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1.
Environ Sci Technol ; 58(19): 8576-8586, 2024 May 14.
Artigo em Inglês | MEDLINE | ID: mdl-38696240

RESUMO

Humic acid (HA) is ubiquitous in natural aquatic environments and effectively accelerates decontamination by permanganate (Mn(VII)). However, the detailed mechanism remains uncertain. Herein, the intrinsic mechanisms of HA's impact on phenolics oxidation by Mn(VII) and its intermediate manganese oxo-anions were systematically studied. Results suggested that HA facilitated the transfer of a single electron from Mn(VII), resulting in the sequential formation of Mn(VI) and Mn(V). The formed Mn(V) was further reduced to Mn(III) through a double electron transfer process by HA. Mn(III) was responsible for the HA-boosted oxidation as the active species attacking pollutants, while Mn(VI) and Mn(V) tended to act as intermediate species due to their own instability. In addition, HA could serve as a stabilizer to form a complex with produced Mn(III) and retard the disproportionation of Mn(III). Notably, manganese oxo-anions did not mineralize HA but essentially changed its composition. According to the results of Fourier-transform ion cyclotron resonance mass spectrometry and the second derivative analysis of Fourier-transform infrared spectroscopy, we found that manganese oxo-anions triggered the decomposition of C-H bonds on HA and subsequently produced oxygen-containing functional groups (i.e., C-O). This study might shed new light on the HA/manganese oxo-anion process.


Assuntos
Substâncias Húmicas , Manganês , Oxirredução , Fenóis , Manganês/química , Fenóis/química , Ânions , Compostos de Manganês/química , Óxidos/química , Poluentes Químicos da Água/química
2.
Gen Physiol Biophys ; 43(3): 197-207, 2024 May.
Artigo em Inglês | MEDLINE | ID: mdl-38774920

RESUMO

The cystic fibrosis transmembrane conductance regulator (CFTR) Cl- channel uses positively charged amino-acid side-chains to form binding sites for permeating anions. These binding sites have been investigated experimentally using a number of anionic probes. Mutations that alter the distribution of positive and negative charges within the pore have differential effects on the binding of monovalent versus divalent anions. This study uses patch clamp recording from wild-type and pore-mutant forms of CFTR to investigate small trivalent anions (Co(NO2)63-, Co(CN)3- and IrCl63-) as potential probes of anion binding sites. These anions caused weak block of Cl- permeation in wild-type CFTR (Kd ≥ 700 µM) when applied to the intracellular side of the membrane. Mutations that increase the density of positive charge within the pore (E92Q, I344K, S1141K) increased the binding affinity of these anions 80-280-fold, and also greatly increased the voltage-dependence of block, consistent with fixed charges in the pore affecting monovalent : multivalent anion selectivity. However, high-affinity pore block by Co(NO2)63-apparently did not alter channel gating, a hallmark of high-affinity binding of divalent Pt(NO2)42- ions within the pore. This work increases the arsenal of probes available to investigate anion binding sites within Cl- channel pores.


Assuntos
Ânions , Regulador de Condutância Transmembrana em Fibrose Cística , Ativação do Canal Iônico , Regulador de Condutância Transmembrana em Fibrose Cística/metabolismo , Regulador de Condutância Transmembrana em Fibrose Cística/genética , Regulador de Condutância Transmembrana em Fibrose Cística/química , Ânions/metabolismo , Humanos , Animais , Sítios de Ligação , Mutação
3.
Bioorg Chem ; 147: 107421, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38714118

RESUMO

Targeting the homeostasis of anions and iron has emerged as a promising therapeutic approach for the treatment of cancers. However, single-targeted agents often fall short of achieving optimal treatment efficacy. Herein we designed and synthesized a series of novel dual-functional squaramide-hydroxamic acid conjugates that are capable of synergistically modulating the homeostasis of anions and iron. Among them, compound 16 exhibited the most potent antiproliferative activity against a panel of selected cancer cell lines, and strong in vivo anti-tumor efficacy. This compound effectively elevated lysosomal pH through anion transport, and reduced the levels of intracellular iron. Compound 16 could disturb autophagy in A549 cells and trigger robust apoptosis. This compound caused cell cycle arrest at the G1/S phase, altered the mitochondrial function and elevated ROS levels. The present findings clearly demonstrated that synergistic modulation of anion and iron homeostasis has high potentials in the development of promising chemotherapeutic agents with dual action against cancers.


