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1.
Methods Mol Biol ; 2599: 141-162, 2023.
Artículo en Inglés | MEDLINE | ID: mdl-36427148

RESUMEN

Eukaryotic transcriptional regulatory factors, such as transcription factors and epigenetic regulatory factors, must locate, bind, and assemble at specific genomic regions to execute functions within the complex and crowded environment of the nucleus. These dynamic processes are typically at nonequilibrium, so quantifying their binding and target-search processes within the native environment is essential for understanding transcriptional mechanisms. Live-cell single-molecule tracking (SMT) is an emerging technique that can be utilized to observe molecular trajectories of individual transcriptional regulatory complexes within the nucleus. Here, we describe the use of live-cell SMT to observe trajectories of individual transcriptional regulatory complexes. We delineate the imaging analysis to obtain chromatin-bound fraction and residence time. Finally, we elaborate on the kinetic modeling to estimate target-search parameters. These binding and target-search parameters facilitate the understanding of how transcription is spatially and temporally regulated under physiological and pathological conditions.


Asunto(s)
Imagen Individual de Molécula , Factores de Transcripción , Factores de Transcripción/genética , Cinética , Física , Núcleo Celular
2.
Bioresour Technol ; 367: 128252, 2023 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-36334864

RESUMEN

Enzymatic hydrolysis is the key step limiting the efficiency of the biorefinery of lignocellulosic biomass. Enzymes involved in enzymatic hydrolysis and their interactions with biomass should be comprehended to form the basis for looking for strategies to improve process efficiency. This article updates the contemporary research on the properties of key enzymes in the lignocellulose biorefinery and their interactions with biomass, adsorption, and hydrolysis. The advanced analytical techniques to track the interactions for exploiting mechanisms are discussed. The challenges and prospects for future research are outlined.


Asunto(s)
Lignina , Biomasa , Lignina/metabolismo , Hidrólisis , Adsorción
3.
J Hazard Mater ; 443(Pt B): 130324, 2023 Feb 05.
Artículo en Inglés | MEDLINE | ID: mdl-36444053

RESUMEN

The contamination of saline soil with hazardous petroleum hydrocarbons is a common problem across coastal areas globally. Bioaugmentation combined with chemical treatment is an emerging remediation technique, but it currently shows low efficiency under high saline environments. In this study, we screened and used a novel halotolerant lipolytic fungal consortium (HLFC) combined with hematite (Fe2O3) for the bioremediation of diesel contaminated saline soils. The changes in total petroleum hydrocarbons (TPH) concentrations, enzyme activity, and microbial diversity were compared among different treatments (HLFC, hematite, hematite-HLFC, and control). The results showed that TPH degradation was significantly (P < 0.05) enhanced in hematite-HLFC (47.59-88.01%) and HLFC (24.26-72.04%) amended microcosms across all salinity levels, compared to the treatments of hematite (23.71-66.26%) and control (6.39-55.20%). TPH degradation was positively correlated with lipase and laccase enzyme activities, electrical conductivity, and the water holding capacity of the soil. Analyses of the microbial community structure showed that microbial richness decreased, while evenness increased in HLFC and hematite-HLFC treatments. The relative abundances of Alicyclobacillus, Sediminibacillus, Alcanivorax, Penicillium, Aspergillus, and Candida genera were significantly high in hematite-HLFC and HLFC amended microcosms. Our findings provide a promising new microbial-based technique, which can degrade TPH efficiently in saline soil.

