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1.
Chemistry ; 26(27): 6056-6063, 2020 May 12.
Artigo em Inglês | MEDLINE | ID: mdl-32133687

RESUMO

The properties of LnIII -HPDO3A complexes as relaxation enhancers and paraCEST agents are essentially related to the hydroxylpropyl moiety. A series of three HPDO3A derivatives, with small modifications to the hydroxyl arm, were herein investigated to understand how heightened control can be gained over the parameters involved in the design of these agents. A full 1 H and 17 O-NMR relaxometric analysis was conducted and demonstrated that increasing the length of the OH group from the lanthanide centre significantly enhanced the water exchange rate of the gadolinium complex, but with a subsequent reduction in kinetic stability. Alternatively, the introduction of an additional methyl group, which increased the steric bulk around the OH moiety, resulted in the formation of almost exclusively the TSAP isomer (95 %) as identified by 1 H-NMR of the europium complex. The gadolinium analogue of this complex also exhibited a very fast water exchange rate, but with no detectable loss of kinetic stability. This complex therefore demonstrates a notable improvement over Gd-HPDO3A.


Assuntos
Meios de Contraste/química , Gadolínio/química , Elementos da Série dos Lantanídeos/química , Imagem por Ressonância Magnética/métodos , Európio/química , Compostos Heterocíclicos/química , Cinética , Compostos Organometálicos/química , Água
2.
Bioelectrochemistry ; 132: 107449, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-31918058

RESUMO

Dysregulation of the cardiac ryanodine receptor (RYR2) by luminal Ca2+ has been implicated in a life-threatening, stress-induced arrhythmogenic disease. The mechanism of luminal Ca2+-mediated RYR2 regulation is under debate, and it has been attributed to Ca2+ binding on the cytosolic face (the Ca2+ feedthrough mechanism) and/or the luminal face of the RYR2 channel (the true luminal mechanism). The molecular nature and location of the luminal Ca2+ site is unclear. At the single-channel level, we directly probed the RYR2 luminal face by Eu3+, considering the non-permeant nature of trivalent cations and their high binding affinities for Ca2+ sites. Without affecting essential determinants of the Ca2+ feedthrough mechanism, we found that luminal Eu3+ competitively antagonized the activation effect of luminal Ca2+ on RYR2 responsiveness to cytosolic caffeine, and no appreciable effect was observed for luminal Ba2+ (mimicking the absence of luminal Ca2+). Importantly, luminal Eu3+ caused no changes in RYR2 gating. Our results indicate that two distinct Ca2+ sites (available for luminal Ca2+ even when the channel is closed) are likely involved in the true luminal mechanism. One site facing the lumen regulates channel responsiveness to caffeine, while the other site, presumably positioned in the channel pore, governs the gating behavior.


Assuntos
Cálcio/metabolismo , Európio/química , Miocárdio/metabolismo , Canal de Liberação de Cálcio do Receptor de Rianodina/metabolismo , Animais , Cafeína/farmacologia , Humanos , Ativação do Canal Iônico/efeitos dos fármacos
3.
Chem Asian J ; 15(1): 85-90, 2020 Jan 02.
Artigo em Inglês | MEDLINE | ID: mdl-31729130

RESUMO

We recently found that [Eu(pda)2 ]- (pda: 1,10-phenanthroline-2,9-dicarboxylic acid), which has an achiral structure in crystals, exhibits circularly polarized luminescence (CPL) in aqueous solutions containing chiral amino acids such as arginine and histidine. CPL measurements were performed for agar gel, which includes an aqueous solution of [Eu(pda)2 ]- and chiral arginine or histidine. The spectral shape, concentration, and pH dependences on CPL intensity in the agar gels were very close to those in aqueous solutions, indicating that the CPL of the EuIII complex in the agar gels was induced by mechanism similar to that in aqueous solutions. We performed spatially resolved CPL measurements using a laboratory-built microscopic CPL spectroscopic system for agar-gel samples, where d- and l- amino acids were separately dispersed. We successfully recorded CPL imaging maps showing spatial dispersions of d- and l-amino acid in the agar gels.


