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1.
J Chromatogr A ; 1621: 461075, 2020 Jun 21.
Artigo em Inglês | MEDLINE | ID: mdl-32354558

RESUMO

The role of individual functional groups has been assessed with regard to surface charge and chromatographic retention. Coatings were prepared from various fragments of the chiral zwitterionic materials Chiralpak ZWIX(+) and ZWIX(-). The different chromatographic ligands allowed fine tuning of the surface charge. Chiralpak ZWIX phases showed strongly negative ζ-potentials over the entire pH-range. Zwitterionic congeners with quinuclidine and sulfonic acid moieties but lacking the quinolone ring in the ligand structure exhibited shifted ζ-potentials of around + 5 to 20 mV depending on the surrounding residues. Capillary electrophoretic mobilitiy measurements with the chromatographic ligands and molecular dynamics simulations were carried out to offer some explanation of these surface charge differences of the distinct zwitterionic stationary phases. The new mixed-mode phases were also chromatographically characterized by simple RP and HILIC tests. The results allowed their positioning within a large variety of different commercially available RP, HILIC and mixed-mode phases, which were evaluated as well, by multivariate data processing using principal component analysis. The new mixed-mode phases overall exhibit reasonable hydrophilicity-lipophilicity balance and enable retention of ionic compounds by additional ionic interactions through weak anion-exchange (WAX-type), strong cation-exchange (SCX-type) or both (RP/ZWIX-type). Hence, the new RP/ZWIX phases can be flexible tools for selectivity tuning in RP and HILIC separations.


Assuntos
Cromatografia por Troca Iônica/métodos , Ânions/química , Cátions/química , Eletroforese Capilar , Interações Hidrofóbicas e Hidrofílicas , Ligantes , Simulação de Dinâmica Molecular
2.
Phys Chem Chem Phys ; 22(16): 8409-8417, 2020 Apr 29.
Artigo em Inglês | MEDLINE | ID: mdl-32270834

RESUMO

Metalloproteins are crucial to many biological processes, such as photosynthesis, respiration, and efficient electron transport. Zinc is the most common transition metal found in proteins and is critical for structure, function and stability, however the effects from the electronic properties of a bound zinc ion on electron transfer are not clearly defined. Here, a series of ß-strand and 310-helical peptides, capable of binding Zn2+via suitably positioned His residues, was synthesized and their ability to undergo electron transfer in the presence and absence of Zn2+ studied by electrochemical and computational means. The ß-strand peptide was shown to be conformationally pre-organized, with this geometry maintained on complexation with zinc. Electrochemical studies show a significant increase in charge transport, following binding of the zinc ion to the ß-strand peptide. In contrast, complexation of zinc to the helical peptide disrupts the intramolecular hydrogen bonding network known to facilitate electron transfer and leads to a loss of secondary structure, resulting in a decrease in charge transfer. These experimental and computational studies reveal an interplay, which demonstrates that bound zinc enhances charge transfer by changing the electronic properties of the peptide, and not simply by influencing secondary structure.


Assuntos
Cátions/química , Modelos Químicos , Mimetismo Molecular , Peptídeos/química , Proteínas/química , Oxirredução
3.
Ecotoxicol Environ Saf ; 197: 110572, 2020 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-32283410

RESUMO

The abuse of tetracycline arises the risk of antibiotic resistance genes and has been paid much attention. To understand the potential bioavailability of tetracycline (TC) in soil environments, this study explored the behaviors of TC adsorbing to six types of soils sampled from different regions of China. Moreover, the solution pH and existence of Cd2+ effect on TC sorption to soils were investigated to understand the influential factors affecting TC sorption. The results showed that the soil properties and sorption capacity of TC varied significantly with different soils. The sorption capacity of TC to soils might be largely affected by cation exchange capacity (CEC) and soil organic carbon (SOC), while the sorption rate, interaction strength and equilibrium sorption binding might be affected by soil pH, pHPZC, soil inorganic carbon (SIC) and H content. The result of solution pH effect suggested that the predominant sorption mechanism for acid soils might be hydrophobic interactions between soils and H2TC0, and the cation exchange was possibly proposed as the primary mechanism for TC sorption to alkaline soils. Furthermore, the presence of Cd2+ might increase TC sorption to acid soil, while reduce TC sorption to alkaline soil. It is expected that this study may provide important information for predicting the potential fate of TC (or similar antibiotics) in different soils, and thus helping to assess the bioavailability of TC in soils.


