatives, 1P-LSD have been controlled as designated substances (Shitei Yakubutsu) under the Pharmaceutical and Medical Device Act in Japan since April 2016. For the legislation of the other derivatives identified in this study, the evaluation of their pharmacological properties are now in progress.


Assuntos
Drogas Desenhadas/análise , Drogas Ilícitas/análise , Dietilamida do Ácido Lisérgico/análise , Papel , Cromatografia Líquida/métodos , Cromatografia Gasosa-Espectrometria de Massas/métodos , Dietilamida do Ácido Lisérgico/análogos & derivados , Dietilamida do Ácido Lisérgico/química , Espectroscopia de Ressonância Magnética/métodos , Espectrometria de Massas/métodos , Espectrometria de Fluorescência/métodos
10.
Food Chem ; 327: 127058, 2020 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-32464462

RESUMO

A "turn-on" fluorescence sensor was developed for total detection of fumonisin B1, B2 and B3 (FB1, FB2 and FB3) in maize samples. Rhodamine B isothiocyanate (RBITC) and gold nanoparticles (AuNPs) were employed as the energy donor-acceptor pairs. The intensity of restored fluorescence was inversely proportional to the concentration of the FBs. The limit of detection (LOD) of the sensor for FB1 was 23.80 pg/mL. The coefficient of variation (CV) was both less than 7% for intra- and inter-assay. The linear range was from 51.39 to 2125.92 pg/mL. The average recoveries of FBs from maize samples were ranged from 88.7% to 107.2%. The correlation coefficient of the results between the developed sensor and LC-MS/MS was 0.9970. To fulfill the procedure of the assay, only 46 min was needed. These results suggest that the fluorescence "turn-on" sensor has great potential applications in the analysis of FBs in maize samples.


Assuntos
Cisteamina/química , Fumonisinas/análise , Espectrometria de Fluorescência/métodos , Contaminação de Alimentos/análise , Ouro/química , Limite de Detecção , Nanopartículas Metálicas/química , Rodaminas/química , Zea mays/química , Zea mays/metabolismo
12.
Anal Chim Acta ; 1113: 43-51, 2020 May 29.
Artigo em Inglês | MEDLINE | ID: mdl-32340668

RESUMO

This study fabricated a dual-emission probe consisting of monolayer MoS2 quantum dots (M - MoS2 QDs) and L-cystine-linked boron-dipyrromethene (L-Cys-BODIPY) molecules for ratiometric sensing of biothiols, thiol product-related enzyme reactions, and ratiometric imaging of glutathione (GSH)-related reactions in HeLa cells. The formation of L-Cys-BODIPY-adsorbed M - MoS2 QDs (named as BODIPY-M-MoS2 QDs) was demonstrated by comparing them with M - MoS2 QDs using transmission electron microscopy, atomic force microscopy, and X-ray photoelectron spectroscopy. The BODIPY-M-MoS2 QDs exhibited dual-emission bands, excellent biocompatibility, and good resistance to photobleaching. It was found that the adsorbed L-Cys-BODIPY molecules rarely quenched the fluorescence of M - MoS2 QDs, and meanwhile, they were self-quenched by π-π stacking between each BODIPY backbones. The presence of biothiols induced the reduction of weakly fluorescent L-Cys-BODIPY to strongly fluorescent of L-cysteine-conjugated BODIPY. Since having a much higher molar absorption coefficient than L-Cys-BODIPY, the liberated L-cysteine-conjugated BODIPY behaved as an effective inner filter to absorb the excitation light and subsequently quenched the fluorescence of M - MoS2 QDs. The appearance of L-cysteine-conjugated BODIPY could barely affected to the fluorescence lifetime of M - MoS2 QDs, confirming the inner filter effect of L-cysteine-conjugated BODIPY onto the fluorescence of M - MoS2 QDs. The present probe not only provided a linear ratiometric response to 1-10 mM GSH, 1-10 µM cysteine, and 1-10 µM of homocysteine but also remarkably showed the ratiometric detection of thiol products from the reactions of 1-900 units L-1 S-adenosylhomocysteine (SAH) hydrolase and SAH as well as 1-850 units L-1 GSH reductase and disulfide GSH. Additionally, the present probe was well-suited for ratiometric imaging of intracellular GSH levels in non-treated and drug-treated HeLa cells.


