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1.
Int J Nanomedicine ; 14: 5697-5711, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31413570

RESUMO

Purpose: Calcium (Ca) and magnesium (Mg) ions have been used as promising bioactive ions in the surface chemistry modification of titanium (Ti) bone implants to increase bone regeneration capacity. However, it is not clear which (Ca or Mg) plays the more important role in the early osteogenic differentiation of mesenchymal stem cells (MSCs) when applied to the surface of commercially available microstructured Ti implants. This study investigated the relative effect of these two ions on the early osteogenic functionality of primary mouse bone marrow MSCs in order to obtain insights into the surface design of Ti implants with enhanced early osteogenic capacity. Methods and results: Wet chemical treatment was performed to modify a microrough Ti implant surface using Ca or Mg ions. Both the Ca and Mg-incorporated surfaces accelerated early cellular events and the subsequent osteogenic differentiation of MSCs compared with an unmodified microrough Ti surface. Surface Mg modification exhibited a more potent osteoblast differentiation-promoting effect than the Ca modification. Surface Mg incorporation markedly inhibited the phosphorylation of ß-catenin. Conclusion: These results indicate that alteration of the surface chemistry of microstructured Ti implants by wet chemical treatment with Mg ions exerts a more effect on promoting the early osteogenic differentiation of MSCs than Ca ions by enhancing early cellular functions, including focal adhesion development and stabilization of intracellular ß-catenin.


Assuntos
Cálcio/farmacologia , Magnésio/farmacologia , Células-Tronco Mesenquimais/citologia , Osteogênese/efeitos dos fármacos , Próteses e Implantes , Titânio/farmacologia , Animais , Cátions Bivalentes/farmacologia , Adesão Celular/efeitos dos fármacos , Diferenciação Celular/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Forma Celular/efeitos dos fármacos , Adesões Focais/efeitos dos fármacos , Íons , Células-Tronco Mesenquimais/efeitos dos fármacos , Células-Tronco Mesenquimais/ultraestrutura , Camundongos , Fosforilação/efeitos dos fármacos , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Propriedades de Superfície , Água/química , Difração de Raios X , beta Catenina/metabolismo
2.
J Chem Theory Comput ; 15(8): 4602-4614, 2019 Aug 13.
Artigo em Inglês | MEDLINE | ID: mdl-31268700

RESUMO

Many biological processes are based on molecular recognition between highly charged molecules such as nucleic acids, inorganic ions, charged amino acids, etc. For such cases, it has been demonstrated that molecular simulations with fixed partial charges often fail to achieve experimental accuracy. Although incorporation of more advanced electrostatic models (such as multipoles, mutual polarization, etc.) can significantly improve simulation accuracy, it increases computational expense by a factor of 5-20×. Indirect free energy (IFE) methods can mitigate this cost by modeling intermediate states at fixed-charge resolution. For example, an efficient "reference" model such as a pairwise Amber, CHARMM, or OPLS-AA force field can be used to derive an initial estimate, followed by thermodynamic corrections to a more advanced "target" potential such as the polarizable AMOEBA model. Unfortunately, all currently described IFE methods encounter difficulties reweighting more than ∼50 atoms between resolutions due to extensive scaling of both the magnitude of the thermodynamic corrections and their statistical uncertainty. We present an approach called "simultaneous bookending" (SB) that is fundamentally different from existing IFE methods based on a tunable sampling approximation, which permits scaling to thousands of atoms. SB is demonstrated on the relative binding affinity of Mg2+/Ca2+ to a set of metalloproteins with up to 2972 atoms, finding no statistically significant difference between direct AMOEBA results and those from correcting Amber to AMOEBA. The ability to change the resolution of thousands of atoms during reweighting suggests the approach may be applicable in the future to protein-protein binding affinities or nucleic acid thermodynamics.


Assuntos
Cálcio/metabolismo , Cátions Bivalentes/metabolismo , Magnésio/metabolismo , Metaloproteínas/metabolismo , Animais , Cálcio/química , Cátions Bivalentes/química , Bases de Dados de Proteínas , Humanos , Magnésio/química , Metaloproteínas/química , Simulação de Acoplamento Molecular , Simulação de Dinâmica Molecular , Ligação Proteica , Software , Eletricidade Estática , Termodinâmica
3.
Bioresour Technol ; 291: 121818, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31344637

RESUMO

A novel mesoporous biochar (PBC) was facilely prepared from Medulla tetrapanacis. PBC exhibited high efficiency for the sorption of Cu2+ (458.72 mg/g) and Pb2+ (1031.23 mg/g) ions, and these values were higher than that of reported literatures. In the multi-metal system, the maximum sorption capacity for Cu2+, Pb2+, Cr3+, and Fe3+ were 430.88 mg/g, 701.63 mg/g, 696.67 mg/g, and 697.01 mg/g, respectively, and the removal efficiencies of those ions were more than 80% at a metal ion concentration of 200 mg/L. Furthermore, the PBC was effective for the treatment of industrial effluent wastewater. The ash content (45.46%) of the PBC was higher than that of most other biochar derived from lignocellulosic biomass. Complexation, precipitation, π-π interactions, ion exchange, and physical sorption were the main sorption mechanisms. Overall, PBC is an inexpensive product, which is simply synthesized and an excellent adsorbent for heavy metal ion removal.