Assuntos
Antineoplásicos , Apoptose , Proliferação de Células , Desenho de Fármacos , Ensaios de Seleção de Medicamentos Antitumorais , Homeostase , Ácidos Hidroxâmicos , Ferro , Humanos , Antineoplásicos/farmacologia , Antineoplásicos/síntese química , Antineoplásicos/química , Ferro/metabolismo , Ferro/química , Proliferação de Células/efeitos dos fármacos , Homeostase/efeitos dos fármacos , Relação Estrutura-Atividade , Ácidos Hidroxâmicos/farmacologia , Ácidos Hidroxâmicos/química , Ácidos Hidroxâmicos/síntese química , Estrutura Molecular , Apoptose/efeitos dos fármacos , Ânions/química , Ânions/farmacologia , Relação Dose-Resposta a Droga , Animais , Linhagem Celular Tumoral , Camundongos , Quinina/análogos & derivados
4.
Dalton Trans ; 53(20): 8633-8641, 2024 May 21.
Artigo em Inglês | MEDLINE | ID: mdl-38695060

RESUMO

Poor cellular permeability greatly hampers the utilization of anionic Ir(III) complexes, though efficiently emissive and remarkably stable, in cell-based diagnosis. To overcome this barrier, we present the development of an alkaline phosphatase (ALP)-responsive, anionic, and aggregation-induced emission (AIE)-active Ir(III) complex (Ir1) for specific recognition of osteosarcoma cells. Containing phosphate moieties, Ir1 exhibits a net -1 charge, enabling charge repulsion from the cell membrane and resulting in low cellular uptake and good biocompatibility in normal osteoblast cells. Upon ALP-mediated hydrolysis of phosphate groups, the resulting dephosphorylated product, Ir2, demonstrates a positive charge and increased lipophilicity, promoting cellular uptake and activating its AIE properties for specific recognition of osteosarcoma cells that express elevated levels of ALP. This study elucidates the role of ALP as an ideal trigger for enhancing the cellular permeability of phosphate ester-containing Ir(III) complexes, thus expanding the potential of anionic Ir(III) complexes for biomedical applications.


Assuntos
Fosfatase Alcalina , Ânions , Complexos de Coordenação , Irídio , Osteossarcoma , Irídio/química , Humanos , Osteossarcoma/patologia , Osteossarcoma/metabolismo , Fosfatase Alcalina/metabolismo , Complexos de Coordenação/química , Complexos de Coordenação/síntese química , Complexos de Coordenação/farmacologia , Ânions/química , Linhagem Celular Tumoral
5.
Chemosphere ; 358: 142215, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38701865

RESUMO

The existence of microplastics (MPs) in water is a significant global concern since they have the potential to pose a threat to human health. Therefore, there is a need to develop a sustainable treatment technology for MPs removal, as the conventional methods are inadequate to address this problem. Coagulation is a typical process in treatment plants that can capture MPs before releasing them into the environment. In this work, the removal behaviors of polyamide (PA), polystyrene (PS), and polyethylene (PE) MPs were systematically investigated through coagulation processes using aluminum sulfate (Al2(SO4)3) and Moringa oleifera (MO) seeds extract. Subsequently, the coagulation performance of Al2(SO4)3 was improved by the separate addition of anionic polyacrylamide (APAM) and naturally derived MO. Results showed that Al2(SO4)3 in combination with APAM had better performance than Al2(SO4)3 or MO alone. In the Al2(SO4)3+APAM system, the removal efficiencies were 93.47%, 81.25%, and 29.48% for PA, PS, and PE MPs, respectively. Furthermore, the effectiveness of the Al2(SO4)3 and MO blended system was approximately similar to the Al2(SO4)3+APAM system. However, the required amount of Al2(SO4)3 was decreased to 50% in the Al2(SO4)3+MO system compared to the optimal dosage in the Al2(SO4)3 system alone. The combination of 40 mg/L of Al2(SO4)3 and 60 mg/L of MO resulted in removal efficiencies of 92.99%, 80.48%, and 28.94% for PA, PS, and PE MPs, respectively. The high efficacy of these enhanced methods was due to the synergic effects of charge neutralization and agglomeration adsorption, which were validated through zeta potential assessments and visual analysis using scanning electron microscopy (SEM) images. In the case of experimental conditions, initial pH had little impact on removal efficiency, while NaCl salinity and stirring speed directly affected MPs removal. Consequently, this research took a step toward finding a green strategy to remove MPs from water systems.


