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1.
Int J Biol Macromol ; 272(Pt 1): 132842, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38830490

RESUMO

Eco-friendly and renewable sodium alginate, as a potential alternative to fossil resources, has attracted considerable attention in wastewater treatment field. Herein, we develop a SA/PEI/PEG (sodium alginate/polyethyleneimine/polyethylene glycol diglycidyl ether) adsorbent in which SA was functionalized by PEI/PEG via a facile but effective strategy of one-pot gelation of aqueous SA/PEI/PEG solution. Systematic investigations were accomplished to explore the effects of adsorbent factors on the adsorption performances of the adsorbent towards the anionic dyes CR (congo red), AB-10B (amido black-10B), and AB-25 (acid blue-25). Strikingly, the SA/PEI/PEG exhibited exceptional adsorption performance to CR (2782 mg g-1, 90.6 %), AB-10B (1369 mg g-1, 90.9 %) and AB-25 (4221 mg g-1, 92.6 %) at 30 °C, pH = 3, 200 r min-1 and oscillated 24 h, and demonstrating exceptional reusability after six cycles of adsorption-desorption cycles. Furthermore, the three kinetic, four isothermic and one thermodynamic models were used to investigate the adsorption behaviors of the adsorbent towards these dyes. The possible adsorption mechanism is suggested: Hydrogen bond interactions and electrostatic attractions between SA/PEI/PEG and the dyes primarily contribute to exceptional adsorption capacity. The SA/PEI/PEG adsorbent endowed with easy fabrication, extraordinary adsorption capacity and excellent reusability promises potential application prospects in wastewater purification industry.


Assuntos
Alginatos , Corantes , Poluentes Químicos da Água , Purificação da Água , Alginatos/química , Adsorção , Corantes/química , Poluentes Químicos da Água/química , Poluentes Químicos da Água/isolamento & purificação , Purificação da Água/métodos , Ânions/química , Cinética , Polietilenoglicóis/química , Concentração de Íons de Hidrogênio , Polietilenoimina/química , Termodinâmica
2.
Mikrochim Acta ; 191(7): 401, 2024 Jun 17.
Artigo em Inglês | MEDLINE | ID: mdl-38884887

RESUMO

The simultaneous discrimination and detection of multiple anions in an aqueous solution has been a major challenge due to their structural similarity and low charge radii. In this study, we have constructed a supramolecular fluorescence sensor array based on three host-guest complexes to distinguish five anions (F-, Cl-, Br-, I-, and ClO-) in an aqueous solution using anionic-induced fluorescence quenching combined with linear discriminant analysis. Due to the different affinities of the three host-guest complexes for each anion the anion quenching efficiency for each host-guest complex was likewise different, and the five anions were well recognized. The fluorescence sensor array not only distinguished anions at different concentrations (0.5, 10, and 50 µM) with 100% accuracy but also showed good linearity within a certain concentration range. The limit of detection (LOD) was < 0.5 µM. Our interference study showed that the developed sensor array had good anti-interference ability. The practicability of the developed sensor array was also verified by the identification and differentiation of toothpaste brands with different fluoride content and the prediction of the iodine concentration in urine combined with machine learning.


Assuntos
Ânions , Iodo , Limite de Detecção , Aprendizado de Máquina , Espectrometria de Fluorescência , Ânions/urina , Ânions/química , Iodo/urina , Iodo/química , Espectrometria de Fluorescência/métodos , Cremes Dentais/química , Corantes Fluorescentes/química , Fluoretos/química , Fluoretos/urina , Análise Discriminante
3.
Anal Chem ; 96(24): 9969-9974, 2024 Jun 18.
Artigo em Inglês | MEDLINE | ID: mdl-38847356