Assuntos
Carvão Vegetal/química , Cobre/química , Chumbo/química , Adsorção , Biomassa , Cátions Bivalentes/química , Troca Iônica
4.
Analyst ; 144(16): 4908-4916, 2019 Aug 21.
Artigo em Inglês | MEDLINE | ID: mdl-31312834

RESUMO

A new benzothiazole azo dye [(E)-1-((6-methoxybenzo[d]thiazole-2-yl)diazenyl)naphthalene-2,6-diol] (also known as "BAN"), has been synthesised and used as a chemosensor for the rapid and selective detection of mercury(ii) ions in water. The pink coloured chemosensor turns blue when reacted with mercury(ii) ions due to the formation of a 2 : 1 coordination complex. The complex formation causes a bathochromic shift of the chemosensor's UV absorption peak from 540 to 585 nm and turns on a highly selective fluorescence emission at 425 nm. The change in the optical property of BAN upon complexation with mercury(ii) was confirmed by ab initio calculations. The new chemosensor was used to quantify mercury(ii) ions in water by fluorescence spectroscopy down to 5 × 10-8 M (10 ppb). The limit of detection (LOD) of Hg2+ was 9.45 nM (1.8 ppb) which satisfies the maximum allowable Hg2+ concentration in drinking water that is set by the WHO. The BAN-Hg(ii) complex was used for the determination of cysteine (Cys) in aqueous solution by UV-Vis spectroscopy down to 1 × 10-7 M. The thiol-containing amino acid preferentially coordinates the mercury ions of the BAN-Hg(ii) complex. This causes dissociation of the blue-coloured complex and the liberation of the pink-coloured BAN dye. The colour change of the BAN-Hg(ii) complex from blue to pink was selective to the Cys biothiol while other non-thiol containing amino acids did not cause a colour change. For the in-field application, filter paper strips were loaded with the BAN-Hg(ii) complex and used as a disposable sensor for the detection of cysteine (Cys) by the naked eye. Therefore, the BAN chemosensor offers a sensitive, and rapid tool for the detection of mercury(ii) in water. In addition, the BAN-Hg(ii) complex can be used as a simple and selective chemosensor of the screening of purified biothiols, such cysetine, homocysteine and glutathione in biology research and pharmaceutical/food industries.


Assuntos
Benzotiazóis/síntese química , Corantes Fluorescentes/síntese química , Mercúrio/análise , Compostos de Sulfidrila/análise , Poluentes Químicos da Água/análise , Cátions Bivalentes , Cor , Simulação por Computador , Complexos de Coordenação/química , Cisteína/análise , Teoria da Densidade Funcional , Glutationa/análise , Concentração de Íons de Hidrogênio , Ligantes , Limite de Detecção , Espectrometria de Fluorescência
5.
Anal Bioanal Chem ; 411(23): 6165-6172, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31312882

RESUMO

The copper(II) ion (Cu2+) has played an indispensable role in diverse kinds of functional physiological processes of organisms, which has become of growing interest. Despite the fact that numerous Cu2+ test papers using fluorescent probes have been fabricated, sensors featuring the ratiometric property that integrates quenched probes and an inner standard dye are rarely reported. Herein, a two-component ratiometric sensor in a paper-based device is proposed to realize highly selective Cu2+ detection. To overcome shortcomings such as low signal-to-noise ratio and incorrect response of the quenching probe, a novel BODIPY-based turn-off probe (P2017) is designed and introduced into the paper-based device with better water solubility and selectivity for Cu2+ detection. Furthermore, a reference dye (B001), exhibiting an emission at 690 nm when the excitation wavelength is 480 nm, is also introduced into the paper-based device. These two components can enhance the quality of the signal as P2017 is sensitively quenched by Cu2+, while B001 with a photostable property, serving as an internal benchmark, is unable to react with Cu2+. The results indicated that the two components provided a new concept for optimizing paper-based device fabrication and developing accurate, simple, and inexpensive Cu2+ detection methods, which could be potentially applied to monitor human health and the environment in remote areas. Graphical abstract.