Assuntos
Ágar/química , Arginina/análise , Complexos de Coordenação/química , Európio/química , Histidina/análise , Fenantrolinas/química , Géis/química , Concentração de Íons de Hidrogênio , Medições Luminescentes/instrumentação , Estrutura Molecular
4.
Talanta ; 206: 120202, 2020 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-31514885

RESUMO

Tetracycline (TC), a widely-used antibiotic to treat bacterial infections, combines with Eu3+ to form a stable EuTC complex that has a low fluorescence (FL) yield because of Eu3+ coordination with water molecules. We report a simple, label-free ratiometric fluorescent platform for sensitively and selectively sensing of TC, using L-histidine caped gold nanoclusters (His-AuNCs) as a FL indicator and an enhancer of Eu3+ FL. The His-AuNCs were prepared via chemical reduction of Au(III) by L-histidine, which was a reducer and a protecting agent. The His-AuNCs exhibited good photostability, outstanding stability toward high ionic strengths, storage stability, and favorable optical properties. In the absence of TC, the AuNCs-Eu3+ system displays strong FL emission at 475 nm (F475) from the His-AuNCs and weak FL at 620 nm from Eu3+ (F620) with excitation at 375 nm. TC quenches the His-AuNC FL and greatly enhances the Eu3+ emission. This is attributed to an enhancement of the EuTC complex fluorescence by the His-AuNCs. Thus, a ratiometric F620/F475 FL signal can be used for TC detection by simply mixing AuNCs and Eu3+. Under the optimized conditions, the linear range from 10 nM to 60 µM and a detection limit of 4 nM (S/N = 3) for TC were obtained. The application of the assay platform for the detection of TC in environmental and biological samples was demonstrated. The sensing platform has advantages of easy preparation, rapid response, high sensitivity, and good selectivity.


Assuntos
Európio/química , Corantes Fluorescentes/química , Ouro/química , Nanopartículas Metálicas/química , Tetraciclina/sangue , Antibacterianos/sangue , Antibacterianos/química , Complexos de Coordenação/química , Fluorescência , Histidina/química , Lagos/análise , Lagos/química , Limite de Detecção , Espectrometria de Fluorescência/métodos , Tetraciclina/química , Poluentes Químicos da Água/análise , Poluentes Químicos da Água/química
5.
Chemosphere ; 239: 124771, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31520970

RESUMO

Sorption of radionuclides on mineral surfaces retards their migration in the environment of a repository. Presence of organic ligands, however, affects sorption and consequently influences their transport behavior. In this study, we quantify the sorption of Eu(III) onto quartz surfaces as a function of pH in the absence and presence of diethylenetriaminepentaacetic acid (DTPA). Batch sorption experiments show a pH-dependent sorption of Eu(III) on quartz. The presence of DTPA results in slightly higher sorption of Eu(III) at neutral to slightly acidic pH and considerably lower sorption at alkaline conditions. Sorption experiments were simulated using the Diffuse Double Layer Model (DDLM) with single sorption sites (≡QOH) and monodentate surface complexation. The reactions were established based on the aqueous speciation calculation under the experimental conditions, and the thermodynamic constants of surface reactions were obtained and refined by numerical optimization. Results of surface complexation modeling show the formation of a surface species ≡QOHEuDTPA2-, explaining the elevated sorption of Eu(III) at neutral to slightly acidic pH. In contrast, dissolved EuDTPA2- complex species are present at alkaline pH, resulting in an enhanced mobility of Eu(III).


Assuntos
Európio/química , Modelos Químicos , Ácido Pentético/química , Quartzo/química , Adsorção , Concentração de Íons de Hidrogênio , Poluentes Radioativos do Solo/química , Termodinâmica
6.
Talanta ; 208: 120438, 2020 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-31816755

