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1.
J Photochem Photobiol B ; 203: 111774, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31931386

RESUMO

Zeolitic imidazole framework (ZIF) is an emerging class of metal organic frameworks exhibiting unique features such as crystalline nature with tunable pore size, large surface area and biocompatible nature. Exceptional thermal and chemical stabilities of ZIF-L make it a suitable candidate for biomedical applications. The present study has focused on the single step fabrication of catechin encapsulated ZIF-L and evaluation of its antibiofilm efficiency, larvicidal activity and dye degradation ability. The as- prepared CA@ZIF-L nanocomposite was characterized by spectroscopic and microscopic techniques. The results revealed that the CA@ZIF-L showed significant toxicity against mosquito larvae in a dose dependent manner with the IC50 63.43±1.25 µg/mL. CA@ZIF-L showed dose dependent reduction of biofilm formation in both ATCC and clinical MRSA strains. In addition, CA@ZIF-L exhibited excellent photocatalytic activity with around 92% degradation of methylene blue under direct sunlight. Overall, the present work highlights the possibility of employing the multifunctional CA@ZIF-L nanocomposite as a suitable material for biomedical and photocatalytic applications.


Assuntos
Biofilmes/efeitos dos fármacos , Catequina/química , Estruturas Metalorgânicas/química , Nanocompostos/toxicidade , Zeolitas/química , Animais , Catálise , Culicidae/efeitos dos fármacos , Culicidae/crescimento & desenvolvimento , Imidazóis/química , Larva/efeitos dos fármacos , Luz , Staphylococcus aureus Resistente à Meticilina/fisiologia , Azul de Metileno/química , Nanocompostos/química , Tamanho da Partícula , Fotólise/efeitos da radiação
2.
Chem Commun (Camb) ; 56(3): 360-363, 2020 Jan 02.
Artigo em Inglês | MEDLINE | ID: mdl-31825399

RESUMO

A crystalline biohybrid with a 4 : 1 protein : cucurbituril mass ratio is presented. This result was achieved by engineering additional cucurbit[7]uril (Q7) binding sites into a ß-propeller protein. In contrast to the parent protein, Q7-controlled assembly of the engineered variant occurred in solution, as evidenced by NMR and SAXS measurements.


Assuntos
Proteínas de Bactérias/química , Hidrocarbonetos Aromáticos com Pontes/química , Imidazóis/química , Sequência de Aminoácidos , Proteínas de Bactérias/metabolismo , Sítios de Ligação , Hidrocarbonetos Aromáticos com Pontes/metabolismo , Imidazóis/metabolismo , Lectinas/química , Lectinas/genética , Lectinas/metabolismo , Ressonância Magnética Nuclear Biomolecular , Ralstonia solanacearum/metabolismo , Espalhamento a Baixo Ângulo , Difração de Raios X
3.
Chemistry ; 26(1): 198-205, 2020 Jan 02.
Artigo em Inglês | MEDLINE | ID: mdl-31643112

RESUMO

A 2D supramolecular organic framework (SOF) based on synthetic macrocycles has been constructed in water by a self-assembly strategy. Two new organic monomers of this SOF, possessing viologen and azobenzene functional groups, form a stimuli-responsive host-guest system upon cooperatively binding with cucurbit[8]uril rings. The reversible formation and dissociation of 2D SOF can be realized by the isomerization of azobenzene under ultraviolet and visible light. The light-responsive property of the SOF is highly reversible and stable for up to four cycles. Moreover, azoreductase produced by Escherichia coli can reduce the N=N double bond of azobenzene entities, resulting in fluorescence recovery of the system. As an excellent and effective fluorescent probe, the SOF can detect azoreductase activity for real-time monitoring of the growth process of Escherichia coli. The dual-stimuli responsive 2D SOF is envisioned to drive the development of responsive devices with complex functions.


