Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 11 de 11
Filtrar
Mais filtros










Base de dados
Intervalo de ano de publicação
1.
Molecules ; 27(15)2022 Aug 07.
Artigo em Inglês | MEDLINE | ID: mdl-35956978

RESUMO

A method is proposed for the preparation of stable sols of nanocrystalline cerium dioxide in nonpolar solvents, based on surface modification of CeO2 nanoparticles obtained by thermal hydrolysis of concentrated aqueous solutions of ammonium cerium(IV) nitrate with residues of 2-ethylhexanoic and octanoic acids. The synthesis was carried out at temperatures below 100 °C and did not require the use of expensive and toxic reagents. An assessment of the radical-scavenging properties of the obtained sols using the superoxide anion-radical neutralization model revealed that they demonstrate notable antioxidant activity. The results obtained indicate the potential of the nanoscale cerium dioxide sols in nonpolar solvents to be used for creating nanobiomaterials possessing antioxidant properties.


Assuntos
Cério , Nanopartículas , Antioxidantes/química , Cério/química , Nanopartículas/química , Solventes
2.
Polymers (Basel) ; 13(6)2021 Mar 17.
Artigo em Inglês | MEDLINE | ID: mdl-33802821

RESUMO

The development of advanced composite biomaterials combining the versatility and biodegradability of polymers and the unique characteristics of metal oxide nanoparticles unveils new horizons in emerging biomedical applications, including tissue regeneration, drug delivery and gene therapy, theranostics and medical imaging. Nanocrystalline cerium(IV) oxide, or nanoceria, stands out from a crowd of other metal oxides as being a truly unique material, showing great potential in biomedicine due to its low systemic toxicity and numerous beneficial effects on living systems. The combination of nanoceria with new generations of biomedical polymers, such as PolyHEMA (poly(2-hydroxyethyl methacrylate)-based hydrogels, electrospun nanofibrous polycaprolactone or natural-based chitosan or cellulose, helps to expand the prospective area of applications by facilitating their bioavailability and averting potential negative effects. This review describes recent advances in biomedical polymeric material practices, highlights up-to-the-minute cerium oxide nanoparticle applications, as well as polymer-nanoceria composites, and aims to address the question: how can nanoceria enhance the biomedical potential of modern polymeric materials?

3.
Mater Sci Eng C Mater Biol Appl ; 108: 110494, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31924007

RESUMO

Photochromic tungsten oxide (WO3) nanoparticles stabilized by polyvinylpyrrolidone (PVP) were synthesized to evaluate their potential for biomedical applications. PVP-stabilized tungsten oxide nanoparticles demonstrated a highly selective cytotoxic effect on normal and cancer cells in vitro. WO3 nanoparticles were found to induce substantial cell death in osteosarcoma cells (MNNG/HOS cell line) with a half-maximal inhibitory concentration (IC50) of 5 mg/mL, while producing no, or only minor, toxicity in healthy human mesenchymal stem cells (hMSc). WO3 nanoparticles induced intracellular oxidative stress, which led to apoptosis type cell death. The selective anti-cancer effects of WO3 nanoparticles are due to the pH sensitivity of tungsten oxide and its capability of reactive oxygen species (ROS) generation, which is expressed in the modulation of genes involved in reactive oxygen species metabolism, mitochondrial dysfunction, and apoptosis.


Assuntos
Antineoplásicos/farmacologia , Nanopartículas Metálicas/química , Neoplasias/tratamento farmacológico , Óxidos/química , Povidona/farmacologia , Tungstênio/química , Apoptose/efeitos dos fármacos , Materiais Biocompatíveis/química , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Citoesqueleto/metabolismo , Ensaios de Seleção de Medicamentos Antitumorais , Humanos , Concentração de Íons de Hidrogênio , Concentração Inibidora 50 , Células-Tronco Mesenquimais/efeitos dos fármacos , Microscopia Eletrônica de Transmissão , Mitocôndrias/patologia , Nanopartículas/química , Osteossarcoma/tratamento farmacológico , Estresse Oxidativo , Espécies Reativas de Oxigênio
4.
Molecules ; 24(21)2019 Oct 25.
Artigo em Inglês | MEDLINE | ID: mdl-31731434