4.
J Pharm Biomed Anal ; 223: 115152, 2023 Jan 20.
Artículo en Inglés | MEDLINE | ID: mdl-36399908

RESUMEN

Aromatic aldehydes act as allosteric effectors of hemoglobin (AEH), forming Schiff-base adducts with the protein to increase its oxygen (O2) affinity; a desirable property in sickle cell disease (SCD) treatment, as the high-O2 affinity hemoglobin (Hb) does not polymerize and subsequently prevents erythrocytes sickling. This study reports the development, validation, and application of a weak cation-exchange HPLC assay - quantifying the appearance of Hb-AEH adduct - as a "universal" method, allowing for the prioritization of AEH candidates through an understanding of their Hb binding affinity and kinetics. Concentration- and time-dependent Hb binding profiles of ten AEHs were determined with HPLC, followed by the appropriate non-linear modeling to characterize their steady-state binding affinity (KDss), and binding kinetics second-order association (kon) and first-order dissociation (koff) rate constants. Vanillin-derived AEHs exhibited enhanced binding affinity to Hb, primarily due to their faster kon. Across AEH, kon and koff values are strongly correlated (r = 0.993, n = 7), suggesting that modifications of the AEH scaffold enhanced their interactions with Hb as intended, but inadvertently increased their Hb-AEH adduct dissociation. To our knowledge, the present study is the first to provide valuable insight into Hb binding kinetics of antisickling aromatic aldehydes, and the assay will be a useful platform in screening/prioritizing drug candidates for SCD treatment.


Asunto(s)
Aldehídos , Hemoglobina A , Cromatografía Líquida de Alta Presión , Bases de Schiff , Oxígeno
5.
J Hazard Mater ; 443(Pt B): 130209, 2023 Feb 05.
Artículo en Inglés | MEDLINE | ID: mdl-36327836

RESUMEN

Petroleum leakages can seriously damage the soil environment and cause a persistent harm to human health, due to the release of heavy oil pollutants with a high viscosity and high molecular weight. In this paper, biochar aerogel materials were successfully prepared under 600, 700 and 800 â„ƒ (accordingly labeled as 600-aerogel, 700-aerogel and 800-aerogel) with green, sustainable and abundant sisal leaves as raw materials for the remediation of heavy oil-contaminated soil. The remediation performances of biochar aerogel supplement for heavy oil-contaminated soil were investigated, while microbial abundance and community structure were characterized. The degradation efficiency of 600-aerogel, 700-aerogel and 800-aerogel treatments was accordingly 80.69%, 86.04% and 86.62% after 60 days. Apart from adsorption behavior, biostimulation strengthened the degradation efficiency, according to findings from first-order degradation kinetics. Biochar aerogel supplement basically increased genera microbial abundance for Sinomonas, Streptomyces, Sphingomonas and Massilia with petroleum degradation abilities through microorganisms' biostimulation. Sinomonas as the dominant genus with the highest abundance probably contributed much higher capacities to heavy oil degradation. This study can provide an inspiring reference for the development of green carbon-based materials to be applied in heavy oil-contaminated soils through biostimulation mechanisms.


Asunto(s)
Petróleo , Contaminantes del Suelo , Humanos , Biodegradación Ambiental , Contaminantes del Suelo/metabolismo , Hidrocarburos/metabolismo , Microbiología del Suelo , Carbón Orgánico/química , Petróleo/metabolismo , Suelo/química
6.
J Hazard Mater ; 443(Pt B): 130247, 2023 Feb 05.
Artículo en Inglés | MEDLINE | ID: mdl-36345060

RESUMEN

Long-term and extensive usage of thiamethoxam, the second-generation neonicotinoid insecticide, has caused a serious threat to non-target organisms and ecological security. Efficient immobilized microorganism techniques are a sustainable solution for bioremediation of thiamethoxam contamination. A Gram-negative aerobic bacterium Chryseobacterium sp H5 with high thiamethoxam-degrading efficiencies was isolated from activated sludge. Then we developed a novel polyvinyl alcohol (PVA)/sodium alginate (SA)/biochar bead with this functional microbe immobilization to enhance the biodegradation and removal of thiamethoxam. Results indicated that the total removal and biodegradation rate of thiamethoxam with PVA/SA/biochar (0.7 %) beads with Chryseobacterium sp H5 immobilization at 30 °C and pH of 7.0 within 7 d reached about 90.47 % and 68.03 %, respectively, much higher than that using PVA/SA immobilized microbes (75.06 %, 56.05 %) and free microbes (61.72 %). Moreover, the PVA/SA/biochar (0.7 %) immobilized microbes showed increased tolerance to extreme conditions. Biodegradation metabolites of thiamethoxam were identified and two intermediates were first reported. Based on the identified biodegradation intermediates, cleavage of C-N between the 2-chlorothiazole ring and oxadiazine, dichlorination, nitrate reduction and condensation reaction would be the major biodegradation routes of thiamethoxam. Results of this work suggested the novel PVA/SA/biochar beads with Chryseobacterium sp H5 immobilization would be helpful for the effective bioremediation of thiamethoxam contamination.


