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1.
Phys Chem Chem Phys ; 21(37): 20628-20640, 2019 Sep 25.
Artigo em Inglês | MEDLINE | ID: mdl-31495862

RESUMO

Methionine synthase (MetH) is a methylcobalamin (MeCbl)-dependent mammalian enzyme which plays a critical role in carrying out the transfer of a methyl group from methyl tetrahydrofolate to homocysteine to generate methionine and tetrahydrofolate. This catalytic cycle proceeds via cleavage of a Co-C bond which is formally heterolytic. This cleavage results in a structural change in the MeCbl cofactor bound to an enzyme. Unlike the native catalysis, upon photoexcitation, the Co-C bond in MeCbl-bound MetH generates the Co(ii)/CH3 radical pairs (RPs). Protein residues of the cap domain, particularly phenylalanine708 (F708) and leucine 715 (L715), which surrounds the upper face of the MeCbl cofactor, inhibit the photolysis of MeCbl by caging the CH3 radical and inducing the geminate recombination of the Co(ii)/CH3 RP. A molecular-level understanding of these effects requires a detailed investigation of the low-lying electronic states. Toward this, we have mutated the F708 residue with alanine (A708) and constructed the potential energy surfaces (PESs) for the low-lying S1 electronic state using a combined quantum mechanics/molecular mechanics (QM/MM) approach. The S1 PESs for the wild-type (WT) and mutant enzymes are the result of crossing of two electronic states, namely metal-to-ligand charge transfer (MLCT) and ligand field (LF) states, indicated by a seam. It is shown that the topologies of the S1 PESs are significantly modulated by introducing a mutation at the F708 position. Specifically, for the WT enzyme, the energy barrier of photoreaction and the energy difference between MLCT and LF minima are markedly higher than those of its mutant counterpart. Moreover, mutation influences the photoactivation of the Co-C bond in enzyme-bound MeCbl by decreasing the rate of geminate recombination and altering the rate of radical pair formation. This theoretical insight was also compared with transient absorption spectroscopic (TAS) studies which are in good agreement with the present findings.


Assuntos
5-Metiltetra-Hidrofolato-Homocisteína S-Metiltransferase/genética , Carbono/química , Cobalto/química , Vitamina B 12/análogos & derivados , 5-Metiltetra-Hidrofolato-Homocisteína S-Metiltransferase/metabolismo , Modelos Químicos , Estrutura Molecular , Mutação/genética , Fotólise , Domínios Proteicos/genética , Vitamina B 12/metabolismo
2.
Chem Commun (Camb) ; 55(67): 10019-10022, 2019 Aug 28.
Artigo em Inglês | MEDLINE | ID: mdl-31378803

RESUMO

We report a facile hydrothermal method to synthesize a novel mesoporous graphitic carbon nitride (MCN)@NiCo2O4 nanocomposite, which can be used as a solid phase microextraction coating for high efficiency extraction and preconcentration of trace polychlorinated biphenyls and polycyclic aromatic hydrocarbons in human serum samples.


Assuntos
Poluentes Ambientais/sangue , Nanocompostos/química , Nitrilos/química , Bifenilos Policlorados/sangue , Hidrocarbonetos Policíclicos Aromáticos/sangue , Cobalto/química , Humanos , Limite de Detecção , Níquel/química , Microextração em Fase Sólida/instrumentação , Microextração em Fase Sólida/métodos
3.
An Acad Bras Cienc ; 91(3): e20180237, 2019 Jul 29.
Artigo em Inglês | MEDLINE | ID: mdl-31365648

RESUMO

The aim of this study was to develop polyurethane (PU) wound dressing incorporated with cobalt nitrate using electrospinning technique. The morphology analysis revealed that the developed composites exhibited reduced fiber and pore diameter than the pristine PU. The electrospun membranes exhibited average porosity in the range of 67% - 71%. Energy-dispersive X-ray spectra (EDS) showed the presence of cobalt in the PU matrix. The interaction of cobalt nitrate with PU matrix was evident in Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA). The contact angle results indicated the improved wettability of the prepared PU/cobalt nitrate composites (82° ± 2) than the pure PU (100° ± 1). The incorporation of cobalt nitrate into the PU matrix enhanced the surface roughness and mechanical strength as evident in the atomic force microscopy (AFM) and tensile test analysis. The blood compatibility assays revealed the anticoagulant nature of the prepared composites by displaying prolonged blood clotting time than the PU control. Further, the developed composite exhibited less toxicity nature as revealed in the hemolysis and cytotoxicity studies. It was observed that the PU wound dressing added with cobalt nitrate fibers exhibited enhanced physicochemical, better blood compatibility parameters and enhanced fibroblast proliferation rates which may serve as a potential candidate for wound dressings.