RESUMO

Epinephrine (EP) is an essential catecholamine in the human body. Currently, most EP detection methods are not suitable for in vivo detection due to material limitations. An organic small molecule fluorescent probe based on a chemical cascade reaction for the detection of EP was designed. Anionic heptamethine cyanine dye was selected as a fluorescent dye because of its NIR fluorescence emission with excellent biocompatibility. The secondary amine of EP nucleophilically attacks the carbonate of the probe with its stronger nucleophilicity and further undergoes intramolecular nucleophilic cyclization to release the fluorophore. Other substances containing only primary amines or no ß-OH lack reaction competitiveness due to their weaker nucleophilicity or inability to undergo further cyclization. The fluorescence recovery of the probe was linearly related to the EP concentration of 2-75 µmol/L. The detection limit was 0.4 µmol/L. The recovery rate was 94.78-111.32%. Finally, we successfully achieved bioimaging of EP in living cells and EP analogue in nematodes.


Assuntos
Carbocianinas , Epinefrina , Corantes Fluorescentes , Corantes Fluorescentes/química , Corantes Fluorescentes/síntese química , Humanos , Epinefrina/análise , Carbocianinas/química , Animais , Imagem Óptica , Ânions/química , Ânions/análise , Caenorhabditis elegans , Limite de Detecção , Raios Infravermelhos , Células HeLa , Estrutura Molecular
4.
J Enzyme Inhib Med Chem ; 39(1): 2346523, 2024 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-38847581

RESUMO

Toxoplasmosis, induced by the intracellular parasite Toxoplasma gondii, holds considerable implications for global health. While treatment options primarily focusing on folate pathway enzymes have notable limitations, current research endeavours concentrate on pinpointing specific metabolic pathways vital for parasite survival. Carbonic anhydrases (CAs, EC 4.2.1.1) have emerged as potential drug targets due to their role in fundamental reactions critical for various protozoan metabolic processes. Within T. gondii, the Carbonic Anhydrase-Related Protein (TgCA_RP) plays a pivotal role in rhoptry biogenesis. Notably, α-CA (TcCA) from another protozoan, Trypanosoma cruzi, exhibited considerable susceptibility to classical CA inhibitors (CAIs) such as anions, sulphonamides, thiols, and hydroxamates. Here, the recombinant DNA technology was employed to synthesise and clone the identified gene in the T. gondii genome, which encodes an α-CA protein (Tg_CA), with the purpose of heterologously overexpressing its corresponding protein. Tg_CA kinetic constants were determined, and its inhibition patterns explored with inorganic metal-complexing compounds, which are relevant for rational compound design. The significance of this study lies in the potential development of innovative therapeutic strategies that disrupt the vital metabolic pathways crucial for T. gondii survival and virulence. This research may lead to the development of targeted treatments, offering new approaches to manage toxoplasmosis.


Assuntos
Inibidores da Anidrase Carbônica , Anidrases Carbônicas , Clonagem Molecular , Toxoplasma , Toxoplasma/enzimologia , Anidrases Carbônicas/metabolismo , Anidrases Carbônicas/genética , Cinética , Inibidores da Anidrase Carbônica/farmacologia , Inibidores da Anidrase Carbônica/química , Inibidores da Anidrase Carbônica/síntese química , Relação Estrutura-Atividade , Relação Dose-Resposta a Droga , Estrutura Molecular , Ânions/química , Ânions/farmacologia , Ânions/metabolismo
5.
Anal Chem ; 96(21): 8800-8806, 2024 May 28.
Artigo em Inglês | MEDLINE | ID: mdl-38742421