Asunto(s)
Chryseobacterium , Alcohol Polivinílico , Biodegradación Ambiental , Alcohol Polivinílico/química , Alginatos/química , Tiametoxam , Células Inmovilizadas
7.
J Environ Sci (China) ; 124: 139-145, 2023 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-36182124

RESUMEN

The photochemical behavior of organic pollutants in ice is poorly studied in comparison to aqueous photochemistry. Here we report a detailed comparison of ice and aqueous photodegradation of two representative OH-PAHs, 2-hydroxyfluorene (2-OHFL) and 9-hydroxyfluorene (9-OHFL), which are newly recognized contaminants in the wider environment including colder regions. Interestingly, their photodegradation kinetics were clearly influenced by whether they reside in ice or water. Under the same simulated solar irradiation (λ > 290 nm), OHFLs photodegraded faster in ice than in equivalent aqueous solutions and this was attributed to the specific concentration effect caused by freezing. Furthermore, the presence of dissolved constituents in ice also influenced photodegradation with 2-OHFL phototransforming the fastest in 'seawater' ice (k = (11.4 ± 1.0) × 10-2 min-1) followed by 'pure-water' ice ((8.7 ± 0.4) × 10-2 min-1) and 'freshwater' ice ((8.0 ± 0.7) × 10-2 min-1). The presence of dissolved constituents (specifically Cl-, NO3-, Fe(III) and humic acid) influences the phototransformation kinetics, either enhancing or suppressing phototransformation, but this is based on the quantity of the constituent present in the matrixes, the specific OHFL isomer and the matrix type (e.g., ice or aqueous solution). Careful derivation of key photointermediates was undertaken in both ice and water samples using tandem mass spectrometry. Ice phototransformation exhibited fewer by-products and 'simpler' pathways giving rise to a range of hydroxylated fluorenes and hydroxylated fluorenones in ice. These results are of importance when considering the fate of PAHs and OH-PAHs in cold regions and their persistence in sunlit ice.


Asunto(s)
Hidrocarburos Policíclicos Aromáticos , Contaminantes Químicos del Agua , Compuestos Férricos , Fluorenos/análisis , Sustancias Húmicas/análisis , Hielo/análisis , Cinética , Fotólisis , Hidrocarburos Policíclicos Aromáticos/análisis , Agua/química , Contaminantes Químicos del Agua/análisis
8.
J Environ Sci (China) ; 124: 61-75, 2023 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-36182167

RESUMEN

Polycyclic aromatic hydrocarbons (PAHs) and their oxygenated derivates (O-PAHs) are identified in soils and groundwater of industrialized sites and contribute to the risk for Humans and the Environment. Nevertheless, data are scarce in literature concerning their retention and transfer in soils and no soil - water partition coefficients are available for these compounds. Sorption of two PAHs, fluorene and acenaphthene and two O-PAHs, 9H-fluorenone and dibenzofuran onto two soils with different organic carbon contents was evaluated and compared by determining their sorption isotherms. Effect of ionic strength and liquid to solid ratio, on fluorene and fluorenone sorption was also evaluated. Sorption equilibrium is achieved within less than 24 hr of mixing and linear sorption models best fit the isotherm data. Acenaphthene and dibenzofuran are similarly sorbed onto the soil. KD of fluorene is higher than the one of fluorenone, showing a smaller affinity of fluorenone towards the solid phase. This means that O-PAH could form larger contamination plumes in groundwater than PAHs. Decreasing the L/S ratio from 100 to 50 and 30, increases the sorption of fluorenone onto the soil by 56% and 67% respectively, while the sorption of fluorene is slightly increased. Increasing the ionic strength of the aqueous phase also modifies the sorption of fluorenone, contrary to the sorption of fluorene which is slightly affected.


