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1.
ACS Appl Mater Interfaces ; 13(24): 28650-28661, 2021 Jun 23.
Artigo em Inglês | MEDLINE | ID: mdl-34124895

RESUMO

Novel and effective radiosensitizers that can enhance radiosensitivity of tumor tissues and increase the local radiation dose are highly desirable. In this work, templated by bovine serum albumin (BSA), Bi2Se3-MnO2 nanocomposites (Bi2Se3-MnO2@BSA) were fabricated via biomineralization, while Bi2Se3 nanodots act as radiosensitizers to increase the local radiation dosage because of their strong X-ray attenuation ability, and MnO2 with catalase-like activity can increase the oxygen concentration in tumors by triggering the decomposition of tumor endogenous H2O2 so as to improve the hypoxia-associated radioresistance of tumors. Owing to the interaction of the two components in the interface, Bi2Se3-MnO2@BSA showed promoted catalytic activity compared to MnO2@BSA, favoring tumor radiotherapy (RT) sensitization. BSA templating enabled the nanocomposites with high colloidal stability and biocompatibility as well as satisfactory tumor targeting both in vitro and in vivo; thus, an enhanced RT efficacy was obtained. Moreover, the proposed Bi2Se3-MnO2@BSA exhibited excellent performances in computerized tomography and magnetic resonance imaging. Thus, this work provides a tumor microenvironment-responsive multifunctional theranostic nanoagent with an improved performance for imaging-guided tumor RT sensitization.


Assuntos
Antineoplásicos/uso terapêutico , Bismuto/uso terapêutico , Compostos de Manganês/uso terapêutico , Nanocompostos/uso terapêutico , Neoplasias/tratamento farmacológico , Óxidos/uso terapêutico , Radiossensibilizantes/uso terapêutico , Compostos de Selênio/uso terapêutico , Animais , Antineoplásicos/síntese química , Antineoplásicos/efeitos da radiação , Bismuto/química , Catálise/efeitos da radiação , Bovinos , Linhagem Celular Tumoral , Meios de Contraste/síntese química , Meios de Contraste/efeitos da radiação , Meios de Contraste/uso terapêutico , Feminino , Células Endoteliais da Veia Umbilical Humana , Humanos , Peróxido de Hidrogênio/química , Peróxido de Hidrogênio/metabolismo , Compostos de Manganês/química , Compostos de Manganês/efeitos da radiação , Camundongos Endogâmicos BALB C , Nanocompostos/química , Nanocompostos/efeitos da radiação , Neoplasias/diagnóstico por imagem , Óxidos/química , Óxidos/efeitos da radiação , Oxigênio/metabolismo , Medicina de Precisão , Radiossensibilizantes/síntese química , Radiossensibilizantes/efeitos da radiação , Compostos de Selênio/química , Compostos de Selênio/efeitos da radiação
2.
Chemosphere ; 262: 128082, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-33182100

RESUMO

As important natural oxidants and adsorbents, manganese (Mn) oxide minerals affect the speciation, bioavailability and fate of pollutants and nutrient elements. It was found that birnessite-type Mn(IV) oxide minerals can be formed in the presence of NO3- and solar irradiation. However, the photochemical formation and transformation processes from Mn2+ to Mn(IV) oxide minerals remain unclear. In this work, the Mn(IV) oxide minerals were confirmed to be photochemically formed mainly due to the disproportionation of Mn(III) intermediates generated from the oxidation of Mn2+ in the presence of NO3- under UV light irradiation. The oxidation rate of Mn2+ to Mn(IV) oxide minerals decreased with increasing initial Mn2+ concentration due to the lower disproportionation rate. The increase in NO3- concentration, pH and temperature promoted Mn2+ photochemical oxidation. The photochemical formation rate of Mn(IV) oxide minerals increased with increasing ligand concentrations at low ligand concentrations. Ligands affected the formation of Mn(IV) oxide minerals by promoting the formation and reducing the reactivity of Mn(III) intermediates. Overall, this work reveals the important role of Mn(III) intermediates in the formation of natural Mn oxide minerals.