Assuntos
Cádmio/análise , Carbono/análise , Poluentes do Solo/química , Solo/química , Tetraciclina/química , Adsorção , Antibacterianos/análise , Antibacterianos/química , Cádmio/química , Cátions/análise , Cátions/química , China , Concentração de Íons de Hidrogênio , Poluentes do Solo/análise , Tetraciclina/análise
4.
Nat Commun ; 11(1): 1608, 2020 03 30.
Artigo em Inglês | MEDLINE | ID: mdl-32231209

RESUMO

The emerging resistance of crop pathogens to fungicides poses a challenge to food security and compels discovery of new antifungal compounds. Here, we show that mono-alkyl lipophilic cations (MALCs) inhibit oxidative phosphorylation by affecting NADH oxidation in the plant pathogens Zymoseptoria tritici, Ustilago maydis and Magnaporthe oryzae. One of these MALCs, consisting of a dimethylsulfonium moiety and a long alkyl chain (C18-SMe2+), also induces production of reactive oxygen species at the level of respiratory complex I, thus triggering fungal apoptosis. In addition, C18-SMe2+ activates innate plant defense. This multiple activity effectively protects cereals against Septoria tritici blotch and rice blast disease. C18-SMe2+ has low toxicity in Daphnia magna, and is not mutagenic or phytotoxic. Thus, MALCs hold potential as effective and non-toxic crop fungicides.


Assuntos
Cátions/farmacologia , Produtos Agrícolas/efeitos dos fármacos , Fungicidas Industriais/farmacologia , Doenças das Plantas/prevenção & controle , Substâncias Protetoras/farmacologia , Animais , Ascomicetos/efeitos dos fármacos , Cátions/química , Daphnia/efeitos dos fármacos , Descoberta de Drogas , Grão Comestível/microbiologia , Fibroblastos/efeitos dos fármacos , Fungicidas Industriais/química , Humanos , Mitocôndrias/efeitos dos fármacos , Oryza/microbiologia , Doenças das Plantas/microbiologia , Substâncias Protetoras/química , Triticum/microbiologia , Ustilago/efeitos dos fármacos
5.
Food Chem ; 322: 126757, 2020 Aug 30.
Artigo em Inglês | MEDLINE | ID: mdl-32283378

RESUMO

In the present work, for the first time, the filamentous fungus Fusarium sp. was utilized for devising a novel method for pre-concentration and determination of trace amounts of Pb(II), Cu(II), Cd(II), and Zn(II) ions, using a mini-column packed with Fusarium-coated multi-walled carbon nanotubes and inductively coupled plasma-optical emission spectrometry. Optimal analytical conditions including pH, ionic strength, elution solution, sample and eluent flow rates, and sample volume were determined. The detection limits were 0.39, 0.060, 0.021, and 0.025 ng mL-1 for Pb(II), Cu(II), Cd(II), and Zn(II) cations, respectively. This new method demonstrated a high performance for the analytes, and their adsorption was not affected by the different co-existing ions. The present procedure was validated by the analysis of standard reference materials, since the obtained data were in close agreement with reference values. Finally, this new procedure was successfully applied to analysis of heavy metal cations in natural food and water samples.