Assuntos
Substâncias Macromoleculares/química , NADH NADPH Oxirredutases/metabolismo , Compostos Azo/química , Hidrocarbonetos Aromáticos com Pontes/química , Escherichia coli/metabolismo , Imidazóis/química , Isomerismo , Luz , Substâncias Macromoleculares/metabolismo , NADH NADPH Oxirredutases/química , NADH NADPH Oxirredutases/genética , Proteínas Recombinantes/biossíntese , Proteínas Recombinantes/química , Espectrometria de Fluorescência
4.
Ecotoxicol Environ Saf ; 187: 109836, 2020 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-31675504

RESUMO

Toxicity of 13 ionic liquids (ILs) corresponding to different families were studied by inhibition respiration assays (15 min) using activated sludge. Toxicity increased as increasing the number of carbons in the alkyl-chain of imidazolium-based ILs, with EC50 values from 4.19 to 0.17 for 1-ethyl-3-methylimidazolium chloride ([Emim][Cl]) and 1-octyl-3-methylimidazolium chloride ([Omim][Cl]), respectively. An increase in toxicity was observed for aromatic-based ILs (pyridinium- and imidazolium-based ILs) due to the hydrophobic character of the head groups in comparison with linear structures as phosphonium and ammonium cations. Among to the anions studied fixing [Emim]+ as cation, [HSO4]- and [NTf2]- presented low EC50 values (0.34 mM and 1.69 mM, respectively) while [Cl]- and [EtSO4]- were considered harmless anions due to the hydrophilic character of chloride and the organic nature of [EtSO4]-. ILs toxicity/inhibition was determined by adding a biodegradable compound and measuring the sludge response after being in contact with the ILs for at least 15 h. The exposure of sewage sludge to ILs for more than 15 min used in short inhibition assays caused more toxic effect on microorganisms, even for [Choline][NTf2], previously defined as practically harmless (EC50 = 2.79 mM). Biodegradability assays confirmed the biodegradable nature of choline cation, related with TOC conversion of 40%, only due to cation consumption. No oxygen consumption or even lysis of microbial cells was observed for Tetrabutylammonium bis(trifluoromethylsulfonyl)imide and for 1-Ethyl-3-methylimidazolium hydrogensulphate due to the presence of anions previously defined as hazardous ([NTf2]- and [HSO4]-), maintaining their recalcitrant character to sewage systems.


Assuntos
Imidazóis/toxicidade , Líquidos Iônicos/toxicidade , Esgotos/microbiologia , Ânions , Biodegradação Ambiental , Cátions , Interações Hidrofóbicas e Hidrofílicas , Imidazóis/química , Líquidos Iônicos/química , Estrutura Molecular
5.
Chemosphere ; 239: 124735, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31499306

RESUMO

A key challenge in adsorption process of toxic organic and inorganic species is the design and development of adsorbent materials bearing an abundance of accessible adsorption sites with high affinity to achieve both fast adsorption kinetics and elevated adsorption capacity for toxic contaminants. Herein, a novel anion-exchange adsorbent based on fibrous silica nanospheres KCC-1 was synthesized by a facile hydrothermal-assisted post-grafting modification of KCC-1 with 1-methyl-3- (triethoxysilylpropyl)imidazolium chloride for the first time. Silica fibers with micro-mesoporous structure display the proper combination of features to serve as a potential scaffold for decorating adsorption sites to create desired ion-exchange adsorbent. The obtained N-methylimidazolium-functionalized KCC-1 (MI-Cl-KCC-1) with fibrous nanosphere morphology showed a high surface area (∼241 m2 g-1) and high pore volume (0.81 m2 g-1). The adsorption behaviors of toxic hexavalent chromium from aqueous media by the MI-Cl-KCC-1 were systematically studied using the batch method. The adsorption rate was relatively fast, and MI-Cl-KCC-1 possesses a high capacity for the adsorption of Cr(VI). The maximum Cr(VI) adsorption was obtained at pH 3.0-4.0. Different non-linear isotherm equations were tested for choosing an appropriate adorption isotherm behavior, and the adsorption data for MI-Cl-KCC-1 were consistent with the Langmuir model with a maximum adsorption capacity of 428 ±â€¯8 mg g-1.