RESUMO

The threatening of antibiotic drugs for human and environment is being paid more and more attention. Ciprofloxacin (CIP), a strong quinolone antibiotic drug widely used in therapeutic treatments, is the most frequently detected in surface waters among the fluoroquinolones, which represents animal and human health risks. A novel highly fluorescent Ga-based hybrid (Eu3+@1) has been synthesized based on metal-organic framework (MOF) by encapsulating lanthanide cations Eu3+ in its channels. The as-synthesized compound possesses excellent water and pH-independent stability. It displays week red luminescence of Eu3+ in itself and can sense the CIP concentration as turn-on fluorescent probe in the human urine. With addition of CIP, the evident luminescence enhancement is clearly observed from the Eu3+@1. Linear correlation between the fluorescence intensity and the concentration of CIP is investigated, proving the excellent performance of Eu3+@1 in the detection of CIP with linear range (0.01-0.2 mg/mL) and low detection limit (2.4 ppm or 2.4 µg/mL). The response time is also very quick, less than 3 min. Based on these findings, we introduce AND logic gate strategy to the probe. The input of the logic gates (0, 1), (0, 1, 1), (1, 1, 1) cause the different outputs of CIP determination "LOW" (<25 ppm),"NORMAL" (25-76 ppm), "HIGH" (>76 ppm), respectively. The novel strategy can be applied for a real-time CIP concentration evaluation by intelligent discrimination.


Assuntos
Antibacterianos/urina , Ciprofloxacino/urina , Európio/química , Corantes Fluorescentes/química , Gálio/química , Estruturas Metalorgânicas/química , Antibacterianos/química , Ciprofloxacino/química , Humanos , Lógica , Luminescência
7.
Talanta ; 208: 120368, 2020 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-31816769

RESUMO

The rapid and sensitive visualization of 2,6-dipicolinic acid (DPA, a unique anthrax biomarker) is essential to prevent anthrax disease or biological terrorist attack. In this study, a Eu3+-labeled ethylenediaminetetraacetic acid loaded hyperbranched polyethyleneimine carbon nanodot (hPEI-CD-EDTA-Eu3+) nanoprobe has been proposed for the ratiometric DPA detection. The sensing mechanism is based on the rapid DPA-Eu3+ chelation within 30 s and subsequent enhanced fluorescence emission through the antenna effect. With the introduction of EDTA chelating unit, the resulted fluorescence of Eu3+-complex is greatly enhanced, which endows sensitive DPA perception. By employing hPEI-CD as the internal reference, ratiometric DPA sensing is realized with a good linearity in the concentration range from 1.0 to 100 nM, with a limit of detection of 190 pM (S/N = 3). The specific chelation affinity between Eu3+ and DPA provides satisfying selectivity over other amino acids and ions. Using nanoprobe-loaded polyvinylidene fluoride paper as the analytical device, point-of-care DPA visualization is achieved. Furthermore, the practical application of designed paper device is validated by the visual detection of metabolic DPA-release from Bacillus subtilis spores.


Assuntos
Bacillus subtilis/metabolismo , Carbono/química , Ácido Edético/química , Európio/química , Limite de Detecção , Nanoestruturas/química , Ácidos Picolínicos/análise , Biomarcadores/análise , Biomarcadores/sangue , Biomarcadores/química , Biomarcadores/metabolismo , Corantes Fluorescentes/química , Humanos , Ácidos Picolínicos/sangue , Ácidos Picolínicos/química , Ácidos Picolínicos/metabolismo , Polietilenoimina/química
8.
Biosens Bioelectron ; 148: 111791, 2020 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-31677526

RESUMO

A smartphone-integrated ratiometric fluorescent sensing system (DPA-Ce-GMP-Eu) for visual and point-of-care testing (POCT) of tetracycline with high sensitivity and accuracy was developed. The blue fluorescence of DPA-Ce-GMP was changed into red by doping with Eu3+ duo to the energy transfer from Ce3+ to Eu3+. Upon exposure to tetracycline, coordination between Eu3+ and tetracycline blocks energy transfer from Ce3+ to Eu3+, converting the fluorescent color from red to blue. The tetracycline detection can be realized within a wide concentration range from 0.01 µM to 45 µM. The limit of detection (LOD) reaches as low as 6.6 nM. To realize quantitative point-of-care detection in real samples, a portable device with smartphone as signal reader and analyzer is further designed to integrate with the DPA-Ce-GMP-Eu sensing platform. The Color Picker APP installed in the smartphone can convert the Red, Green and Blue (RGB) channels of the fluorescence images into digital values. With milk as real sample, tetracycline can be on-site detected with LOD of 10.8 nM. This developed platform presents a great promise for POCT in practical application with merits of low cost, easy carry, simple operation, and excellent selectivity and repeatability.


