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1.
Int J Mol Sci ; 21(17)2020 Aug 20.
Artigo em Inglês | MEDLINE | ID: mdl-32825444

RESUMO

At the moment, there are no U.S. Food and Drug Administration (U.S. FDA)-approved drugs for the treatment of COVID-19, although several antiviral drugs are available for repurposing. Many of these drugs suffer from polymorphic transformations with changes in the drug's safety and efficacy; many are poorly soluble, poorly bioavailable drugs. Current tools to reformulate antiviral APIs into safer and more bioavailable forms include pharmaceutical salts and cocrystals, even though it is difficult to classify solid forms into these regulatory-wise mutually exclusive categories. Pure liquid salt forms of APIs, ionic liquids that incorporate APIs into their structures (API-ILs) present all the advantages that salt forms provide from a pharmaceutical standpoint, without being subject to solid-state matter problems. In this perspective article, the myths and the most voiced concerns holding back implementation of API-ILs are examined, and two case studies of API-ILs antivirals (the amphoteric acyclovir and GSK2838232) are presented in detail, with a focus on drug property improvement. We advocate that the industry should consider the advantages of API-ILs which could be the genesis of disruptive innovation and believe that in order for the industry to grow and develop, the industry should be comfortable with a certain element of risk because progress often only comes from trying something different.


Assuntos
Aciclovir/química , Antivirais/química , Betacoronavirus/efeitos dos fármacos , Butiratos/química , Crisenos/química , Infecções por Coronavirus/tratamento farmacológico , Pneumonia Viral/tratamento farmacológico , Aciclovir/farmacologia , Antivirais/farmacologia , Disponibilidade Biológica , Butiratos/farmacologia , Química Farmacêutica/métodos , Crisenos/farmacologia , Reposicionamento de Medicamentos/métodos , Humanos , Líquidos Iônicos/química , Pandemias , Solubilidade
2.
Ecotoxicol Environ Saf ; 205: 111187, 2020 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-32853869

RESUMO

Ionic liquids have been becoming new 'green solvent' because of the low saturation vapor pressure, less volatilization and more recycling utilization. Since most ILs are soluble in water, it should be indispensable to evaluate the ecotoxicology effect of ILs on aquatic environment before using them widely. Based on the concept of norm index, a set of norm descriptors were proposed for anions, cations and ILs. The whole IL structure optimization method has been used to build a predictive norm index-based quantitative structure-toxicity relationship model for the toxicity of ILs on Vibrio fischeri. Statistical results indicated that norm descriptors were reliable and robust in expressing the relationship between structural information and toxicity of ILs. Meanwhile, a series of ILs without experimental values were predicted based on this stable QSTR model. The results indicated that for imidazole-based ILs, an increase in the length of substituent in the branch could enhance the toxicity of ILs on Vibrio fischeri, and the branch contains hydroxyl group, double bond or triple bonds might reduce the toxicity of ILs. Results obtained in this present work would be valuable for the molecular design and the toxicity evaluation toward aquatic organism of ILs.


Assuntos
Aliivibrio fischeri/efeitos dos fármacos , Imidazóis , Líquidos Iônicos , Modelos Teóricos , Solventes , Ânions/química , Cátions/química , Ecotoxicologia/métodos , Imidazóis/química , Imidazóis/toxicidade , Líquidos Iônicos/química , Líquidos Iônicos/toxicidade , Valor Preditivo dos Testes , Relação Quantitativa Estrutura-Atividade , Solventes/química , Solventes/toxicidade
3.
J Chromatogr A ; 1626: 461384, 2020 Aug 30.
Artigo em Inglês | MEDLINE | ID: mdl-32797857

RESUMO

More and more various chemical media are being applied in enantioseparation; among them, ionic liquids (ILs) have attracted the long-term attention in this decade as green designable solvents. This paper provides comprehensive overview for the applications of ILs in chiral extraction, gas chromatography, liquid chromatography, capillary electrophoresis and other techniques for enantioseparation. Additionally, the important resolution mechanisms based on ILs have also been summarized and discussed. This review focuses on the latest development of enantioseparation methods by using ILs in various modes, leading to meaningful and valuable information to related fields and thus promotes further research and application of reported methods.