Assuntos
Fusarium/química , Metais Pesados/análise , Nanotubos de Carbono/química , Extração em Fase Sólida , Espectrofotometria/métodos , Adsorção , Cátions/química , Células Imobilizadas/química , Cobre/análise , Água Doce/análise , Concentração de Íons de Hidrogênio , Chumbo/análise , Chumbo/isolamento & purificação , Limite de Detecção , Metais Pesados/isolamento & purificação , Metais Pesados/normas , Concentração Osmolar , Padrões de Referência , Espectrofotometria/normas
6.
J Chromatogr A ; 1622: 461095, 2020 Jul 05.
Artigo em Inglês | MEDLINE | ID: mdl-32334852

RESUMO

A two-membrane electrodialytic carbonate eluent generator (EDG) for ion chromatography (IC) is described. It is in a sandwich-like configuration, in which the central eluent channel is spatially isolated from two outer regenerant channels by stacked cation exchange membranes (CEMs) and anion exchange membranes (AEMs). A platinum screen electrode is placed in each of two outer regenerant channels. The electrode at the CEMs side is set as an anode with respect to the electrode at the AEMs side being cathode. Potassium carbonate and/or bicarbonate solution is pumped into the regenerant channel as feed solution. The electromigration of carbonate and/or bicarbonate and potassium from feed solution respectively through AEMs and CEMs will form a gas-free eluent. With this configuration, ion transport behavior through AEMs was explored. The device demonstrated good reproducibility, as indicated by the relative standard deviation of retention time of less than 0.08%.


Assuntos
Carbonatos , Técnicas de Química Analítica , Cromatografia por Troca Iônica , Bicarbonatos/química , Carbonatos/química , Cátions/química , Técnicas de Química Analítica/instrumentação , Técnicas de Química Analítica/métodos , Cromatografia por Troca Iônica/instrumentação , Eletrodos , Potássio/química , Reprodutibilidade dos Testes
7.
Chemosphere ; 249: 126531, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32213392

RESUMO

The mineral composition and surface physico-chemical properties, i.e., specific surface area (SSA), cation exchange capacity (CEC), and surface charge of recent sediments and their submicron mineral fractions from different sedimentological environments of the Eastern Adriatic were investigated. The influence of organic matter on these properties was also investigated. It was shown that illite and mixed-layered clay minerals (MLCM) were ubiquitous and showed no size-related preferences while the occurrence of smectites, chlorites, and kaolinites varied. The smectites content increased and the chlorites decreased slightly with decreasing particle size. The sediments from the carbonate-rich environment contained no smectites or chlorites and had the highest kaolinite content. For the first time, in the recent sediments of the Adriatic Sea the poorly- and the well-crystallised kaolinite (Kl and KlD) were distinguished. While Kl predominates in the submicron-sized fraction, KlD occurred only in micron-sized fractions. Authigenic aragonite of submicron-sized was determined in a distinct environment of the semi-enclosed marine lake. The differences in mineral composition and particle size of sediments and their separated fractions were reflected in a wide range of the SSA and CEC values obtained. The highest values of SSA and CEC were determined in the phyllosilicates-rich submicron-sized fractions range, 109 m2g-1 and 87.4 cmol+kg-1, respectively. The submicron-sized fraction from aragonite-rich marine lake showed the lowest values of SSA (56.4 m2g-1) and CEC (38.8 cmol+kg-1), which are still unexpectedly high for carbonate-rich environments. The removal of organic matter resulted in a significant increase in SSA and CEC, up to 150% and 76%, respectively.


Assuntos
Monitoramento Ambiental , Sedimentos Geológicos/química , Poluentes Químicos da Água/análise , Carbonato de Cálcio , Cátions/química , Argila , Itália , Caulim/química , Lagos , Minerais/análise , Minerais/química , Propriedades de Superfície
8.
Artigo em Inglês | MEDLINE | ID: mdl-32163903

RESUMO

Although the electrokinetic injection mode is applicable for direct introduction of ionic components from highly viscous samples, this is the first work which studies this special feature of capillary electrophoresis for this purpose. 9 metal cations were determined in honey utilizing direct injection, zone electrophoretic separation and indirect UV detection of the sample components. Reproducibility better than 4 RSD% was found for peak areas and the LOD values ranged between 0.045 and 0.44 mg/kg when injection parameters were set to 7.5 kV × 5 s. In order to remedy the quantitation problems arising from mobility and matrix bias, the applicability of the internal universal calibration was examined. It was found that in cases where the mobilities of cations do not differ from the mobilities of the monitoring ion and the internal universal standard (IUS) by more than 10%, the obtained results agreed well with the data measured with ICP-OES.