Assuntos
Cromo/isolamento & purificação , Imidazóis/química , Nanoestruturas/química , Poluentes Químicos da Água/isolamento & purificação , Adsorção , Ânions , Cromo/química , Imidazóis/síntese química , Troca Iônica , Cinética , Micro-Ondas , Dióxido de Silício/química , Poluentes Químicos da Água/química , Purificação da Água/métodos
6.
Chemosphere ; 239: 124708, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31505442

RESUMO

The discharge of phenol, a harmful pollutant, in the environment poses a threat to human health. With the rapid urbanization and industrialization of the land, there is a pressing need to find new technologies and efficient adsorption materials to address phenol contamination. As a potential adsorbent candidate, sepiolite (SEP) has garnered much interest owing to its large specific surface area, and excellent adsorption performance and biocompatibility. Herein, nanocomposite CESEP/ZIF-8, consisting of zeolite imidazole framework (ZIF-8) and hydrochloric acid-modified SEP (CESEP), was prepared and examined toward the adsorption of phenol. Adsorption equilibrium was achieved within 150 min at initial phenol solution concentrations of 10 and 20 mg/L. However, complete removal was not achieved. Accordingly, biodegradation was introduced. Microorganism Pseudomonas putida was immobilized onto CESEP/ZIF-8, which afforded synergistic adsorption and biodegradation action. Phenol at solution concentrations of 10 and 20 mg/L was effectively removed within 13 and 24 h, respectively (as opposed to 21 and 36 h when phenol was removed in the presence of free Pseudomonas putida solely). The synergistic physical-biological treatment presented herein is expected to have great potential in the field of wastewater treatment.


Assuntos
Biodegradação Ambiental , Imidazóis/química , Nanocompostos/química , Fenol/isolamento & purificação , Pseudomonas putida/metabolismo , Poluentes Químicos da Água/isolamento & purificação , Purificação da Água/métodos , Zeolitas , Adsorção , Cinética , Fenol/metabolismo , Fenóis/isolamento & purificação , Fenóis/metabolismo , Águas Residuárias/química , Poluentes Químicos da Água/metabolismo , Purificação da Água/normas
7.
Chemosphere ; 240: 124947, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31568943

RESUMO

This work studies the effect of the cation and anion on the biodegradability and inhibition of imidazolium- and choline-based ionic liquids (ILs) using activated sludge. Six commercial ILs, formed by combination of 1-Butyl-3-methylimidazolium (Bmim+) and N,N,N-trimethylethanolammonium (Choline+) cations and chloride (Cl-), acetate (Ac-) and bis(trifluoromethanesulfonyl)imide (NTf2-) anions were evaluated, all representative counter-ions with markedly different toxicity and biodegradability. Inherent and fast biodegradability tests were used to evaluate both the microorganism inhibition and the IL biodegradability. In addition, the ecotoxicological response (EC50) of the ILs was studied using activated sludge and Vibrio fischeri (Microtox® test). Bmim+ and NTf2- can be considered as non-biodegradable, whereas aerobic microorganisms easily degraded Choline+ and Ac-. The biodegradation pattern of each cation/anion is nearly unaffected by counter-ion nature. Moreover, concentrations of CholineNTf2 higher than 50 mg/L caused a partial inhibition on microbial activity, in good concordance with its low EC50 (54 mg/L) measured by respiration inhibition test, which alerts on the negative environmental impact of NTf2-containing ILs on the performance of sewage treatment plants.