Assuntos
Cromatografia Gasosa/métodos , Cromatografia Líquida de Alta Pressão/métodos , Eletroforese Capilar/métodos , Líquidos Iônicos/química , Ligantes , Extração Líquido-Líquido , Extração em Fase Sólida , Estereoisomerismo
4.
J Chromatogr A ; 1627: 461395, 2020 Sep 13.
Artigo em Inglês | MEDLINE | ID: mdl-32823100

RESUMO

Nowadays, enantioseparation of racemic pharmaceuticals in preparations is a prime concern by drug authorities across the globe. In the present work, it was attempted to develop novel enantioselective extraction method for five clinically used drugs (atenolol, propranolol, metoprolol, racecadotril, and raceanisodamine in their tablets) as racemates. The enantioselective solid-liquid extraction of these racemic drugs was carried out successfully by the use of chiral ionic liquid (CIL) in combination with a metal organic framework (MOF) for the first time. The composite CIL@MOF was synthesized from tropine based chiral ionic liquids with L-proline anion ([CnTr][L-Pro], n=3-6) and HKUST-1 type MOF, which was comprehensively characterized before being used as sorbent for enantioselective dispersive solid-liquid extraction. Preliminary selection of appropriate CIL was carried out on thin layer chromatography (TLC); under the joint participation of copper ion in the developing reagent, [C3Tr][L-Pro] ionic liquid showed better resolution performance with ΔRf value of 0.35 between the enantiomers was obtained for racemic atenolol. Moreover, the effect of copper salt dosage, amount of CIL, soli-liquid ratio and extraction time were investigated. The optimal conditions were obtained after thorough investigations; i.e. sample solution: ethanol, elution solvent: methanol, solid-liquid ratio: 12.5 mg:50 mL, amount of copper salt: 8 mg L-1, amount of impregnated CIL: 30% and extraction time of 30 min. As a result, enantiomeric excess values are 90.4%, 95%, 92%, 81.6% and 83.2% for atenolol, propranolol, metoprolol, racecadotril and raceanisodamine, respectively. The developed enantioselective method was validated following ICH guidelines and it was proved to be simple, effective and enantioselective way for separation of racemic pharmaceuticals with similar behaviors.


Assuntos
Líquidos Iônicos/química , Estruturas Metalorgânicas/química , Preparações Farmacêuticas/isolamento & purificação , Extração em Fase Sólida/métodos , Antagonistas Adrenérgicos beta/análise , Antagonistas Adrenérgicos beta/isolamento & purificação , Atenolol/análise , Atenolol/isolamento & purificação , Cromatografia Líquida de Alta Pressão/métodos , Cobre/química , Metoprolol/análise , Metoprolol/isolamento & purificação , Preparações Farmacêuticas/análise , Propranolol/análise , Propranolol/isolamento & purificação , Solventes/química , Estereoisomerismo
5.
J Chromatogr A ; 1628: 461486, 2020 Sep 27.
Artigo em Inglês | MEDLINE | ID: mdl-32822970

RESUMO

In this work, an inexpensive, fast, and selective ionic liquid modified graphene oxide (GO-IL) was synthesized and electrochemically deposited on the inner surface of a stainless-steel tube. Then, it was applied for circulated headspace in-tube solid-phase microextraction (CHS-IT-SPME) of naphthalene from honey samples. Next, the coated tube was replaced with the sample loop of a six-port injection valve for on-line desorption and further HPLC-UV analysis of naphthalene. The sorbent was characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy (FT-IR), and energy-dispersive X-ray spectroscopy (EDX). Different parameters affecting the procedure efficiency, including extraction temperature, extraction time, salt concentration, and sample volume were optimized by central composite design and response surface methodology. Under the optimum conditions, the calibration curve was linear within the range of 0.3-200 ng mL-1, with a regression coefficient of 0.9972. The limits of detection (LOD) and quantification (LOQ) were found to be 0.1 ng mL-1 and 0.3 ng mL-1, respectively. Intra-day and inter-day RSDs% for three replicate measurements of naphthalene at the concentration of 10 ng mL-1 were obtained 3.9% and 5.0%, respectively. Also, good tube-to-tube reproducibility of 5.3% was achieved. Finally, the method was successfully applied for measuring trace amounts of naphthalene in honey samples. Relative recoveries were calculated within the range of 90.0-106.5%, indicating excellent efficiency of the proposed method.