Assuntos
Cisteína/análise , Corantes Fluorescentes/química , Glutationa/análise , Homocisteína/análise , Pontos Quânticos/química , Compostos de Boro/química , Cistina/química , Dissulfetos/química , Células HeLa , Humanos , Limite de Detecção , Molibdênio/química , Espectrometria de Fluorescência/métodos
13.
Chemosphere ; 254: 126830, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32330758

RESUMO

Excitation-emission matrix (EEM) fluorescence spectroscopy is a powerful tool for the characterization of dissolved organic matter (DOM) in wastewater systems. It is of particular value if its utility could be extended by connecting the spectral features to hydrophobicity, one of the fundamental physicochemical properties of DOM. In this study, we employed a DAX-8 resin column to fractionate the hydrophobic/philic components of DOM and determine the relative degree of hydrophobicity by adjusting the critical retention factor (k'cr, the ratio of treated water sample volume to column volume). A higher k'cr would result in a higher hydrophobicity of the column effluent. At different k'cr values (5, 10, 25, 50, 100, and 200), the EEM characteristics of the obtained DOM components were inspected, including overall properties (average fluorescence per total organic carbon and UV absorbance), regional properties (fluorescence regional integration (FRI) and its secondary parameters), and energy-related properties (energy level of the excited states, Stokes shift for relaxation of the excited states, and fluorescence lifetime). In case studies of a wastewater membrane bioreactor and an oxidation ditch, plenty of the EEM properties varied significantly with logk'cr (r > 0.9, p < 0.05). The average fluorescence per UV absorbance (reflecting quantum yield), fluorescence proportion at Stokes shift ≥ 1.1 µm-1, and some secondary FRI parameters presented the best linear fitting with logk'cr, suggesting a smooth variation of the π-conjugated structures with the relative degree of DOM hydrophobicity. This may help to further understand the relationship between EEM fingerprints and DOM hydrophobicity.


Assuntos
Monitoramento Ambiental , Poluentes Químicos da Água/análise , Reatores Biológicos , Fracionamento Químico , Fluorescência , Substâncias Húmicas/análise , Interações Hidrofóbicas e Hidrofílicas , Espectrometria de Fluorescência/métodos , Águas Residuárias/análise , Águas Residuárias/química
14.
AAPS PharmSciTech ; 21(4): 122, 2020 Apr 26.
Artigo em Inglês | MEDLINE | ID: mdl-32337617

RESUMO

This study aimed to investigate the effect of pH-mediated surface properties of bovine serum albumin (BSA) on protein aggregation and the changes of protein structure and colloidal stability at different solution pH levels. The hydrophobicity of BSA surface was characterized by endogenous fluorescence spectroscopy, fluorescence quenching of acrylamide, and fluorescence probe. The results showed that the hydrophobicity of BSA surface was similar at pH 5, 6, 7.4, followed by pH 4, 8, 9, 10, and finally by pH 3 and 11 with strong acidity and alkalinity. The positive charge on the BSA surface was increased gradually with the decrease of solution pH, while the negative charge on protein surface was increased gradually with the increase of solution pH. The degree of protein aggregation was examined by turbidimetry, flow cytometry, and SDS-PAGE. The results showed that the oscillating aggregation of BSA did not change with the solution pH, but was partially dependent on the relative contribution of electrostatic and hydrophobic interactions between the protein molecules. In addition, the secondary structure, conformational stability, unfolding degree, and colloidal stability of proteins were investigated by circular dichroism, fluorescence spectroscopy, protein pulse hydrolysis, and dynamic light scattering, respectively. The results suggested that the solution pH could change the structure and stability of the protein at different levels. Solution pH has distinct effects on the structural stability of protein at different levels. The change of protein surface properties mediated by solution pH is related to protein aggregation.


Assuntos
Agregados Proteicos , Soroalbumina Bovina/química , Água/química , Animais , Bovinos , Dicroísmo Circular/métodos , Corantes Fluorescentes/química , Corantes Fluorescentes/metabolismo , Concentração de Íons de Hidrogênio , Interações Hidrofóbicas e Hidrofílicas , Estrutura Secundária de Proteína , Soroalbumina Bovina/metabolismo , Espectrometria de Fluorescência/métodos , Eletricidade Estática , Propriedades de Superfície , Água/metabolismo
15.
Chemosphere ; 252: 126559, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32220721