Assuntos
Mel/análise , Metais/análise , Cátions/química , Eletroforese Capilar , Limite de Detecção , Espectrometria de Massas , Padrões de Referência , Reprodutibilidade dos Testes
9.
Food Chem ; 319: 126543, 2020 Jul 30.
Artigo em Inglês | MEDLINE | ID: mdl-32146290

RESUMO

Rapid and precise detection of Tl+ and Pb2+ is important to prevent water poisoning and environmental pollution. Gold nanoparticles (AuNPs) have gained focus for heavy metal ion detection but cannot yet achieve accurate quantitative analyses when Tl+ and Pb2+ coexist. We propose a sensitive, flexible, and low-cost method for the qualitative and quantitative analysis of binary Tl+/Pb2+ mixtures based on AuNP sensors. Partial least squares, back interval partial least squares and data fusion applied to analyze UV-Vis spectral data according to the AuNPs aggregation behavior, revealed discrete responses to the target analytes. The limits of detection for Tl+ and Pb2+ in the binary mixture were 5.23 and 1.76 nM, respectively, and good linear dependence was obtained. The method was successfully applied to the detection of both ions in tap and mineral water. This method can reveal water poisoning and environmental pollution events to ensure drinking water safety.


Assuntos
Água Potável/química , Chumbo/análise , Nanopartículas Metálicas/química , Tálio/análise , Cátions/química , Ouro
10.
Chem Pharm Bull (Tokyo) ; 68(2): 129-132, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32009079

RESUMO

Efficient methods for delivery of antisense DNA or small interfering RNA (siRNA) are highly needed. Cationic materials, which are conventionally used for anionic oligonucleotide delivery, have several drawbacks, including aggregate formation, cytotoxicity and a low endosome escape efficiency. In this report a bio-reactive mask (i.e., disulfide unit) for cationic amino groups was introduced, and the mask was designed such that it was removed at the target cell surface. Insolubility and severe cellular toxicity caused by exposed cationic groups are avoided when using the mask. Moreover, the disulfide unit used to mask the cationic group enabled direct delivery of oligonucleotides to the cell cytosol. The molecular design reported is a promising approach for therapeutic applications.


Assuntos
DNA Antissenso/administração & dosagem , RNA Interferente Pequeno/administração & dosagem , Aminas/química , Animais , Cátions/química , DNA Antissenso/química , DNA Antissenso/genética , DNA Antissenso/farmacocinética , Dissulfetos/química , Inativação Gênica , Células HeLa , Humanos , Masculino , Camundongos Endogâmicos ICR , RNA Interferente Pequeno/química , RNA Interferente Pequeno/genética , RNA Interferente Pequeno/farmacocinética , Transfecção/métodos
11.
Int J Nanomedicine ; 15: 1073-1094, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32103956