Asunto(s)
Agua Subterránea , Hidrocarburos Policíclicos Aromáticos , Contaminantes del Suelo , Acenaftenos , Adsorción , Carbono , Dibenzofuranos , Fluorenos , Humanos , Hidrocarburos Policíclicos Aromáticos/análisis , Suelo , Contaminantes del Suelo/análisis , Agua
9.
Methods Mol Biol ; 2558: 63-74, 2023.
Artículo en Inglés | MEDLINE | ID: mdl-36169856

RESUMEN

The covalently bound FAD cofactor in monoamine oxidase (MAO) is reduced by the amine substrate and reoxidized by oxygen. Visible spectroscopy provides a convenient tool to study the interaction of ligands and the kinetics of the half-reactions for mechanistic investigations. Equilibrium redox titrations allow measurement of redox potentials, while rapid mixing experiments allow determination of the rate of reduction by different substrates and of covalent adduct formation by irreversible inactivators. Three techniques are described: (1) measuring ligand interactions by alterations in the spectrum, especially at 495 nm; (2) reducing MAO, including the essentials for anaerobic procedures; and (3) studying kinetics of reduction, reoxidation, or inactivation of MAO.


Asunto(s)
Flavina-Adenina Dinucleótido , Monoaminooxidasa , Aminas , Flavina-Adenina Dinucleótido/metabolismo , Cinética , Ligandos , Monoaminooxidasa/metabolismo , Oxidación-Reducción , Oxígeno , Análisis Espectral
10.
Methods Mol Biol ; 2578: 83-101, 2023.
Artículo en Inglés | MEDLINE | ID: mdl-36152282

RESUMEN

Microarray assay formats gained popularity in the 1990s, first implemented in DNA-based arrays but later adopted for use with proteins, namely antibodies, peptides, low molecular weight (LMW) molecules, such as lipids, and even tissues. In nucleic acid-based affinity assays and arrays, but not in protein or peptide arrays, the specificity and affinity of complementary strand interactions can be deduced from or adjusted through modifications to the nucleotide sequence. Arrays of LMW molecules are characterized by largely uniform but low binding affinities. Multiplexed protein-based affinity assays, such as microarrays, might present an additional challenge due to heterogeneity of antigen properties and of their binding affinities. The use of peptides instead of proteins reduces physical heterogeneity of these reagents through either the widened peptide selection options or rational sequence engineering. However, rational engineering of binding affinities remains an unmet need, and peptide-binding affinities to the respective antipeptide antibodies could vary by orders of magnitude. Hence, multiplexing of such assays by using a microarray format and data analysis and interpretation requires some knowledge of their binding affinities. Low-throughput binding assays to characterize such peptide-antipeptide antibodies interactions are widely available, but scaling-up of traditional protein- and peptide-binding assays might present practical challenges. Here, we describe fast label-free practical approach especially suitable for estimating peptide-binding affinities. The method in question relies on commercially available biolayer interferometry-based equipment with a protocol which can be easily scaled-up, subject to user needs and equipment availability.


Asunto(s)
Anticuerpos , Ácidos Nucleicos , Anticuerpos/metabolismo , ADN/metabolismo , Lípidos , Ácidos Nucleicos/metabolismo , Péptidos/química , Unión Proteica , Proteínas/metabolismo
11.
Methods Mol Biol ; 2570: 141-153, 2023.
Artículo en Inglés | MEDLINE | ID: mdl-36156780

RESUMEN

Due to their high specificity and affinity to target molecules, aptamers can be used as powerful tools in diagnostics, therapeutics, and environmental or food analytics. For the use in various applications, the detailed characterization of their binding behavior is an important step after selection to determine the interaction strength between the aptamer and its target and to find the best kinetics depending on the field of application. The surface plasmon resonance (SPR) spectroscopy is a powerful technology to investigate important parameters in molecular interaction, for example, kinetics, affinity, and specificity. The most-used system is the Biacore™ SPR system which comprises an optical biosensor for label-free monitoring of binding events in real time based on SPR. This biophysical phenomenon describes the changes in refractive index on a sensor surface which can be used to measure binding events and to determine kinetic constants. In this chapter, a detailed protocol for the determination of kinetic constants for protein-aptamer interaction is provided. An 82-nt long ssDNA aptamer which are targeted against human urokinase is used as a model system for determination of binding and dissociation constants using Biacore™ SPR technology. A detailed note section provides useful tips and pitfalls at the end of this chapter.