Assuntos
Materiais Biocompatíveis/administração & dosagem , Cobalto/administração & dosagem , Teste de Materiais , Engenharia Tecidual , Cicatrização , Materiais Biocompatíveis/química , Cobalto/química , Humanos , Microscopia Eletrônica de Varredura , Espectroscopia de Infravermelho com Transformada de Fourier
4.
Analyst ; 144(17): 5284-5291, 2019 Sep 07.
Artigo em Inglês | MEDLINE | ID: mdl-31372627

RESUMO

5,10,15,20-Tetrakis(4-carboxyl phenyl)porphyrin (Por) modified Co(OH)2 deposited on the surface of GO nanocomposites (Por/Co(OH)2/GO) were prepared and characterized by transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and XRD. For the first time, H2TCPP/Co(OH)2/GO is found to have enhanced peroxidase-like activity and catalyze the oxidation of the substrate 3,3,5,5-tetramethylbenzidine (TMB) by hydrogen peroxide (H2O2). Notably, the colorless TMB rapidly transformed into blue oxTMB in just 60 s, which was easily observed visually. The catalytic kinetics of H2TCPP/Co(OH)2/GO is in accord with the Michaelis-Menten equation. The catalytic mechanism of H2TCPP/Co(OH)2/GO nanocomposites is attributed to hydroxyl radicals (˙OH), due to decomposition of H2O2, which is verified by using terephthalic acid as a fluorescent probe. What's more, H2O2 can be detected in a wide linear detection range from 5 to 35 mM with a detection limit of 0.385 mM. Furthermore, based on the excellent peroxidase-like activity of H2TCPP/Co(OH)2/GO, a colorimetric sensor is established to sensitively detect glutathione (GSH) in a linear range from 10 to 300 µM with a low detection limit of 9.5 µM.


Assuntos
Cobalto/química , Grafite/química , Hidróxidos/química , Nanocompostos/química , Peroxidases/química , Porfirinas/química , Benzidinas/química , Materiais Biomiméticos , Técnicas Biossensoriais/métodos , Catálise , Glutationa/análise , Peróxido de Hidrogênio/química , Radical Hidroxila/química , Cinética , Limite de Detecção , Oxirredução , Sensibilidade e Especificidade , Propriedades de Superfície
5.
Phys Chem Chem Phys ; 21(28): 15779-15786, 2019 Jul 17.
Artigo em Inglês | MEDLINE | ID: mdl-31282523

RESUMO

Small-molecule fluorescent probes having optimized optical properties, such as high photostability and brightness, local microenvironment sensitivity and specific subcellular localizations, are increasingly available. Although the basis for designing efficient fluorophores for bioimaging applications is well established, implementing an improvement in a given photophysical characteristic always tends to compromise another optical property. This problem has enormous consequences for in vivo imaging, where ensuring a specific localization and precise control of the probe response is challenging. Herein we discuss a fluorescent probe, CC334, as a case study of the chromenylium-cyanine family that commonly exhibits highly complex photophysical schemes and highly interfered bioanalytical responses. By an exhaustive and concise analysis of the CC334 optical responses including detailed spectroscopic calibrations, steady-state microenvironment effects, ultrafast photophysics analysis and computational studies, we elucidate a new strategy to apply the probe in the singlet oxygen reactive oxygen species (1O2-ROS) monitoring using in vitro and in vivo models. The probe provides a new avenue for designing fluorescent probes to understand the dynamic behavior of subcellular environments.


