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1.
Int J Nanomedicine ; 15: 2501-2513, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32368037

RESUMO

Purpose: The extracellular matrix (ECM) labyrinthine network secreted by mesenchymal stem cells (MSCs) provides a microenvironment that enhances cell adherence, proliferation, viability, and differentiation. The potential of graphene-based nanomaterials to mimic a tissue-specific ECM has been recognized in designing bone tissue engineering scaffolds. In this study, we investigated the expression of specific ECM proteins when human fat-derived adult MSCs adhered and underwent osteogenic differentiation in the presence of functionalized graphene nanoparticles. Methods: Graphene nanoparticles with 6-10% oxygen content were prepared and characterized by XPS, FTIR, AFM and Raman spectroscopy. Calcein-am and crystal violet staining were performed to evaluate viability and proliferation of human fat-derived MSCs on graphene nanoparticles. Alizarin red staining and quantitation were used to determine the effect of graphene nanoparticles on osteogenic differentiation. Finally, immunofluorescence assays were used to investigate the expression of ECM proteins during cell adhesion and osteogenic differentiation. Results: Our data show that in the presence of graphene, MSCs express specific integrin heterodimers and exhibit a distinct pattern of the corresponding bone-specific ECM proteins, primarily fibronectin, collagen I and vitronectin. Furthermore, MSCs undergo osteogenic differentiation spontaneously without any chemical induction, suggesting that the physicochemical properties of graphene nanoparticles might trigger the expression of bone-specific ECM. Conclusion: Understanding the cell-graphene interactions resulting in an osteogenic niche for MSCs will significantly improve the application of graphene nanoparticles in bone repair and regeneration.


Assuntos
Proteínas da Matriz Extracelular/metabolismo , Grafite/farmacologia , Células-Tronco Mesenquimais/metabolismo , Nanopartículas/química , Osteogênese/efeitos dos fármacos , Diferenciação Celular/efeitos dos fármacos , Células Cultivadas , Humanos , Integrinas/metabolismo , Células-Tronco Mesenquimais/efeitos dos fármacos , Oxigênio/química , Espectroscopia Fotoeletrônica , Multimerização Proteica
2.
Int J Nanomedicine ; 15: 2515-2527, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32368038

RESUMO

Purpose: Reactive oxygen species (ROS)-induced oxidative stress plays a key role in the pathogenesis and progression of psoriasis by causing inflammation. Antioxidative strategies eradicating ROS may serve as effective and easy treatment options for psoriasis, while nanozymes with intrinsic antioxidant enzyme-like activity have not been explored for psoriasis treatment. The aim of this study is to fabricate ß-cyclodextrins (ß-CDs)-modified ceria nanoparticles (ß-CDs/CeO2 NPs) with drug-loaded and multimimic-enzyme activities for combinational psoriasis therapy. Methods: The ß-CDs/CeO2 NPs were synthesized by a hydrothermal method using unmodified ß-CDs as a protecting agent. The structure, size and morphology were analyzed by dynamic light scattering, transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FTIR) spectroscopy. Considering the superoxide dismutase (SOD)- and catalase-mimetic activities, the in vitro antioxidant activity of the ß-CDs/CeO2 NPs was investigated. After dithranol (DIT) was loaded, the drug-loading capacity and release profile were determined by UV-visible light spectrophotometer and high-performance liquid chromatography. The anti-psoriatic efficacy was studied in the imiquimod (IMQ)-induced mouse model on the basis of morphological evaluation, psoriasis area and severity index calculation (PASI), and inflammatory cytokine expression. Results: The average particle size of the blank ß-CDs/CeO2 NPs was 60.89±0.32 nm with a polydispersity index (PDI) of 0.12, whereas that of the DIT-loaded NPs was 79.38±1.06 nm with a PDI of 0.27. TEM results showed the as-prepared NPs formed a uniform quasi-spherical shape with low polydispersity. XPS indicates synthesized NPs have a mixed Ce3+/Ce4+ valence state. FTIR spectroscopy confirmed the presence of ß-CDs and DIT in the NPs. Inhibition of superoxide anion rate by NPs could be reached to 79.4% in the presence of 200 µg/mL, and elimination of H2O2 efficiency reached about 50% in the presence of 40 µg/mL, demonstrating excellent superoxide dismutase- and catalase-mimicking activities, thereby providing remarkable cryoprotection against ROS-mediated damage. Furthermore, ß-CDs on the surface endowed the NPs with drug-loading function via host-guest interactions. The entrapment efficiency and drug loading of DIT are 94.7% and 3.48%, respectively. The in vitro drug release curves revealed a suitable release capability of DIT@ß-CDs/CeO2 NPs under physiological conditions. In IMQ-induced psoriatic model, the DIT@ß-CDs/CeO2 NPs exhibited excellent therapeutic effect. Conclusion: This study may pave the way for the application of nanozyme ß-CDs/CeO2 NPs as a powerful tool for psoriasis therapy.