RESUMO

A series of carbon aerogels (C-AGs) were prepared by the pyrolysis of resorcinol-formaldehyde aerogels at 700-1100 °C as potential supercapacitor electrodes, and their texture and electrochemical properties were determined. The specific surface area of all C-AGs was in the range of 700-760 m2/g, their electron conductivity increased linearly from 0.4 to 4.46 S/cm with an increase of the pyrolysis temperature. The specific capacitance of electrode material based on C-AGs reached 100 F/g in sulfuric acid and could be realized at a 2 A/g charge-discharge current, which makes it possible to use carbon aerogels as electrode materials.


Assuntos
Carbono/química , Formaldeído/química , Géis/química , Resorcinóis/química , Capacitância Elétrica , Condutividade Elétrica , Eletroquímica , Eletrodos , Géis/síntese química , Nitrogênio/química , Temperatura
5.
Molecules ; 24(18)2019 Sep 14.
Artigo em Inglês | MEDLINE | ID: mdl-31540041

RESUMO

The electrorheological (ER) effect was experimentally observed in dielectric suspensions containing tungsten oxide (WO3) modified with surfactant molecules (sodium dodecyl sulfate (SDS) and dodecylamine (DDA)) in electric fields up to several kilovolts per millimeter. The dielectric properties of WO3 suspensions in silicone oil were analyzed, depending on the frequency of the electric field, in the range from 25 to 106 Hz. Unmodified WO3 suspensions, as well as suspensions modified with sodium dodecyl sulfate, were shown to exhibit a positive electrorheological effect, whereas suspensions modified with dodecylamine demonstrated a negative electrorheological effect. The quantitative characteristics of the negative electrorheological effect in the strain-compression and shear regimes were obtained for the first time. Visualization experiments were performed to see the chain structures formed by WO3 particles modified with sodium dodecyl sulfate, as well as for dynamic electroconvection in electrorheological fluids containing WO3 modified with dodecylamine. The negative electrorheological effect was shown to be associated with the processes of phase separation in the electric field, which led to a multiplicative effect and a strong electroconvection of the suspension at field strengths above 1 kV/mm.


Assuntos
Aminas/química , Técnicas Eletroquímicas , Óxidos/química , Reologia , Dodecilsulfato de Sódio/química , Tensoativos/química , Tungstênio/química , Suspensões
6.
Molecules ; 25(1)2019 Dec 30.
Artigo em Inglês | MEDLINE | ID: mdl-31905983

RESUMO

Tungsten oxide-based bulk and nanocrystalline materials are widely used as photocatalytic and photo- and electrochromic materials, as well as materials for biomedical applications. In our work, we focused our attention on the effect of sodium cations on the structure and photochromic properties of the WO3@PVP aqueous sols. To establish the effect, the sols were synthesized by either simple pH adjusting of sodium or ammonium tungstates' solutions, or using an ion exchange technique to remove the cations from the materials to the greatest possible extent. We showed that the presence of sodium cations in WO3@PVP favors the formation of reduced tungsten species (W+5) upon UV irradiation of the materials, strongly affecting their photochromic and photocatalytic properties. The pronounced photoreductive properties of WO3@PVP sols in photocatalytic reactions were demonstrated. Due to photoreductive properties, photochromic sols of tungsten oxide can act as effective photoprotectors in photooxidation processes. We believe that our work provides a considerable contribution to the elucidation of photochromic and redox phenomena in WO3-based materials.