Assuntos
Cromatografia Líquida/métodos , Galvanoplastia/métodos , Grafite/química , Mel/análise , Líquidos Iônicos/química , Naftalenos/isolamento & purificação , Sistemas On-Line , Microextração em Fase Sólida/métodos , Cromatografia Líquida de Alta Pressão , Limite de Detecção , Nanoestruturas/química , Nanoestruturas/ultraestrutura , Reprodutibilidade dos Testes
6.
J Chromatogr A ; 1625: 461331, 2020 Aug 16.
Artigo em Inglês | MEDLINE | ID: mdl-32709357

RESUMO

In this work, a novel imidazolium bonding method was proposed for the synthesis of hydrophilic interaction liquid chromatography (HILIC) stationary phases. One obtained stationary phase (SilprAprImCl) was derived from direct reaction between N-(3-aminopropyl)-imidazole and 3-chloropropylated silica gel. Other two materials (SilprAprImBF4 and SilprAprImTf2N) were obtained from SilprAprImCl by ion exchange reaction, respectively. Fourier-transform infrared spectroscopy and elemental analysis afforded the proofs of successful imidazolium immobilization and satisfied bonding efficiency. Various polar compounds such as saccharides, nucleosides, and nucleobases were utilized to evaluate the retention behaviours of these materials in HILIC mode. Different effects from mobile composition, column temperature, imidazolium unite and paired anions (Cl-, BF4-, and Tf2N-) in imidazolium were proved and discussed. Separation mechanism and the role of the imidazolium ions were also investigated in mobile phases with different pH. Moreover, chromatographic stability was evaluated by consecutive injections. Finally, the reliability of these stationary phases was demonstrated by the separation of oligosaccharides in real fructooligosaccharides samples.


Assuntos
Cromatografia Líquida/métodos , Interações Hidrofóbicas e Hidrofílicas , Imidazóis/química , Propanóis/química , Ânions , Concentração de Íons de Hidrogênio , Imidazóis/síntese química , Líquidos Iônicos/química , Nucleosídeos/química , Nucleosídeos/isolamento & purificação , Oligossacarídeos/química , Propanóis/síntese química , Reprodutibilidade dos Testes , Temperatura
7.
Food Chem ; 333: 127534, 2020 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-32673948

RESUMO

A new kind of multi-component membrane was prepared by combining gelatin solution, porogen and an inclusion complex of ionic liquid (IL) and beta-cyclodextrin (ß-CD) in a simple physical manner for selective separation of tea polyphenols (TPs) from green tea crude extracts. After screening, it was found that the resulting membrane containing the IL of dicationic N-vinylimidazole proline salt ([VIm]2C3[l-pro]2) had the excellent performance for the enrichment of the target molecules. Then the newly-developed film was comprehensively characterized by scanning electron microscopy, conductivity, thermogravimetry and spectral analysis. Under pressure driving, the adsorption from an aqueous solution of a mixture of TPs and theophylline on IL@ß-CD-Gel membrane showed that the adsorption capacity for TPs was 303.45 mg/g with removal percentages of 94.38%. The experimental data fit well with pseudo-second-order model and Freundlich model. By using this composite material, a new technology of membrane separation for selective adsorption of TPs was finally established.


Assuntos
Fracionamento Químico/métodos , Gelatina/química , Líquidos Iônicos/química , Membranas Artificiais , Polifenóis/isolamento & purificação , Chá/química , beta-Ciclodextrinas/química , Polifenóis/análise
8.
Food Chem ; 333: 127518, 2020 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-32712545