Assuntos
Aliivibrio fischeri/efeitos dos fármacos , Biodegradação Ambiental , Colina/análise , Hidrocarbonetos Fluorados/química , Imidazóis/análise , Imidazóis/química , Imidas/química , Compostos de Amônio Quaternário/química , Ecotoxicologia , Líquidos Iônicos/análise , Esgotos/química , Purificação da Água/métodos
8.
Talanta ; 206: 120245, 2020 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-31514823

RESUMO

A novel L-tryptophan (L-Trp) electrochemical sensor is fabricated, which is based on the molecularly imprinted copolymer (MIP) of dual -functional monomers and ionic liquid (i.e. 1-butyl-3-methylimidazolium hexafluorophosphate) functionalized multi-walled carbon nanotubes (MWCNTs@IL). The MWCNTs@IL is prepared via ion exchange, while the MIP is synthesized by using L-Trp as template, styrene and 4-vinylbenzoic acid as functional monomers, Triton X-100 as emulsifier, 1, 2-divinylbenzene as cross-linking reagent and K2S2O8 as initiator. Prior to copolymerization the functional monomer 4-vinylbenzoic acid is combined with the template molecule by forming amide bond. The template molecule is eluted by hydrolysis, and rebound by electrostatic, hydrogen-bond and π-π interaction. To construct L-Trp sensor a little of Nafion is introduced to enhance the stability and to promote rebinding. The resulting sensor Nafion-MIP-MWCNTs@IL/GCE shows a wide linear range (8 nM-26 µM) and a low detection limit (6 nM). It is successfully applied to the determination of L-Trp in oral liquid and human serum samples.


Assuntos
Técnicas Eletroquímicas/métodos , Polímeros/química , Triptofano/sangue , Técnicas Eletroquímicas/instrumentação , Eletrodos , Polímeros de Fluorcarboneto/química , História Medieval , Humanos , Imidazóis/química , Limite de Detecção , Impressão Molecular/métodos , Nanotubos de Carbono/química , Polimerização , Polímeros/síntese química , Reprodutibilidade dos Testes , Estereoisomerismo , Estireno/química , Estirenos/química , Triptofano/química
9.
J Agric Food Chem ; 68(4): 1071-1078, 2020 Jan 29.
Artigo em Inglês | MEDLINE | ID: mdl-31841622

RESUMO

Grapes are among the most popular fruits globally, and various fungicides are widely applied to grape crops. As such, the presence of multiple fungicide residues and dietary risks in grapes has become the focus of significant attention. In this study, an easy-to-implement and sensitive UPLC-MS/MS approach was developed to simultaneously determine pyraclostrobin, dimethomorph, cymoxanil, cyazofamid and its metabolite CCIM in grapes via QuEChERS. This approach achieved 78.1-106.0% recovery and a 0.01 mg kg-1 limit of quantitation (LOQ). Field trials revealed that these compounds had degradation half-lives ranging from 0.9 to 13.3 days. And their terminal residues ranging from < LOQ to 1.36 mg kg-1 were below the official maximum residue limit (MRL) in China. The short-term risk for each tested fungicide was below 54%. The long-term risk of individual chemicals ranged from 0.0086% to 3.1%, and their cumulative risk was 4.4%. Results indicated that the dietary risk of these fungicides in grapes was minor.


Assuntos
Fungicidas Industriais/química , Resíduos de Praguicidas/química , Vitis/química , China , Contaminação de Alimentos/análise , Frutas/química , Meia-Vida , Imidazóis/química , Medição de Risco , Estrobilurinas/química , Sulfonamidas/química
10.
Eur J Med Chem ; 185: 111832, 2020 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-31718944

RESUMO

Imidazolium salts have shown great promise as anticancer materials. A new imidazolium salt (TPP1), with a triphenylphosphonium substituent, has been synthesized and evaluated for in vitro and in vivo cytotoxicity against bladder cancer. TPP1 was determined to have a GI50 ranging from 200 to 250 µM over a period of 1 h and the ability to effectively inhibit bladder cancer. TPP1 induces apoptosis, and it appears to act as a direct mitochondrial toxin. TPP1 was applied intravesically to a bladder cancer mouse model based on the carcinogen N-butyl-N-(4-hydroxybutyl)nitrosamine (BBN). Cancer selectivity of TPP1 was demonstrated, as BBN-induced tumors exhibited apoptosis but normal adjacent urothelium did not. These results suggest that TPP1 may be a promising intravesical agent for the treatment of bladder cancer.