RESUMO

Negative-ion electron capture dissociation (niECD) is an anion MS/MS technique that provides fragmentation analogous to conventional ECD, including high peptide sequence coverage and retention of labile post-translational modifications (PTMs). niECD has been proposed to be the most efficient for salt-bridged zwitterionic precursor ion structures. Several important PTMs, e.g., sulfation and phosphorylation, are acidic and can, therefore, be challenging to characterize in the positive-ion mode. Furthermore, PTM-friendly techniques, such as ECD, require multiple precursor ion-positive charges. By contrast, singly charged ions, refractory to ECD, are most compatible with niECD. Because electrospray ionization (ESI) typically yields multiply charged ions, we sought to explore matrix-assisted laser desorption/ionization (MALDI) in combination with niECD. However, the requirement for zwitterionic gaseous structures may preclude efficient niECD of MALDI-generated anions. Unexpectedly, we found that niECD of anions from MALDI is not only possible but proceeds with similar or higher efficiency compared with ESI-generated anions. Matrix selection did not appear to have a major effect. With MALDI, niECD is demonstrated up to m/z ∼4300. For such larger analytes, multiple electron captures are observed, resulting in triply charged fragments from singly charged precursor ions. Such charge-increased fragments show improved detectability. Furthermore, significantly improved (∼20-fold signal-to-noise increase) niECD spectral quality is achieved with equivalent sample amounts from MALDI vs ESI. Overall, the reported combination with MALDI significantly boosts the analytical utility of niECD.


Assuntos
Ânions , Elétrons , Peptídeos , Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por Matriz , Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por Matriz/métodos , Ânions/química , Peptídeos/química , Peptídeos/análise , Sequência de Aminoácidos
6.
Anal Methods ; 16(23): 3692-3700, 2024 Jun 13.
Artigo em Inglês | MEDLINE | ID: mdl-38805075

RESUMO

Polar pesticides such as anionic or ionisable compounds have always provided a challenge for analytical chemists. Methods of analysis have been developed using a range of techniques including normal phase chromatography, ion-pairing, derivatisation and HILIC or multi-mode chromatography. These work well with some of these compounds but, except for HILIC, all of them have their limitations and none of them cover the range required by legislation. Some of these compounds, glyphosate, chlorate and phosphonic acid, are found regularly in a range of food matrices, and therefore reliable methods of analysis are essential. This study describes an ion chromatography method with tandem mass spectrometry detection which not only covers the full range of compounds required by legislation but also can be expanded to include other anionic or ionisable pesticides and metabolites. These include glyphosate and its metabolites, glufosinate and its metabolites, ethephon and its metabolites as well as fosetyl aluminium, chlorate and perchlorate. The method is fully validated according to the performance criteria from the SANTE guidelines for the analysis of pesticides in food and feed over a wide range of matrices, including milk, infant formula, cereals and fruits and vegetables. Over 300 food samples have analysed as part of our routine monitoring program.


Assuntos
Grão Comestível , Frutas , Praguicidas , Espectrometria de Massas em Tandem , Verduras , Espectrometria de Massas em Tandem/métodos , Grão Comestível/química , Verduras/química , Frutas/química , Praguicidas/análise , Leite/química , Fórmulas Infantis/química , Animais , Contaminação de Alimentos/análise , Humanos , Análise de Alimentos/métodos , Resíduos de Praguicidas/análise , Ânions/análise , Glicina/análogos & derivados , Glicina/análise , Glicina/química , Cromatografia por Troca Iônica/métodos
7.
Int J Mol Sci ; 25(10)2024 May 11.
Artigo em Inglês | MEDLINE | ID: mdl-38791275

RESUMO

A comprehensive thermodynamic and structural study of the complexation affinities of tetra (L1), penta (L2), and hexaphenylalanine (L3) linear peptides towards several inorganic anions in acetonitrile (MeCN) and N,N-dimethylformamide (DMF) was carried out. The influence of the chain length on the complexation thermodynamics and structural changes upon anion binding are particularly addressed here. The complexation processes were characterized by means of spectrofluorimetric, 1H NMR, microcalorimetric, and circular dichroism spectroscopy titrations. The results indicate that all three peptides formed complexes of 1:1 stoichiometry with chloride, bromide, hydrogen sulfate, dihydrogen phosphate (DHP), and nitrate anions in acetonitrile and DMF. In the case of hydrogen sulfate and DHP, anion complexes of higher stoichiometries were observed as well, namely those with 1:2 and 2:1 (peptide:anion) complexes. Anion-induced peptide backbone structural changes were studied by molecular dynamic simulations. The anions interacted with backbone amide protons and one of the N-terminal amine protons through hydrogen bonding. Due to the anion binding, the main chain of the studied peptides changed its conformation from elongated to quasi-cyclic in all 1:1 complexes. The accomplishment of such a conformation is especially important for cyclopeptide synthesis in the head-to-tail macrocyclization step, since it is most suitable for ring closure. In addition, the studied peptides can act as versatile ionophores, facilitating transmembrane anion transport.