Assuntos
Benzopiranos/química , Corantes Fluorescentes/química , Corantes Fluorescentes/metabolismo , Cobalto/química , Ferrocianetos/química , Quinolinas/química , Espécies Reativas de Oxigênio/química , Análise Espectral
6.
Food Chem ; 297: 124930, 2019 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-31253279

RESUMO

A new microfluidic chemiluminescence (MF-CL) method for rapidly assaying the total antioxidant capacity (TAC) of apple and pomegranate juices and honey samples was developed. The method exploited the NaHCO3-H2O2-Co2+ CL reaction. It was found that gallic acid (GA), catechin, caffeic acid, ferulic acid and rutin, as selected phenolic antioxidants, could suppress the CL reaction. The linear range and limit of detection of the method for the antioxidants were as follows: 0.5-3 mg L-1 and 0.27 mg L-1 for GA, 0.2-5.0 mg L-1 and 0.17 mg L-1 for catechin, 0.03-2.0 mg L-1 and 0.03 mg L-1 for caffeic acid, 0.3-2.0 mg L-1 and 0.23 mg L-1 for ferulic acid and 0.3-4.0 mg L-1 and 0.15 mg L-1 for rutin. GA was used as the standard, and the TAC of the fruit juices and honey samples as presented as GA equivalents (GAE). MF-CL was compared with DPPH and Folin-Ciocalteau (FC) methods.


Assuntos
Antioxidantes/química , Sucos de Frutas e Vegetais/análise , Mel/análise , Dispositivos Lab-On-A-Chip , Medições Luminescentes/métodos , Cobalto/química , Ácido Gálico/química , Peróxido de Hidrogênio/química , Medições Luminescentes/instrumentação , Bicarbonato de Sódio/química
7.
Food Chem ; 297: 124947, 2019 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-31253290

RESUMO

Newly developed combination of magnetic cobalt particles based dispersive solid-phase microextraction (Co-MP-DSPME) and slotted quartz tube attached flame atomic absorption spectrometry (SQT-FAAS) was utilized to determine lead at trace levels in tea samples. Co-MPs' adsorbent properties were tested and validated for their selectiveness to lead. Only with a few and short extraction steps (i.e. adding MPs, mixing, decanting and eluting) analyte was extracted from sample solution rapidly and efficiently. Limit of detection (LOD) and limit of quantification (LOQ) for the developed method (Co-MP-DSPME-SQT-FAAS) were found to be 7.77 µg/L and 25.9 µg/L, respectively. Matrix matching strategy was performed and outcomes indicated that the developed method is applicable with the high percent recovery values of 110.1 ±â€¯4.5 and %102.9 ±â€¯4.2 for 100 and 300 µg/kg lead standard spiked black tea samples, respectively. The method was also applied to standard reference material to check the accuracy of the method.


Assuntos
Contaminação de Alimentos/análise , Chumbo/análise , Microextração em Fase Sólida/métodos , Espectrofotometria Atômica/métodos , Chá/química , Cobalto/química , Análise de Alimentos/métodos , Limite de Detecção , Quartzo/química , Sensibilidade e Especificidade , Microextração em Fase Sólida/instrumentação , Espectrofotometria Atômica/instrumentação
8.
Bioelectrochemistry ; 129: 235-241, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31226524

RESUMO

During tribocorrosion of biomedical alloys, potentials may shift cathodically across the metal-oxide-electrolyte interface resulting in the increased reduction of local oxygen and water molecules. The products of reduction are thought to include reactive oxygen species (ROS) as well as hydroxide ions. Using fluorescent probes, developed for labeling intracellular ROS-based hydroxyl radicals (OH·) and hydrogen peroxide (H2O2), ROS generation due to reduction reactions at cathodically biased CoCrMo alloy surfaces was measured directly. Using terephthalic acid (TA) and pentafluorosulfonylbenzene-fluorescein (PFF) as fluorescent dosimeters, it was found that OH· and H2O2 concentrations increased up to 16 h and 2 h, respectively. Decreases in fluorescence past these time points were attributed to the continuous onset of reduction reactions consuming both the ROS and/or dosimeter. It was also found that voltages below and including -600 mV (vs. Ag/AgCl) produced measurable quantities of H2O2 after two hours of polarization, with concentrations increasing with decreasing potentials up to -1000 mV. The detection and quantification of ROS in a clinical setting could help us better understand the role of ROS in the inflammatory response as well as their impact on corrosion behavior of biomedical alloys.