Assuntos
Técnicas Biossensoriais/instrumentação , Compostos de Boro/química , Cobre/análise , Corantes Fluorescentes/química , Papel , Cátions Bivalentes/análise , Desenho de Equipamento , Células Hep G2 , Humanos
6.
Chemistry ; 25(52): 12145-12158, 2019 Sep 18.
Artigo em Inglês | MEDLINE | ID: mdl-31271481

RESUMO

Urease uses a cluster of two NiII ions to activate a water molecule for urea hydrolysis. The key to this unsurpassed enzyme is a change in the conformation of a flexible structural motif, the mobile flap, which must be able to move from an open to a closed conformation to stabilize the chelating interaction of urea with the NiII cluster. This conformational change brings the imidazole side chain functionality of a critical histidine residue, αHis323, in close proximity to the site that holds the transition state structure of the reaction, facilitating its evolution to the products. Herein, we describe the influence of the solution pH in modulating the conformation of the mobile flap. High-resolution crystal structures of urease inhibited in the presence of N-(n-butyl)phosphoric triamide (NBPTO) at pH 6.5 and pH 7.5 are described and compared to the analogous structure obtained at pH 7.0. The kinetics of urease in the absence and presence of NBPTO are investigated by a calorimetric assay in the pH 6.0-8.0 range. The results indicate that pH modulates the protonation state of αHis323, which was revealed to have pKa =6.6, and consequently the conformation of the mobile flap. Two additional residues (αAsp224 and αArg339) are shown to be key factors for the conformational change. The role of pH in modulating the catalysis of urea hydrolysis is clarified through the molecular and structural details of the interplay between protein conformation and solution acidity in the paradigmatic case of a metalloenzyme.


Assuntos
Níquel/química , Urease/química , Amidas/química , Catálise , Domínio Catalítico , Cátions Bivalentes , Concentração de Íons de Hidrogênio , Hidrólise , Cinética , Compostos Organofosforados/química , Conformação Proteica , Ureia/química
7.
Nat Commun ; 10(1): 3067, 2019 07 11.
Artigo em Inglês | MEDLINE | ID: mdl-31296851

RESUMO

WalKR (YycFG) is the only essential two-component regulator in the human pathogen Staphylococcus aureus. WalKR regulates peptidoglycan synthesis, but this function alone does not explain its essentiality. Here, to further understand WalKR function, we investigate a suppressor mutant that arose when WalKR activity was impaired; a histidine to tyrosine substitution (H271Y) in the cytoplasmic Per-Arnt-Sim (PASCYT) domain of the histidine kinase WalK. Introducing the WalKH271Y mutation into wild-type S. aureus activates the WalKR regulon. Structural analyses of the WalK PASCYT domain reveal a metal-binding site, in which a zinc ion (Zn2+) is tetrahedrally-coordinated by four amino acids including H271. The WalKH271Y mutation abrogates metal binding, increasing WalK kinase activity and WalR phosphorylation. Thus, Zn2+-binding negatively regulates WalKR. Promoter-reporter experiments using S. aureus confirm Zn2+ sensing by this system. Identification of a metal ligand recognized by the WalKR system broadens our understanding of this critical S. aureus regulon.


Assuntos
Proteínas de Bactérias/metabolismo , Histidina Quinase/metabolismo , Proteínas Serina-Treonina Quinases/metabolismo , Staphylococcus aureus/metabolismo , Zinco/metabolismo , Substituição de Aminoácidos , Proteínas de Bactérias/química , Proteínas de Bactérias/genética , Cátions Bivalentes/metabolismo , Histidina/genética , Histidina Quinase/química , Histidina Quinase/genética , Simulação de Dinâmica Molecular , Mutação , Proteínas Serina-Treonina Quinases/química , Proteínas Serina-Treonina Quinases/genética , Regulon/genética , Staphylococcus aureus/genética , Tirosina/genética
8.
Environ Sci Process Impacts ; 21(7): 1153-1163, 2019 Jul 17.
Artigo em Inglês | MEDLINE | ID: mdl-31157350