RESUMO

In this study, fluorescent dissolved organic matter (FDOM) in real printing and dyeing wastewater (PDW) during full-scale two-stage treatment was characterized using excitation-emission matrix (EEM), apparent molecular weight (AMW) cutoff by centrifugal ultrafiltration and high-performance liquid chromatography with fluorescence detector (HPLC-FLD). EEMs of PDW during treatment were relatively invariable with two typical and dominant peaks (P1, 275/320 nm and P2, 230/340 nm). The removal rates of P1 intensity and P2 intensity were both lower than those of DOC or UVA254 during the 1st stage and 2nd stage treatment. The <3 kDa fraction made major contribution to DOC, UVA254, P1 and P2 intensity. The DOM fractions with different AMW exhibited different removal behaviors during the 1st stage and 2nd stage treatment. The <3 kDa fraction of FDOM was poorly removed by biological treatment alone. The HPLC-FLD multi-emission scan results indicated that the major part of FDOM clusters were hydrophilic and they were more difficult to remove than the transphilic and hydrophobic FDOM clusters. According to the physicochemical properties of FDOM in PDW, selective adsorption and advanced oxidation process could be prior options for PDW advanced treatment.


Assuntos
Eliminação de Resíduos Líquidos/métodos , Adsorção , Cromatografia Líquida de Alta Pressão , Corantes , Substâncias Húmicas/análise , Interações Hidrofóbicas e Hidrofílicas , Peso Molecular , Impressão Tridimensional , Espectrometria de Fluorescência/métodos , Águas Residuárias/química
16.
PLoS One ; 15(3): e0230646, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32208468

RESUMO

Pesticides, widely used in modern agriculture, could potentially cause environmental pollution and affect human lives. Hence, the development of a highly sensitive sensing element to detect pesticide residues is crucial for food safety and ecosystem protection. Optical methods based on fluorescence properties provide an ideal approach for screening and quantification of these compounds in different medias including water, plant, and nutritional products. The development of fluorescence emitting carbon dot-based sensors for monitoring pesticides has attracted great attention in recent years. In comparison to other fluorophores, carbon dots have more promising optical features, higher quantum yields and better biocompatibility. This article aims to present a novel fluorescent sensing method of diazinon, glyphosate, and amicarbazone using plant-based carbon dots. A comprehensive characterization of carbon dots obtained from cauliflower was performed by methods including UV-visible, FTIR spectroscopy, fluorometry, AFM, DLS, and zeta sizer. Following this step, carbon dots were used to detect pesticides. The fluorescence quenching property of carbon dots has been utilized to identify detection limit of 0.25, 0.5, and 2 ng ml-1 for diazinon, amicarbazone, and glyphosate, respectively. Also, real sample study revealed that the detection of pesticides accompanied by our developed nano-sensor is repeatable and accurate. According to carbon dots specificity determination, the prepared nano sensor does not have the potential to identify "bromacil" and "dialen super" pesticides but the other three mentioned pesticides are detectable. The results confirm that synthesized green carbon dots are well qualified for application in food safety and environmental monitoring.


Assuntos
Carbono/química , Praguicidas/análise , Pontos Quânticos/química , Espectrometria de Fluorescência/métodos , Diazinon/análise , Monitoramento Ambiental , Contaminação de Alimentos/análise , Glicina/análogos & derivados , Glicina/análise , Limite de Detecção , Lycopersicon esculentum/química , Lycopersicon esculentum/metabolismo , Triazóis/análise
17.
Food Chem ; 318: 126506, 2020 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-32126473

RESUMO

Orange peels were applied as precursors to synthesize carbon dots (CDs) via a one-step green hydrothermal method. The relationship between quantum yield and volatile oils in 14 different varieties of orange peels were investigated. The CDs showed strong blue fluorescence and were further modified with EDTA. Compared with the CDs, the CDs@EDTA exhibited higher sensitivity for Cr(VI) detection with a LOD of 10 nM. The CDs@EDTA was proved to be an effective fluorescent sensor element for Cr(VI) detection in water samples with recoveries ranged from 92.09% to 104.87% (RSD < 5%). Moreover, CDs@EDTA/Cr(VI) system was further developed as a fluorescent "off-on" sensor for ascorbic acid (AA) detection with a LOD of 0.1 µM. Further, the sensor had been successfully applied for the analysis of AA in fresh oranges and commercial orange juices. The recoveries of AA in fresh oranges and orange juices were 92.58-106.76% and 91.54-104.95%, respectively.