Assuntos
Cério/química , Nanopartículas/química , Psoríase/terapia , beta-Ciclodextrinas/química , Animais , Catalase/metabolismo , Linhagem Celular , Sobrevivência Celular , Terapia Combinada , Depuradores de Radicais Livres/química , Hidrodinâmica , Imiquimode/farmacologia , Imiquimode/uso terapêutico , Masculino , Camundongos Endogâmicos BALB C , Nanopartículas/ultraestrutura , Tamanho da Partícula , Espectroscopia Fotoeletrônica , Psoríase/tratamento farmacológico , Espécies Reativas de Oxigênio/metabolismo , Pele/efeitos dos fármacos , Pele/patologia , Espectroscopia de Infravermelho com Transformada de Fourier , Superóxido Dismutase/metabolismo , Fator de Necrose Tumoral alfa/metabolismo , beta-Ciclodextrinas/síntese química
3.
J Chromatogr A ; 1623: 461065, 2020 Jul 19.
Artigo em Inglês | MEDLINE | ID: mdl-32448558

RESUMO

We report the preparation of high performance, sputtered, polydimethylsiloxane (PDMS)-coated solid phase microextraction (SPME) fibers that show negligible carry-over and phase bleed. This process involves sputtering silicon onto silica fibers and functionalizing the resulting porous nanostructures with ultrathin films of vapor-deposited PDMS. Different thicknesses of silicon (0.25, 0.8, and 1.8 µm) and PDMS (8, 16, and 36 nm) were produced and their extraction efficiencies evaluated. The deposition of PDMS was confirmed by time-of-fight secondary ion mass spectrometry (ToF-SIMS), X-ray photoelectron spectroscopy (XPS), spectroscopic ellipsometry (SE), and contact angle goniometry on model, planar silicon substrates. These fibers were investigated using direct immersion SPME coupled with gas chromatography-mass spectrometry (GC-MS) analysis of a series of polycyclic aromatic hydrocarbons (PAHs), which are carcinogenic pollutants. The 1.8 µm thick silicon coating with 16 nm of PDMS (Si (1.8 µm)/PDMS (16 nm)) produced the best response among the combinations tested. Conditions for the extraction of PAHs with this fiber were optimized and its extraction performance was compared to that of a commercial 7 µm PDMS fiber. The linearity (1-110 µgL-1), repeatability (RSD%, n = 3) (17% ave.), and minimum detection limits (0.6-1.5 µgL-1) of the sputtered fibers were determined and found to be superior to the commercial 7 µm PDMS fiber in many respects. Carry-over and phase bleed from commercial PDMS-based SPME fibers are two of their major drawbacks, which decrease their lifetimes and usefulness. Minimal carry-over and phase bleed were observed for our sputtered PDMS-coated fibers. In particular, our fiber only shows 12% of the phase bleed of the comparable commercial fiber. In addition, it shows no carry-over for analytes with retention times greater than pyrene, and only 5% of the carry-over of the other analytes. Our fibers could be used for at least 300 injections without any significant loss of performance.


Assuntos
Dimetilpolisiloxanos/química , Silício/química , Microextração em Fase Sólida/métodos , Cromatografia Gasosa-Espectrometria de Massas , Limite de Detecção , Espectroscopia Fotoeletrônica , Hidrocarbonetos Policíclicos Aromáticos/análise , Temperatura , Fatores de Tempo , Água/química , Poluentes Químicos da Água/análise
4.
Chemosphere ; 251: 126382, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32443238

RESUMO

A single metal Pd/γ-Al2O3 catalyst and a bimetallic Pd-Ce/γ-Al2O3 catalyst were prepared by the equal-volume impregnation method to investigate the effect of CeO2 loading on the catalytic oxidation of toluene. The specific surface area, surface morphology, and redox performance of the catalyst were characterized by N2 desorption, scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray photoelectron spectroscopy (XPS), H2-TPR, O2-TPD, and electron paramagnetic resonance (EPR). The results showed that bimetal catalysts loaded CeO2 had smaller nano-PdO particles than those of the Pd/γ-Al2O3 catalyst. Compared with the catalyst of 0.2Pd/γ-Al2O3 (percentage of mass, the same as below), the catalyst doped with 0.3CeO2 had a stronger reduction peak, which was shifted to the low-temperature zone by more than 80 °C. The results of XPS and O2-TPD showed that the introduction of CeO2 provided more surface oxygen vacancy for the catalyst and enhanced its catalytic oxidation ability, and the amount of desorbed O2 increased from 3.55 µmol/g to 8.54 µmol/g. The results of EPR were that the addition of CeO2 increased the content of active oxygen species and oxygen vacancies on the surface of the catalysts, which might be due to the supply of electrons to the O2 and PdO during the Ce3+toCe4+ conversion process. That could have accelerated the catalytic reaction process. Compared with the single precious metal catalyst, the T10 and T90 of the Pd-Ce/γ-Al2O3 catalyst were decreased by 22 °C and 40 °C, respectively.