RESUMO

Purpose: This study demonstrated improved transdermal delivery of rifampicin-loaded cationic nanoemulsion gel to treat systemic and cutaneous tuberculosis using capmul, labrasol, and acconon, which exert anti-Mycobacterium activities. This approach enhanced drug permeation across the skin, increased therapeutic efficacy, and reduced dose-related side effects. Methods: Design Expert® was used to optimize formulations (Smix ratio and capmul as independent factors), which were prepared using a slow spontaneous titration method. The optimized nanoemulsion was incorporated into carbopol gel to allow for topical application and comparative assessments. Nanoemulsions and gels were evaluated for size, size distribution, shape, zeta potential, percent spread, viscosity, in vitro hemolysis, in vitro release, and ex vivo skin permeation and deposition. A mechanistic evaluation was performed using scanning electron microscopy. Furthermore, in vivo pharmacokinetic and irritation studies were performed. Results: The optimized cationic nanoemulsion (OCNE-1) was characterized by small particle size (≤100 nm), had optimal viscosity, percent spread, zeta potential, and percent drug release, and was hemocompatible. The OCNE-1T gel exhibited higher permeation flux (51.32 ± 0.5 µg/cm2 hr), permeation coefficient (2.566 ± 0.08 cm/hr), drug deposition (994.404 µg/cm2), and enhancement ratio (7.16) than those of the OCNE-1 nanoemulsion or drug solution. Scanning electron microscopy was used to characterize the mechanism of enhanced permeation. An In vivo study showed that the Cmax and area under the curve following transdermal application were 4.34- and 4.74-fold higher than those following oral administration. Conclusion: Transdermal delivery of rifampicin could be a promising alternative to conventional approaches to treat systemic and local tuberculosis, and other bacterial infections.


Assuntos
Antituberculosos/administração & dosagem , Emulsões/administração & dosagem , Rifampina/administração & dosagem , Tuberculose/tratamento farmacológico , Resinas Acrílicas/química , Administração Cutânea , Animais , Antituberculosos/farmacocinética , Antituberculosos/farmacologia , Disponibilidade Biológica , Caprilatos/química , Cátions/química , Emulsões/farmacologia , Excipientes/química , Géis/química , Géis/farmacologia , Glicerídeos/química , Mycobacterium/efeitos dos fármacos , Nanoestruturas/administração & dosagem , Nanoestruturas/química , Tamanho da Partícula , Ratos Sprague-Dawley , Rifampina/farmacocinética , Rifampina/farmacologia , Pele/efeitos dos fármacos , Tuberculose Cutânea/tratamento farmacológico
12.
Phys Rev Lett ; 124(5): 058101, 2020 Feb 07.
Artigo em Inglês | MEDLINE | ID: mdl-32083903

RESUMO

We report that trivalent cobalt hexammine cations decrease the persistence length, stretching modulus, helical density, and size of plectonemes formed under torque of DNA but increase those of RNA. Divalent magnesium cations, however, decrease the persistence lengths, contour lengths, and sizes of plectonemes while increasing the helical densities of both DNA and RNA. The experimental results are explained by different binding modes of the cations on DNA and RNA in our all-atom molecular dynamics simulations. The significant variations of the helical densities and structures of DNA and RNA duplexes induced by high-valent cations may affect interactions of the duplexes with proteins.


Assuntos
DNA/química , RNA de Cadeia Dupla/química , Cátions/química , Cobalto/química , Elasticidade , Magnésio/química , Magnetismo/instrumentação , Magnetismo/métodos , Modelos Químicos , Modelos Moleculares , Simulação de Dinâmica Molecular , Pinças Ópticas , RNA/química
13.
Mar Drugs ; 18(2)2020 Feb 12.
Artigo em Inglês | MEDLINE | ID: mdl-32059424

RESUMO

One of the essential fatty acids with therapeutic impacts on human health is known to be omega-3 polyunsaturated fatty acids (PUFA). More lately, ionic liquids (ILs) have received significant attention among scientists in overcoming the disadvantages of traditional solvents in biomass lipid extraction. However, the large pool of cations and anions possibly accessible will lead to a growing number of innovatively synthesized ILs. Nevertheless, the exhaustive measurement of all these systems is economically impractical. The conductive screening model for real solvents (COSMO-RS) is considered a precious approach with the availability of a few models to predict the characteristics of ILs. This work introduces the estimate of capacity values at infinite dilution for a range of ILs using COSMO-RS software as part of solid-liquid extraction. This favorable outcome presented that the capacity values of the IL molecules are extremely dependent on both anions and cations. Among the 352 combinations of cation/anion tested, short alkyl chain cations coupled with inorganic anions were found to be most efficient and therefore superior in the extraction method. Sulphate-, chloride-, and bromide-based ILs were found to have higher extraction capacities in contrast with the remainders, while propanoate revealed an extraordinary capacity when combined with ethyl-based cations. Eventually, the predicted results from COSMO-RS were validated through the experimentally calculated extraction yield of alpha-linolenic acid (ALA) compound from Nannochloropsis sp. microalgae. Three selected ILs namely [EMIM][Cl], [TMAm][Cl], and [EMPyrro][Br] were selected from COSMO-RS for empirical extraction purpose and the validation results pinpointed the good prediction capability of COSMO-RS.