Assuntos
Nanopartículas/química , Óxidos/química , Povidona/química , Sódio/química , Tungstênio/química , Catálise , Cátions , Concentração de Íons de Hidrogênio , Estrutura Molecular , Tamanho da Partícula , Processos Fotoquímicos , Espalhamento a Baixo Ângulo , Raios Ultravioleta , Difração de Raios X
7.
ACS Biomater Sci Eng ; 4(7): 2453-2462, 2018 Jul 09.
Artigo em Inglês | MEDLINE | ID: mdl-33435109

RESUMO

Cerium oxide nanoparticles (nanoceria) are regarded as one of the most promising inorganic antioxidants for biomedical applications. Considering nanoceria as a potential therapeutic agent, we aimed to develop a robust system for its intracellular delivery using layer-by-layer polyelectrolyte microcapsules. We have shown that citrate-stabilized cerium oxide nanoparticles can be effectively incorporated into the structure of polyelectrolyte microcapsules made from biodegradable and nonbiodegradable polymers. The structure and morphology of synthesized microcapsules were investigated and analyzed using confocal laser scanning microscopy, scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy, and UV/vis spectroscopy. Results of experiments in vitro on B50 neuroblastoma cells confirmed nanoceria delivery into the cell while maintaining their antioxidant properties. The results presented confirm polyelectrolyte microcapsules to be an efficient intracellular delivery system for therapeutic nanoparticles.

8.
Antiviral Res ; 127: 1-9, 2016 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-26769398

RESUMO

We have demonstrated the influence of cerium dioxide nanoparticles on the immunogenicity of the influenza vaccine on an example of liquid split inactivated Vaxigrip vaccine. Antibody titers were analyzed using the hemagglutination inhibition (HI) assay. Seroprotection, seroconversion, the geometric mean titers (GMTs) and the factor increase (FI) in the GMTs were calculated. The effect of nano-ceria surface stabilizer on the enhancement of immunogenicity was shown. The vaccine modified by citrate-stabilized nano-ceria, in contrast to a non-modified Vaxigrip vaccine, did not provide an adequate level of seroprotection, and seroconversion after vaccination was 66.7% on days 49-63 for virus strain А(H1N1) and 100% on day 49 for virus strain B/Yamagata. For the low immunogenic influenza B virus, the rise in antibody titers (GMT/IF) was 24.38/3.28 after the first injection and 50.40/6.79 on day 49. For the vaccine modified by non-stabilized nano-ceria, for all virus strains under study, on day 63, upon immunization notable levels of seroprotection, seroconversion and GMT/IF were registered (higher than for the non-modified Vaxigrip vaccine). The successful attempt to modify the influenza vaccine demonstrates the possible ways of increasing the specific activity of vaccines using nano-ceria.


Assuntos
Cério/farmacologia , Vírus da Influenza A Subtipo H1N1/imunologia , Vírus da Influenza A Subtipo H3N2/imunologia , Vírus da Influenza B/imunologia , Vacinas contra Influenza/imunologia , Nanopartículas/administração & dosagem , Animais , Anticorpos Antivirais/sangue , Anticorpos Antivirais/imunologia , Formação de Anticorpos/efeitos dos fármacos , Formação de Anticorpos/imunologia , Cério/química , Cério/imunologia , Feminino , Testes de Inibição da Hemaglutinação/métodos , Vacinas contra Influenza/química , Vacinas contra Influenza/farmacologia , Camundongos , Microscopia Eletrônica de Transmissão , Nanopartículas/química , Vacinas de Produtos Inativados/química , Vacinas de Produtos Inativados/imunologia , Vacinas de Produtos Inativados/farmacologia
9.
Langmuir ; 27(21): 13293-301, 2011 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-21916478