Assuntos
Tolueno/química , Óxido de Alumínio/química , Catálise , Cério/química , Chumbo/química , Oxirredução , Oxigênio/química , Espectroscopia Fotoeletrônica
5.
Chemosphere ; 255: 126942, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32387732

RESUMO

Knowledge of the geochemical behavior of uranium is critical for the safe disposal of radioactive wastes. Biotite, a Fe(II)-rich phyllosilicate, is a common rock-forming mineral and a major component of granite or granodiorite. This work comprehensively studied the sorption of U(VI) on biotite surface with batch experiments and analyzed the uranium speciation with various spectroscopic techniques, including X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM) and time-resolved fluorescence spectra (TRFS). Our results indicated that uranyl ions could penetrate into the interlayer of biotite, this ion-exchange process was pH-dependent and only favorable under acidic condition. Instead of precipitation or reduction to uraninite, the TRFS results strongly suggests U(VI) forms surface complexes under the neutral and alkaline condition, though the number and structure of surface species could not be identified accurately. Besides, the oxidation of biotite with peroxide hydrogen showed that structural Fe(II) would have a very low redox reactivity. With leaching experiments, zeta potential analysis and thermodynamics calculation, we discussed the possible reasons for inhibition of U(VI) reduction at the biotite-water interface. Our results may provide insight on interaction mechanism of uranium at mineral-water interface and help us understand the migration behavior of uranium in natural environments.


Assuntos
Silicatos de Alumínio/química , Compostos Ferrosos/química , Urânio/química , Concentração de Íons de Hidrogênio , Troca Iônica , Minerais , Oxirredução , Espectroscopia Fotoeletrônica , Resíduos Radioativos , Dióxido de Silício , Termodinâmica
6.
Chemosphere ; 253: 126662, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32268253

RESUMO

In this study, pyrite (FeS2) was used as a novel activator of calcium peroxide (CaO2) for the degradation of diethyl phthalate (DEP) in both aqueous solution and soil. DEP (10 mg/L) in aqueous solution was completely degraded within 5.0 min by the FeS2 (0.30 g/L)/CaO2 (1.0 mM) system at pH 3.5. X-ray diffraction (XRD), scanning electron microscopy (SEM), electron paramagnetic resonance (EPR), free radical quenching, and X-ray photoelectron spectroscopy (XPS) were used to elucidate the mechanism of the catalytic decomposition of CaO2, radical formation and DEP degradation in the presence of by pyrite. The results show that hydroxyl radicals (OH) are the dominant active species responsible for DEP degradation. Surface or lattice Fe(II) of FeS2 readily activates H2O2 generated by CaO2 decomposition to produce OH, while the reducing sulfur species of FeS2 promotes the regeneration of surface of Fe(II) that catalyzes the production of additional OH, leading to the efficiently oxidative degradation of DEP. Although high concentration of common anions, such as Cl-, NO3-, SO42-, and HCO3-, exert inhibitory effects on DEP degradation by pyrite/CaO2, the reaction system can still efficiently degrade DEP in realistic soil. It was observed that 78% of DEP (25 mg kg-1) was degraded by 2.5% CaO2 (w/w) and 0.5% FeS2 (w/w) within 24 h. These results provide new insight into the mechanistic processes of CaO2 activation and OH formation by the novel FeS2 catalyst, demonstrating a promising alternative to the traditional H2O2-base Fenton process for contaminated soil remediation.


Assuntos
Ferro/química , Peróxidos/química , Ácidos Ftálicos/química , Sulfetos/química , Catálise , Espectroscopia de Ressonância de Spin Eletrônica , Radicais Livres , Peróxido de Hidrogênio/química , Radical Hidroxila/química , Oxirredução , Espectroscopia Fotoeletrônica , Enxofre
7.
Int J Nanomedicine ; 15: 2095-2118, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32273705