RESUMO

Tetracycline is one of the most commonly used antibiotics in the world. Eventually, large amounts of this contaminant will enter into the subsurface environment, where a variety of ions exist. In this study, the effects of divalent metal cations (Mg2+, Ca2+, Pb2+ and Cu2+) and inorganic anions (Cl-, NO3-, SO42- and H2PO4-) on the transport of tetracycline in saturated porous media were investigated. Both batch and column experiments were conducted to determine the interactions between tetracycline and sand. Batch sorption experimental results showed that the presence of divalent metal cations could increase the sorption of tetracycline onto sand due to the cation-bridging mechanism. When Na+ was the counterion in the background solution, anions caused a significant decrease in tetracycline sorption owing to the occupation of some adsorption sites by anions and the decrease of electrostatic attraction. Column experiments indicated that the inhibition effects of divalent cations followed the order of Cu2+ > Pb2+ > Ca2+ ≈ Mg2+; the regular pattern might be related to their different complexing strengths. The presence of inorganic anions enhanced the mobility of tetracycline following the order of H2PO4- > SO42- > NO3- > Cl-. Transport-enhancement effects of anions were ascribed to competition between inorganic anions and tetracycline for deposition sites on sand surfaces. However, when Ca2+ was the counterion, the differences in the breakthrough curve of tetracycline among three inorganic anions (i.e., SO42-, NO3- and Cl-) were very small. In this case, the transport-inhibiting effects of anions could be counterbalanced by the transport-enhancement effects of the cation-bridging effect. Also, the two-site nonequilibrium transport model was applied to analyze the transport data. Findings from this study improve our understanding of the transport of tetracycline in saturated aquifer materials.


Assuntos
Ânions/química , Cátions Bivalentes/química , Modelos Teóricos , Dióxido de Silício/química , Tetraciclina/análise , Poluentes Químicos da Água/análise , Adsorção , Porosidade , Tetraciclina/química , Poluentes Químicos da Água/química
9.
Biochimie ; 163: 101-107, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31175919

RESUMO

Saccharomyces cerevisiae has high level of inorganic polyphosphate and a multicomponent system of its metabolism, including polyphosphatases Ppx1, Ppn1, Ddp1, and Ppn2. The aim of the study was to construct the yeast strain overexpressing Ppn2 and to compare the properties of Ppn2, Ppx1, Ppn1, and Ddp1 purified from overexpressing strains of S. cerevisiae. We overexpressed Ppn2 in S. cerevisiae under a strong constitutive promoter of the yeast glyceraldehyde-3-phosphate dehydrogenase-encoding gene and suggested biochemical criteria for distinguishing among yeast polyphosphatases, which is important for their identification and understanding of their functions. Ppn2, Ppn1, and Ddp1 had endopolyphosphatase activities, whereas Ppx1 did not. Ppx1 and Ppn1 exhibited high and Ddp1 and Ppn2 low exopolyphosphatase activity: 240, 500, 0.05 and 0.1 U/mg protein, respectively. The enzymes had distinct patterns of exopolyphosphatase activities stimulation by divalent metal ions. Ppn2, Ppn1 and Ddp1 displayed endopolyphosphatase activity in the presence of 1 mM Mg2+. The endopolyphosphatase activities of Ppn2 and Ppn1 were induced by 0.01 mM of Co2+ or Zn2+, whereas that of Ddp1 required 0.1 mM of these cations. The endopolyphosphatase activity of Ppn1 was inhibited by 0.01 mg mL-1 of heparin, while endopolphosphatase activity of Ppn2 was weakly sensitive to 0.25 mg mL-1 of heparin. The Ppx1 and Ppn1 activity with guanosine tetraphosphate was nearly 80% of activity with long-chain polyphosphates. The Ppn1 hydrolyzed dATP, while Ppx1 did not. The differences in the mode of polyphosphate hydrolysis, substrate specificity, metal ion dependence and cell localization suggest distinct roles of these enzymes in yeast.


Assuntos
Hidrolases Anidrido Ácido/metabolismo , Polifosfatos/metabolismo , Proteínas de Saccharomyces cerevisiae/metabolismo , Saccharomyces cerevisiae/enzimologia , Hidrolases Anidrido Ácido/genética , Cátions Bivalentes/metabolismo , Hidrólise , Microrganismos Geneticamente Modificados , Proteínas de Saccharomyces cerevisiae/genética , Especificidade por Substrato
10.
Pharm Res ; 36(8): 119, 2019 Jun 04.
Artigo em Inglês | MEDLINE | ID: mdl-31165279