RESUMO

Here we describe the galvanic exchange of surface-grown Ag nanorods (NRs) and nanowires (NWs) with PdCl(4)(2-) as a function of the PdCl(4)(2-) concentration. The morphology of the resulting AgPd alloy nanostructures depends on the galvanic exchange rate, which increases with increasing PdCl(4)(2-) concentration over a specific concentration range. When the concentration of PdCl(4)(2-) exceeds 7.5 × 10(-5) M (or ratio of moles of PdCl(4)(2-) in solution to moles of Ag on the surface > 542), rapid galvanic exchange results in Pd deposition over the entire Ag nanostructure in the early stages of exchange. When the concentration of PdCl(4)(2-) is in the range of 1.0 × 10(-5) to 5.0 × 10(-5) M (moles of PdCl(4)(2-) in solution to moles of Ag on the surface = 13-54), Pd deposition occurs preferentially at high energy twin plane defects in the form of well-spaced nanoparticles during the early stages of exchange. In later stages, the Pd deposits grow and coalescence into a rough shell, and etching of the Ag leads to a presumably hollow nanostructure. Composition analysis by linear sweep voltammetry as a function of time shows that the galvanic exchange rate is much slower than the diffusion-limited rate and, when correlated with UV-vis spectroscopy, shows that less than 10% Pd in the nanostructure completely dampens the Ag-localized surface plasmon band.


Assuntos
Nanotecnologia/métodos , Nanotubos/química , Paládio/química , Prata/química , Propriedades de Superfície , Fatores de Tempo
10.
Anal Chem ; 82(13): 5844-50, 2010 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-20527732

RESUMO

Here we describe the electrochemical oxidation of an assembly of gold nanoparticles (Au NPs) attached to glass/indium-tin-oxide (ITO) electrodes as a function of particle size. We synthesized Au NP arrays with NP diameters ranging from 8 to 250 nm by electrodeposition of Au from HAuCl(4) in H(2)SO(4) at potentials of -0.2 to 0.8 V versus Ag/AgCl using chronocoulometry to keep the amount of Au deposited constant. The average Au NP size increased with increasing deposition potential. The chemical reduction of HAuCl(4) by NaBH(4) in trisodium citrate solution led to 4 nm average diameter Au NPs, which we chemisorbed to the glass/ITO electrode. Linear sweep voltammograms (LSVs) obtained on the glass/ITO/Au NP (4 to 250 nm) electrodes (with a constant coverage of Au in terms of Au atoms per cm(2)) from 0.5 to 1.1 V in 0.01 M potassium bromide plus 0.1 M HClO(4) showed a positive shift in oxidation potential from 734 +/- 1 mV to 913 +/- 19 mV with increasing Au NP diameter. The shift agrees qualitatively with that predicted by a shift in the redox potential based on a difference in free energy associated with a change in surface energy as a function of particle size. On the basis of the charge during Au deposition versus the charge during oxidation, the oxidation process produces a mixture of Au(III)Br(4)(-) (25%) and Au(I)Br(2)(-) (75%). A glass/ITO electrode coated with a mixture of 4 and 250 nm Au NPs revealed 2 oxidation peaks, consistent with the two Au NP size populations present on the surface.

11.
J Am Chem Soc ; 132(1): 70-2, 2010 Jan 13.
Artigo em Inglês | MEDLINE | ID: mdl-20000318

RESUMO

Here we quantify the electrochemical oxidation of Ag nanoparticles (NPs) as a function of size by electrostatically attaching Ag NPs synthesized by seed-mediated growth in the presence of citrate (diameter = 8 to 50 nm) to amine-functionalized indium-tin oxide coated glass electrodes (Glass/ITO), obtaining a linear sweep voltammogram from 0.1 V, where Ag(0) is stable, up to 1.0 V, and observing the peak potential (E(p)) for oxidation of Ag(0) to Ag(+). Electrostatic attachment to the organic linker presumably removes direct interactions between Ag and ITO and allows control over the total Ag coverage by altering the soaking time. This is important as both metal-electrode interactions and overall Ag coverage can affect E(p). E(p) shifts positive from an average of 275 to 382 mV as the Ag NP diameter increases for a constant Ag coverage and under conditions of planar diffusion, suggesting a shift in E(p) due to a thermodynamic shift in E(0) for the Ag/Ag(+) redox couple with size. The negative shift in E(p) with decreasing Ag NP radius follows the general trend predicted by theory and agrees with previous qualitative experimental observations. A better understanding of metal nanostructure oxidation is crucial considering their potential use in many different applications and the importance of metal corrosion processes at the nanoscale.

SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...