RESUMO

A multifunctional visual observation of magnetic ionic liquid (MIL) benzyltrioctylammonium thiocyanatecobalt (II) [N8,8,8,B+]2[Co(SCN)42-] with the long-chain alkyl and benzyl group structures was designed and synthesized as microextraction phase. Designed new structural MIL displays good hydrophobicity, high extraction capacity for both aromatic and aliphatic compounds, and has obvious color markers (blue color) which is easy visual separation from aqueous solution through a magnet. In the present work, a green, efficient and rapid samples pretreatment method based on simultaneous derivatization and extraction of aromatic (tyramine, histamine, phenylethylamine, tryptamine) and aliphatic (spermidine and spermine) biogenic amines (BAs) were performed. Microwave-assisted derivatization coupled with MIL-dispersive liquid-liquid microextraction (DLLME) was established for the determination of six BAs in different food samples via HPLC. The method was successfully applied for the analysis of beer and milk samples, and the recoveries of analytes were 93.0-110.3% and 91.2-111.6%, respectively. The limits of detection (LODs) were 0.51-1.49 µg L-1 for six BAs. These results have demonstrated that the proposed method has offered an effective, accurate, and sensitive methodology for BAs residue detection in food sample, and this method has great potential for the routine analysis of large numbers of samples on measuring different kinds of compounds.


Assuntos
Aminas Biogênicas/isolamento & purificação , Líquidos Iônicos/química , Microextração em Fase Líquida/métodos , Magnetismo , Micro-Ondas , Animais , Cerveja/análise , Aminas Biogênicas/análise , Cromatografia Líquida de Alta Pressão , Interações Hidrofóbicas e Hidrofílicas , Limite de Detecção , Leite/química
9.
J Chromatogr A ; 1623: 461192, 2020 Jul 19.
Artigo em Inglês | MEDLINE | ID: mdl-32505285

RESUMO

An imidazolium ionic-liquid-modified phenolic resin (ILPR) was synthesized using 3-aminophenol as a functional monomer, glyoxylic acid as a green cross-linker, and polyethylene glycol 6000 as a porogen. The obtained ILPR showed better extraction of benzoylurea plant hormones thidiazuron and forchlorfenuron than the unmodified phenolic resin because the imidazolium IL provides more interaction modes with the analytes. ILPR, as a tailored adsorbent for solid-phase extraction, was coupled with high-performance liquid chromatography (ILPR‒SPE‒HPLC) for the simultaneous determination of thidiazuron and forchlorfenuron in cucumbers. Good linearity of the ILPR‒SPE‒HPLC method was obtained, ranging from 0.0100 to 5.00 µg g-1 with a correlation coefficient (r) ≥ 0.9999. The recoveries of spiked samples ranged from 91.4% to 100.7% with a relative standard deviation of ≤ 6.0%.


Assuntos
Cucumis sativus/química , Formaldeído/química , Imidazóis/química , Líquidos Iônicos/química , Fenóis/química , Compostos de Fenilureia/isolamento & purificação , Polímeros/química , Piridinas/isolamento & purificação , Extração em Fase Sólida/métodos , Tiadiazóis/isolamento & purificação , Cromatografia Líquida de Alta Pressão , Formaldeído/síntese química , Líquidos Iônicos/síntese química , Cinética , Fenóis/síntese química , Polímeros/síntese química , Reprodutibilidade dos Testes
10.
Food Chem ; 331: 127342, 2020 Nov 30.
Artigo em Inglês | MEDLINE | ID: mdl-32590266

RESUMO

Four novel organic magnetic ionic liquids were synthesized and characterized. A new method of in-situ magnetic ionic liquid dispersive liquid-liquid microextraction coupled with HPLC was established to simultaneously separate, preconcentrate and determine trace amount of sulfonamides in milk samples for the first time. In this work, extraction procedure was free of volatile organic solvent. Extraction equilibrium was immediately achieved without further operation such as vortex shaking. Magnetic separation of two phases was effectively achieved by applying external magnetic field without need of centrifugation. Furthermore, only a very small amount of inorganic salts were generated. This is the first time to realize all these advantages in an analytical method. Under the optimal conditions, satisfactory enrichment factors, precisions, linear range and low limit of detection and quantitation were acquired. The validated method was successfully applied in the simultaneous analysis of 5 sulfonamides in real milk samples.