Assuntos
Antibacterianos/análise , Técnicas Biossensoriais/instrumentação , Contaminação de Alimentos/análise , Smartphone/instrumentação , Tetraciclina/análise , Animais , Cério/química , Desenho de Equipamento , Európio/química , Fluorescência , Corantes Fluorescentes/química , Análise de Alimentos/instrumentação , Limite de Detecção , Leite/química , Carne de Porco/análise , Espectrometria de Fluorescência/instrumentação
9.
Mater Sci Eng C Mater Biol Appl ; 106: 110295, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31753350

RESUMO

Hexagonal nanocrystalline powders of the non-doped Ca10(PO4)6(OH)2 as well as activated with Ag+ and Eu3+ ions were synthesized by using different wet chemistry methods. Moreover, the obtained hydroxyapatite was loaded with Ag0, as well as nitroimidazole antimicrobials: metronidazole and tinidazole. The structural properties of the products were analyzed by X-ray diffraction (XRD), scanning (SEM) and transmission (TEM) electron microscopy as well as infrared (IR) and Raman spectroscopy. The photoluminescence properties of the Eu3+ and Ag+ co-doped Ca10(PO4)6(OH)2 were characterized via the PL emission, excitation spectra and the luminescence decay curve. The antimicrobial activity of the obtained materials against Prevotella bivia and Parabacteroides distasonis was studied. The cytotoxicity assessment was carried out on the human osteosarcoma cell line (U2OS) as well as human red blood cells (RBC). The choice of the in vitro model was based on the fact that U2OS is a cancer cell line derived from bone tissue which is rich in apatites that play a pivotal role in the extracellular matrix formation. RBCs are the most abundant blood cells and they are used as a cell model in the study of biocompatibility of new prepared biocompounds with potential medical applications. The obtained multifunctional materials do not exhibit the haemolytic activity, therefore, they could be used as a promising antimicrobial agent and for anaerobic bacteria.


Assuntos
Bacteroidetes/efeitos dos fármacos , Materiais Biocompatíveis/farmacologia , Hidroxiapatitas/química , Nanocompostos/química , Prevotella/efeitos dos fármacos , Adsorção , Animais , Materiais Biocompatíveis/síntese química , Materiais Biocompatíveis/química , Sedimentação Sanguínea/efeitos dos fármacos , Bovinos , Linhagem Celular Tumoral , Sobrevivência Celular/efeitos dos fármacos , Európio/química , Hemólise/efeitos dos fármacos , Humanos , Testes de Sensibilidade Microbiana , Muramidase/química , Nanocompostos/toxicidade , Soroalbumina Bovina/química , Prata/química
10.
Molecules ; 25(1)2019 Dec 23.
Artigo em Inglês | MEDLINE | ID: mdl-31878051

RESUMO

We have synthesized and examined several complexes of lanthanides with diamides of 2,2'-bipyridyl-6,6'-dicarboxylic acid bearing various hetaryl-based side chains for the elucidation of the effect of the heterocycle on the structure and properties of the ligands. The multigram scale methods for the preparation of various N-alkyl-hetaryls and their diamides were developed. The solid state structure of 6-methyl-2-pyridylamide of 2,2'-bipyridyl-6,6'-dicarboxylic acid possesses a flat structure where the conformation is completely different from that previously observed for N-alkylated 2,2'-bipyridyl-6,6'-dicarboxamides and 2,6-pyridinedicarboxamides. The complexes of new ligands were synthesized and NMR and X-Ray studied their structure in solution and solid state. The results demonstrate that complexes possess the same structures both in solid state and in solution. Stability constants of the complexes were less when comparing with dimethyl-substituted diamides, but higher than for unsubstituted dianilide. Contrarily, the extraction ability of 2-pyridyl-diamide is significantly lower than for corresponding anilide. Specific interaction of extractant with solvent molecules, which is not available for electron-sink pyridine amides, can explain this. The luminescence of new Eu complexes was significantly higher than for all previously 2,2'-bipyridyl-6,6'-dicarboxamides and QY reaches 18%. Asymmetry ratios of Eu complexes were 25% higher when compared other complexes with 2,2'-bipyridyl-6,6'-dicarboxamides, which indicates large deviation from the inversion center.