Asunto(s)
Aptámeros de Nucleótidos , Técnicas Biosensibles , Aptámeros de Nucleótidos/química , Fenómenos Biofísicos , Técnicas Biosensibles/métodos , Humanos , Cinética , Resonancia por Plasmón de Superficie/métodos , Activador de Plasminógeno de Tipo Uroquinasa
12.
Methods Mol Biol ; 2563: 413-424, 2023.
Artículo en Inglés | MEDLINE | ID: mdl-36227486

RESUMEN

Biomolecular condensation has emerged as a key organizing principle governing the formation of membraneless cellular assemblies. Revealing the mechanism of formation of biomolecular condensates requires the quantitative examination of their growth kinetics. Here, we introduce mass balance imaging (MBI) as a general method to study compositional growth dynamics based on fluorescent images of multicomponent clusters. MBI allows the visualization and measurement of composition-dependent growth rates of biomolecular condensates and other assemblies. We provide a computational pipeline and demonstrate the applicability of our method by investigating cortical assemblies containing N-WASP (WSP-1) and F-actin that appear during oocyte cortex activation in C. elegans. In general, the method can be broadly implemented to identify interactions that underlie growth kinetics of multicomponent assemblies in vivo and in vitro.


Asunto(s)
Actinas , Orgánulos , Animales , Condensados Biomoleculares , Caenorhabditis elegans , Cinética
13.
Spectrochim Acta A Mol Biomol Spectrosc ; 284: 121802, 2023 Jan 05.
Artículo en Inglés | MEDLINE | ID: mdl-36070674

RESUMEN

Diflunisal (5-(2,4-Difluorophenyl)salicylic acid, DIF), salicylic acid (SAL) derivative, which, on the one hand, is active pharmaceutical ingredient, on the other hand, belongs to the compounds exhibiting excited-state intramolecular proton transfer (ESIPT) behaviour was used to study the drug interactions with poly(vinyl alcohol) (PVA) matrix. For clarifying the nature and mechanisms of the drug-matrix interactions the salicylic acid (SAL) molecule was selected as the model active ESIPT compound, whose physicochemical properties in different media are well understood. The solute-solvent interactions (non-specific (dipole-dipole) versus specific (hydrogen bonding)) of DIF and SAL with different neat solvents were investigated using the steady-state spectroscopic technique. The solvent effect on spectral behaviours of DIF and SAL was analyzed based on the parametric solvent scales. In order to identify functional groups in the PVA matrices, determine the structure present in the studied molecule-PVA system and thus obtain information about the potential interactions between PVA and the studied molecules, the Raman spectra of pure PVA, SAL-PVA and DIF-PVA systems were measured. It has been shown that the molecular structure of the active substance entrapped in the polymer matrix affects the structure of the polymer, i.e., isotactic (SAL-PVA) versus syndiotactic (DIF-PVA) structure. The analysis of drug release kinetics revealed that the DIF is more strongly bound to PVA in comparison to SAL, which confirms conclusions drawn from the analysis of the Raman spectra i.e., the isotactic structure of SAL-PVA material results in a faster initial release process of weakly bound, located on the surface of the polymer SAL molecules.


Asunto(s)
Diflunisal , Alcohol Polivinílico , Enlace de Hidrógeno , Preparaciones Farmacéuticas , Polímeros/química , Alcohol Polivinílico/química , Protones , Ácido Salicílico , Solventes
14.
Rev. bras. med. esporte ; 29: e2022_0171, 2023. tab
Artículo en Inglés | LILACS | ID: biblio-1394839

RESUMEN

ABSTRACT Introduction: Muscle strength is directly related to its cross-sectional area and the volume of its fibers, but there is no absolute linear relationship between hypertrophy and improvement in athletic performance. Under this complex perspective, muscle training strategies have been implemented to promote relevant muscle strength and improve overall athletic ability. Objective: Explore the impacts of muscle strength training on young athletes based on sport kinetic principles. Methods: we adopted the method of intragroup statistical comparison with body indexes of 10 volunteers undergoing muscle training focused on the core and lower limb set. Results: Muscle strength gain was effectively verified via electromyogram, and the test of athletic skills showed an evolution in jumping, balance, and reduction of wrong passes. Conclusion: Evidence-based muscle training can increase muscle strength and promote sports skill gain in young athletes. Level of evidence II; Therapeutic studies - investigation of treatment results.