Assuntos
Antineoplásicos/farmacologia , Imidazóis/farmacologia , Compostos Organofosforados/farmacologia , Neoplasias da Bexiga Urinária/tratamento farmacológico , Animais , Antineoplásicos/síntese química , Antineoplásicos/química , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Relação Dose-Resposta a Droga , Ensaios de Seleção de Medicamentos Antitumorais , Feminino , Humanos , Imidazóis/síntese química , Imidazóis/química , Masculino , Camundongos , Modelos Moleculares , Estrutura Molecular , Neoplasias Experimentais/tratamento farmacológico , Neoplasias Experimentais/patologia , Compostos Organofosforados/síntese química , Compostos Organofosforados/química , Relação Estrutura-Atividade , Neoplasias da Bexiga Urinária/patologia
11.
Anal Bioanal Chem ; 412(4): 983-991, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31848668

RESUMO

Hemoglobin (Hb)-imprinted poly(ionic liquid)s (HIPILs) were prepared on the surface of Au electrode modified with gold nanodendrites (Au/ND/HIPILs). HIPILs were synthesized with 1-vinyl-3-propyl imidazole sulfonate ionic liquids as functional monomers via electrochemically mediated atom transfer radical polymerization (eATRP) catalyzed by Hb. The Au/ND/HIPILs electrode was examined by cyclic voltammetry (CV), scanning electron microscope (SEM), and X-ray photoelectron spectroscopy (XPS). The Au/ND/HIPILs electrode was also used as an electrochemical sensor to determine Hb by differential pulse voltammetry (DPV). Under the optimal conditions, the detection range of Hb was from 1.0 × 10-14 to 1.0 × 10-4 mg/mL with a limit of detection of 5.22 × 10-15 mg/mL (S/N = 3). Compared with other methods, the sensor based on poly(ionic liquid)s had the broader linear range and lower detection limit. Graphical Abstract.


Assuntos
Ouro/química , Hemoglobinas/análise , Líquidos Iônicos/química , Nanopartículas Metálicas/química , Impressão Molecular/métodos , Animais , Técnicas Biossensoriais/métodos , Catálise , Bovinos , Imidazóis/química , Limite de Detecção , Polimerização
12.
Talanta ; 207: 120284, 2020 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-31594616

RESUMO

Magnetic carbon nanotubes (CNTs) with encapsulated Co nanoparticles (Co@CNTs), was synthesized by exploiting the one-step pyrolysis strategy using ZIF-67 as template. The as-synthesized Co@CNTs is provided with the nanopores, a large specific surface area, and strong magnetic response. The obtained Co@CNTs was used as magnetic solid-phase extraction adsorbents to extract two profens including flurbiprofen and ketoprofen. The parameters of extraction efficiency, involving extraction time, sample solution volume, ionic strength, pH and the conditions of desorption efficiency, were optimized in detail. After determined by high-performance liquid chromatography-ultraviolet (HPLC-UV), the results evinced that Co@CNTs showed a high extraction efficiency with high enrichment factors of 832 and 672. The good linear range of both flurbiprofen and ketoprofen were all 5.0-1000 ng L-1, with the limit of detection were 0.60 ng L-1 and 0.70 ng L-1, respectively. Furthermore, a valid method for the extraction of flurbiprofen and ketoprofen from human serum was established. The spiking recoveries of two profens were between 86.74% and 97.22%, and the relative standard deviation was less than 6.55%. Co@CNTs can be repeatedly used at least 10 times, indicating its excellent regeneration and reusability. The results demonstrated that the Co@CNTs materials exhibits high enrichment ability and extraction efficiency, playing great promise in MSPE.