Assuntos
Cromo/química , Cobalto/química , Corantes Fluorescentes/química , Peróxido de Hidrogênio/análise , Radical Hidroxila/análise , Molibdênio/química , Espécies Reativas de Oxigênio/análise , Ligas/química , Eletrodos , Fluoresceína/química , Oxirredução , Ácidos Ftálicos/química , Espectrometria de Fluorescência/métodos
9.
J Microbiol Biotechnol ; 29(6): 913-922, 2019 Jun 28.
Artigo em Inglês | MEDLINE | ID: mdl-31154745

RESUMO

Magnetic Ni0.7Co0.3Fe2O4 nanoparticles that were prepared via the rapid combustion process were functionalized and modified to obtain magnetic Ni0.7Co0.3Fe2O4@SiO2-CHO nanocomposites, on which penicillin G acylase (PGA) was covalently immobilized. Selections of immobilization concentration and time of fixation were explored. Catalytic performance of immobilized PGA was characterized. The free PGA had greatest activity at pH 8.0 and 45oC while immobilized PGA's a ctivities peaked a t pH 7.5 and 45°C. Immobilized PGA had better thermal stability than free PGA at the range of 30-50°C for different time intervals. The activity of free PGA would be 0 and that of immobilized PGA still retained some activities at 60°C after 2 h. Vmax and Km of immobilized PGA were 1.55 mol/min and 0.15 mol/l, respectively. Free PGA's Vmax and Km separately were 0.74 mol/min and 0.028 mol/l. Immobilized PGA displayed more than 50% activity after 10 successive cycles. We concluded that immobilized PGA with magnetic Ni0.7Co0.3Fe2O4@SiO2-CHO nanocomposites could become a novel example for the immobilization of other amidohydrolases.


Assuntos
Cobalto/química , Enzimas Imobilizadas/química , Nanopartículas de Magnetita/química , Nanocompostos/química , Níquel/química , Penicilina Amidase/química , Penicilina Amidase/metabolismo , Catálise , Estabilidade Enzimática , Enzimas Imobilizadas/metabolismo , Glutaral/química , Concentração de Íons de Hidrogênio , Dióxido de Silício/química , Temperatura Ambiente
10.
Inorg Chem ; 58(11): 7324-7334, 2019 Jun 03.
Artigo em Inglês | MEDLINE | ID: mdl-31081333

RESUMO

The development of metallogels widens the span of sensing activity as it opens new opportunities to develop chemosensors through metal-ligand interactions. Herein, a new nitrile-substituted 1,3,5-tricarboxamide-based gelator G4 has been fabricated and shows aggregate-induced enhanced emission (AIEE) after gelation in the presence of water. A dimethylformamide (DMF) solution of the gelator shows rapid crystallization, but addition of water to a DMF solution of gelator G4 leads to gelation at room temperature. In addition, gelator G4 was used for the formation of metallogels, and among them, the cobalt metallogel has been found to be effective for sensing l-tryptophan in the gel state through the quenching of AIEE. Interestingly, the gel is also effective in sensing bovine serum albumin protein at the nanomolar level, which contains an l-tryptophan residue. The limit of detection of Co(II)G4 for selective sensing of tryptophan has been found to be 2.4 × 10-8 M. To the best of our knowledge, there have been no reports to date of a metallogel being utilized to discriminate and selectively sense an amino acid and a protein. The gelation properties of the organic gelator molecule and metallogels have been explored through various spectroscopic tools and physicochemical experiments.


Assuntos
Técnicas de Química Analítica/instrumentação , Cobalto/química , Triptofano/análise , Dimetilformamida/química , Modelos Moleculares , Conformação Molecular , Temperatura Ambiente , Fatores de Tempo , Triptofano/química , Água/química
11.
Talanta ; 201: 286-294, 2019 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-31122425

RESUMO

Herein, high performance peroxidase-like activity of zinc and cobalt bi-metal metal-organic framework (ZnCo MOF) is reported and applied for the sensitive measurement of atropine. ZnCo MOF was synthesized by the reaction of 2-methylimidazole with Zn and Co (II) cations in aqueous media. The colorimetric and fluorometric experiments were applied to investigate the catalytic activity of obtained MOF, using o-phenylenediamine (OPD) and terephthalic acid (TA) peroxidase substrates, respectively. The results demonstrated the more efficient mimetic behavior of ZnCo MOF compared with common Zn or Co MOFs. Besides, it was found that atropine hindered the catalytic action of ZnCo MOF and this effect was intensified by increasing the atropine concentration. So, it was considered to design a sensitive analytical assay for atropine detection. To assure a high specific recognition, molecularly imprinted polymer (MIP)-based extraction using magnetic graphene oxide supports was applied to extract atropine before its determination. The combination between the high specific extraction and great catalytic activity of ZnCo MOF led to the ultrasensitive and reliable determination of atropine. The best linear range of calibration graph was achieved using fluorometric detection system for 0.1-45 ng mL-1 atropine concentrations, and detection limit (3Sb/m) was 27 pg mL-1. The relative standard deviations (RSD %) for the determination of 1, and 10 ng mL-1 atropine (n = 5) were 2.13% and 3.08%, respectively. The explained fluorometric assay was examined for the measurement of atropine in biological fluids (Recoveries were in the range of 95.90-103.57%), and the results were validated by an official method.