RESUMO

PURPOSE: The purpose of this study was to characterize and detail the mechanism of a smart Ca2+ release depot (Ca3(PO4)2) about its ability for sustainable inhibition on peptide acylation within PLGA microspheres. METHODS: The octreotide acetate release and acylation kinetics were analyzed by RP-HPLC. Changes of Ca2+ concentration and adsorption behavior were determined by a Calcium Colorimetric Assay Kit. The inner pH changes were delineated by a classic pH sensitive probe, Lysosensor yellow/ blue® dextran. Morphological changes of microspheres, adsorption between polymer and additive, transformation of Ca3(PO4)2 were characterized using SEM, FTIR and SSNMR separately. RESULTS: Before and after microspheres formulation, the property and effectiveness of Ca3(PO4)2 were investigated. Compared with a commonly used calcium salt (CaCl2), high encapsulation efficiency (96.56%) of Ca3(PO4)2 guarantees lasting effectiveness. In an increasingly acidic environment that simulated polymer degradation, the poorly water-soluble Ca3(PO4)2 could absorb protons and transform into the more and more soluble CaHPO4 and Ca(H2PO4)2 to produce sufficient Ca2+ according to severity of acylation. The corresponding Ca2+ produce capacity fully met the optimum inhibition requirement since the real-time adsorption sites (water-soluble carboxylic acids) inside the degrading microspheres were rare. A sustained retention of three switchable calcium salts and slow release of Ca2+ were observed during the microsphere incubation. FTIR results confirmed the long-term inhibition effect induced by Ca3(PO4)2 on the adsorption between drug and polymer. CONCLUSIONS: With the presence of the smart Ca2+ depot (Ca3(PO4)2) in the microspheres, a sustainable and long-term inhibition of peptide acylation was achieved.


Assuntos
Cálcio/química , Microesferas , Peptídeos/química , Copolímero de Ácido Poliláctico e Ácido Poliglicólico/química , Acilação , Adsorção , Fosfatos de Cálcio/química , Cátions Bivalentes , Portadores de Fármacos , Liberação Controlada de Fármacos , Concentração de Íons de Hidrogênio , Cinética , Octreotida/química , Prótons , Solubilidade , Eletricidade Estática , Água/química
11.
Food Chem ; 293: 455-462, 2019 Sep 30.
Artigo em Inglês | MEDLINE | ID: mdl-31151634

RESUMO

To explore the protein surface properties treated by Pulsed Electric Field (PEF) with metal ions, we employed ovalbumin as the object and added three divalent metal ions (Ca2+, Cu2+ and Ba2+), respectively. The changes in surface hydrophobicity and surface tension were evaluated. Raman, FTIR, and fluorescence were used to record their structure variations. The results show that the surface hydrophobicity and surface tension of ovalbumin increased with the adding of metal ions. It was caused by the burial of some hydrophobic residues and variation of hydrophobic interaction between molecules, which was consistent with the results of spectra. With the combination of metal ions and PEF, the surface hydrophobicity and surface tension of ovalbumin showed an enhanced trend at first and then reduced with pulse time. These results demonstrate that metal ions and PEF have crucial influences on surface properties, that might afford a theoretical basis for the production and application of ovalbumin.


Assuntos
Eletricidade , Metais/química , Ovalbumina/química , Cátions Bivalentes/química , Interações Hidrofóbicas e Hidrofílicas , Espectroscopia de Infravermelho com Transformada de Fourier , Análise Espectral Raman , Propriedades de Superfície
12.
Chemistry ; 25(42): 9967-9972, 2019 Jul 25.
Artigo em Inglês | MEDLINE | ID: mdl-31056773

RESUMO

3,3'-Diformyl-1,1'-bi-2-naphthol or its methoxymethyl-protected derivative is found to undergo a highly selective reaction with excess bromine in CH2 Cl2 at reflux to give the novel 5,5',6,6'-tetrabrominated product (S)- or (R)-2. The observed electrophilic substitution at the 5,5'-positons of an optically active binaphthyl compound is unprecedented. Unlike unbrominated 3,3'-diformyl-1,1'-bi-2-naphthol, which is not suitable for fluorescent recognition in water, compound (S)-2, in combination with Zn2+ , exhibits a highly enantioselective fluorescent response toward amino acids in aqueous solution (HEPES buffer, pH 7.4). It is further found that the condensation product of (R)-2 with tryptophan, (R)-3, shows dual-responsive emissions toward amino acids; the short wavelength (λ1 =350 nm) emission is sensitive to the concentration of the substrate regardless of the chiral configuration and the long wavelength (λ2 >500 nm) emission is highly enantioselective. Thus, the use of (R)-3 allows the simultaneous determination of the concentration and enantiomeric composition of an amino acid sample from one fluorescence measurement.


Assuntos
Aldeídos/química , Aminoácidos/análise , Corantes Fluorescentes/química , Naftalenos/química , Cátions Bivalentes , Conformação Molecular , Estereoisomerismo , Água , Zinco/química
13.
Soft Matter ; 15(20): 4178-4186, 2019 May 22.
Artigo em Inglês | MEDLINE | ID: mdl-31062781

RESUMO

A novel cellular automaton (CA) for simulating biological membrane rupture is proposed. Constructed via simple rules governing deformation, tension, and fracture, the CA incorporates ideas from standard percolation models and bond-based fracture methods. The model is demonstrated by comparing simulations with experimental results of a double bilayer lipid membrane expanding on a solid substrate. Results indicate that the CA can capture non-trivial rupture morphologies such as floral patterns and the saltatory dynamics of fractal avalanches observed in experiments. Moreover, the CA provides insight into the poorly understood role of inter-layer adhesion, supporting the hypothesis that the density of adhesion sites governs rupture morphology.