RESUMO

Purpose: Zinc (Zn), an essential trace element in the body, has stable chemical properties, excellent osteogenic ability and moderate immunomodulatory property. In the present study, a Zn-incorporated TiO2 nanotube (TNT) was fabricated on titanium (Ti) implant material. We aimed to evaluate the influence of nano-scale topography and Zn on behaviors of murine RAW 264.7 macrophages. Moreover, the effects of Zn-incorporated TNT surface-regulated macrophages on the behaviors and osteogenic differentiation of murine MC3T3-E1 osteoblasts were also investigated. Methods: TNT coatings were firstly fabricated on a pure Ti surface using anodic oxidation, and then nano-scale Zn particles were incorporated onto TNTs by the hydrothermal method. Surface topography, chemical composition, roughness, hydrophilicity, Zn release pattern and protein adsorption ability of the Zn-incorporated TiO2 nanotube surface were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS), surface profiler, contact angle test, Zn release test and protein adsorption test. The cell behaviors and both pro-inflammatory (M1) and pro-regenerative (M2) marker gene and protein levels in macrophages cultured on Zn-incorporated TNTs surfaces with different TNT diameters were detected. The supernatants of macrophages were extracted and preserved as conditioned medium (CM). Furthermore, the behaviors and osteogenic properties of osteoblasts cultured in CM on various surfaces were evaluated. Results: The release profile of Zn on Zn-incorporated TNT surfaces revealed a controlled release pattern. Macrophages cultured on Zn-incorporated TNT surfaces displayed enhanced gene and protein expression of M2 markers, and M1 markers were moderately inhibited, compared with the LPS group (the inflammation model). When cultured in CM, osteoblasts cultured on Zn-incorporated TNTs showed strengthened cell proliferation, adhesion, osteogenesis-related gene expression, alkaline phosphatase activity and extracellular mineralization, compared with their TNT counterparts and the Ti group. Conclusion: This study suggests that the application of Zn-incorporated TNT surfaces may establish an osteogenic microenvironment and accelerate bone formation. It provided a promising strategy of Ti surface modification for a better applicable prospect.


Assuntos
Fatores Imunológicos/farmacologia , Macrófagos/efeitos dos fármacos , Nanotubos , Osteoblastos/efeitos dos fármacos , Osteogênese/efeitos dos fármacos , Zinco/farmacocinética , Animais , Diferenciação Celular/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Meios de Cultivo Condicionados/farmacologia , Regulação da Expressão Gênica/efeitos dos fármacos , Macrófagos/imunologia , Camundongos , Microscopia Eletrônica de Varredura , Nanotubos/química , Osteoblastos/citologia , Osteogênese/genética , Espectroscopia Fotoeletrônica , Células RAW 264.7 , Propriedades de Superfície , Titânio/química , Difração de Raios X , Zinco/química
8.
Nat Commun ; 11(1): 2051, 2020 04 28.
Artigo em Inglês | MEDLINE | ID: mdl-32345967

RESUMO

A key challenge for designing hybrid materials is the development of chemical tools to control the organization of inorganic nanoobjects at low scales, from mesoscopic (~µm) to nanometric (~nm). So far, the most efficient strategy to align assemblies of nanoparticles consists in a bottom-up approach by decorating block copolymer lamellae with nanoobjects. This well accomplished procedure is nonetheless limited by the thermodynamic constraints that govern copolymer assembly, the entropy of mixing as described by the Flory-Huggins solution theory supplemented by the critical influence of the volume fraction of the block components. Here we show that a completely different approach can lead to tunable 2D lamellar organization of nanoparticles with homopolymers only, on condition that few elementary rules are respected: 1) the polymer spontaneously allows a structural preorganization, 2) the polymer owns functional groups that interact with the nanoparticle surface, 3) the nanoparticles show a surface accessible for coordination.


Assuntos
Nanopartículas Metálicas/química , Peptídeos/química , Platina/química , Polímeros/química , Nanopartículas Metálicas/ultraestrutura , Espectroscopia Fotoeletrônica , Polimerização
9.
Chemosphere ; 249: 126497, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32273124

RESUMO

According to the search in the state of the art, no antecedents were found in which photocatalytic degradation of 17α-methyltestosterone (MT) hormone has been carried out using doped-TiO2. Nor have the transformation products formed during the heterogeneous photocatalysis (FH) been identified. Therefore, in this study we analyzed the photocatalytic degradation of the MT in aqueous solution, using doped TiO2 with Sm3+ or Gd3+ at 0.3 and 0.5 %wt. Thermal treatment temperature (500 °C and 800 °C) and MT (20 mgL-1) mineralization were also studied. All photocatalysts were synthesized using the sol-gel method and characterized by X-ray Diffraction (XRD), Specific Surface Area (BET), Ultraviolet-visible Spectroscopy (UV-vis), High-Resolution Transmission Electron Microscope/Energy-Dispersive X-ray analysis (HRTEM/EDS) and, X-ray photoelectron spectroscopy (XPS), and photoluminescence (PL). MT mineralization was followed by a total organic carbon analyzer (TOC). The route of the photocatalytic mineralization of the hormone was obtained from the analysis of intermediate compounds determined by high performance liquid chromatography coupled to mass spectrometry (LC-TOF-MS). The results showed that TM and its transformation products were not degraded by photolysis. However, the degree of mineralization of the hormone was greater when the photocatalytic process was used. The photocatalytic efficiency was related to the dopant concentration, dopant type and thermal treatment. Therefore, Sm (0.3%)/TiO2 calcined at 500 °C showed the best performance for photocatalytic mineralization of MT.