Assuntos
Complexos de Coordenação/química , Ácidos Dicarboxílicos/química , Elementos da Série dos Lantanídeos/química , Conformação Molecular , 2,2'-Dipiridil/química , Európio/química , Ligantes , Luminescência , Espectroscopia de Ressonância Magnética , Modelos Moleculares , Estrutura Molecular , Piridinas/química
11.
Chem Commun (Camb) ; 55(99): 14918-14921, 2019 Dec 25.
Artigo em Inglês | MEDLINE | ID: mdl-31769771

RESUMO

A porous NH2-MOF-76(Eu) (MOF 1) with unexpected non-luminescence was designed and synthesized. It exhibits selective fluorescence recovery for sensing dipicolinic acid (DPA), a biomarker of Bacillus anthracis. Moreover, a new europium-based MOF (MOF 2) with evident channel changes was obtained through a single-crystal to single-crystal phase transition.


Assuntos
Bacillus anthracis/isolamento & purificação , Európio/química , Estruturas Metalorgânicas/química , Transição de Fase , Biomarcadores , Cristalização , Cristalografia por Raios X , Luminescência , Ácidos Picolínicos/análise
12.
Anal Chim Acta ; 1092: 93-101, 2019 Dec 27.
Artigo em Inglês | MEDLINE | ID: mdl-31708038

RESUMO

A novel homogeneous assay system QTR-FRET (Quencher modulated Time-Resolved Förster Resonance Energy Transfer) combining quenching resonance energy transfer (QRET) and time-resolved Förster resonance energy transfer (TR-FRET) was developed to reduce background signal in the conventional energy transfer applications. The TR-FRET functionality is often limited by the lanthanide donor background signal leading to the use of low donor concentration. QTR-FRET reduces this background by introducing soluble quencher molecule, and in this work the concept functionality was proven and compared to previously introduced QRET and TR-FRET technologies. Comparison was performed with three different Eu3+-chelates exhibiting different luminescent lifetime and stability. The side-by-side comparison of the three signaling systems and Eu3+-chelates was demonstrated in a model assay with Eu3+-chelate conjugated biotin and streptavidin (SA) or Cy5-SA conjugate. Comparison of the methodologies showed increased signal-to-background ratios when comparing QTR-FRET to TR-FRET, especially at high Eu3+-biotin concentrations. Quenching the non-bound Eu3+-biotin improved the assay performance, which suggests that an improved assay performance can be attained with the QTR-FRET method. QTR-FRET is expected to be especially useful for Eu3+-labeled ligands with low affinity or assays requiring high Eu3+-ligand concentration. The QTR-FRET indicated potential for multi-analyte approaches separately utilizing the direct QRET-type Eu3+-chelate signal and energy transfer signal readout in a single-well. This potential was hypothesized with Avi-KRAS nucleotide exchange assay as a second biologically relevant model system.


Assuntos
Quelantes/química , Complexos de Coordenação/química , Európio/química , Transferência Ressonante de Energia de Fluorescência/métodos , Biotina/análise , Carbocianinas/química , Corantes Fluorescentes/química , Humanos , Ligantes , Proteínas Proto-Oncogênicas p21(ras)/análise , Estreptavidina/química
13.
J Fluoresc ; 29(6): 1285-1290, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31701327

RESUMO

In this study, the bio-inspired self-cracking substrate can be employed as a template to control the formation of a robust mirco-patterning film. Uniform materials with variable diameters are achieved by optimizing the egg white/water ratios and reaction temperature. The incorporated europium ions exhibit its typical f-f transitions in patterned films. Moreover, the mechanical property and excellent transmittance features have been demonstrated. The current approach can be extended to design two-dimensional nanofabrication of different materials.