Assuntos
Membrana Celular/metabolismo , Bicamadas Lipídicas/química , Animais , Células CHO , Cálcio/química , Cátions Bivalentes , Simulação por Computador , Cricetulus , Feminino , Fractais , Interações Hidrofóbicas e Hidrofílicas , Modelos Biológicos , Termodinâmica
14.
Soft Matter ; 15(20): 4200-4207, 2019 May 22.
Artigo em Inglês | MEDLINE | ID: mdl-31070656

RESUMO

Herein, we have designed and synthesized a novel forky peptide D3F3 that transforms into a hydrogel through crosslinking induced by ZIs stimuli. We have employed D3F3 as a suitable drug carrier that is conjugated with DOX. Since the concentration of zinc ions necessary for triggering gelation falls into the physiological range present in prostate tissue, while other cationic ions fail to trigger at physiological concentrations, the peptide-based drug delivery system (DDS) is injectable and would achieve prostate tissue-specific self-assembly in situ. The D3F3 hydrogels exhibited an optimal gelation time, satisfactory mechanical strength (can be enhanced after incorporation of DOX) as well as excellent thixotropic properties. The DDS reserved some DOX in the prostate 24 h after the injection, making local sustained release possible. In addition, the peptide materials demonstrated no cytotoxicity against normal fibroblast cells and no damage was observed to the prostate tissue of rats. The drug release followed a non-Fickian diffusion model, with no burst release observed. Importantly, the DOX-hydrogel system exhibited good anti-cancer efficacy when incubated with prostate cancer cells DU-145. Therefore, this study lays the groundwork for the future design of tissue-specific DDSs that are triggered by cationic ions (e.g. zinc ions), and the platform could be further developed to incorporate other potent drugs utilized in the field of prostate cancer therapy, thereby increasing their potency and reducing their side effects.


Assuntos
Antineoplásicos/administração & dosagem , Doxorrubicina/administração & dosagem , Portadores de Fármacos/química , Hidrogéis/química , Oligopeptídeos/síntese química , Neoplasias da Próstata/tratamento farmacológico , Animais , Ácido Aspártico/química , Cátions Bivalentes , Linhagem Celular Tumoral , Sobrevivência Celular/efeitos dos fármacos , Reagentes para Ligações Cruzadas/química , Humanos , Concentração de Íons de Hidrogênio , Masculino , Camundongos , Células NIH 3T3 , Próstata , Zinco/química
15.
Acta Crystallogr F Struct Biol Commun ; 75(Pt 5): 377-384, 2019 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-31045567

RESUMO

With better tools for data processing and with synchrotron beamlines that are capable of collecting data at longer wavelengths, sulfur-based native single-wavelength anomalous dispersion (SAD) phasing has become the `first-choice' method for de novo protein structure determination. However, for many proteins native SAD phasing can be simplified by taking advantage of their interactions with natural metal cofactors that are stronger anomalous scatterers than sulfur. This is demonstrated here for four unique domains of a 1.5 MDa calcium-dependent adhesion protein using the anomalous diffraction of the chelated calcium ions. In all cases, low anomalous multiplicity X-ray data were collected on a home-source diffractometer equipped with a chromium rotating anode (λ = 2.2909 Å). In all but one case, calcium SAD phasing alone was sufficient to allow automated model building and refinement of the protein model after the calcium substructure had been determined. Given that Ca atoms will be present in a significant percentage of proteins that remain uncharacterized, many aspects of the data-collection and processing methods described here could be broadly applied for routine de novo structure elucidation.


Assuntos
Adesinas Bacterianas/química , Proteínas de Bactérias/química , Cálcio/química , Gelo/análise , Marinomonas/química , Adesinas Bacterianas/genética , Adesinas Bacterianas/metabolismo , Sequência de Aminoácidos , Organismos Aquáticos , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Sítios de Ligação , Cálcio/metabolismo , Cátions Bivalentes , Clonagem Molecular , Temperatura Baixa , Cristalografia por Raios X , Escherichia coli/genética , Escherichia coli/metabolismo , Expressão Gênica , Vetores Genéticos/química , Vetores Genéticos/metabolismo , Modelos Moleculares , Ligação Proteica , Conformação Proteica em alfa-Hélice , Conformação Proteica em Folha beta , Domínios e Motivos de Interação entre Proteínas , Multimerização Proteica , Proteínas Recombinantes/química , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Difração de Raios X
16.
Chem Commun (Camb) ; 55(42): 5882-5885, 2019 May 25.
Artigo em Inglês | MEDLINE | ID: mdl-31037281