Assuntos
Metiltestosterona/química , Fotólise , Catálise , Microscopia Eletrônica de Transmissão , Espectroscopia Fotoeletrônica , Titânio/química , Difração de Raios X
10.
Environ Sci Pollut Res Int ; 27(16): 20055-20065, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32236807

RESUMO

It is very necessary to produce bio-activated carbon for special use with easy procedure and low cost. One kind of huge surface area microporous bio-material was successfully prepared from agricultural residues (peanut shell, Arachis hypogaea Linn.) and beneficially applied to control elemental mercury (Hg0) in simulated coal-fired flue gas in this study. The possible effects of experimental factors including activator, reaction temperature, and flue components were investigated. The physicochemical properties of the prepared adsorbents were characterized by Brunauer-Emmett-Teller (BET), scanning electron microscopy with energy-dispersive X-ray spectrometry (SEM-EDX), and X-ray photoelectron spectroscopy (XPS). The results indicated that the peanut shell activated carbon presented excellent Hg0 removal efficiency near 90% at 150 °C. The characterization analysis indicated that the removal characteristics were governed by both physical adsorption and chemical adsorption. The chemisorbed mercury on the activated carbon was mainly distinguished into mercuric chloride (HgCl2) and mercuric oxide (HgO). The presence of C-Cl and O* promoted Hg0 into HgCl2 and HgO. Zinc chloride could not only improve the micropore quantity of activated carbon but also have remarkably positive effects on the elemental mercury removal. This study provided a practical and easy preparation method of bio-activated carbon for Hg0 removal with low cost. Graphical Abstract.


Assuntos
Mercúrio , Adsorção , Arachis , Carvão Vegetal , Espectroscopia Fotoeletrônica
11.
Ecotoxicol Environ Saf ; 195: 110459, 2020 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-32182533

RESUMO

This work was conducted to study the effect of soil pH (4.0, 6.0, and 8.0) on the transport, fractionation, and oxidation of trivalent chromium [Cr(III)]. Variation in pH altered soil chemical and mineralogical properties such as zeta potential, cation exchange capacity and redox potential of natural soil. Breakthrough curves and batch sorption experiments coupled with fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) analyses demonstrated that the easy mobility of Cr(III) in pH 4.0 soil was dominated by the limited coordination effect. The high retention of Cr(III) in pH 8.0 soil was mainly ascribed to the hydrolysis. Incubation experiments indicated that the proportions of Cr in exchangeable fraction decreased with increasing of soil pH and incubation time, and kinetics analysis revealed that the time dependent transformation was controlled by mass transfer and chemical processes (e.g., hydrolysis, ion association). The XPS confirmed the oxidation of Cr(III) in pH 8.0 soil during the incubation period. Furthermore, the content of toxic hexavalent chromium [Cr(VI)] was positively associated with time and initial concentration of Cr(III) released. These results revealed the hazardousness of Cr(III) in soil contaminated simultaneously by inorganic acid and alkali.


Assuntos
Cromo/análise , Poluentes do Solo/análise , Solo/química , Adsorção , Cromo/química , Concentração de Íons de Hidrogênio , Cinética , Oxirredução , Espectroscopia Fotoeletrônica , Espectroscopia de Infravermelho com Transformada de Fourier
12.
Chemosphere ; 252: 126560, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32222519

RESUMO

The novel ion-imprinted montmorillonite nanosheets/chitosan (IIMNC) gel beads were prepared for selective adsorption of Cu2+. The IIMNC gel beads were characterized by scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS). The results showed that IIMNC was successfully assembled and rich in honeycombed pores, which performed well in the removal of Cu2+ through the synergistic effect of montmorillonite nanosheets and chitosan. The elimination of copper was followed by pseudo-second-order model and was enhanced by introduced montmorillonite nanosheets (MMTNS) because MMTNS attracted Cu(Ⅱ) by its negative charge and provided active adsorption sites through its high performance of cation exchange. This composite gel also showed excellent reusability, performing well in the removal of Cu2+ after undergoing adsorption-desorption in five cycles, because the adsorption sites of MMTNS can be continually reactivated by NaOH solution. More importantly, its high selectivity for Cu2+ provides a feasible way to recover Cu2+ from wastewater containing various cations.