Assuntos
Contaminação de Alimentos/análise , Líquidos Iônicos/química , Microextração em Fase Líquida/métodos , Leite/química , Sulfonamidas/análise , Animais , Cromatografia Líquida de Alta Pressão/métodos , Análise de Alimentos/métodos , Limite de Detecção , Fenômenos Magnéticos , Reprodutibilidade dos Testes , Solventes/química
11.
J Chromatogr A ; 1623: 461175, 2020 Jul 19.
Artigo em Inglês | MEDLINE | ID: mdl-32505279

RESUMO

An ionic liquid hybrid zwitterionic polymer capillary microextraction (CME) column was prepared for the biomimetic enrichment of glycopeptides by one-step copolymerization of 2-methacryloyloxyethyl phosphorylcholine (MPC) and 1-butyl-3-vinylimidazolium bromide, in the presence of crosslinker trimethylolpropane trimethacrylate (TMA). The resultant monolith was characterized by scanning electron microscopy (SEM), fourier transform infrared (FT-IR) spectroscopy and pore size distribution measurement. Due to the incorporation of zwitterionic MPC owning a unique biomimic structure (i.e. hydrophilic cation/anion and hydrophobic long-alkyl chain), the monolithic column has large pore size and good biocompatibility, exhibiting high extraction efficiency, permeability and fast mass transfer to targets. Besides, the use of ionic liquids (ILs) as co-monomer in the polymerization endows the monolith with enhanced mechanical stability, uniformity and multiple interactions. The prepared column was successfully applied in CME coupled to capillary electrochromatography (CEC) for the efficient enrichment and separation of glycopeptide antibiotics in foodstuff. The method demonstrated a wide linear range (50.0-18000.0 µg L-1), low detection limits (5.0-10.0 µg L-1, S/N = 3) and satisfied recoveries (76.0-109.7%). This work shows the advantage of fine-tuning biomimetic monoliths in application-specific CME-CEC.


Assuntos
Antibacterianos/análise , Eletrocromatografia Capilar/métodos , Glicopeptídeos/análise , Líquidos Iônicos/química , Antibacterianos/isolamento & purificação , Materiais Biomiméticos , Fracionamento Químico , Análise de Alimentos/métodos , Glicopeptídeos/isolamento & purificação , Interações Hidrofóbicas e Hidrofílicas , Imidazóis/química , Metacrilatos/química , Microscopia Eletrônica de Varredura , Fosforilcolina/análogos & derivados , Fosforilcolina/química , Polimerização , Polímeros/química , Espectroscopia de Infravermelho com Transformada de Fourier , Compostos de Vinila/química
12.
J Chromatogr A ; 1624: 461219, 2020 Aug 02.
Artigo em Inglês | MEDLINE | ID: mdl-32540068

RESUMO

The alpha-emitter 225Ac (t1/2 = 9.92 d) is currently under development for targeted alpha-particle therapy of cancer, and accelerator production of 225Ac via proton irradiation of thorium targets requires robust separations of 225Ac from chemically similar fission product lanthanides. Additionally, the lanthanide elements represent critical components in modern technologies, and radiolanthanides such as 140Nd (t1/2 = 3.37 d) also have potential application in the field of nuclear medicine. The ionic liquid, 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([Bmim][NTf2]), combined with the diglycolamide extractant, N,N-dioctyldiglycolamic acid (DODGAA), was adsorbed on macroporous resin support to produce a solvent impregnated resin (SIR) that was investigated for separations of 225Ac and lanthanides. The equilibrium distribution coefficients (Kd) of the rare earth elements (Sc(III), Y(III), Ln(III)), 225Ac(III), Th(IV), and U(VI) on the prepared DODGAA/[Bmim][NTf2]-SIR were determined from batch adsorption experiments in HCl and HNO3 media. The DODGAA/[Bmim][NTf2]-SIR exhibited preferential uptake of the heavier lanthanide elements while allowing for the separation of the lighter lanthanides. Column separations utilizing the DODGAA/[Bmim][NTf2]-SIR were effective at separating the lighter lanthanides from each other, and separating 225Ac from a mixture of lanthanides, 213Bi, and 225Ra without the need for additional complexing agents.