RESUMO

Spinach aptamer fluorescence requires formation of a tripartite complex composed of folded RNA, a GFP-like fluorophore, and selective cation coordination. 2'F pyrimidine modified Spinach has retained fluorescence, increased chemical stability, and accelerated cation association via increased G-quadruplex dynamics, thereby reducing readout time and enhancing Spinach utility for aqueous Pb2+ detection.


Assuntos
Aptâmeros de Nucleotídeos/química , Chumbo/química , Ribose/química , Cátions Bivalentes , Dicroísmo Circular , Fluorescência , Corantes Fluorescentes/química , Quadruplex G , Técnicas In Vitro , Conformação de Ácido Nucleico , Espectrometria de Fluorescência
17.
Artigo em Inglês | MEDLINE | ID: mdl-31045468

RESUMO

The sorption ability of biogenic hydroxyapatite (BHAP) towards heavy metal ions (Pb, Cu, Ni, Cd, and Zn) is compared with functionalized BHAP powders with caffeic acid (CA) and 3,4-dihydroxybenzoic acid (3,4-DHBA). The functionalization of the BHAP with either CA or 3,4-DHBA is indicated by the appearance of the colored powders due to the formation of the interfacial charge transfer (ICT) complexes. The detailed characterization of as-prepared and functionalized BHAP samples was performed using transmission electron microscopy, reflection spectroscopy, thermogravimetric analysis and determination of zeta potential. All three sorbents clearly displayed preferential sorption of Pb ions when the total concentration of multi-component equimolar solutions of heavy metal ions is high. It should be emphasized that the sorption capacity of functionalized BHAP with either CA or 3,4-BHAP was found to be higher, up to 60%, compared to as-prepared BHAP without the decrease of selectivity towards Pb ions.


Assuntos
Ácidos Cafeicos/química , Cátions Bivalentes/química , Durapatita/química , Hidroxibenzoatos/química , Metais Pesados/química , Adsorção , Soluções
18.
Water Res ; 159: 313-323, 2019 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-31102860

RESUMO

In the last two years, the rapidly rising demand for lithium has exceeded supply, resulting in a sharp increase in the price of the metal. Conventional electric driven membrane processes can separate Li+ from divalent cations, but there is virtually no commercial membrane that can efficiently and selectively extract Li+ from a solution containing chemically similar ions such as Na+ and K+. Here, we show that the different movement behavior of Li+ ion within the sub-nanometre channel leads to Li+ ion-selectivity and high transport rate. Using inexpensive negatively charged 2D subnanometer hydrous phyllosilicate channels with interlayer space of 0.43 nm in a membrane-like morphology, we observed that for an interlayer spacing of below 1 nm, Li+ ions move along the length of the channel by jumping between its two walls. However, for above 1 nm spacing, the ions used only one channel wall to jump and travel. Molecular dynamic (MD) simulation also revealed that ions within the nanochannel exhibit acceleration-deceleration behavior. Experimental results showed that the nanochannels could selectively transport monovalent ions of Li+> Na+> and K+ while excluding other ions such as Cl- and Ca2+, with the selectivity ratios of 1.26, 1.59 and 1.36 for Li+/Na+, Li+/K+, and Na+/K+ respectively, which far exceed the mobility ratios in traditional porous ion exchange membranes. The findings of this work provide researchers with not only a new understanding of ions movement behavior within subnanometer confined areas but also make a platform for the future design of ion-selective membranes.


Assuntos
Lítio , Sódio , Cátions Bivalentes , Cátions Monovalentes , Membranas
19.
J Colloid Interface Sci ; 551: 101-110, 2019 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-31075625