Assuntos
Complexos de Coordenação/química , Európio/química , Imagem Óptica , Complexos de Coordenação/síntese química , Clara de Ovo/química , Estrutura Molecular , Tamanho da Partícula , Propriedades de Superfície , Temperatura
14.
Chem Commun (Camb) ; 55(83): 12479-12482, 2019 Oct 25.
Artigo em Inglês | MEDLINE | ID: mdl-31566643

RESUMO

The electrochemiluminescence (ECL) from europium hydroxide nanorods (EHNs) was reported for the first time using K2S2O8 as an efficient cathodic co-reactant, and an ultrasensitive ECL aptasensor based on the system for the detection of thrombin has been formulated successfully.


Assuntos
Técnicas Eletroquímicas , Európio/química , Hidróxidos/química , Medições Luminescentes , Nanotubos/química , Trombina/análise , Humanos , Tamanho da Partícula , Propriedades de Superfície , Trombina/metabolismo
15.
Mater Sci Eng C Mater Biol Appl ; 105: 110057, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31546380

RESUMO

The present work introduces ternary Ln(III) (Ln = Eu, Yb, Lu) complexes with thenoyltriflouro1,3-diketonate (TTA-) and phosphine oxide derivative (PhO) as building blocks for core-shell nanoparticles with both Eu(III)- or Yb(III)-centered luminescence and the dual Eu(III)-Yb(III)-centered luminescence. Solvent-mediated self-assembly of the complexes is presented herein as the procedure for formation of EuLu, EuYb and YbLu heterometallic or homometallic cores coated by hydrophilic polystyrenesulfonate-based shells. Steady state and time resolved Eu-centered luminescence in homolanthanide and heterolanthanide EuLu and EuYb cores is affected by Eu → Eu and Eu → Yb energy transfer due to a close proximity of the lanthanide blocks within the core of nanoparticles. The Eu → Yb energy transfer is highlighted to be the reason for the enhancement of the NIR Yb-centered luminescence. Efficient cellular uptake, low cytotoxicity towards normal and cancer cells, and sensing ability of EuYb nanoparticles on lomefloxacin additives via both red and NIR channels make them promising as cellular imaging agents and sensors.


Assuntos
Antineoplásicos , Citotoxinas , Európio , Luminescência , Nanopartículas Metálicas , Neoplasias , Itérbio , Antineoplásicos/química , Antineoplásicos/farmacologia , Citotoxinas/química , Citotoxinas/farmacologia , Európio/química , Európio/farmacologia , Células HeLa , Humanos , Nanopartículas Metálicas/química , Nanopartículas Metálicas/uso terapêutico , Neoplasias/diagnóstico por imagem , Neoplasias/tratamento farmacológico , Itérbio/farmacologia
16.
Molecules ; 24(18)2019 Sep 12.
Artigo em Inglês | MEDLINE | ID: mdl-31547345

RESUMO

Three 1,4,7,10-tetraazacyclododecane-based ligands disubstituted in 1,4-positions with phosphonic acid, phosphonate monoethyl-ester, and H-phosphinic acid pendant arms, 1,4-H4do2p, 1,4-H2do2pOEt, and 1,4-H2Bn2do2pH, were synthesized and their coordination to selected metal ions, Mg(II), Ca(II), Mn(II), Zn(II), Cu(II), Eu(III), Gd(III), and Tb(III), was investigated. The solid-state structure of the phosphonate ligand, 1,4-H4do2p, was determined by single-crystal X-ray diffraction. Protonation constants of the ligands and stability constants of their complexes were obtained by potentiometry, and their values are comparable to those of previously studied analogous 1,7-disubstitued cyclen derivatives. The Gd(III) complex of 1,4-H4do2p is ~1 order of magnitude more stable than the Gd(III) complex of the 1,7-analogue, probably due to the disubstituted ethylenediamine-like structural motif in 1,4-H4do2p enabling more efficient wrapping of the metal ion. Stability of Gd(III)-1,4-H2do2pOEt and Gd(III)-H2Bn2do2pH complexes is low and the constants cannot be determined due to precipitation of the metal hydroxide. Protonations of the Cu(II), Zn(II), and Gd(III) complexes probably takes place on the coordinated phosphonate groups. Complexes of Mn(II) and alkali-earth metal ions are significantly less stable and are not formed in acidic solutions. Potential presence of water molecule(s) in the coordination spheres of the Mn(II) and Ln(III) complexes was studied by variable-temperature NMR experiments. The Mn(II) complexes of the ligands are not hydrated. The Gd(III)-1,4-H4do2p complex undergoes hydration equilibrium between mono- and bis-hydrated species. Presence of two-species equilibrium was confirmed by UV-Vis spectroscopy of the Eu(III)-1,4-H4do2p complex and hydration states were also determined by luminescence measurements of the Eu(III)/Tb(III)-1,4-H4do2p complexes.