RESUMO Introdução: A força muscular está ligada diretamente à área de sua seção transversal e ao volume de suas fibras, porém não há relação linear absoluta entre hipertrofia e melhora no desempenho atlético. Sob essa complexa perspectiva, estratégias de treinamento muscular vêm sendo implementadas para promover a força muscular relevante, no intuito de promover a melhora da capacidade atlética geral. Objetivo: Explorar os impactos do treinamento de força muscular nos jovens atletas baseado nos princípios cinéticos do esporte. Métodos: adotou-se o método de comparação estatística intragrupo com índices corporais de 10 voluntários submetidos ao treinamento muscular focado no conjunto do core e membros inferiores. Resultados: O ganho de força muscular foi efetivamente constatado via eletromiograma e o teste das habilidades atléticas demonstrou uma evolução no salto, equilíbrio e redução de passes errados. Conclusão: O treinamento muscular baseado em evidências consegue aumentar a força muscular e promover o ganho de habilidade esportiva nos jovens atletas. Nível de evidência II; Estudos terapêuticos - investigação dos resultados do tratamento.


RESUMEN Introducción: La fuerza muscular está directamente relacionada con su área transversal y con el volumen de sus fibras, pero no existe una relación lineal absoluta entre la hipertrofia y la mejora del rendimiento deportivo. Bajo esta compleja perspectiva, se han implementado estrategias de entrenamiento muscular para promover la fuerza muscular pertinente, con el fin de promover la mejora de la capacidad atlética general. Objetivo: Explorar los impactos del entrenamiento de la fuerza muscular en jóvenes atletas basándose en los principios de la cinética deportiva. Métodos: se adoptó el método de comparación estadística intragrupo con los índices corporales de 10 voluntarios sometidos a un entrenamiento muscular centrado en todo el núcleo y las extremidades inferiores. Resultados: La ganancia de fuerza muscular se verificó eficazmente a través del electromiograma y la prueba de habilidades atléticas mostró una evolución en los saltos, el equilibrio y la reducción de los pases erróneos. Conclusión: El entrenamiento muscular basado en la evidencia puede aumentar la fuerza muscular y promover la ganancia de habilidades deportivas en los atletas jóvenes. Nivel de evidencia II; Estudios terapéuticos - investigación de los resultados del tratamiento.


Asunto(s)
Humanos , Adulto Joven , Rendimiento Atlético/fisiología , Entrenamiento de Fuerza/métodos , Atletas , Deportes Juveniles/fisiología
15.
Food Chem ; 399: 133972, 2023 Jan 15.
Artículo en Inglés | MEDLINE | ID: mdl-36027810

RESUMEN

Pomegranate (Punica grantum L.) fruit juice was concentrated by forward osmosis or thermal evaporation and the samples were stored at ambient (25 °C) and accelerated (37 °C) storage conditions. The anthocyanin content of raw, reconstituted forward osmosis as well as reconstituted thermally evaporated pomegranate juice were 421.1, 414.4 and 357.2 mg/kg respectively. The physicochemical attributes of pomegranate juice concentrate such as anthocyanin content, antioxidant activity, browning index, and hydroxymethyl furfural showed that the quality of the concentrate was markedly affected by storage conditions. Based on the hydroxymethyl furfural content (≤25 mg/kg), it was concluded that the forward osmosis concentrated juices could be stored at ambient and accelerated conditions for ∼101 and ∼66 days, respectively. While, thermally concentrated juice could only be stored for less ∼31 and ∼3 days, respectively. Forward osmosis could be a method to concentrate pomegranate juice with minimum effect on quality attributes with extended shelf life.