Assuntos
Líquidos Iônicos/química , Microalgas/química , Ácido alfa-Linoleico/química , Ânions/química , Cátions/química , Química Computacional , Íons/química , Modelos Moleculares , Estrutura Molecular , Temperatura , Termodinâmica
14.
Chemistry ; 26(20): 4599-4606, 2020 Apr 06.
Artigo em Inglês | MEDLINE | ID: mdl-31943433

RESUMO

This study reports a combined Cambridge Structural Database and theoretical DFT study of charge assisted chalcogen bonds involving sulfonium, selenonium, and telluronium cations. The chalcogen bond has been recently defined by IUPAC as the net attractive interaction between an electrophilic region associated with a chalcogen atom in a molecular entity and a nucleophilic region in another, or the same, molecular entity. Divalent chalcogen atoms typically have up to two σ-holes and forms up to two ChBs; the same holds for tetravalent chalcogens which adopt a seesaw arrangement. In sulfonium, selenonium, and telluronium salts chalcogen atoms form three covalent bonds, three σ-holes are located opposite to these bonds, and up to three charge assisted ChBs can be formed between these holes and the counterions. The covalent bond arrangement around these chalcogen atoms is similar to trivalent pnictogen atoms and translates into a similar pattern of noncovalent interactions. We have found and studied this type of charge-assisted chalcogen bonds in various sulfonium ion-containing inhibitors of glucosidase, for example, salacinol and kotalanol.


Assuntos
Cátions/química , Calcogênios/química , Glucosidases/antagonistas & inibidores , Calcogênios/análise , Modelos Moleculares
15.
Chem Soc Rev ; 49(3): 865-907, 2020 Feb 07.
Artigo em Inglês | MEDLINE | ID: mdl-31957756

RESUMO

Supramolecular chemistry is a central topic in modern chemistry. It touches on many traditional disciplines, such as organic chemistry, inorganic chemistry, physical chemistry, materials chemistry, environmental chemistry, and biological chemistry. Supramolecular hosts, inter alia macrocyclic hosts, play critical roles in supramolecular chemistry. Calix[4]pyrroles, non-aromatic tetrapyrrolic macrocycles defined by sp3 hybridized meso bridges, have proved to be versatile receptors for neutral species, anions, and cations, as well as ion pairs. Compared to the parent system, octamethylcalix[4]pyrrole and its derivatives bearing simple appended functionalities, strapped calix[4]pyrroles typically display enhanced binding affinities and selectivities. In this review, we summarize advances in the design and synthesis of strapped calix[4]pyrroles, as well as their broad utility in molecular recognition, supramolecular extraction, separation technology, ion transport, and as agents capable of inhibiting cancer cell proliferation. Future challenges within this sub-field are also discussed.


Assuntos
Calixarenos/química , Calixarenos/metabolismo , Porfirinas/química , Porfirinas/metabolismo , Ânions/química , Apoptose , Cátions/química , Permeabilidade da Membrana Celular , Cristalização , Modelos Moleculares , Estrutura Molecular , Compostos Orgânicos/química , Relação Estrutura-Atividade , Termodinâmica
16.
Chem Commun (Camb) ; 56(8): 1255-1258, 2020 Jan 25.
Artigo em Inglês | MEDLINE | ID: mdl-31898700

RESUMO

Here we demonstrated that the stiffness of cationized gelatin nanoparticles determined the efficiency of RNAi in myeloid leukemia cells when the particle size and surface charges were kept constant. The siRNA delivery system with an elastic modulus of 0.87 MPa showed the largest siRNA uptake and RNAi efficiency for hard-to-transfect suspension cells.