Assuntos
Atropina/sangue , Colorimetria/métodos , Grafite/química , Estruturas Metalorgânicas/química , Extração em Fase Sólida/métodos , Espectrometria de Fluorescência/métodos , Adulto , Materiais Biomiméticos/síntese química , Materiais Biomiméticos/química , Cobalto/química , Humanos , Limite de Detecção , Fenômenos Magnéticos , Masculino , Estruturas Metalorgânicas/síntese química , Pessoa de Meia-Idade , Impressão Molecular , Peroxidase/química , Porosidade , Zinco/química
12.
Carbohydr Polym ; 216: 54-62, 2019 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-31047082

RESUMO

Biodegradable, antimicrobial, and semiconducting cellulosic composite was synthesized by in-situ polymerization of polyaniline in the presence of cellulose. The cobalt ferrite nanoparticles (CFO-NPs) were added during the polymerization process to acquire this composite magnetic property. The CFO-NPs were prepared by sol-gel method with average particles size less than 50 nm. The nanocomposites were characterized by Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) and energy-dispersive X-ray (EDX). In addition, their magnetic, dielectric constant, dielectric loss, and conductivity behaviors were studied. The magnetization (Ms) and conductivity increased up to 3.7 emu/g and 3.5 × 10-3 S/cm, respectively, with increasing CFO-NPs content. The prepared electromagnetic nanocomposite exhibits highly efficient biodegradability and antimicrobial activity against Escherichia coli, Bacillus subtilis, and Candida albicans. The antimicrobial activity increased with increasing CFO-NPs while the biodegradability decreased.


Assuntos
Compostos de Anilina/farmacologia , Celulose/farmacologia , Cobalto/farmacologia , Compostos Férricos/farmacologia , Nanocompostos/química , Nanopartículas/química , Compostos de Anilina/síntese química , Compostos de Anilina/química , Antibacterianos/síntese química , Antibacterianos/química , Antibacterianos/farmacologia , Antifúngicos/síntese química , Antifúngicos/química , Antifúngicos/farmacologia , Bacillus subtilis/efeitos dos fármacos , Plásticos Biodegradáveis/síntese química , Plásticos Biodegradáveis/química , Plásticos Biodegradáveis/farmacologia , Candida albicans/efeitos dos fármacos , Celulose/análogos & derivados , Celulose/síntese química , Cobalto/química , Condutividade Elétrica , Escherichia coli/efeitos dos fármacos , Compostos Férricos/síntese química , Compostos Férricos/química , Fenômenos Magnéticos , Tamanho da Partícula
13.
Artif Cells Nanomed Biotechnol ; 47(1): 1746-1757, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31062618

RESUMO

To evaluate the safety and efficacy of novel cobalt complex with sulindac (Co-SLD), the zebrafish and oral squamous cell carcinoma CAL27 were investigated in the present study. The developmental toxicity of Co-SLD ranging from 5 to 20 µM was determined by exposure to 3-144-h post-fertilization (hpf) zebrafish. Our data showed that Co-SLD did not cause to the appreciable toxicity at low concentration (5 and 10 µM). A remarkable toxicity was observed at high concentration (20 µM), including increased mortality and malformation, delayed hatchability, reduced heart rate as well as suppressed behaviour. With regard to the antitumor activity of Co-SLD, inhibited cell growth and migration capability were outstandingly observed in oral squamous cell carcinoma treated with 10 and 20 µM Co-SLD, which could be mainly attributed to the Co-SLD-elicited mitochondrial damage as marked by the depression of mitochondrial membrane potential, ROS accumulation and ATP depletion. Furthermore, administration of 10 µM Co-SLD was an optimal concentration not only to avoid the normal tissue toxicity, but also to enhance the killing of cancer cells via disrupting mitochondrial dysfunction. Taken together the above results demonstrated the desirable response of oral squamous cell carcinoma to Co-SLD.