Assuntos
Flurbiprofeno/isolamento & purificação , Cetoprofeno/isolamento & purificação , Imãs/química , Nanotubos de Carbono/química , Compostos Organometálicos/química , Extração em Fase Sólida/métodos , Adsorção , Cobalto/química , Flurbiprofeno/sangue , Flurbiprofeno/química , Humanos , Imidazóis/química , Cetoprofeno/sangue , Cetoprofeno/química , Nanopartículas Metálicas/química
13.
J Phys Chem Lett ; 10(24): 7817-7822, 2019 Dec 19.
Artigo em Inglês | MEDLINE | ID: mdl-31682445

RESUMO

We present the spectrum of the S1 ← S0 transition of an anionic model for the chromophore of the green fluorescent protein in vacuo at cryogenic temperatures, showing previously unresolved vibrational features, and resolving the band origin at 20 930 cm-1 (477.8 nm) with unprecedented accuracy. The vibrational spectrum establishes that the molecule is in the Z isomer at low temperature. At increased temperature, the S1 ← S0 band shifts to the red, which we tentatively attribute to emergent population of the E isomer.


Assuntos
Compostos de Benzilideno/química , Corantes Fluorescentes/química , Proteínas de Fluorescência Verde/química , Imidazóis/química , Modelos Moleculares , Temperatura Baixa , Íons/química , Isomerismo , Nitrogênio/química , Processos Fotoquímicos , Conformação Proteica , Solventes/química , Espectrometria de Fluorescência/métodos , Termodinâmica , Vibração
14.
Chem Commun (Camb) ; 55(95): 14351-14354, 2019 Nov 26.
Artigo em Inglês | MEDLINE | ID: mdl-31720601

RESUMO

We present the first application of hydrophobic tagging to a non-covalent inhibitor of protein-protein interactions. Nutlin-3a-HT, created by fusing the hydrophobic tag HyT13 to the MDM2-p53 interaction inhibitor Nutlin-3a, prevented cellular accumulation of MDM2 upon p53 reactivation, and had a stronger effect on cell viability and the induction of apoptosis than Nutlin-3a.


Assuntos
Interações Hidrofóbicas e Hidrofílicas , Imidazóis/farmacologia , Piperazinas/farmacologia , Proteínas Proto-Oncogênicas c-mdm2/metabolismo , Proteína Supressora de Tumor p53/metabolismo , Apoptose/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Relação Dose-Resposta a Droga , Células HCT116 , Humanos , Imidazóis/química , Estrutura Molecular , Piperazinas/química , Ligação Proteica/efeitos dos fármacos , Proteínas Proto-Oncogênicas c-mdm2/química , Relação Estrutura-Atividade , Proteína Supressora de Tumor p53/química
15.
Ecotoxicol Environ Saf ; 186: 109784, 2019 Dec 30.
Artigo em Inglês | MEDLINE | ID: mdl-31634657

RESUMO

Surface-active ionic liquids (SAILs) belonging to the series of N-alkylmethylimidazolium halides [C8mimX] (X = Br, Cl, and BF4) and [CnmimBr] (n = 10, 12, 14, and 16) were employed to understand the influence of hydrophobicity of alkyl chain length and the chaotropicity of counter-ions of SAILs on the micellization, antimicrobial action and cytotoxicity properties. The micellization phenomenon of SAILs in an aqueous environment was examined employing tensiometry and steady-state fluorescence spectrophotometry. The corresponding interfacial parameters viz., critical micelle concentration (CMC), effectiveness (γCMC), surface pressure (ПCMC), maximum surface excess concentration (Гmax), and the minimum area engaged per molecule (Amin) at the air-water interface were evaluated at 303.15 K. These experimental findings were monitored and geometrically optimized theoretically using Gaussian software to highlight the recent advances in this field of theoretical calculations for putative structure. The simulation descriptors correlated the micellization behavior as a function of hydrophobicity which may contribute to obtaining awareness on their ecological behavior and fate. In addition, the biological screening of all the examined SAILs was undertaken with a combined experimental and theoretical (optimized) method against bacteria and fungus. Results revealed that SAILs with the alkyl chain-length greater than C8- act as a fair antimicrobial agent against the selected microbial strain which is attributed to the enhanced degree of SAILs hydrophobicity. The cytotoxicity of these imidazolium-based SAILs was also assessed on the cervical human cell line (HeLa) using the MTT cell viability assay and the data thus obtained were subjected to statistical analysis.