Assuntos
Gelatina/química , Leucemia Mieloide/patologia , Nanopartículas/química , Interferência de RNA , Cátions/química , Sobrevivência Celular/efeitos dos fármacos , Sistemas de Liberação de Medicamentos , Humanos , Células K562 , Leucemia Mieloide/tratamento farmacológico , Tamanho da Partícula , RNA Interferente Pequeno/química , RNA Interferente Pequeno/farmacologia , Propriedades de Superfície
17.
Molecules ; 25(1)2020 Jan 06.
Artigo em Inglês | MEDLINE | ID: mdl-31935863

RESUMO

Herein, we report the development of chitosan (CH)-based bio-composite modified with acrylonitrile (AN) in the presence of carbon disulfide. The current work aimed to increase the Lewis basic centers on the polymeric backbone using single-step three-components (chitosan, carbon disulfide, and acrylonitrile) reaction. For a said purpose, the thiocarbamate moiety was attached to the pendant functional amine (NH2) of chitosan. Both the pristine CH and modified CH-AN bio-composites were first characterized using numerous analytical and imaging techniques, including 13C-NMR (solid-form), Fourier-transform infrared spectroscopy (FTIR), elemental investigation, thermogravimetric analysis, and scanning electron microscopy (SEM). Finally, the modified bio-composite (CH-AN) was deployed for the decontamination of cations from the aqueous media. The sorption ability of the CH-AN bio-composite was evaluated by applying it to lead and copper-containing aqueous solution. The chitosan-based CH-AN bio-composite exhibited greater sorption capacity for lead (2.54 mmol g-1) and copper (2.02 mmol g-1) than precursor chitosan from aqueous solution based on Langmuir sorption isotherm. The experimental findings fitted better to Langmuir model than Temkin and Freundlich isotherms using linear regression method. Different linearization of Langmuir model showed different error functions and isothermal parameters. The nonlinear regression analysis showed lower values of error functions as compared with linear regression analysis. The chitosan with thiocarbamate group is an outstanding material for the decontamination of toxic elements from the aqueous environment.


Assuntos
Cátions/química , Quitosana/química , Descontaminação/métodos , Tiocarbamatos/química , Acrilonitrila/química , Adsorção , Dissulfeto de Carbono/química , Espectroscopia de Ressonância Magnética , Espectroscopia de Infravermelho com Transformada de Fourier , Termogravimetria , Água/química
18.
Carbohydr Polym ; 230: 115614, 2020 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-31887875

RESUMO

Fluorescent bioprobs are in urgent demand to monitor important biological events in biomedicine. However, the aggregation-caused quenching character, high toxicity, water-insolubility and easy leakage property of conventional small molecular dyes hinder the development in this area. In this work, an aggregation-induced emission (AIE) bioconjugate was synthesised by labeling tetraphenylethylene (TPE) to quaternized chitosan (QCS). The TPE-QCS bioconjugate emits strong fluorescence even in solid state, and is cationic and water-soluble over a wide range of pH values. The TPE-QCS aqueous solution stained HeLa cells by dose- and time-depent manner and imaged living cells with bright fluorescence. Futhermore, the cationic bioconjugate was readily internalized by cells through endocytosis, and further aggragated to large sizes and adhered to negatively charged organelle membranes inside cells achieving fluorescent cell imaging with fluorescence enhancement and leakage-free staining. The AIE-active TPE-QCS with cationic nature, good water-solubility over a wide pH range and unique cell imaging properties could trace HeLa cells for as long as 23 passages, that was obviously superior to existing commercial cellular tracer, so has promising application prospects as ultra long-term tracer in biomedical field.