Assuntos
Bentonita/química , Quitosana/química , Eliminação de Resíduos Líquidos/métodos , Adsorção , Cátions , Cobre/química , Concentração de Íons de Hidrogênio , Cinética , Nanoestruturas , Espectroscopia Fotoeletrônica , Espectroscopia de Infravermelho com Transformada de Fourier , Águas Residuárias
13.
Phys Chem Chem Phys ; 22(14): 7193-7200, 2020 Apr 08.
Artigo em Inglês | MEDLINE | ID: mdl-32195495

RESUMO

We report a joint negative ion photoelectron spectroscopy (NIPES) and computational study on the electronic structures and noncovalent interactions of a series of cyclodextrin-closo-dodecaborate dianion complexes, χ-CD·B12X122- (χ = α, ß, γ; X = H, F). The measured vertical/adiabatic detachment energies (VDEs/ADEs) are 1.15/0.93, 3.55/3.20, 3.90/3.60, and 3.85/3.60 eV for B12H122- and its α-, ß-, γ-CD complexes, respectively; while the corresponding values are 1.90/1.70, 4.00/3.60, 4.33/3.95, and 4.30/3.85 eV for the X = F case. These results show that the inclusion of B12X122- into the CD cavities greatly increases the electronic stability of the dianions. The effect of electronic stabilization for ß-CD is roughly the same as for γ-CD, both being considerably stronger than that for α-CD. Density functional theory (DFT) based geometry optimization reveals that B12X122- are inserted into CDs increasingly deeper from α-CD to γ-CD. The calculated VDEs and ADEs agree with the experiments well, particularly, reproducing the electron binding energy (EBE) trends. The molecular orbital analyses indicate that the most loosely bound photodetached electrons originate from the guest B12X122- moieties. In addition to a shift of all signals to a larger EBE, significant changes in the signal patterns are observed. At low EBE, this is due to the splitting of highly degenerate B12X122- orbitals, while at high EBE, photodetachment from CD oxygens contributes to the new bands. The guest B12X122- and host CD noncovalent, size-specific interaction based on the independent gradient model (IGM) and energy decomposition analysis (EDA) is dominated by electrostatic interactions. The analysis further unravels unambiguously the existence of dihydrogen bonding and how it affects the total energy that stabilizes the host-guest complexes of CDs·B12H122- compared to the general hydrogen bonding interaction in CDs·B12F122-. This work clearly exhibits strong influences on the electronic structures of dodecaborates upon clustering with CDs, with both size (α-, ß-, and γ-) and molecular (X = H or F) specificities, thus providing critical molecular-level information on the cyclodextrin-closo-dodecaborate interactions of interest to medical applications, e.g., boron neutron capture therapy.


Assuntos
Ânions/química , Compostos de Boro/química , Espectroscopia Fotoeletrônica , Química Computacional , Estrutura Molecular
14.
Chemosphere ; 251: 126369, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32163779

RESUMO

Thermal modification was simply performed on molybdenite to enhance the adsorption of Pb(II) in aqueous solutions, and the root of this phenomenon was well studied in this work. Various thermal modification temperatures at 300 °C, 400 °C and 500 °C were applied to modify the surface property of molybdenite, producing different degrees of edge defect and surface wettability in molybdenite samples. Contact angle tests, atomic force microscopy (AFM) observations and adsorption tests illustrated that molybdenite thermally modified at 400 °C contained most edge defects and achieved a 147.846 mg/g Pb(II) adsorption, which was almost 10 times of that obtained by natural molybdenite. The adsorption experiment also indicated that the increase of surface hydrophilia of molybdenite would slightly benefit the Pb(II) adsorption. The X-ray photoelectron spectroscope (XPS) exhibited that a strong chemical adsorption existed between Pb(II) and S elements. AFM study further demonstrated that the interaction between Pb(II) and S atoms exposed at the triangular edges of molybdenite were the intrinsic reason for the great enhancement of Pb(II) adsorption. This work provides a new insight to absorb Pb(II) in aqueous solutions using natural molybdenite.


Assuntos
Chumbo/química , Poluentes Químicos da Água/química , Adsorção , Cinética , Espectroscopia Fotoeletrônica , Soluções , Propriedades de Superfície , Água/química
15.
Chemosphere ; 252: 126450, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32222522

RESUMO

Nanoplastics (NPs), which are broken down from large pieces of plastics and caused water environment pollution, are becoming an emerging environmental problem due to their stable structure, high mobility, and easy interactions with ambient organic compounds. Separation of NPs by flocculation may be an effective approach for remediation of NPs contaminated-water. Aluminum ion has been used as a highly efficient flocculant in sewage treatment, and calcium ion also shows excellent sedimentation performance for impurities under high pH conditions. In this study, composite metal calcium-aluminum (Ca/Al) ions were used as flocculants, achieving a settling efficiency of NPs almost as high as 80%. The effects of pH and Ca/Al flocculant ratios on the zeta potentials, solution stability, as well as sedimentation efficiency of NPs were investigated. Results showed that the crystal formation of Ca/Al flocs increased with pH. The contact and adsorption mechanism of NPs by Ca/Al flocs were confirmed by X-ray diffraction, scanning electron microscope, Fourier Transform Infrared Spectrometer, and X-ray photoelectron spectroscopy. The capture of NPs by Ca/Al flocculants could provide a new insight for the treatment of NPs from aqueous environment.