Assuntos
Complexos de Coordenação/química , Gadolínio/química , Compostos Heterocíclicos/química , Organofosfonatos/química , Meios de Contraste , Complexos de Coordenação/síntese química , Cristalografia por Raios X , Európio/química , Ligantes , Espectroscopia de Ressonância Magnética , Manganês/química , Ácidos Fosfínicos/química , Potenciometria , Espectrofotometria Ultravioleta , Temperatura
17.
ACS Appl Mater Interfaces ; 11(39): 36081-36089, 2019 Oct 02.
Artigo em Inglês | MEDLINE | ID: mdl-31508936

RESUMO

Anthrax spores have been a determining risk to human beings and animals across the world. As such, the qualitative monitoring toward dipicolinic acid (DPA), the unique biomarker of bacillus anthracis, is highly desired and being moved forward in health management. Herein, a breathing zeolite-like supramolecular assembly (ZSA), with the sra topology and 1D hexagon channel, is designed by controlling the bridging angle of the ditopic ligand after systematic analysis in topology. The solvent-dependent dynamic behavior is illustrated by powder X-ray diffraction and reflected in tunable luminescent emission based on solvent polarity parameters. According to the structural result and theoretical analysis, Eu3+ is anchored within the framework to form a ratiometric luminescent sensor successfully because of the abundant potential active site. After DPA addition, the resulting composite shows a sensitive and selective response in the linear range of 0-7.0 µM stemmed from absorbance energy-transfer emission and preferential coordination. The work we presented here may enrich the sensing platforms containing lanthanides and expand the potential application of ZSAs in clinical analysis.


Assuntos
Antraz/diagnóstico , Bacillus anthracis , Európio/química , Medições Luminescentes , Ácidos Picolínicos/análise , Zeolitas/química , Biomarcadores
18.
Phys Chem Chem Phys ; 21(38): 21213-21222, 2019 Oct 14.
Artigo em Inglês | MEDLINE | ID: mdl-31418759

RESUMO

Trivalent actinides and their lanthanide homologues are being scrutinized for their potential health risk when ingested as a result of a range of industrial activities such as mining. Importantly, these ions are known to exhibit high affinity towards calmodulin (CaM). In case of their inadvertent uptake, the holoproteins that are occupied by these cations may block signal transduction pathways or increase the concentration of these ions in intact cells, which could lead to accumulation in human organs. Accordingly, this investigation employed spectroscopy, computational chemistry, calorimetry, and biochemistry to study the results of metal ion substitution on the protein structure, enzymatic activity and chemo- and cytotoxicity of An3+/Ln3+ ions. As will be demonstrated herein, our data confirm the higher affinity of Cm3+ and Eu3+ compared to Ca2+ to all 4 binding sites of CaM, with one site differing from the remaining three. This higher-affinity site will complex Eu3+ in an exothermic fashion; in contrast, ion binding to the three lower-affinity EF-hands was found to be endothermic. The overall endothermic binding process is ascribed to the loss of the hydration shells of the trivalent ions upon protein binding. These findings are supported by extensive quantum chemical calculations of full holo-CaM, which were performed at the MP2 level using the fragment molecular orbital method. The exceptional binding site (EF-hand 3) features fewer negatively charged residues compared to the other EF-hands, thereby allowing Eu3+ and Cm3+ to carry one or two additional waters compared to Ca2+-CaM, while also causing the structure of Cm3+/Eu3+-CaM to become slightly disordered. Moreover, the enzymatic activity decreases somewhat in comparison to Ca2+-CaM. By utilizing a combination of techniques, we were able to generate a comprehensive picture of the CaM-actinide/lanthanide system from the molecular level to its functional impact. Such knowledge could also be applied to other metal-binding proteins.