Assuntos
Resinas Acrílicas , Microplásticos , Poluentes Químicos da Água , Purificação da Água , Poluentes Químicos da Água/química , Resinas Acrílicas/química , Purificação da Água/métodos , Moringa oleifera/química , Ânions/química , Adsorção , Poliestirenos/química
6.
Environ Sci Technol ; 58(19): 8597-8606, 2024 May 14.
Artigo em Inglês | MEDLINE | ID: mdl-38687950

RESUMO

NiFe layered double hydroxides (NiFe-LDH) exhibited an outstanding performance and promising application potential for removing ozone. However, the effect of interlayer anions on ozone removal remains ambiguous. Here, a series of NiFe-LDH with different interlayer anions (F-, Cl-, Br-, NO3-, CO32-, and SO42-) were prepared to investigate the effect of the interlayer anion on ozone removal for the first time. It was found that the interlayer anions are a key factor affecting the water resistance of the NiFe-LDH catalyst under moist conditions. NiFe-LDH-CO32- exhibited the best water resistance, which was much better than that of NiFe-LDH containing other interlayer anions. The in situ DIRFTS demonstrates that the carbonates in the interlayer of NiFe-LDH-CO32- will undergo coordination changes through the interaction with water molecules under moist conditions, exposing new metal sites. As a result, the newly exposed metal sites could activate water molecules into hydroxyl groups that act as active sites for catalyzing ozone decomposition. This work provides a new insight into the interlayer anions of LDH, which is important for the design and development of LDH catalysts with excellent ozone removal properties.


Assuntos
Ânions , Hidróxidos , Ozônio , Ozônio/química , Hidróxidos/química , Catálise , Ânions/química
7.
Biophys Chem ; 310: 107248, 2024 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-38653174

RESUMO

Understanding oligomerization and aggregation of the amyloid-ß protein is important to elucidate the pathological mechanisms of Alzheimer's disease, and lipid membranes play critical roles in this process. In addition to studies reported by other groups, our group has also reported that the negatively-charged lipid bilayers with a high positive curvature induced α-helix-to-ß-sheet conformational transitions of amyloid-ß-(1-40) upon increase in protein density on the membrane surface and promoted amyloid fibril formation of the protein. Herein, we investigated detailed mechanisms of the conformational transition and oligomer formation of the amyloid-ß protein on the membrane surface. Changes in the fractions of the three protein conformers (free monomer, membrane-bound α-helix-rich conformation, and ß-sheet-rich conformation) were determined from the fluorescent spectral changes of the tryptophan probe in the protein. The helix-to-sheet structural transition on the surface was described by a thermodynamic model of octamer formation driven by entropic forces including hydrophobic interactions. These findings provide useful information for understanding the self-assembly of amyloidogenic proteins on lipid membrane surfaces.


Assuntos
Peptídeos beta-Amiloides , Fosfolipídeos , Termodinâmica , Peptídeos beta-Amiloides/química , Peptídeos beta-Amiloides/metabolismo , Fosfolipídeos/química , Bicamadas Lipídicas/química , Bicamadas Lipídicas/metabolismo , Ânions/química , Fragmentos de Peptídeos/química , Fragmentos de Peptídeos/metabolismo , Conformação Proteica em Folha beta , Estrutura Secundária de Proteína , Humanos , Multimerização Proteica
8.
J Org Chem ; 89(10): 6877-6891, 2024 May 17.
Artigo em Inglês | MEDLINE | ID: mdl-38662908

RESUMO

Anions have a profound effect on the properties of soluble proteins. Such Hofmeister effects have implications in biologics stability, protein aggregation, amyloidogenesis, and crystallization. However, the interplay between the important noncovalent interactions (NCIs) responsible for Hofmeister effects is poorly understood. To contribute to improving this state of affairs, we report on the NCIs between anions and ammonium and guanidinium hosts 1 and 2, and the consequences of these. Specifically, we investigate the properties of cavitands designed to mimic two prime residues for anion-protein NCIs─lysines and arginines─and the solubility consequences of complex formation. Thus, we report NMR and ITC affinity studies, X-ray analysis, MD simulations, and anion-induced critical precipitation concentrations. Our findings emphasize the multitude of NCIs that guanidiniums can form and how this repertoire qualitatively surpasses that of ammoniums. Additionally, our studies demonstrate the ease by which anions can dispense with a fraction of their hydration-shell waters, rearrange those that remain, and form direct NCIs with the hosts. This raises many questions concerning how solvent shell plasticity varies as a function of anion, how the energetics of this impact the different NCIs between anions and ammoniums/guanidiniums, and how this affects the aggregation of solutes at high anion concentrations.