Assuntos
Compostos de Manganês/química , Manganês/química , Minerais/química , Óxidos/química , Luz Solar , Manganês/efeitos da radiação , Compostos de Manganês/efeitos da radiação , Minerais/efeitos da radiação , Modelos Teóricos , Oxirredução , Óxidos/efeitos da radiação , Processos Fotoquímicos , Temperatura
3.
J Mater Chem B ; 8(36): 8356-8367, 2020 09 23.
Artigo em Inglês | MEDLINE | ID: mdl-32794542

RESUMO

The integration of advanced diagnostic contrast agents with versatile therapeutic drugs is an effective method for cancer treatment. However, combining various biocompatible theranostic modalities into a single platform at the nanoscale is a challenging assignment. In this work, we report a simple chemical synthetic route for producing a homogeneous hybrid nanoflower shaped morphology based on Au@Mn3O4 magneto-plasmonic nanomaterials. The synthetic mechanism of the nanoflowers is well-matched with the heteroepitaxial growth phenomena by which the nano-petals of Mn3O4 generated on the surface of the Au core. The food and drug administration (FDA) in the USA approved the use of triblock polymer Pluronic F-127 to enhance the biocompatibility of Au@Mn3O4 hybrid nanoflowers. The prepared hybrid nanoflowers produce a significant photothermal heating effect with a thermal transduction efficiency of 38%, comparable to the nanorods and nanoparticles of gold (Au). The hybrid junction reveals promising optical and magnetic properties and the prepared Au@Mn3O4 nanoflowers not only exhibit strong near-infrared (NIR) absorption to produce excellent photothermal efficacy under irradiation with an 808 nm NIR laser, but also demonstrate a significant T1-weighted magnetic resonance (MR) image enhancement in vitro and in vivo. The histopathology assessments indicate only negligible toxicity of the nanoflowers to major organs. Therefore, the hybrid Au@Mn3O4 nanoflowers exhibit great potential in T1-weighted MR-imaging and photothermal therapy, opening up new possibilities for synthesizing novel bio-compatible, homogeneous, and shape controllable nanostructures with multifunctional applications.


Assuntos
Meios de Contraste/uso terapêutico , Nanopartículas Metálicas/uso terapêutico , Neoplasias/diagnóstico por imagem , Neoplasias/tratamento farmacológico , Animais , Linhagem Celular Tumoral , Meios de Contraste/síntese química , Meios de Contraste/efeitos da radiação , Feminino , Ouro/química , Ouro/efeitos da radiação , Ouro/uso terapêutico , Raios Infravermelhos , Imageamento por Ressonância Magnética/métodos , Compostos de Manganês/química , Compostos de Manganês/efeitos da radiação , Compostos de Manganês/uso terapêutico , Nanopartículas Metálicas/química , Nanopartículas Metálicas/efeitos da radiação , Camundongos Nus , Óxidos/química , Óxidos/efeitos da radiação , Óxidos/uso terapêutico , Terapia Fototérmica/métodos , Nanomedicina Teranóstica
4.
Angew Chem Int Ed Engl ; 59(32): 13557-13561, 2020 08 03.
Artigo em Inglês | MEDLINE | ID: mdl-32374941

RESUMO

The high reactive oxygen species (ROS) generation ability and simple construction of sonosensitizer systems remain challenging in sonodynamic therapy against the hypoxic tumor. In this work, we rationally prepared MOF-derived double-layer hollow manganese silicate nanoparticle (DHMS) with highly effective ROS yield under ultrasound irradiation for multimodal imaging-guided sonodynamic therapy (SDT). The presence of Mn in DHMS increased ROS generation efficiency because it could be oxidized by holes to improve the electron-hole separation. Moreover, DHMS could produce oxygen in the tumor microenvironment, which helps overcome the hypoxia of the solid tumor and thus enhance the treatment efficiency. In vivo experiments demonstrated efficient tumor inhibition in DHMS-mediated SDT guided by ultrasound and magnetic resonance imaging. This work presents a MOF-derived nanoparticle with sonosensitive and oxygen generating ability, which provides a promising strategy for tumor hypoxia in SDT.


Assuntos
Antineoplásicos/uso terapêutico , Estruturas Metalorgânicas/uso terapêutico , Nanopartículas/uso terapêutico , Neoplasias/tratamento farmacológico , Oxigênio/uso terapêutico , Animais , Antineoplásicos/efeitos da radiação , Antineoplásicos/toxicidade , Linhagem Celular Tumoral , Compostos de Manganês/efeitos da radiação , Compostos de Manganês/uso terapêutico , Estruturas Metalorgânicas/efeitos da radiação , Estruturas Metalorgânicas/toxicidade , Camundongos , Imagem Multimodal , Nanopartículas/efeitos da radiação , Oxigênio/química , Espécies Reativas de Oxigênio/metabolismo , Silicatos/efeitos da radiação , Silicatos/uso terapêutico , Silicatos/toxicidade , Hipóxia Tumoral/efeitos dos fármacos , Microambiente Tumoral/efeitos dos fármacos , Ondas Ultrassônicas
5.
J Hazard Mater ; 377: 227-236, 2019 09 05.
Artigo em Inglês | MEDLINE | ID: mdl-31170571