Assuntos
Calmodulina/química , Calmodulina/metabolismo , Cúrio/química , Európio/química , Sítios de Ligação , Cálcio/química , Cátions , Simulação de Dinâmica Molecular , Conformação Proteica , Água
19.
Mikrochim Acta ; 186(8): 584, 2019 07 30.
Artigo em Inglês | MEDLINE | ID: mdl-31363852

RESUMO

The construction of multiple fluorescent nanosensors for intracellular studies is a challenging task because spectral overlap of indicator probes can lead to cross-talk and mutual interference. This work describes biodegradable nanosensors that can simultaneously measure three intracellular parameters (temperature, pH and oxygen concentration). Bovine serum albumin (BSA) is selected as the scaffold to construct the triple nanosensor by covalent immobilization four fluorophores on BSA. The following luminophores were used: (a) fluorescein as a probe for pH values, (b) a platinum(II) porphyrin complex for oxygen; (c) a europium(III) clathrate complex for temperature, and (d) a rhodamine B as a reference dye. The nanoparticles have a size of 20 nm and show excellent biocompatibility and good brightness. The nanosensors were used for ratiometric imaging of intracellular pH values, oxygen and temperature in HeLa cells. The triple nanosensor responds reversibly and this can be used for real-time tracing of these key parameters. Owing to their biodegradable feature, the use of this kind of triple nanosensor reduce the stress on cellular activities because less nanosensors can be used to gather the total information. Graphical abstractA triple nanosensor for simultaneously ratiometrically sensing intracellular pH, oxygen and temperature values was constructed by covalently labelling four fluorophores on a single serum albumin protein. The nanosensor shows good sensitivity, biocompatibility, is biodegradable and suitable for continuously measuring these important parameters.


Assuntos
Técnicas Biossensoriais , Corantes Fluorescentes/química , Európio/química , Fluoresceína/química , Células HeLa , Humanos , Concentração de Íons de Hidrogênio , Oxigênio/análise , Platina/química , Rodaminas/química , Soroalbumina Bovina/química , Temperatura
20.
Mikrochim Acta ; 186(8): 577, 2019 07 26.
Artigo em Inglês | MEDLINE | ID: mdl-31346718

RESUMO

The authors describe the preparation of gold nanoclusters (AuNCs) capped with kojic acid. The capped AuNCs exhibit bright green fluorescence (peaking at 500 nm upon excitation at 375 nm), a nanosecond lifetime (0.37 ns), and a quantum yield (QY) of 22% in aqueous solution. This is higher than most of the previously reported AuNCs. The QY increases to 58% due to aggregation-induced emission in ethanol solution, and the lifetime is prolonged to 1.3 ns. The fluorescence of the KA-AuNCs is quenched by Eu(III) ion but is recovered by addition of phosphate due to its stronger affinity for Eu(III). Under the catalytic action of alkaline phosphatase (ALP), ascorbic acid phosphate (AAP) is transformed to free phosphate. On this basis, a fluorogenic assay for ALP was established. Response is linear in the 0.2 to 20 U·L-1 activity range, and the detection limit is 0.04 U·L-1 (at S/N = 3). The assay was successfully applied to the determination of the activity of ALP in spiked human serum and also to screen for its inhibitors. Graphical abstractHighly luminescent and stable gold nanoclusters (AuNCs) with aggregation-induced emission property were synthesized through non-thiolate ligand kojic acid (KA) and demonstrated as an efficient probe for screening for alkaline phosphatase (ALP) activity and its inhibitors.


Assuntos
Fosfatase Alcalina/metabolismo , Fluorometria/métodos , Nanopartículas Metálicas/química , Pironas/química , Fosfatase Alcalina/antagonistas & inibidores , Fosfatase Alcalina/sangue , Inibidores Enzimáticos/química , Inibidores Enzimáticos/metabolismo , Európio/química , Ouro/química , Humanos , Limite de Detecção , Fosfatos/química , Fosfatos/metabolismo , Teoria Quântica
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