Assuntos
Ânions , Termodinâmica , Ânions/química , Peptídeos/química , Peptídeos/metabolismo , Ligação de Hidrogênio , Simulação de Dinâmica Molecular , Acetonitrilas/química , Dimetilformamida/química , Dicroísmo Circular
8.
Int J Biol Macromol ; 269(Pt 2): 132153, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38729494

RESUMO

Hollow vesicles are promising in water treatment due to their unique structure of the membrane and inner cavity. However, the adsorption capacity needs to be improved for targeted pollutants. Herein, millimeter-scale hollow vesicles were prepared with a one-step process of sequential stirring and grafting using chitosan, diallyldimethylammonium chloride, and sodium alginate as raw materials with the purpose of efficient removal of anionic dyes from wastewater. The composite vesicles were characterized using scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and X-ray diffraction. The hollow vesicles showed the structure of the cationic membrane and the inner cavity, facilitating the dye adsorption. The adsorption capacity for the anionic dye Reactive Black 5 reached 698.1 mg/g, more than twice that of the binary composite vesicles without graft. The adsorption kinetics and isotherm data coincided with the pseudo-second-order and Langmuir models, respectively, and the adsorption mechanism was monolayer chemisorption. Moreover, the vesicles worked well in wide ranges of environment pH, temperature, and co-existing pollutants. They also possessed excellent cyclic regeneration performance, in which 93 % of the initial adsorption capacity was maintained after four cycles. These results indicate that the millimeter-scale hollow vesicles exhibit broad application prospects for wastewater purification.


Assuntos
Alginatos , Quitosana , Corantes , Compostos de Amônio Quaternário , Poluentes Químicos da Água , Purificação da Água , Quitosana/química , Alginatos/química , Adsorção , Compostos de Amônio Quaternário/química , Poluentes Químicos da Água/química , Corantes/química , Purificação da Água/métodos , Cinética , Ânions/química , Concentração de Íons de Hidrogênio , Águas Residuárias/química , Naftalenossulfonatos/química , Compostos Alílicos
9.
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
10.
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
11.
Int J Biol Macromol ; 270(Pt 1): 132056, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38704070

RESUMO

Since the potential carcinogenic, toxic and non-degradable dyes trigger serious environmental contamination by improper treatment, developing novel adsorbents remains a major challenge. A novel high efficiency and biopolymer-based environmental-friendly adsorbent, chitosan­sodium tripolyphosphate-melamine sponge (CTS-STPP-MS) composite, was prepared for Orange II removing with chitosan as raw material, sodium tripolyphosphate as cross-linking agent. The composite was carefully characterized by SEM, EDS, FT-IR and XPS. The influence of crosslinking conditions, dosage, pH, initial concentration, contacting time and temperature on adsorption were tested through batch adsorption experiments. CTS-STPP-MS adsorption process was exothermic, spontaneous and agreed with Sips isotherm model accompanying the maximum adsorption capacity as 948 mg∙g-1 (pH = 3). Notably, the adsorption performance was outstanding for high concentration solutions, with a removal rate of 97 % in up to 2000 mg∙L-1 OII solution (100 mg sorbent dosage, 50 mL OII solution, pH = 3, 289.15 K). In addition, the adsorption efficiency yet remained 97.85 % after 5 repeated adsorption-desorption cycles. The driving force of adsorption was attributed to electrostatic attraction and hydrogen bonds which was proved by adsorption results coupled with XPS. Owing to the excellent properties of high-effective, environmental-friendly, easy to separate and regenerable, CTS-STPP-MS composite turned out to be a promising adsorbent in contamination treatment.