Assuntos
Actínio/isolamento & purificação , Cromatografia por Troca Iônica/métodos , Glicolatos/química , Imidazóis/química , Elementos da Série dos Lantanídeos/química , Líquidos Iônicos/química , Elementos da Série dos Lantanídeos/isolamento & purificação , Porosidade , Solventes/química , Espectrofotometria Atômica
13.
J Chromatogr A ; 1624: 461264, 2020 Aug 02.
Artigo em Inglês | MEDLINE | ID: mdl-32540086

RESUMO

Gas-liquid chromatography is an effective method to determine infinite dilution activity coefficients (γ∞). Wall-coated open-tubular (WCOT) column which offers more advantages over packed column should be a preferable column type; however, the small carrier gas flow rate and stationary phase amount in WCOT columns limit its application in the determination of γ∞. Mathematical strategy made some progress to avoid the quantification problem in the determination of γ∞ by static-wall-coated open-tubular (SWCOT) columns. However, the previously reported strategy was based on the assumption that SWCOT column was geometrically an ideal hollow cylinder, which indeed deviates from the reality. In this study, without that assumption, we derived a new microgeometry-independent equation by using the relationship between the hold-up volume (VM) and the volume of stationary phase (VL), and used it to measure the γ∞ of various organic solutes in two ionic liquids (ILs) 1­butyl­3-methylimidazolium dicyanamide and 1,3-dibutyronitrile-imidazolium bis((trifluoromethyl)sulfonyl)imide, both of which contain double cyano groups in the anion or cation. Phase loading study was adopted to eliminate the influence of interfacial adsorption to partition. The infinite dilution partial molar excess enthalpy, selectivity and capacity were directly calculated from the experimental γ∞ values, and the linear solvation energy relationship (LSER) model was used to characterize the specific properties of both ILs. This new established equation will promote the application of SWCOT columns in thermodynamic measurement and benefit the fast screening of novel solvents for chemical separation processes.


Assuntos
Cromatografia Gasosa/métodos , Adsorção , Imidazóis/química , Líquidos Iônicos/química , Dióxido de Silício/química , Cloreto de Sódio/química , Soluções , Solventes , Termodinâmica
14.
J Chromatogr A ; 1621: 461085, 2020 Jun 21.
Artigo em Inglês | MEDLINE | ID: mdl-32376018

RESUMO

Two analytical methodologies based on the combined use of hydroxypropyl-ß-cyclodextrin and two different amino acid-based chiral ionic liquids (tetrabutylammonium-L-lysine or tetrabutylammonium-L-glutamic acid) in electrokinetic chromatography were developed in this work to perform the enantioselective determination of econazole and sulconazole in pharmaceutical formulations. The influence of different experimental variables such as buffer concentration, applied voltage, nature and concentration of the ionic liquid, temperature and injection time, on the enantiomeric separation was investigated. The combination of hydroxypropyl-ß-cyclodextrin and tetrabutylammonium-L-lysine under the optimized conditions enabled to achieve the enantiomeric determination of both drugs with high enantiomeric resolution (3.5 for econazole and 2.4 for sulconazole). The analytical characteristics of the developed methodologies were evaluated in terms of linearity, precision, LOD, LOQ and recovery showing good performance for the determination of both drugs which were successfully quantitated in pharmaceutical formulations. This work reports the first analytical methodology enabling the enantiomeric determination of sulconazole in pharmaceutical formulations.


Assuntos
2-Hidroxipropil-beta-Ciclodextrina/química , Cromatografia Capilar Eletrocinética Micelar/métodos , Econazol/análise , Ácido Glutâmico/química , Imidazóis/análise , Líquidos Iônicos/química , Lisina/química , Compostos de Amônio Quaternário , Estereoisomerismo , Temperatura , Fatores de Tempo
15.
Food Chem ; 326: 126988, 2020 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-32447162

RESUMO

In this study, a simple and quick ionic liquid- based ultrasonic-assisted microextraction (IL-UA-ME) procedure has been improved for extraction of melamine in dairy productsfollowed by UV-VIS spectrometry. For the analysis of stability and reactivity of melamine and its some metal complexes, quantum chemical parameters like frontier orbital energy-HOMO-LUMO energy gap, hardness and softness were calculated using computational chemistry tools. The results regarding to stability analysis made considering density functional theory showed that theoretical data obtained are compatible with experimentally obtained results, and Fe-melamine complex is more stable compared to others. Under optimum conditions, the linearity was in the range of 0.05-400 ng mL-1 with detection limit of 0.015 ng mL-1. Following the validation studies, recovery and relative standard deviation were obtained in range of 92.5-104.3% and 1.4-2.1%, respectively. The first research article in which experimental and theoretical studies are used together for the determination of melamine in dairy products.