Assuntos
Líquidos Iônicos/química , Tensoativos/química , Anti-Infecciosos/química , Anti-Infecciosos/farmacologia , Sobrevivência Celular/efeitos dos fármacos , Células HeLa , Humanos , Interações Hidrofóbicas e Hidrofílicas , Imidazóis/química , Líquidos Iônicos/farmacologia , Micelas , Tensoativos/farmacologia , Água/química
16.
Chem Commun (Camb) ; 55(90): 13506-13509, 2019 Nov 07.
Artigo em Inglês | MEDLINE | ID: mdl-31626260
17.
Chem Commun (Camb) ; 55(92): 13820-13823, 2019 Nov 14.
Artigo em Inglês | MEDLINE | ID: mdl-31664274

RESUMO

A supramolecular nanocapsule was constructed by the ternary host-guest complexation of azobenzene (Azo) and methylviologen (MV) to cucurbit[8]uril (CB[8]) and the subsequent self-assembly. The supramolecular nanocapsule with both glutathione peroxidase (GPx) and superoxide dismutase (SOD) activities can mimic the intracellular enzymatic reactive oxygen species (ROS) defense system.


Assuntos
Antioxidantes/química , Hidrocarbonetos Aromáticos com Pontes/química , Imidazóis/química , Nanocápsulas/química , Células 3T3 , Animais , Compostos Azo/química , Materiais Biocompatíveis/química , Materiais Biocompatíveis/metabolismo , Sobrevivência Celular/efeitos dos fármacos , Glutationa Peroxidase/química , Glutationa Peroxidase/metabolismo , Camundongos , Microscopia Confocal , Nanocápsulas/toxicidade , Paraquat/química , Espécies Reativas de Oxigênio/química , Superóxido Dismutase/química , Superóxido Dismutase/metabolismo
18.
J Chem Theory Comput ; 15(11): 5829-5844, 2019 Nov 12.
Artigo em Inglês | MEDLINE | ID: mdl-31593627

RESUMO

A powerful computational strategy to determine the equilibrium association constant of two macromolecules with explicit-solvent molecular dynamics (MD) simulations is the "geometric route", which considers the reversible physical separation of the bound complex in solution. Nonetheless, multiple challenges remain to render this type of methodology reliable and computationally efficient in practice. In particular, in one, formulation of the geometric route relies on the potential of mean force (PMF) for physically separating the two binding partners restrained along a straight axis, which must be selected prior to the calculation. However, practical applications indicate that the calculation of the separation PMF along the predefined rectilinear pathway may be suboptimal and slowly convergent. Recognizing that a rectilinear straight separation pathway is generally not representative of how the protein complex physically separates in solution, we put forth a novel theoretical framework for binding free-energy calculations, leaning on the optimal curvilinear minimum free-energy path (MFEP) determined from the string method. The proposed formalism is validated by comparing the results obtained using both rectilinear and curvilinear pathways for a prototypical host-guest complex formed by cucurbit[7]uril (CB[7]) binding benzene, and for the barnase-barstar protein complex. On the basis of multi-microsecond MD calculations, we find that the calculations following the traditional rectilinear pathway and the string-based curvilinear pathway agree quantitatively, but convergence is faster with the latter.