Assuntos
Quitosana/análogos & derivados , Corantes Fluorescentes/química , Nanoconjugados/química , Células 3T3 , Absorção de Radiação , Animais , Cátions/química , Endocitose , Células HeLa , Humanos , Camundongos , Polimerização , Solubilidade , Estilbenos/química , Raios Ultravioleta
19.
Carbohydr Polym ; 231: 115687, 2020 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-31888837

RESUMO

The intractable toxicity of cationic polymers limits their applicability in gene transport and controlled release. In consideration of the good biocompatibility and biofunctionality of dextran, herein we design and synthesize two types of amino group-containing cationic copolymers based on dextran by the copolymerization of cationic monomers from dextran backbones. Additionally, allyl crosslinkers containing disulfide bonds were introduced into polymerization, that made the copolymer crosslinked by disulfide. The resultant coacervates were formed from the self-assembly of cationic coplymers and anionic genes, and redox-responsive disulfide branch points endow coacervates with reducing environment responsiveness. The in vitro experiments showed that the dextran-based coacervates were sensitive to the reducing environment and underwent cleavage, which resulted in an effective release, uptake, and transfection of the genes by 293T cells. In addition, dextran-based coacervates can be used to carry siRNA into cancer cells with a high transfection efficiency, demonstrating their potential applicability in treatment against cancer.


Assuntos
Técnicas de Transferência de Genes , Neoplasias/genética , Polímeros/química , RNA Interferente Pequeno/genética , Ânions/química , Materiais Biocompatíveis/química , Materiais Biocompatíveis/farmacologia , Cátions/química , Proliferação de Células/genética , Dextranos/química , Dissulfetos/química , Células HEK293 , Humanos , Neoplasias/terapia , Oxirredução , Polímeros/farmacologia , RNA Interferente Pequeno/farmacologia , Transfecção
20.
Talanta ; 209: 120581, 2020 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-31892020

RESUMO

Conjugated polyelectrolytes (CPEs) have been widely used as reporters in colorimetric assays targeting nucleic acids. CPEs provide naked eye detection possibility by their superior optical properties however, as concentration of target analytes decrease, trace amounts of nucleic acid typically yield colorimetric responses that are not readily perceivable by naked eye. Herein, we report a pixelated analysis approach for correlating colorimetric responses of CPE with nucleic acid concentrations down to 1 nM, in plasma samples, utilizing a smart phone with an algorithm that can perform analytical testing and data processing. The detection strategy employed relies on conformational transitions between single stranded nucleic acid-cationic CPE duplexes and double stranded nucleic acid-CPE triplexes that yield distinct colorimetric responses for enabling naked eye detection of nucleic acids. Cationic poly[N,N,N-triethyl-3-((4-methylthiophen-3-yl)oxy)propan-1-aminium bromide] is utilized as the CPE reporter deposited on a polyvinylidene fluoride (PVDF) membrane for nucleic acid assay. A smart phone application is developed to capture and digitize the colorimetric response of the individual pixels of the digital images of CPE on the PVDF membrane, followed by an analysis using the algorithm. The proposed pixelated approach enables precise quantification of nucleic acid assay concentrations, thereby eliminating the margin of error involved in conventional methodologies adopted for interpretation of colorimetric responses, for instance, RGB analysis. The obtained results illustrate that a ubiquitous smart phone could be utilized for point of care colorimetric nucleic acids assays in complex matrices without requiring sophisticated software or instrumentation.


Assuntos
Colorimetria/métodos , Ácidos Nucleicos/sangue , Polieletrólitos/química , Técnicas Biossensoriais/instrumentação , Técnicas Biossensoriais/métodos , Cátions/química , Colorimetria/instrumentação , Desenho de Equipamento , Humanos , Ácidos Nucleicos/análise , Papel , Sistemas Automatizados de Assistência Junto ao Leito , Polímeros/química , Polivinil/química , Smartphone , Tiofenos/química
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