Assuntos
Microplásticos/química , Poluentes Químicos da Água/química , Adsorção , Alumínio/química , Cálcio/química , Floculação , Concentração de Íons de Hidrogênio , Íons , Espectroscopia Fotoeletrônica , Águas Residuárias/química , Água/química , Poluentes Químicos da Água/análise , Difração de Raios X
16.
Nat Commun ; 11(1): 1207, 2020 03 05.
Artigo em Inglês | MEDLINE | ID: mdl-32139700

RESUMO

The emergence of antibiotic resistant bacteria is a major threat to the practice of modern medicine. Photobactericidal agents have obtained significant attention as promising candidates to kill bacteria, and they have been extensively studied. However, to obtain photobactericidal activity, an intense white light source or UV-activation is usually required. Here we report a photobactericidal polymer containing crystal violet (CV) and thiolated gold nanocluster ([Au25(Cys)18]) activated at a low flux levels of white light. It was shown that the polymer encapsulated with CV do not have photobactericidal activity under white light illumination of an average 312 lux. However, encapsulation of [Au25(Cys)18] and CV into the polymer activates potent photobactericidal activity. The study of the photobactericidal mechanism shows that additional encapsulation of [Au25(Cys)18] into the CV treated polymer promotes redox reactions through generation of alternative electron transfer pathways, while it reduces photochemical reaction type-ІІ pathways resulting in promotion of hydrogen peroxide (H2O2) production.


Assuntos
Escherichia coli/efeitos dos fármacos , Escherichia coli/efeitos da radiação , Ouro/farmacologia , Luz , Nanopartículas/química , Compostos de Sulfidrila/química , Violeta Genciana/farmacologia , Testes de Sensibilidade Microbiana , Espectroscopia Fotoeletrônica , Espécies Reativas de Oxigênio/metabolismo
17.
J Chromatogr A ; 1620: 460932, 2020 Jun 07.
Artigo em Inglês | MEDLINE | ID: mdl-32029266

RESUMO

Although various cyclodextrins (CDs) have been utilized to prepare organic polymer-based monolithic columns, there were few reports on fabrication of cyclodextrin functionalized hybrid monolithic columns. Herein, a sulfobutylether ß-cyclodextrin (SBE-ß-CD)-silica hybrid monolithic column was prepared by "one-step" method via the co-polymerization of hydrolyzed organosiloxane precursors and glycidyl methacrylate-sulfobutylether ß-cyclodextrin (GMA-SBE-ß-CD). The morphologies of prepared monolithic columns were observed by optical microscopy and scanning electron microscopy (SEM). The sulfobutylether ß-cyclodextrin was incorporated into the polymeric structure, which was demonstrated by energy dispersive X-ray spectroscopy (EDS), Fourier-transform infrared spectroscopy (FTIR) spectrum and X-ray photoelectron spectroscopy (XPS). The resulting columns were used for chiral separations of twenty six racemic compounds, and satisfactory separation selectivity was obtained. Compared with other two kinds of neutral cyclodextrin (ß-CD and HP-ß-CD) based hybrid monoliths, sulfobutylether ß-cyclodextrin-silica hybrid monolith showed superior chiral resolution. These results demonstrated the sulfobutylether ß-cyclodextrin-silica hybrid monolithic column was promising in chiral compounds analysis.


Assuntos
Eletrocromatografia Capilar , Dióxido de Silício/química , beta-Ciclodextrinas/química , 2-Hidroxipropil-beta-Ciclodextrina/química , Compostos de Epóxi/química , Metacrilatos/química , Microscopia Eletrônica de Varredura , Espectroscopia Fotoeletrônica , Polimerização , Polímeros/química , Estereoisomerismo
18.
Int J Nanomedicine ; 15: 1229-1238, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32110019

RESUMO

Introduction: In the last years, the utilization of phytomedicines has increased given their good therapeutic activity and fewer side effects compared to allopathic medicines. However, concerns associated with the biocompatibility and toxicity of natural compounds, limit the phytochemical therapeutic action, opening the opportunity to develop new systems that will be able to effectively deliver these substances. This study has developed a nanocomposite of chitosan (CS) functionalized with graphene oxide (GO) for the delivery of proanthocyanidins (PAs), obtained from a grape seed extract (Ext.). Methods: The GO-CS nanocomposite was covalently bonded and was characterized by Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), atomic force microscopy (AFM) and by dynamic light scattering (DLS). The loading and release of Ext. from the GO-CS nanocomposite were performed in simulated physiological, and the cytotoxicity of the raw materials (GO and Ext.) and nanocomposites (GO-CS and GO-CS-Ext.) was determined using a human kidney cell line (HEK 293). Results: The chemical characterization indicated that the covalent union was successfully achieved between the GO and CS, with 44 wt. % CS in the nanocomposite. The GO-CS nanocomposite was thermostable and presented an average diameter of 480 nm (by DLS). The Ext. loading capacity was approximately 20 wt. %, and under simulated physiological conditions, 28.4 wt.% Ext. (g) was released per g of the nanocomposite. GO-CS-Ext. was noncytotoxic, presenting a 97% survival rate compared with 11% for the raw extract and 48% for the GO-CS nanocomposite at a concentration of 500 µg mL-1 after 24 hrs. Conclusion: Due to π-π stacking and hydrophilic interactions, GO-CS was reasonably efficient in binding Ext., with high loading capacity and Ext. release from the nanocomposite. The GO-CS nanocomposite also increased the biocompatibility of PAs-rich Ext., representing a new platform for the sustained release of phytodrugs.