Assuntos
Carcinoma de Células Escamosas/patologia , Cobalto/química , Complexos de Coordenação/química , Complexos de Coordenação/farmacologia , Mitocôndrias/efeitos dos fármacos , Neoplasias Bucais/patologia , Sulindaco/química , Animais , Antineoplásicos/química , Antineoplásicos/farmacologia , Antineoplásicos/toxicidade , Apoptose/efeitos dos fármacos , Pontos de Checagem do Ciclo Celular/efeitos dos fármacos , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Complexos de Coordenação/toxicidade , Relação Dose-Resposta a Droga , Humanos , Locomoção/efeitos dos fármacos , Mitocôndrias/patologia , Peixe-Zebra
14.
Environ Sci Pollut Res Int ; 26(19): 19523-19539, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31077043

RESUMO

The present paper describes the sono-assisted adsorption (sono-adsorption) of methylene blue (MB), methyl violet (MV), and Nile blue (NB) from aqueous solution by AC/CoFe2O4 magnetic composite. FT-IR, TGA-DTG, VSM, XRD, TEM, SEM, EDX, Map, and Raman analysis were used to characterize the magnetic composite. The magnetization saturation value of AC/CoFe2O4 magnetic composite was determined to be 53.06 emu/g. Dye sono-adsorption efficiency was increased by increasing adsorbent dose, pH value, and contact time, but not dye concentration. Pseudo-first-order, pseudo-second-order, and intra-particle diffusion models were used to study the kinetic behavior of the cationic dye sono-adsorption. The sono-adsorption kinetics was reasonably followed by pseudo-second-order model (R2 > 0.998). The results showed that the Freundlich model (R2 > 0.976) was more able to describe the sono-adsorption equilibrium behavior than Langmuir, D-R, and Scatchard models. The maximum sono-adsorption capacity of NB, MV, and MB was determined as 86.24, 83.90, and 87.48 mg/g, respectively. Based on the parameters derived from isotherm modeling (RL, n, and E), the sono-adsorption process of cationic dyes is desirable and physical. An increase in NaCl concentration reduced the sono-adsorption efficiency for all dyes. Also, the adsorption-desorption of AC/CoFe2O4 magnetic was studied up to 10 stages, and it was confirmed that the sono-adsorption efficiency is acceptable up to the eight stage. AC/CoFe2O4 magnetic composite is, therefore, an affordable and recyclable adsorbent to remove the molecule of NB, MV, and MB dyes from aqueous media.


Assuntos
Carvão Vegetal/química , Cobalto/química , Corantes/análise , Compostos Férricos/química , Nanopartículas de Magnetita/química , Poluentes Químicos da Água/análise , Purificação da Água/métodos , Adsorção , Difusão , Violeta Genciana/análise , Concentração de Íons de Hidrogênio , Cinética , Azul de Metileno/análise , Oxazinas/análise
15.
Adv Mater ; 31(27): e1901893, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31095804

RESUMO

Tumor hypoxia compromises the therapeutic efficiency of photodynamic therapy (PDT) as the local oxygen concentration plays an important role in the generation of cytotoxic singlet oxygen (1 O2 ). Herein, a versatile mesoporous nanoenzyme (NE) derived from metal-organic frameworks (MOFs) is presented for in situ generation of endogenous O2 to enhance the PDT efficacy under bioimaging guidance. The mesoporous NE is constructed by first coating a manganese-based MOFs with mesoporous silica, followed by a facile annealing process under the ambient atmosphere. After removing the mesoporous silica shell and post-modifying with polydopamine and poly(ethylene glycol) for improving the biocompatibility, the obtained mesoporous NE is loaded with chlorin e6 (Ce6), a commonly used photosensitizer in PDT, with a high loading capacity. Upon the O2 generation through the catalytic reaction between the catalytic amount NE and the endogenous H2 O2 , the hypoxic tumor microenvironment is relieved. Thus, Ce6-loaded NE serves as a H2 O2 -activated oxygen supplier to increase the local O2 concentration for significantly enhanced antitumor PDT efficacy in vitro and in vivo. In addition, the NE also shows T2 -weighted magnetic resonance imaging ability for its in vivo tracking. This work presents an interesting biomedical use of MOF-derived mesoporous NE as a multifunctional theranostic agent in cancer therapy.