Assuntos
Compostos de Amônio , Ânions , Arginina , Guanidina , Lisina , Guanidina/química , Ânions/química , Arginina/química , Compostos de Amônio/química , Lisina/química , Simulação de Dinâmica Molecular
9.
Chemosphere ; 358: 141980, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38670508

RESUMO

Generally, the pH of fluorinated groundwater or many industrial wastewater is neutral, while the majority of metal-modified adsorbents can work efficiently only under acidic conditions. In this study, we synthesized a novel hybrid adsorbent, Mg-Zr-D213, by loading nano-Mg/Zr binary metal (hydrogen) oxides in a strong-base anion exchanger, D213, to enhance the adsorption of fluoride from neutral water. Mg-Zr-D213 exhibited a better fluoride-removal capacity in neutral water than monometallic modified resins. Under the interference of competing anions and coexisting organic acids, Mg-Zr-D213 exhibited superior selectivity. The Langmuir model indicated that the fitted maximum sorption capacity of Mg-Zr-D213 was 41.38 mg/g. The results of column experiments showed that the effective treatment volume of Mg-Zr-D213 was 8-16-times higher than that of D213 for both synthetic groundwater and actual industrial wastewater, and that NaOH-NaCl eluent could effectively recover more than 95% of fluoride. Adsorption experiments with Mg/Zr metal (hydrogen) oxide particles and D213 separately demonstrated a synergistic effect between -N+(CH3)3 and Mg/Zr metal (hydrogen) oxide particles. The ligand exchange or metal-ligand interaction of Mg/Zr metal (hydrogen) oxide particles on fluoride was further demonstrated via X-ray photoelectron spectroscopy. Overall, Mg-Zr-D213 has great potential for enhanced fluoride removal in neutral water.


Assuntos
Fluoretos , Água Subterrânea , Nanopartículas Metálicas , Poluentes Químicos da Água , Purificação da Água , Zircônio , Fluoretos/química , Adsorção , Zircônio/química , Poluentes Químicos da Água/química , Nanopartículas Metálicas/química , Água Subterrânea/química , Purificação da Água/métodos , Ânions/química , Águas Residuárias/química , Óxidos/química , Concentração de Íons de Hidrogênio
10.
J Chromatogr A ; 1722: 464843, 2024 May 10.
Artigo em Inglês | MEDLINE | ID: mdl-38574599

RESUMO

Reversed-phase high performance liquid chromatography (RP-HPLC) is the most widely used chromatographic method. In addition to hydrophobic interactions, additional interactions such as electrostatic interactions may participate in the retention behaviour of an analyte. This makes it possible to use RP-HPLC for many types of analyte. We describe a simple method for separating inorganic anions on a C18 column, in which retention of inorganic anions is almost entirely due to electrostatic interactions. This leads to rapid separations as well as higher theoretical plate numbers. We used 2 mM phosphoric acid containing a low concentration of disodium molybdate as the mobile phase, which allows UV detection of non-UV-absorbing anions. With this method, we determined eight inorganic anions including several non-UV-absorbing anions photometrically at 220 nm. The detection limits of the examined eight inorganic anions calculated at a signal-to-noise ratio of 3 were between 0.3 and 10 µM. The detector response was linear over three orders of magnitude of inorganic anion concentration. The proposed RP-HPLC/UV method was successfully applied to determine inorganic anions in some water samples.