Assuntos
Laticínios/análise , Líquidos Iônicos/química , Triazinas/análise , Complexos de Coordenação/química , Concentração de Íons de Hidrogênio , Limite de Detecção , Teoria Quântica , Microextração em Fase Sólida , Sonicação , Temperatura , Triazinas/química , Triazinas/isolamento & purificação
16.
J Biosci Bioeng ; 130(2): 200-204, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32389469

RESUMO

Ectoine is a zwitterionic amino acid derivative that can be naturally sourced from halophilic microorganisms. The increasing demands of ectoine in various industries have urged the researches on the cost-effective approaches on production of ectoine. Ionic liquids-based aqueous biphasic system (ILABS) was applied to recover Halomonas salina ectoine from cells hydrolysate. The 1-butyl-3-methylimidazolium tetrafluoroborate (Bmim)BF4 was used in the ILABS and the recovery efficiency of ILABS to recover ectoine from H. salina cells lysate was evaluated by determining the effects of phase composition; pHs; crude loading and additional neutral salt (NaCl). The hydrophilic ectoine was targeted to partition to the hydrophilic salt-rich phase. A total yield (YB) of 96.32% ± 1.08 of ectoine was obtained with ILABS of phase composition of 20% (w/w) (Bmim)BF4 and 30% (w/w) sulfate salts; system pH of 5.5 when the 20% (w/w) of crude feedstock was applied to the ILABS. There was no significant enhancement on the ectoine recovery efficiency using the ILABS when NaCl was added, therefore the ILABS composition without the additional neutral salt was recommended for the primary purification of ectoine. Partition coefficient (KE) of 30.80 ± 0.42, purity (PE) of 95.82% and enrichment factor (Ef) of 1.92 were recorded with the optimum (Bmim)BF4/sulfate ILABS. These findings have provided an insight on the feasibility of recovery of intracellular biomolecules using the green solvent-based aqueous system in one single-step operation.


Assuntos
Diamino Aminoácidos/isolamento & purificação , Halomonas/química , Microbiologia Industrial/métodos , Líquidos Iônicos/química , Água/química , Imidazóis , Microbiologia Industrial/economia , Cloreto de Sódio/química
17.
J Chromatogr A ; 1621: 461084, 2020 Jun 21.
Artigo em Inglês | MEDLINE | ID: mdl-32303345

RESUMO

This work presents a new triptycene-based dicationic guanidinium ionic liquid (TPG) as the stationary phase for gas chromatography (GC). To our knowledge, this is the first example of employing a dicationic guanidinium ionic liquid (GIL) for chromatographic analyses. As a result, the TPG column exhibited moderate polarity and column efficiency of 3840 plates/m and 3120 plates/m measured by naphthalene and 1-octanol at 120 °C, respectively. Particularly, the TPG column exhibited distinctly advantageous performance for the challenging Grob test mixture and the isomer mixture of phenols and anilines over the monocationic GIL and its counterpart with dicationic immidazolium units (TP-2IL). Also, it showed higher selectivity towards the isomers of alkanes, alcohols, diethylbenzenes, bromotoluenes, bromonitrobenzenes than the commercial DB-35MS column. Moreover, the TPG column achieved improved thermal stability over the GIL column and excellent repeatability with the RSD values of 0.01-0.05% for run-to-run, 0.11-0.24% for day-to-day and 2.4-4.1% for column-to-column. Its application to GC-MS analysis of the essential oil of Mentha haplocalyx proved its good potential for analysis of complex samples.


Assuntos
Antracenos/química , Guanidina/química , Líquidos Iônicos/química , Alcanos/química , Compostos de Anilina/química , Cromatografia Gasosa-Espectrometria de Massas , Líquidos Iônicos/análise , Isomerismo , Mentha/química , Óleos Voláteis/análise , Fenóis/química , Reprodutibilidade dos Testes , Solventes , Temperatura
18.
Proc Natl Acad Sci U S A ; 117(18): 9832-9839, 2020 05 05.
Artigo em Inglês | MEDLINE | ID: mdl-32317383