Assuntos
Compostos Azo , Quitosana , Triazinas , Poluentes Químicos da Água , Quitosana/química , Quitosana/análogos & derivados , Adsorção , Poluentes Químicos da Água/química , Poluentes Químicos da Água/isolamento & purificação , Triazinas/química , Compostos Azo/química , Compostos Azo/isolamento & purificação , Concentração de Íons de Hidrogênio , Purificação da Água/métodos , Benzenossulfonatos/química , Cinética , Polifosfatos/química , Ânions/química , Temperatura , Corantes/química , Corantes/isolamento & purificação
12.
Int J Biol Macromol ; 269(Pt 2): 131955, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38692542

RESUMO

Dyes pollution is well known for their hazardous impacts on human health and the environment. The removal of dyes from wastewater has become an important issue. In this study, magnetic micrometer-sized particles AL-CTS@MNPs were synthesized from alkaline lignin (AL) and chitosan (CTS) by "one-pot method". The adsorbent presented higher selectivity adsorption effect on anionic dyes than amphoteric and cationic dyes, and even no adsorption effect on cationic methylene blue (MB), which showed that the anionic dyes could be better separated from the other two types of dyes. The adsorption isotherms of the dyes were highly consistent with the Langmuir model, and the maximum adsorption capacity was 329.50 mg/g for methyl orange (MO) and 20.00 mg/g for rhodamine B (RhB). AL-CTS@MNPs showed good adsorption of anionic dyes (MO) in the pH range of 3-9. Meanwhile, the adsorbent AL-CTS@MNPs were also characterized, showing rough surface with specific surface areas of 37.38 m2/g, pore diameter of 95.8 nm and porosity of 17.62 %. The particle sizes were ranged from 800 µm to 1300 µm. The electrostatic attraction and π-π* electron donor-acceptor interactions were the main forces between the adsorbent and anionic dyes. While the electrostatic repulsive force between the adsorbent and the cationic dyes resulted in the non-absorption of MB by AL-CTS@MNPs. Subsequently, the adsorbent maintained a removal rate of >95 % after five adsorption-desorption cycles, demonstrating its excellent stability and recoverability. Ultimately, the prepared AL-CTS@MNPs illuminated good prospect on complex components dyes wastewater treatment.


Assuntos
Quitosana , Corantes , Lignina , Poluentes Químicos da Água , Quitosana/química , Adsorção , Lignina/química , Corantes/química , Corantes/isolamento & purificação , Poluentes Químicos da Água/química , Poluentes Químicos da Água/isolamento & purificação , Ânions/química , Porosidade , Purificação da Água/métodos , Concentração de Íons de Hidrogênio , Azul de Metileno/química , Azul de Metileno/isolamento & purificação , Cinética , Águas Residuárias/química , Nanopartículas de Magnetita/química , Compostos Azo
13.
Int J Biol Macromol ; 269(Pt 1): 131994, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38697431

RESUMO

Nowadays, dye water pollution is becoming increasingly severe. Composite of MXene, ZnS, and chitosan-cellulose material (MX/ZnS/CC) was developed to remove anionic dyes through the synergistic effect of adsorption and photocatalytic degradation. MXene was introduced as the cocatalyst to form Schottky heterostructure with ZnS for improving the separation efficiency of photocarriers and photocatalytic performance. Chitosan-cellulose material mainly served as the dye adsorbent, while also could improve material stability and assist in generation of free radicals for dye degradation. The physics and chemistry properties of MX/ZnS/CC composite were systematically inspected through various characterizations. MX/ZnS/CC composite exhibited good adsorption ability to anionic dyes with adsorption capacity up to 1.29 g/g, and excellent synergistic effects of adsorption and photodegradation with synergistic removal capacity up to 5.63 g/g. MX/ZnS/CC composite performed higher synergistic removal ability and better optical and electrical properties than pure MXene, ZnS, chitosan-cellulose material, and MXene/ZnS. After compounding, the synergistic removal percentage of dyes increased by a maximum of 309 %. MX/ZnS/CC composite mainly adsorbs anionic dyes through electrostatic interactions and catalyzes the generation of •O2-, h+, and •OH to degrade dyes, which has been successfully used to remove anionic dyes from environmental water, achieving a 100 % removal of 50 mg/L dye.