Assuntos
Ânions , Cromatografia de Fase Reversa , Molibdênio , Ácidos Fosfóricos , Ânions/química , Molibdênio/química , Ácidos Fosfóricos/química , Cromatografia de Fase Reversa/métodos , Cromatografia Líquida de Alta Pressão/métodos , Limite de Detecção
11.
J Phys Chem B ; 128(15): 3605-3613, 2024 Apr 18.
Artigo em Inglês | MEDLINE | ID: mdl-38592238

RESUMO

Since Hofmeister's seminal studies in the late 19th century, it has been known that salts and buffers can drastically affect the properties of peptides and proteins. These Hofmeister effects can be conceived of in terms of three distinct phenomena/mechanisms: water-salt interactions that indirectly induce the salting-out of a protein by water sequestration by the salt, and direct salt-protein interactions that can either salt-in or salt-out the protein. Unfortunately, direct salt-protein interactions responsible for Hofmeister effects are weak and difficult to quantify. As such, they are frequently construed of as being nonspecific. Nevertheless, there has been considerable effort to better specify these interactions. Here, we use pentapeptides to demonstrate the utility of the H-dimension of nuclear magnetic resonance (NMR) spectroscopy to assess anion binding using N-H signal shifts. We qualify binding using these, demonstrating the upfield shifts induced by anion association and revealing how they are much larger than the corresponding downfield shifts induced by magnetic susceptibility and other ionic strength change effects. We also qualify binding in terms of how the pattern of signal shifts changes with point mutations. In general, we find that the observed upfield shifts are small compared with those induced by anion binding to amide-based hosts, and MD simulations suggest that this is so. Thus, charge-diffuse anions associate mostly with the nonpolar regions of the peptide rather than directly interacting with the amide N-H groups. These findings reveal the utility of 1H NMR spectroscopy for qualifying affinity to peptides─even when affinity constants are very low─and serve as a benchmark for using NMR spectroscopy to study anion binding to more complex systems.


Assuntos
Peptídeos , Proteínas , Peptídeos/química , Ânions/química , Proteínas/química , Amidas/química , Cloreto de Sódio , Água
12.
J Chromatogr A ; 1722: 464871, 2024 May 10.
Artigo em Inglês | MEDLINE | ID: mdl-38593520

RESUMO

Mixed-mode reversed-phase/anion-exchange chromatography (RP/AEX) is an effective method for the chromatographic analysis of acidic drugs because it combines reversed-phase chromatography (RP) with anion-exchange chromatography (AEX). However, the result repeatability for the RP/AEX analysis of acidic drugs is frequently compromised by the detrimental effects of residual silanol groups in an RP/AEX stationary phase on peak separation and analyte retention. In this study, an RP/weak-AEX stationary phase with amino anion-exchange groups, Sil-AA, was prepared. Subsequently, an RP/strong-AEX stationary phase, Sil-PBQA, was prepared by replacing the amino groups in Sil-AA with a benzene ring and a benzyl-containing quaternary ammonium salt. The chromatographic behaviors of Sil-PBQA and Sil-AA were compared, and the effect of residual silanol groups on the chromatographic behavior of an RP/AEX stationary phase was evaluated. Residual silanol groups not only caused additional electrostatic interactions for acidic analytes, but also competed with the analytes for the anion-exchange sites in an RP/AEX stationary phase. The effects of different salt-containing mobile-phase systems on the analyte-retention behavior of Sil-PBQA were investigated to develop a method that enhanced the repeatability of the RP/AEX acidic-analyte-analysis results obtained using Sil-PBQA and facilitated the separation of nonsteroidal anti-inflammatory drugs on Sil-PBQA. The ideas presented in this paper can improve the separation of peaks and repeatability of results in the RP/AEX analysis of acidic drugs.


Assuntos
Anti-Inflamatórios não Esteroides , Cromatografia de Fase Reversa , Cromatografia de Fase Reversa/métodos , Cromatografia por Troca Iônica/métodos , Anti-Inflamatórios não Esteroides/análise , Anti-Inflamatórios não Esteroides/química , Ânions/química , Ânions/análise , Reprodutibilidade dos Testes , Silanos/química , Concentração de Íons de Hidrogênio , Cromatografia Líquida de Alta Pressão/métodos
13.
Environ Monit Assess ; 196(5): 436, 2024 Apr 09.
Artigo em Inglês | MEDLINE | ID: mdl-38589724