Assuntos
Estruturas Metalorgânicas/química , Nanoestruturas/química , Oxigênio/metabolismo , Fármacos Fotossensibilizantes/administração & dosagem , Porfirinas/administração & dosagem , Hipóxia Tumoral , Animais , Linhagem Celular Tumoral , Sobrevivência Celular/efeitos dos fármacos , Cobalto/química , Humanos , Peróxido de Hidrogênio/metabolismo , Indóis/química , Manganês/química , Camundongos , Óxidos/química , Fotoquimioterapia/métodos , Polietilenoglicóis/química , Polímeros/química , Porosidade , Dióxido de Silício/química , Microambiente Tumoral
16.
Anal Chim Acta ; 1071: 59-69, 2019 Sep 13.
Artigo em Inglês | MEDLINE | ID: mdl-31128756

RESUMO

Early diagnosis of cancer by biomarker detection has been widely studied since it can lead to an increase in patient survival rates. Magnetic nanoparticles (MNPs) play an important role in this field acting as a valuable tool in the biomarker immunocapture and detection. In this work, Co0.25Zn0.75Fe2O4 (CoZnFeONPs) nanoparticles were synthesized and applied as enzyme mimics of peroxidase-like catalysis in a disposable enzyme-free microfluidic immunoarray device (µID). The catalytic activity of CoZnFeONPs was evaluated by hydrogen peroxide detection using cyclic voltammetry and the apparent Michaelis-Menten constant was estimated by Lineweaver-Burk equation showing good Km values. In µID, the immunosensors were assembled with monoclonal antibody against CYFRA 21-1 covalently immobilized on graphene oxide previously deposited on the screen-printed carbon-based electrodes. Under optimized conditions, the method presented a good linear response for CYFRA 21-1 in the range of 3.9-1000 fg mL-1 achieving an ultralow limit of detection (LOD) of 0.19 fg mL-1. For comparison, Fe3O4 nanoparticles (FeONPs) was also synthetized and presented results slight inferior to that obtained with CoZnFeONPs. The methods developed using both MNPs exhibited countless advantages when compared with the immunosensors developed for CYFRA-21-1, previously reported in the literature. The methods were successful applied for the detection of CYFRA 21-1 in real serum samples of healthy and prostate cancer patients and showed good correlation with results obtained with the enzyme-linked immunosorbent assay (ELISA). The CoZnFeONPs associated with the disposable microfluidic immunoarray device provides a simple and effective method for biomarker detection that could satisfy the need for a low-cost and rapid test for early diagnosis of cancer.


Assuntos
Antígenos de Neoplasias/sangue , Biomarcadores Tumorais/sangue , Queratina-19/sangue , Dispositivos Lab-On-A-Chip , Nanopartículas Metálicas/química , Técnicas Analíticas Microfluídicas/métodos , Anticorpos/imunologia , Antígenos de Neoplasias/imunologia , Biomarcadores Tumorais/imunologia , Cobalto/química , Eletrodos , Grafite/química , Humanos , Imunoensaio/instrumentação , Imunoensaio/métodos , Ferro/química , Queratina-19/imunologia , Limite de Detecção , Masculino , Técnicas Analíticas Microfluídicas/instrumentação , Neoplasias da Próstata/sangue , Reprodutibilidade dos Testes , Zinco/química
17.
Environ Sci Pollut Res Int ; 26(19): 19189-19206, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31069657

RESUMO

A rapid synthetic technique is investigated for magnetic nanoparticles (Co1-yCuyFe2-xCexO4 (x = 0, y = 0), (x = 0.05, y = 0), (x = 0, y = 0.5), and (x = 0.05, y = 0.5)). The structure, morphology, optical and magnetic performance of prepared nanoparticles are analyzed by powder XRD, XPS, FT-IR, SEM-EDAX, TEM, DRS, and VSM. The photocatalytic activity of the synthesized nanoparticles for the removal of the Congo red (CR) dye and bisphenol A (BPA) from aqueous solution is examined by UV-visible spectrometer. Research indicates that the co-doping of Cu2+ and Ce3+ showed marked effect on the structural, optical, magnetic, and photocatalytic properties of the CoFe2O4 nanoparticles. DRS showed that the Co0.5Cu0.5Fe1.95Ce0.05O4 nanoparticles have lower band gap energy (0.78 eV) than other synthesized compounds. High removal percentage of CR and BPA (99.09% and 99.33%) was observed within 30 min and 180 min under visible and UV-light illumination respectively using Co0.5Cu0.5Fe1.95Ce0.05O4. The corresponding photocatalytic degradation kinetics and mechanism are analyzed.