Assuntos
Simulação de Dinâmica Molecular , Proteínas/química , Proteínas de Bactérias/química , Proteínas de Bactérias/metabolismo , Benzeno/química , Benzeno/metabolismo , Hidrocarbonetos Aromáticos com Pontes/química , Hidrocarbonetos Aromáticos com Pontes/metabolismo , Imidazóis/química , Imidazóis/metabolismo , Ligação Proteica , Proteínas/metabolismo , Ribonucleases/química , Ribonucleases/metabolismo , Termodinâmica
19.
J Agric Food Chem ; 67(44): 12293-12302, 2019 Nov 06.
Artigo em Inglês | MEDLINE | ID: mdl-31596580

RESUMO

Analyzing the fate of substances in complex matrices, such as processed food, is a major challenge in modern analytical chemistry. However, current regulatory procedures for pesticides only include high temperature hydrolysis of the active substance in water (OECD 507) to simulate food processing. This study shows that heating radiolabeled [imidazolyl-2-14C]prochloraz in virgin rapeseed oil at temperatures up to 240 °C leads to an extensive degradation of the active substance. In total, 11 degradation products were identified. Several of these products were formed by reactions of the active substance with ingredients from the oil. 2-[(1-H-Imidazole-1-carbonyl)(propyl)amino]ethyl oleate (icpame-oleate), a reaction product of an oleic acid moiety and the prochloraz backbone, was identified for the first time. The quantification of prochloraz, icpame-oleate, imidazole, and 2,4,6-trichlorophenol demonstrated the dependency of the degradation process on temperature, heating duration, and type of oil. The obtained results in this study show the enormous impact of high temperature food processing on the fate of pesticides. The necessity to consider matrix related reactions in pesticide regulation is emphasized, and the suitability of the OECD 507 guideline is questioned. Concerning possible toxicological risks of novel degradation products, future studies will have to assess potential hazards or opportunities of food processing, ultimately yielding in safer food.


Assuntos
Imidazóis/química , Resíduos de Praguicidas/química , Óleo de Brassica napus/química , Culinária , Temperatura Alta , Estrutura Molecular
20.
Anal Bioanal Chem ; 411(27): 7293-7301, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31598741

RESUMO

A simple, sensitive, and naked-eye assay of metformin (MET), based on the host-guest molecular recognition of cucurbit[6]uril (CB[6])-modified silver nanoparticles, has been developed for the first time. The molecular recognition between CB[6] and MET is initially demonstrated and the related recognition mechanism is further discussed. CB[6]-modified AgNPs were first synthesized and then characterized by UV-vis spectroscopy, Fourier transform infrared spectroscopy, and transmission electron microscopy. The solution behavior of CB[6] in the presence of AgNO3 was also studied, and the correlative result revealed that AgNPs could combine with the carbonyl portals of CB[6]. On the basis of the molecular recognition of CB[6] and the surface plasmon resonance effect of AgNPs, CB[6]-modified AgNPs were used as visual probes to detect MET. In CB[6]-modified AgNP solution, the aggregation of CB[6]-modified AgNPs induced by MET triggered changes of color and the UV-vis absorption spectrum, which laid the foundation for the visual identification and spectrophotometric determination of MET. Under the optimized detection conditions, the UV-vis spectral assay had a good linear relationship in the range from 3 to 750 µM, and the limit of detection was 1 µM. According to the color changes, the minimum concentration recognized by the naked eye was about 75 µM. Furthermore, this assay has high selectivity for coexisting interferents and was also applied to MET detection in human urine samples. This strategy provides a novel and facile tool for highly selective and sensitive detection of MET. Graphical abstract.


Assuntos
Hidrocarbonetos Aromáticos com Pontes/química , Hipoglicemiantes/urina , Imidazóis/química , Nanopartículas Metálicas/química , Metformina/urina , Prata/química , Colorimetria , Humanos , Limite de Detecção , Nanopartículas Metálicas/ultraestrutura , Espectrofotometria Ultravioleta/métodos , Urinálise/métodos
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