Assuntos
Celulose , Quitosana , Corantes , Poluentes Químicos da Água , Compostos de Zinco , Quitosana/química , Adsorção , Celulose/química , Compostos de Zinco/química , Corantes/química , Corantes/isolamento & purificação , Catálise , Poluentes Químicos da Água/química , Poluentes Químicos da Água/isolamento & purificação , Sulfetos/química , Purificação da Água/métodos , Fotólise , Ânions/química
14.
Colloids Surf B Biointerfaces ; 239: 113941, 2024 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-38744079

RESUMO

The whey protein ß-lactoglobulin (ßLG) forms fibrils similar to the amyloid fibrils in the neurodegenerative diseases due to its higher predisposition of ß-sheets. This study shed light on the understanding different inorganic Keggin polyoxometalates (POMs) interaction with the protein ßLG fibrils. POMs such as Phosphomolybdic acid (PMA), silicomolybdic acid (SMA), tungstosilicic acid (TSA), and phosphotungstic acid (PTA) were used due to their inherent higher anionic charges. The interaction studies were monitored with fluorescence spectra and Thioflavin T assay for both the ßLG monomers and the fibrils initially to elucidate the binding ability of the POMs. The binding of POMs and ßLG is also demonstrated by molecular docking studies. Zeta potential studies showed the electrostatic mediated higher interactions of the POMs with the protein fibrils. Isothermal titration calorimetry (ITC) studies showed that the molybdenum containing POMs have higher affinity to the protein fibrils than the tungsten. This study could help understanding formation of food grade protein fibrils which have profound importance in food industries.


Assuntos
Lactoglobulinas , Simulação de Acoplamento Molecular , Molibdênio , Eletricidade Estática , Lactoglobulinas/química , Molibdênio/química , Compostos de Tungstênio/química , Amiloide/química , Espectrometria de Fluorescência , Polieletrólitos , Ânions
15.
Biophys J ; 123(12): 1735-1750, 2024 Jun 18.
Artigo em Inglês | MEDLINE | ID: mdl-38762755

RESUMO

The light-gated anion channelrhodopsin GtACR1 is an important optogenetic tool for neuronal silencing. Its photochemistry, including its photointermediates, is poorly understood. The current mechanistic view presumes BR-like kinetics and assigns the open channel to a blue-absorbing L intermediate. Based on time-resolved absorption and electrophysiological data, we recently proposed a red-absorbing spectral form for the open channel state. Here, we report the results of a comprehensive kinetic analysis of the spectroscopic data combined with channel current information. The time evolutions of the spectral forms derived from the spectroscopic data are inconsistent with the single chain mechanism and are analyzed within the concept of parallel photocycles. The spectral forms partitioned into conductive and nonconductive parallel cycles are assigned to intermediate states. Rejecting reversible connections between conductive and nonconductive channel states leads to kinetic schemes with two independent conductive states corresponding to the fast- and slow-decaying current components. The conductive cycle is discussed in terms of a single cycle and two parallel cycles. The reaction mechanisms and reaction rates for the wild-type protein, the A75E, and the low-conductance D234N and S97E protein variants are derived. The parallel cycles of channelrhodopsin kinetics, its relation to BR photocycle, and the role of the M intermediate in channel closure are discussed.