Assuntos
Cério/química , Cobalto/química , Cobre/química , Compostos Férricos/química , Nanopartículas/química , Compostos Benzidrílicos/análise , Catálise , Vermelho Congo/análise , Cinética , Fenômenos Magnéticos , Fenóis/análise , Fotoquímica , Propriedades de Superfície , Poluentes Químicos da Água/análise
18.
Int J Mol Sci ; 20(10)2019 May 14.
Artigo em Inglês | MEDLINE | ID: mdl-31091724

RESUMO

Low-frequency electron paramagnetic resonance (EPR) spectra were obtained for the Co complex of ethylene diamine tetraacetic acid (CoEDTA). It was found that the cobalt hyperfine at geff-mid is better resolved at a low frequency, L-band (1.37 GHz), and not resolved at X-band (9.631 GHz), which is the conventional frequency used for most spectra for metal complexes. Resolved cobalt hyperfine lines lead to additional EPR parameters like A-mid for cobalt and a more-accurate determination of g-mid. Resolved hyperfine lines in the L-band, but not the S-band, spectra were obtained at a concentration of 1 mM. Knowing these additional EPR parameters provides a means to better determine the electron density in the ground state orbital for each cobalt complex, as well as to determine differences upon a change of ligation. If zinc sites can be replaced by cobalt, the cobalt spectra for these sites will enhance the characterization of the zinc sites.


Assuntos
Cobalto/química , Ácido Edético/química , Espectroscopia de Ressonância de Spin Eletrônica/métodos , Compostos de Zinco/química
19.
Artigo em Inglês | MEDLINE | ID: mdl-31046561

RESUMO

Acetaminophen, a popular NSAID (Non-steroidal anti-inflammatory drug), was studied for efficacy of removal from aqueous solutions. While Octolig® (a polyethylenediimine covalently attached to silica gel) is able to remove many simple anions and some acidic pharmaceuticals having a pKa value less than 4.5, it lacked efficacy with acetaminophen. Accordingly different transition- metal derivatives of Octolig® were tested by column chromatography using as substrates Octolig® derivatives of copper(II), cobalt(II), iron(III), manganese(II), nickel(II), and zinc(II).


Assuntos
Anti-Inflamatórios não Esteroides/isolamento & purificação , Sílica Gel/química , Poluentes Químicos da Água/isolamento & purificação , Purificação da Água/métodos , Água/química , Acetaminofen/isolamento & purificação , Acetaminofen/farmacocinética , Ânions , Anti-Inflamatórios não Esteroides/farmacocinética , Cromatografia/métodos , Cobalto/química , Cobre/química , Compostos Férricos/química , Humanos , Manganês/química , Níquel/química , Polietilenos/química , Sílica Gel/metabolismo , Soluções/química , Poluentes Químicos da Água/farmacocinética , Zinco/química
20.
Nat Commun ; 10(1): 2303, 2019 05 24.
Artigo em Inglês | MEDLINE | ID: mdl-31127106

RESUMO

The spin state transition from low spin to high spin upon substrate addition is one of the key steps in cytochrome P450 catalysis. External perturbations such as pH and hydrogen bonding can also trigger the spin state transition of hemes through deprotonated histidine (e.g. Cytochrome c). In this work, we report the isolated 2-methylimidazole Cobalt(II) [Co(TPP)(2-MeHIm)] and [Co(TTP)(2-MeHIm)], and the corresponding 2-methylimidazolate derivatives where the N-H proton of axial 2-MeHIm is removed. Interestingly, various spectroscopies including EPR and XAFS determine a high-spin state (S = 3/2) for the imidazolate derivatives, in contrast to the low-spin state (S = 1/2) of all known imidazole analogs. DFT assisted stereoelectronic investigations are applied to understand the metal-ligand interactions, which suggest that the dramatically displaced metal center allowing a promotion eg(dπ) → b1g([Formula: see text]) is crucial for the occurrence of the spin state transition.


Assuntos
Cobalto/química , Heme/química , Prótons , Biocatálise , Cobalto/metabolismo , Cristalografia por Raios X , Sistema Enzimático do Citocromo P-450/metabolismo , Espectroscopia de Ressonância de Spin Eletrônica , Heme/análogos & derivados , Heme/metabolismo , Histidina/química , Concentração de Íons de Hidrogênio , Imidazóis/metabolismo , Ferro/química , Ligantes , Oxirredução
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