RESUMO

Wadi El-Natrun is one of the most observable geomorphological features in the North-Western Desert of Egypt; it contains several old saline and saline soda lakes. This study investigates physicochemical and biochemical characteristics and estimates the total phenolic content (TPC), total flavonoid content (TVC), and bioactivities of sediment, cyanobacteria, and brine shrimp (Artemia salina) in soda lakes, i.e., El-Hamra Lake 1 (H1) and El-Hamra Lake 2 (H2). These soda lakes are unique extreme ecosystems characterized by high pH (> 9.3), high alkalinity, and salinity. Some extremophilic microorganisms are hosted in this ecosystem. The results revealed that the chemical water type of studied lakes is soda-saline lakes according to the calculated percentage sequence of major cations and anions. Sodium ranked first among major cations with an abundance ratio of e% 58, while chloride came first among anions with an abundance ratio of e% 71, and bicarbonate and carbonate occupied the last rank with an abundance of 6%. The biochemical investigations showed that TPC and TVC are present in concern contents of sediment, cyanobacteria, and brine shrimp (A. salina) which contribute 89% of antioxidant capacity and antimicrobial activities. Thus, this study helps better understand the chemical and biochemical adaptations in soda lake ecosystems and explores natural sources with potential applications in antioxidant-rich products and environmental conservation efforts.


Assuntos
Ecossistema , Lagos , Lagos/química , Egito , Antioxidantes , Monitoramento Ambiental/métodos , Ânions , Cátions
14.
Environ Sci Technol ; 58(17): 7628-7635, 2024 Apr 30.
Artigo em Inglês | MEDLINE | ID: mdl-38646668

RESUMO

Partitioning from water to nonaqueous phases is an important process that controls the behavior of contaminants in the environment and biota. However, for ionic chemicals including many perfluoroalkyl and polyfluoroalkyl substances (PFAS), environmentally relevant partition coefficients cannot be predicted using the octanol/water partition coefficient, which is commonly used as a hydrophobicity indicator for neutral compounds. As an alternative, this study measured C18 liquid chromatography retention times of 39 anionic PFAS and 20 nonfluorinated surfactants using isocratic methanol/water eluent systems. By measuring a series of PFAS with different perfluoroalkyl chain lengths, retention factors at 100% water (k0) were successfully extrapolated even for long-chain PFAS. Molecular size was the most important factor determining the k0 of PFAS and non-PFAS, suggesting that the cavity formation process is the key driver for retention. Log k0 showed a high correlation with the log of partition coefficients from water to the phospholipid membrane, air/water interface, and soil organic carbon. The results indicate the potential of C18 retention factors as predictive descriptors for anionic PFAS partition coefficients and the possibility of developing a more comprehensive multiparameter model for the partitioning of anionic substances in general.


Assuntos
Interações Hidrofóbicas e Hidrofílicas , Ânions/química , Adsorção , Fluorocarbonos/química , Tensoativos/química , Água/química , Cromatografia Líquida
15.
Int J Mol Sci ; 25(8)2024 Apr 11.
Artigo em Inglês | MEDLINE | ID: mdl-38673814

RESUMO

Over the past three decades, the synthesis of new ionic liquids (ILs) and the expansion of their use in newer applications have grown exponentially. From the beginning of this vertiginous period, it was known that many of them were hygroscopic, which in some cases limited their use or altered the value of their measured physical properties with all the problems that this entails. In an earlier article, we addressed the hygroscopic grade achieved by the ILs 1-ethyl-3-methylimidazolium chloride, 1-ethyl-3-methylimidazolium bromide, 1-ethyl-3-methylimidazolium methyl sulfate, 1-ethyl-3-methylimidazolium ethyl sulfate, 1-ethyl-3-methylpyridinium ethyl sulfate, 1-ethyl-3-methylimidazolium tosylate, 1-ethyl-3-methylimidazolium tetrafluoroborate, 1-butyl-3-methylimidazolium tetrafluoroborate, 1-dodecyl-3-methylimidazolium tetrafluoroborate, 1-butyl-3-methylpyridinium tetrafluoroborate, 1-butyl-1-methylpiperidinium bis(trifluoromethyl sulfonyl)imide, 1-methyl-1-propylpyrrolidinium bis(trifluoromethyl sulfonyl)imide, 1-butyl-1-methylpyrrolidinium bis(trifluoromethyl sulfonyl)imide, and methyl trioctyl ammonium bis(trifluoromethyl sulfonyl)imide. The objective was to determine the influence of the chemical nature of the compounds, exposed surface area, sample volume, agitation, and temperature. For this purpose, we exposed the samples to abrupt increases in relative humidity from 15 to 100% for days in an atmosphere chamber and then proceeded with the reverse process in a gentle manner. The results show that the sorption of water from the atmosphere depends on the nature of the IL, especially the anion, with the chloride anion being of particular importance (chloride ≫ alkyl sulfates~bromide > tosylate ≫ tetrafluoroborate). It has also been proven for the EMIM-ES and EMIM-BF4 samples that the mechanism of moisture capture is both absorption and adsorption, and that the smaller the exposed surface area, the higher the ratio of the mass of water per unit area.