Assuntos
Ativação do Canal Iônico , Cinética , Rodopsina/metabolismo , Rodopsina/química , Rodopsina/genética , Animais , Ânions/metabolismo , Luz , Modelos Biológicos , Channelrhodopsins/metabolismo , Channelrhodopsins/genética , Channelrhodopsins/química
16.
Int J Biol Macromol ; 271(Pt 1): 132595, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38821803

RESUMO

Biomass chitosan has garnered considerable interest for alkaline anion exchange membranes (AEMs) due to its eco-friendly and sustainable characteristics, low reactant permeability and easily modifiable nature, but it still faces the trade-off between high hydroxide conductivity and sufficient mechanical properties. Herein, a novel functionalized attapulgite clay (f-ATP) with a unique ionic "chain-ball" surface structure was prepared and incorporated with quaternized chitosan (QCS)/polyvinyl alcohol (PVA) matrix to fabricate high-performance composite AEMs. Due to the strengthened interfacial bonding between f-ATP nanofillers and the QCS/PVA matrix, composite membranes are synergistically reinforced and toughened, achieving peak tensile strength and elongation at break of 24.62 MPa and 33.8 %. Meanwhile, abundant ion pairs on f-ATP surface facilitate ion transport in the composite AEMs, with the maximum OH- conductivity of 46 mS cm-1 at 80 °C and the highest residual IEC of 83 % after alkaline treatment for 120 h. Moreover, the assembled alkaline direct methanol fuel cell exhibits a remarkable power density of 49.3 mW cm-2 at 80 °C. This work provides a new strategy for fabricating high-performance anion exchange membranes.


Assuntos
Quitosana , Argila , Compostos de Magnésio , Membranas Artificiais , Álcool de Polivinil , Compostos de Silício , Quitosana/química , Álcool de Polivinil/química , Compostos de Magnésio/química , Compostos de Silício/química , Argila/química , Ânions/química , Troca Iônica , Resistência à Tração , Propriedades de Superfície
17.
Int J Biol Macromol ; 271(Pt 1): 132368, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38761912

RESUMO

The structural stability and therapeutic activity of Stem Bromelain (BM) have been explored by unravelling the interaction of stem BM in presence of two different types of anionic surfactants namely, bile salts, NaC and NaDC and the conventional anionic surfactants, SDDS and SDBS, below, at and above the critical micelle concentration (cmc) in aqueous phosphate buffer of pH 7. Different physicochemical parameters like, surface excess (Γcmc), minimum area of surfactants at air water interface (Amin) etc. are calculated from tensiometry both in absence and presence of BM. Several inflection points (C1, C2 and C3) have been found in tensiometry profile of surfactants in presence of BM due to the conformational change of BM assisted by surfactants. Similar observation also found in isothermal titration calorimetry (ITC) profiles where the enthalpy of micellization (ΔH0obs) of surfactants in absence and presence of BM have calculated. Further, steady state absorption and fluorescence spectra monitoring the tryptophan (Trp) emission of free BM and in presence of all the surfactants at three different temperatures (288.15 K, 298.15 K, and 308.15 K) reveal the nature of fluorescence quenching of BM in presence of bile salts/surfactants. Time resolved fluorescence studies at room temperature also support to determine the several quenching parameters. The binding constant (Kb) of BM with all the surfactants and free energy of binding (∆G0 of bile salts/surfactants with BM at different temperatures have been calculated exploiting steady state fluorescence technique. It is observed that, the binding of NaC with BM is greater as compared to other surfactants while Stern-Volmer quenching constant (KSV) is found greater in presence of SDBS as compared with others which supports the surface tension and ITC data with the fact that surface activity of surfactant(s) is decreasing with the binding of the surfactants at the core or binding pocket of BM. Circular Dichroism (CD) study shows the stability of secondary structure of BM in presence of NaC and NaDC below C3, while BM lost its structural stability even at very low surfactant concentration of SDDS and SDBS which also supports the more involvement of bile salts in binding rather than surfactants. The molecular docking studies have also been substantiated for better understanding the several experimental investigations interaction of BM with the bile salts/surfactants.


Assuntos
Bromelaínas , Micelas , Simulação de Acoplamento Molecular , Tensoativos , Termodinâmica , Bromelaínas/química , Bromelaínas/metabolismo , Tensoativos/química , Concentração de Íons de Hidrogênio , Ânions/química , Espectrometria de Fluorescência , Soluções Tampão
18.
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
19.
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
20.
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
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