RESUMO

G-quadruplex, assembled from a square array of guanine (G) molecules, is an important structure with crucial biological roles in vivo but also a versatile template for ordered functional materials. Although the understanding of G-quadruplex structures is the focus of numerous studies, little is known regarding the control of G-quartet stacking modes and the spontaneous orientation of G-quadruplex fibrils. Here, the effects of different metal ions and their concentrations on stacking modes of G-quartets are elucidated. Monovalent cations (typically K+) facilitate the formation of G-quadruplex hydrogels with both heteropolar and homopolar stacking modes, showing weak mechanical strength. In contrast, divalent metal ions (Ca2+, Sr2+, and Ba2+) at given concentrations can control G-quartet stacking modes and increase the mechanical rigidity of the resulting hydrogels through ionic bridge effects between divalent ions and borate. We show that for Ca2+ and Ba2+ at suitable concentrations, the assembly of G-quadruplexes results in the establishment of a mesoscopic chirality of the fibrils with a regular left-handed twist. Finally, we report the discovery of nematic tactoids self-assembled from G-quadruplex fibrils characterized by homeotropic fibril alignment with respect to the interface. We use the Frank-Oseen elastic energy and the Rapini-Papoular anisotropic surface energy to rationalize two different configurations of the tactoids. These results deepen our understanding of G-quadruplex structures and G-quadruplex fibrils, paving the way for their use in self-assembly and biomaterials.


Assuntos
DNA/química , Quadruplex G , Guanina/química , Hidrogéis/química , Anisotropia , Cátions Bivalentes/química , Cátions Monovalentes/química , DNA/ultraestrutura , Metabolismo Energético/efeitos dos fármacos , Líquidos Iônicos/química , Íons/química , Metais/química , Conformação de Ácido Nucleico/efeitos dos fármacos , Propriedades de Superfície
19.
PLoS One ; 15(4): e0231421, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32310981

RESUMO

Polymers are commonly used in medical device manufacturing, e.g. for drug delivery systems, bone substitutes and stent coatings. Especially hydrogels exhibit very promising properties in this field. Hence, the development of new hydrogel systems for customized application is of great interest, especially regarding the swelling behavior and mechanical properties as well as the biocompatibility. The aim of this work was the preparation and investigation of various polyelectrolyte and poly-ionic liquid based hydrogels accessible by radical polymerization. The obtained polymers were covalently crosslinked with N,N'-methylenebisacrylamide (MBAA) or different lengths of poly(ethyleneglycol)diacrylate (PEGDA). The effect of different crosslinker-to-monomer ratios has been examined. In addition to the compression curves and the maximum degree of swelling, the biocompatibility with L929 mouse fibroblasts of these materials was determined in direct cell seeding experiments and the outcome for the different hydrogels was compared.


Assuntos
Materiais Biocompatíveis/química , Hidrogéis/química , Líquidos Iônicos/química , Acrilamidas/química , Animais , Materiais Biocompatíveis/farmacologia , Linhagem Celular , Sobrevivência Celular/efeitos dos fármacos , Força Compressiva , Hidrogéis/farmacologia , Camundongos , Polietilenoglicóis/química
20.
J Chromatogr A ; 1622: 461127, 2020 Jul 05.
Artigo em Inglês | MEDLINE | ID: mdl-32331778

RESUMO

Gas chromatographic columns based on ionic liquids (ILs) are very promising since the selectivity of these columns can be tuned by both the cation and the anion chemical nature. In this paper, efficiencies of capillary columns based on four phosphonium ionic liquids were studied. The performance of seven columns containing the cation trihexyl(tetradecyl)phosphonium and the anions bromide, chloride, and bis(trifluoromethylsulfonyl)imide was evaluated by measuring the solute band broadening as a function of gas velocities at three temperatures. Hence, classical height equivalent to a theoretical plate (H) against gas velocity (u) plots corresponding to those columns were generated and the data were fitted to the Golay-Guiochon equation with the aim of seeking the optimum conditions to be operated each of them. Band broadening at practical gas velocities is mainly due to poor mass transfer properties of solutes in the (viscous) liquid phases, which limits the achieved efficiencies. These H/u plots proved to be necessary to characterize the column quality at a given temperature, to interpret the band broadening phenomena and thus, to establish the lower temperature limits and the expected plate counts at that temperature.


Assuntos
Cromatografia Gasosa/métodos , Líquidos Iônicos/química , Compostos Organofosforados/química , Ânions , Cátions , Difusão , Dióxido de Silício/química , Temperatura
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