Assuntos
Ânions , Cátions , Líquidos Iônicos , Líquidos Iônicos/química , Ânions/química , Cátions/química , Imidazóis/química , Molhabilidade , Água/química
16.
J Chromatogr A ; 1721: 464861, 2024 Apr 26.
Artigo em Inglês | MEDLINE | ID: mdl-38564931

RESUMO

The covalent attachment of polyoxometalates (POMs) to polymers has been developed as a strategic approach for the advancement of POM-based hybrid materials with versatile applications. In this study, we utilized thiol-maleimide Michael addition to investigate the kinetics and efficacy of the "one-to-one" conjugation between Keggin type POM and polystyrene. We explored the effects of solvent polarity, catalyst, molecular weight of PS and synthetic strategies on the reaction kinetics and efficiency, by means of reverse-phase high-performance liquid chromatography (RP-HPLC). A series of comparative analysis affirmed the superior efficiency of the one-pot method, particularly when facilitated by the addition of a high-polarity solvent and an excess of maleimide. These findings offer valuable insights into the intricate interplay between reaction conditions, kinetics, and selectivity in thiol-maleimide reactions of POMs and polymers. They hold profound implications for advancing the study of POM-based multifunctional materials and the synthesis of complex hybrid molecules.


Assuntos
Ânions , Polieletrólitos , Polímeros , Compostos de Sulfidrila , Polímeros/química , Maleimidas/química , Solventes
17.
Int J Biol Macromol ; 267(Pt 2): 131521, 2024 May.
Artigo em Inglês | MEDLINE | ID: mdl-38608976

RESUMO

Herein, the effects of anionic xanthan gum (XG), neutral guar gum (GG), and neutral konjac glucomannan (KGM) on the dissolution, physicochemical properties, and emulsion stabilization ability of soy protein isolate (SPI)-polysaccharide conjugates were studied. The SPI-polysaccharide conjugates had better water dissolution than the insoluble SPI. Compared with SPI, SPI-polysaccharide conjugates had lower ß-sheet (39.6 %-56.4 % vs. 47.3 %) and α-helix (13.0 %-13.2 % vs. 22.6 %) percentages, and higher ß-turn (23.8 %-26.5 % vs. 11.0 %) percentages. The creaming stability of SPI-polysaccharide conjugate-stabilized fish oil-loaded emulsions mainly depended on polysaccharide type: SPI-XG (Creaming index: 0) > SPI-GG (Creaming index: 8.1 %-21.2 %) > SPI-KGM (18.1 %-40.4 %). In addition, it also depended on the SPI preparation concentrations, glycation times, and glycation pH. The modification by anionic XG induced no obvious emulsion creaming even after 14-day storage, which suggested that anionic polysaccharide might be the best polysaccharide to modify SPI for emulsion stabilization. This work provided useful information to modify insoluble proteins by polysaccharides for potential application.


Assuntos
Emulsões , Óleos de Peixe , Galactanos , Mananas , Gomas Vegetais , Polissacarídeos Bacterianos , Solubilidade , Proteínas de Soja , Mananas/química , Polissacarídeos Bacterianos/química , Gomas Vegetais/química , Emulsões/química , Proteínas de Soja/química , Galactanos/química , Óleos de Peixe/química , Ânions/química
18.
Spectrochim Acta A Mol Biomol Spectrosc ; 315: 124233, 2024 Jul 05.
Artigo em Inglês | MEDLINE | ID: mdl-38583394

RESUMO

A new phenolate-thiazole derivative (L) has been synthesized and structurally characterized.The chemo-sensing activity of L is detected by the naked eye for the aqueous carbonate anion in the pH range of 4 to 8. The selective 'turn-on' fluorescence occurs through the formation of a stable intermediate L∙CO32-(1) following the PET mechanism. The limit of detection (LOD) is found 0.18 µM based on the absorbance-based assay.The quinonoid form of bromophenol unit binds strongly with CO32- through thiazole nitrogen and hydrazinic nitrogen. Further, the selective holding of CO32- anion over other planar tetranuclear anions (e.g., SO32-, NO3-) happens with several intra and intermolecular hydrogen bonds as envisaged by the DFT/TDFT study. The formation mechanism of L∙CO32- is proposed based on experimental and theoretical studies. The biological experiments (MTT and cell imaging)reveal the non-cytotoxicity nature of L and the biocompatible uptake of L mostly in the cytoplasm at physiological pH.