RESUMO

Carbon dots (C-dots) are superior in the aspects of excellent water solubility, good biocompatibility, environmentally friendliness and non-blinking fluorescence. In this work, highly photoluminescent small-size C-dots (QY = 18.8%, quinine sulfate as standard) with narrow size distribution (1.70 ±â€¯0.21 nm) have been synthesized by using citric acid and triethylamine through hydrothermal method. The optimal excitation and emission wavelength of C-dots are 350 nm and 437 nm, respectively. And the prepared C-dots display excitation-independent behavior due to less surface defects and uniform size. Interestingly, the fluorescence of C-dots could be rapidly and selectively quenched by Hg2+ within 200 s at room temperature without further modification. Under optimal conditions, the limit of detection (LOD) was measured to be nanomolar level (2.8 nM) with a linear range of 0.05-7 µM, lower than the previous published reports. Furthermore, our results reveal that static quenching mechanism was dominated in the process in which Hg2+ coordinate with the oxygen-containing groups of C-dots to form nonfluorescent complexes. And only the addition of Hg2+ destroyed the surface defects of C-dots resulting in the fluorescent quenching. The presence of other common interfering metal ions reported in previous literature (Ag+, Cu2+, Fe3+) do not affect the surface defects, which has rarely been reported before. Besides, this sensing platform has been further successfully applied to the label free detection of Hg2+ in tap water and living cells. These conclusions demonstrate the great potential of our C-dots in selective detection of environmental and cellular Hg2+, which may achieve a lot of achievements in clinical diagnosis and other biological researches.


Assuntos
Carbono/química , Corantes Fluorescentes/química , Mercúrio/análise , Pontos Quânticos/química , Poluentes Químicos da Água/análise , Técnicas Biossensoriais/métodos , Cátions Bivalentes , Linhagem Celular , Sobrevivência Celular/efeitos dos fármacos , Humanos , Limite de Detecção , Nitrogênio/química , Imagem Óptica/métodos , Oxigênio/química , Tamanho da Partícula , Sensibilidade e Especificidade , Espectrometria de Fluorescência , Propriedades de Superfície
20.
Molecules ; 24(8)2019 Apr 23.
Artigo em Inglês | MEDLINE | ID: mdl-31018515

RESUMO

At the present time, scientists place a great deal of effort worldwide trying to improve the therapeutic potential of metal complexes of curcumin and curcuminoids. Herein, the synthesis of four homoleptic metal complexes with diacetylcurcumin (DAC), using a ligand designed to prevent the interaction of phenolic groups, rendering metal complexes through the ß-diketone functionality, is reported. Due to their physiological relevance, we used bivalent magnesium, zinc, copper, and manganese for complexation with DAC. The resulting products were characterized by ultraviolet-visible (UV-Vis), fluorescence spectroscopy, infrared spectroscopy (IR), liquid and solid-state nuclear magnetic resonance (NMR), electron paramagnetic resonance (EPR), magnetic moment, mass spectrometry (MS), single crystal, and powder X-ray diffraction (SCXRD and PXRD). Crystallization was achieved in dimethylsulfoxide (DMSO) or N,N-dimethylformamide (DMF) as triclinic systems with space group P-1, showing the metal bound to the ß-diketone function, while the 1H-NMR confirmed the preference of the enolic form of the ligand. Single crystal data demonstrated a 1:2 metal:ligand ratio. The inhibition of lipid peroxidation was evaluated using the thiobarbituric acid reactive substance assay (TBARS). All four metal complexes (Mg, Zn, Cu, and Mn) exhibited good antioxidant effect (IC50 = 2.03 ± 0.27, 1.58 ± 0.07, 1.58 ± 0.15 and 1.24 ± 0.10 µM respectively) compared with butylated hydroxytoluene (BHT) and α-tocopherol. The cytotoxic activity in human cancer cell lines against colon adenocarcinoma (HCT-15), mammary adenocarcinoma (MCF-7), and lung adenocarcinoma (SKLU-1) was found comparable ((DAC)2Mg), or ca. 2-fold higher ((DAC)2Zn) than cisplatin. The acute toxicity assays indicate class 5 toxicity, according to the Organization for Economic Co-operation and Development (OECD) guidelines at doses of 3 g/kg for all complexes. No mortality or changes in the behavior of animals in any of the treated groups was observed. A therapeutic potential can be envisaged from the relevant cytotoxic activity upon human cancer cell lines in vitro and the undetected in vivo acute toxicity of these compounds.


Assuntos
Antineoplásicos Fitogênicos/farmacologia , Antioxidantes/farmacologia , Complexos de Coordenação/farmacologia , Cobre/química , Curcumina/análogos & derivados , Magnésio/química , Manganês/química , Zinco/química , Animais , Antineoplásicos Fitogênicos/síntese química , Antioxidantes/síntese química , Hidroxitolueno Butilado/farmacologia , Cátions Bivalentes , Linhagem Celular Tumoral , Cisplatino/farmacologia , Complexos de Coordenação/síntese química , Cristalografia por Raios X , Curcumina/química , Células Epiteliais , Humanos , Concentração Inibidora 50 , Ligantes , Peroxidação de Lipídeos/efeitos dos fármacos , Células MCF-7 , Masculino , Camundongos , Modelos Moleculares , Testes de Toxicidade Aguda , alfa-Tocoferol/farmacologia
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