Assuntos
Ácido Ascórbico/análise , Carbono/química , Citrus sinensis/química , Sucos de Frutas e Vegetais/análise , Espectrometria de Fluorescência/métodos , Cromo/química , Ácido Edético/química , Fluorescência , Frutas/química , Pontos Quânticos/química , Sensibilidade e Especificidade
18.
Food Chem ; 318: 126508, 2020 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-32146312

RESUMO

This work was aimed to obtain lactoferrin peptides, with anthocyanins-binding capabilities, by using eggplant peels extract as a source of anthocyanins. The chromatographic analysis of the extract evidenced the presence of five individual anthocyanins, with delfinidin-3-rutinoside being identified as the predominant. 20 small peptides were identified, from which four are containing Trp at C-terminal. By estimating the thermodynamic parameters, van der Waals and hydrogen bonding were found to have important roles in binding of anthocyanins to LF and LF-derived peptides. In order to complement the experimental results, the in silico methods were further employed to add single molecule level details on the potential interactions between different peptides and the main anthocyanins from eggplant peels. The docking tests indicated that the Trp containing peptides can bind, with different affinities either delphynidine-3-glycoside or delphynidine-3-rutinoside, therefore explaining the fluorescence quenching results. Our results have indicated a mechanism for the interactions between anthocyanins and LF and its small molecular weight peptides, whereas providing insights for formulating ingredients and foods with enhanced bioactives-binding properties.


Assuntos
Antocianinas/química , Lactoferrina/química , Peptídeos/química , Extratos Vegetais/química , Solanum melongena/química , Animais , Bovinos , Fluorescência , Ligação de Hidrogênio , Modelos Moleculares , Simulação de Acoplamento Molecular , Espectrometria de Fluorescência/métodos , Termodinâmica
19.
Ecotoxicol Environ Saf ; 194: 110447, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32171959

RESUMO

Many reports have investigated the effects of carbon nanotubes (CNTs) on the properties of terrestrial dissolved organic matter (DOM), which could significantly altered its binding affinity for contaminants. However, the effects of CNTs on algogenic DOM are largely unknown. To address this issue, the properties of algogenic DOM released by Prorocentrum donghaiense (P. donghaiense-DOM) under the stress from 0.1 to 10.0 mg/L graphitized multiwalled CNTs were nondestructively characterized by the use of UV-visible absorption and fluorescence excitation-emission matrices with parallel factor analysis. The results showed that the changes in the properties of P. donghaiense-DOM were highly dependent on the CNTs concentration. The properties of P. donghaiense-DOM under 0.1 mg/L CNTs treatment showed no obvious differences compared to the control. The addition of 0.5-10.0 mg/L CNTs changed the release pathways of P. donghaiense-DOM, resulting in significant alterations to the properties of P. donghaiense-DOM. The aromaticity, molecular weight, protein-like and humic-like components were enhanced under stress from 0.5 to 1.0 mg/L CNTs on day 4, which can be ascribed to the overproduction of extracellular DOM (EDOM) that occurred in response to the significant increase in intracellular ROS levels. CNTs at 5.0 and 10.0 mg/L significantly induced membrane damage to P. donghaiense on day 4, which led to the leakage of intracellular DOM (IDOM) and then increased the molecular weight and protein-like components but decreased the aromaticity and humic-like components. After the P. donghaiense recovered to its normal growth under 0.5-10.0 mg/L CNTs treatments, the changes in the properties of P. donghaiense-DOM were attributed to the release pathways of P. donghaiense-DOM that were governed by the production of EDOM and the leakage of IDOM in the stationary and declining phases, respectively.


Assuntos
Dinoflagelados/fisiologia , Nanotubos de Carbono/química , Análise Fatorial , Fluorescência , Substâncias Húmicas/análise , Espectrometria de Fluorescência/métodos
20.
Phys Rev Lett ; 124(10): 108102, 2020 Mar 13.
Artigo em Inglês | MEDLINE | ID: mdl-32216409

RESUMO

Lipid rafts serve as anchoring platforms for membrane proteins. Thus far they escaped direct observation by light microscopy due to their small size. Here we used differently colored dyes as reporters for the registration of both ordered and disordered lipids from the two leaves of a freestanding bilayer. Photoswitchable lipids dissolved or reformed the domains. Measurements of domain mobility indicated the presence of 120 nm wide ordered and 40 nm wide disordered domains. These sizes are in line with the predicted roles of line tension and membrane undulation as driving forces for alignment.


Assuntos
Lipídeos de Membrana/administração & dosagem , Microdomínios da Membrana/química , Colesterol/química , Colesterol/metabolismo , Diglicerídeos/química , Diglicerídeos/metabolismo , Lipídeos de Membrana/química , Lipídeos de Membrana/metabolismo , Microdomínios da Membrana/metabolismo , Proteínas de Membrana/química , Proteínas de Membrana/metabolismo , Microscopia Confocal/métodos , Modelos Químicos , Fosfatidilcolinas/química , Fosfatidilcolinas/metabolismo , Espectrometria de Fluorescência/métodos
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