Assuntos
Ânions , Carbonatos , Teoria da Densidade Funcional , Tiazóis , Cristalografia por Raios X , Tiazóis/química , Ânions/análise , Carbonatos/química , Humanos , Modelos Moleculares , Espectrometria de Fluorescência , Concentração de Íons de Hidrogênio , Limite de Detecção , Fenóis/química , Fenóis/análise , Corantes Fluorescentes/química , Corantes Fluorescentes/síntese química
19.
Mikrochim Acta ; 191(5): 244, 2024 04 05.
Artigo em Inglês | MEDLINE | ID: mdl-38578321

RESUMO

The sensing sensitivity was improved for silver nanoparticles (AgNPs)-based colorimetric biosensors by using the most suitable salt to induce AgNPs aggregation. As for the salt composed of low-affinity anion and monovalent cation, the cation-dependent charge screening effect was the driving force for AgNPs aggregation. Apart from the charge screening effect, both the bridging of multivalent cation to the surface ligand of AgNP and the interaction between anion and Ag contributed to inducing AgNPs aggregation. Considering the higher aggregation efficiency of AgNPs resulted in a narrower sensing range, salt composed of low-affinity anion and monovalent cation was recommended for AgNPs-based colorimetric analysis, which was confirmed by fourfold higher sensitivity of DNA-21 detection using NaF than NaCl. This work inspires further thinking on improving the sensing performance of metal nanomaterials-based sensors from the point of colloidal surface science.


Assuntos
Técnicas Biossensoriais , Nanopartículas Metálicas , Cloreto de Sódio , Prata , Colorimetria/métodos , Ânions , Cátions Monovalentes
20.
Se Pu ; 42(4): 360-367, 2024 Apr.
Artigo em Chinês | MEDLINE | ID: mdl-38566425

RESUMO

The macroporous anion exchange chromatographic medium (FastSep-PAA) was prepared through grafting polyallylamine (PAA) onto polyacrylate macroporous microspheres (FastSep-epoxy). The effects of the synthesis conditions, including the PAA concentration, reaction time, and reaction solution pH, on the ion exchange (IC) of the medium were investigated in detail. When the PAA concentration, reaction time, and reaction solution pH were increased, the IC of the medium increased, and optimal synthesis conditions were then selected in combination with changes of protein binding capacity. A scanning electron microscope was used to examine the surface morphology of the medium. The medium possessed high pore connectivity. Furthermore, the pore structure of the medium was preserved after the grafting of PAA onto the macroporous microspheres. This finding demonstrates that the density of the PAA ligands does not appear to have any discernible impact on the structure of the medium; that is, no difference in the structure of the medium is observed before and after the grafting of PAA onto the microspheres. The pore size and pore-size distribution of the medium before and after grafting were determined by mercury intrusion porosimetry and the nitrogen adsorption method to investigate the relationship between pore size (measured in the range of 300-1000 nm) and protein adsorption. When the pore size of the medium was increased, its protein binding capacity did not exhibit any substantial decrease. An increase in pore size may hasten the mass transfer of proteins within the medium. Among the media prepared, that with a pore size of 400 nm exhibited the highest dynamic-binding capacity (DBC: 70.3 g/L at 126 cm/h). The large specific surface area of the medium and its increased number of protein adsorption sites appeared to positively influence its DBC. When the flow rate was increased, the protein DBC decreased in media with original pore sizes of less than 700 nm. In the case of the medium with an original pore size of 1000 nm, the protein DBC was independent of the flow rate. The protein DBC decreased by 3.5% when the flow rate was increased from 126 to 628 cm/h. In addition, the protein DBC was maintained at 57.7 g/L even when the flow velocity was 628 cm/h. This finding reveals that the diffusion rate of protein molecules at this pore size is less restricted and that the prepared medium has excellent mass-transfer performance. These results confirm that the macroporous polymer anion exchange chromatographic medium developed in this study has great potential for the high-throughput separation of proteins.


Assuntos
Poliaminas , Proteínas , Cromatografia por Troca Iônica/métodos , Adsorção , Proteínas/química , Ânions
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