Assuntos
Nanocompostos/administração & dosagem , Nanocompostos/química , Proantocianidinas/administração & dosagem , Quitosana/química , Sistemas de Liberação de Medicamentos/métodos , Extrato de Sementes de Uva/administração & dosagem , Extrato de Sementes de Uva/química , Extrato de Sementes de Uva/isolamento & purificação , Grafite/química , Células HEK293 , Humanos , Microscopia Eletrônica de Varredura , Espectroscopia Fotoeletrônica , Proantocianidinas/isolamento & purificação , Espectroscopia de Infravermelho com Transformada de Fourier
19.
J Phys Chem Lett ; 11(5): 1873-1880, 2020 Mar 05.
Artigo em Inglês | MEDLINE | ID: mdl-32040318

RESUMO

Lead halide perovskites have recently shown great potential as X-ray scintillators; however, the toxicity of the lead element seriously restricts their applications. Herein we report a new lead-free and self-absorption-free scintillator based on Rb2CuCl3 metal halide. The Rb2CuCl3 exhibits a near-unity photoluminescence quantum yield (99.4%) as well as a long photoluminescence lifetime (11.3 µs). Furthermore, Rb2CuCl3 demonstrates an appreciable light yield of 16 600 photons per megaelectronvolt and a large scintillation response with a linear range from 48.6 nGyair s-1 to 15.7 µGyair s-1. Notably, the detection limit is as low as 88.5 nGyair s-1, enabling a reduced radiation dose to the human body when a medical and security check is conducted. In addition, Rb2CuCl3 exhibits good stability against the atmosphere, continuous ultraviolet light, as well as X-ray irradiation. The combination of the decent scintillation performance, low toxicity and good stability suggests the Rb2CuCl3 could be a possible promising X-ray scintillator.


Assuntos
Cobre/química , Espectroscopia Fotoeletrônica , Teoria Quântica , Rubídio/química , Raios Ultravioleta , Difração de Raios X
20.
Chemosphere ; 249: 126135, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32078853

RESUMO

In this study, a simple sol-gel method was applied for preparing effectual photocatalyst of S-Bi co-doped F-TiO2/SiO2 (S-Bi-F-TiO2/SiO2) nanopowder. Optimal preparation conditions were obtained by optimizing the calcination temperature and the ratio of S and Bi. The synthesized powder was characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), energy dispersive spectrometer (EDS), X-ray photoelectron spectroscopy (XPS), brunauer-emmett-teller (BET), UV-Visible diffuse-reflectance spectroscopy (UV-Vis DRS), photoluminescence spectroscopy (PL) and ammonia adsorption and temperature-programmed desorption (NH3-TPD). The photocatalytic activity was evaluated by the degradation of acrylonitrile under simulated visible light irradiation. S-Bi-F-TiO2/SiO2 nanopowder possess excellent photocatalytic properties under visible light for the degradation of acrylonitrile, when the calcination temperature was 450 °C for 2 h and the ratio of S and Bi was 0.02: 0.007. The degradation efficiency of acrylonitrile reached to 81.9% within 6 min of visible light irradiation. Compared with F-TiO2/SiO2 sample, NH3-TPD and PL results revealed the higher photocatalytic activity for S-Bi-F-TiO2/SiO2, which is mainly due to the increase strength and number of surface acid site with S doping. The co-doping with S & Bi improved the separation of electron-hole pairs and enhanced the photocatalytic oxidizing species. The UV-Vis DRS showed stronger absorption in S-Bi co-doped F-TiO2/SiO2 catalyst as compared to F-TiO2/SiO2 catalyst. XPS results demonstrated the presence of various surface species viz. oxygen vacancies, Ti3+, Ti4+, O2- and OH group.


Assuntos
Acrilonitrila/química , Modelos Químicos , Nanoestruturas/química , Adsorção , Bismuto/química , Catálise , Luz , Microscopia Eletrônica de Transmissão , Espectroscopia Fotoeletrônica , Dióxido de Silício/química , Enxofre , Temperatura , Titânio , Difração de Raios X
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