Asunto(s)
Jugos de Frutas y Vegetales , Granada (Fruta) , Antocianinas/análisis , Frutas/química , Furaldehído/análisis , Cinética , Ósmosis
16.
Food Chem ; 403: 134361, 2023 Mar 01.
Artículo en Inglés | MEDLINE | ID: mdl-36162266

RESUMEN

Self-assembly (formation and crystallization) kinetics of short-chain glucan aggregates (SCGAs) prepared at isothermal conditions (4, 20, 40, and 60℃) with or without nucleation (4℃, 1 h) were investigated. The fastest formation and crystallization rates of SCGA were observed when short-chain glucan was stored at 4℃ and 20℃, respectively. SCGA was not formed at 60℃. However, nucleation resulted in SCGA forming-ability at 60℃. Moreover, nucleation increased the yield in all temperature conditions. SCGA with nucleation decreased the crystal melting transition temperature range. All SCGAs had nanosized particles (<500 nm) with B-type crystal patterns regardless of temperature and nucleation. Consequently, self-assembly temperature and presence of nucleation step could change the physicochemical characteristics of SCGA, and manipulation of the nucleation step is expected to be an effective method to increase the yield of SCGA and produce SCGA at high temperature.


Asunto(s)
Glucanos , Cinética , Cristalización , Temperatura , Temperatura de Transición
17.
J Colloid Interface Sci ; 630(Pt A): 846-854, 2023 Jan 15.
Artículo en Inglés | MEDLINE | ID: mdl-36283267

RESUMEN

HYPOTHESIS: Polyelectrolyte adsorption is considered important in tuning the surface property and the fate of particles; however, often studied on macroscopic surfaces. To gain insights into how polyelectrolytes are adsorbed onto a single particle, it is imperative to utilize techniques capable of elucidating adsorption kinetics on a single-particle level in a controlled flow field. EXPERIMENTS: The polyelectrolyte adsorption kinetics was investigated by electrophoretic mobility measurements combined with the kinetics study onto a single-particle viewpoint using microfluidics and optical tweezers. We directly evaluated the thickness, δH, of adsorbed polyelectrolyte onto a negatively-charged silica particle to deduce the adsorbed polyelectrolyte's conformation. The effect of charge density and salt concentrations were studied. FINDINGS: All polyelectrolytes exhibited dependence of δH on salt concentration. The attractive interactions control the cationic polyelectrolytes adsorption process. The δH depends on charge density indicating more loops and tail confirmation for the weakly-charged polyelectrolytes. The anionic polyelectrolytes showed a dependence of the initial rate and saturation value of δH on salt concentrations, attributed to the repulsion between charged segments and the silica surfaces. Here, we present new insights into the polyelectrolyte adsorption kinetics, particularly the influence of electrostatic interaction from the single-particle perspective, inaccessible to conventional bulk measurements.


Asunto(s)
Microfluídica , Dióxido de Silicio , Adsorción , Polielectrolitos , Cinética , Electrólitos , Pinzas Ópticas
18.
Biochim Biophys Acta Gen Subj ; 1867(1): 130253, 2023 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-36228877

RESUMEN

BACKGROUND: Cells exposed to stress factors experience time-dependent variations of metabolite concentration, acting as reliable sensors of the effective concentration of drugs in solution. NMR can detect and quantify changes in metabolite concentration, thus providing an indirect estimate of drug concentration. The quantification of bactericidal molecules released from antimicrobial-treated biomedical materials is crucial to determine their biocompatibility and the potential onset of drug resistance. METHODS: Real-time NMR measurements of extracellular metabolites produced by bacteria grown in the presence of known concentrations of an antibacterial molecule (irgasan) are employed to quantify the bactericidal molecule released from antimicrobial-treated biomedical devices. Viability tests assess their activity against E. coli and S. aureus planktonic and sessile cells. AFM and contact angle measurements assisted in the determination of the mechanism of antibacterial action. RESULTS: NMR-derived concentration kinetics of metabolites produced by bacteria grown in contact with functionalized materials allows for indirectly evaluating the effective concentration of toxic substances released from the device, lowering the detection limit to the nanomolar range. NMR, AFM and contact angle measurements support a surface-killing mechanism of action against bacteria. CONCLUSIONS: The NMR based approach provides a reliable tool to estimate bactericidal molecule release from antimicrobial materials. GENERAL SIGNIFICANCE: The novelty of the proposed NMR-based strategy is that it i) exploits bacteria as sensors of the presence of bactericidal molecules in solution; ii) is independent of the chemo-physical properties of the analyte; iii) establishes the detection limit to nanomolar concentrations.


Asunto(s)
Antiinfecciosos , Staphylococcus aureus , Escherichia coli , Antibacterianos/farmacología , Antibacterianos/química , Bacterias , Antiinfecciosos/farmacología
19.
Chemosphere ; 310: 136852, 2023 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-36241115

RESUMEN

Iron (Fe) salt was applied extensively to remove phosphorus (P) in wastewater treatment plants (WWTPs). Exploring the formation mechanism of iron-phosphorus compounds (FePs) during the chemical P removal (CPR) process is beneficial to P recovery. In this study, the performance of P removal, FePs speciation analysis and the kinetics of P removal under different conditions (pH, Fe/P molar ratio (Fe/Pmol), type of Fe salt, dissolved organic matters) were comprehensively investigated. More than 95% of P was removed under the optimal conditions with pH = 4.7, Fe/Pmol = 2, FeCl3 or polymeric ferric sulfate (PFS) as the coagulant. The FePs formation mechanism was considerably influenced by reaction conditions. Iron-phosphate compounds were the dominant FePs species (>76%) at pH < 6.2, while more iron oxides were formed at pH ≥ 6.2 with decreased P removal efficiency. When the initial Fe/Pmol was 2, iron-phosphate compound was the only product that was formed by the reaction between PO43- and Fe(III) or Fe(II) ions directly. More iron oxides were generated when the initial Fe/Pmol was 1 or 3. At Fe/Pmol = 1, the Fe(III) was hydrolyzed to form iron oxides and trapped PO43-, while at Fe/Pmol = 3, iron-phosphate compounds were produced firstly and the remaining Fe(III) was hydrolyzed to form iron oxides. The pseudo-second-order kinetic model simulated the chemical P removal process well. The reaction rate of P with Fe(II) was slower than that with Fe(III), but complete removal was still achieved when the reaction time was more than 30 min. Poly-Fe salt exhibited a fast P removal rate, while the removal efficiency depended on its iron content. Organic matters in wastewater with large molecular weight and multiple functional groups (such as humic acids) inhibited P removal rate but hardly affect the removal amount. This study provides an insight into CPR by Fe salts and is beneficial for P recovery in WWTPs.


Asunto(s)
Compuestos Férricos , Compuestos de Hierro , Compuestos Férricos/química , Fósforo/química , Hierro/química , Fosfatos , Compuestos Ferrosos/química , Óxidos/química
20.
Chemosphere ; 310: 136879, 2023 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-36257386

RESUMEN

Despite increasing attention to the influence of unsteady-state volatile organic compounds (VOCs) on the adsorption of activated carbon, studies in this regard are rare. Therefore, in this study, an investigation into the migration and diffusion of unsteady-state VOCs on activated carbon adsorption beds under reverse ventilation was conducted. Here, reverse clean air was introduced when the activated carbon bed reached the penetration point. The influence of reverse ventilation temperature, reverse superficial gas velocity, activated carbon filling height, and different ventilation modes on the adsorption of unsteady toluene by activated carbon were studied. Our experimental results show that when the reverse ventilation temperature increased from 20 °C to 60 °C, the quasi-first-order desorption rate constant increased from 0.00356 min-1 to 0.00807 min-1, an increase in the reverse superficial gas velocity led to a higher rate constant, and at greater reverse superficial gas velocities, the stripping capacity increased. It was observed that the maximum stripping capacity was achieved at a reverse superficial gas velocity of 0.3 m/s. For different activated carbon filling heights, following reverse ventilation, the stripping capacity of a 5 cm and 30 cm activated carbon bed accounted for 41.43% and 65.85% of the original adsorption capacity, respectively. The study concludes that concentration of toluene first increased and then decreased with time under forward ventilation, whereas the concentration gradually decreased under reverse ventilation.


Asunto(s)
Compuestos Orgánicos Volátiles , Adsorción , Carbón Orgánico , Tolueno , Difusión
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