RESUMO

Herein, a heterostructure based on MnO2 and g-C3N4 was constructed on the surface of metallic Ti implants, in which MnO2 favored the transfer and separation of free charges to enhance the photoconversion efficiency of g-C3N4 by 21.11%. Consequently, the yield of ROS was promoted significantly, which denatured protein and damaged DNA to kill bacteria efficiently. In addition, glutathione (GSH, l-γ-glutamyl-l-cysteinyl-glycine) defending oxidative stress in bacteria, was oxidized by MnO2 in the hybrid coating once the bacterial membrane was disrupted by ROS. Hence, after visible light irradiation for 20 min, MnO2/g-C3N4 coating exhibited superior disinfection efficacy of 99.96% and 99.26% against S. aureus and E. coli severally. This work provided a practical sterilization strategy about MnO2/g-C3N4 systems through the synergistic effects of enhanced photodynamic antibacterial therapy and oxidization effect of MnO2 with great biosafety, in which MnO2 enhanced the photocatalyst property of g-C3N4 to generate more ROS and deplete GSH to improve antibacterial efficiency. It will bring more insight into rapid and highly effective disinfection and antibacterial strategy without using traditional high-temperature, ultraviolet ray and antibiotics that cause side-effects.


Assuntos
Grafite/química , Compostos de Manganês/química , Compostos de Nitrogênio/química , Óxidos/química , Processos Fotoquímicos , Esterilização/métodos , Bactérias/metabolismo , Bactérias/efeitos da radiação , Catálise , Membrana Celular/metabolismo , Membrana Celular/efeitos da radiação , Dano ao DNA , Escherichia coli/efeitos da radiação , Glutationa/metabolismo , Grafite/efeitos da radiação , Luz , Compostos de Manganês/efeitos da radiação , Testes de Sensibilidade Microbiana , Modelos Moleculares , Compostos de Nitrogênio/efeitos da radiação , Óxidos/efeitos da radiação , Espécies Reativas de Oxigênio , Staphylococcus aureus/metabolismo , Staphylococcus aureus/efeitos da radiação
6.
Analyst ; 143(20): 4967-4973, 2018 Oct 08.
Artigo em Inglês | MEDLINE | ID: mdl-30225468

RESUMO

A multifunctional nanosystem, which integrates biosensing, bioimaging, and therapeutic functions into a single nanoprobe, is of great significance for biosensing and biomedicine. Near-infrared (NIR) graphene quantum dots (GQDs) have emerged as an attractive bioimaging and therapy tool for exploring biological events because they can provide deep imaging penetration and low fluorescence background and produce 1O2 for PDT. Here, we reported a GQD-based multifunctional two-photon nanoprobe for intracellular tumor-related glutathione (GSH) detection and enhanced photodynamic therapy by reducing GSH levels in cancer cells. By taking the excellent quenching property of MnO2 nanosheets and the reduction ability of GSH, a GQD@MnO2 nanoprobe was developed through adsorption of MnO2 nanosheets onto the surface of GQDs for sensing intracellular tumor-related GSH. The nanoprobe shows a highly sensitive response to GSH in aqueous solutions with a detection limit of 83 nM. It also exhibits a high selectivity toward GSH relative to other biomolecules and electrolytes. In addition, once endocytosed, the MnO2 nanosheets are reduced by intracellular GSH, simultaneously releasing GQDs and decreasing the level of GSH for highly efficient PDT.


Assuntos
Glutationa/análise , Glutationa/metabolismo , Grafite/farmacologia , Fármacos Fotossensibilizantes/farmacologia , Pontos Quânticos/química , Animais , Fluorescência , Grafite/química , Grafite/efeitos da radiação , Grafite/toxicidade , Células HeLa , Humanos , Concentração de Íons de Hidrogênio , Limite de Detecção , Compostos de Manganês/química , Compostos de Manganês/farmacologia , Compostos de Manganês/efeitos da radiação , Microscopia Confocal/métodos , Microscopia de Fluorescência/métodos , Óxidos/química , Óxidos/farmacologia , Óxidos/efeitos da radiação , Óxidos/toxicidade , Fótons , Fármacos Fotossensibilizantes/química , Fármacos Fotossensibilizantes/efeitos da radiação , Fármacos Fotossensibilizantes/toxicidade , Pontos Quânticos/efeitos da radiação , Pontos Quânticos/toxicidade , Ratos
7.
J Am Chem Soc ; 139(43): 15292-15295, 2017 11 01.
Artigo em Inglês | MEDLINE | ID: mdl-28969423

RESUMO

Applicability of phototherapeutic CO-releasing molecules (photoCORMs) is limited because they are activated by harmful and poorly tissue-penetrating near-ultraviolet light. Here, a strategy is demonstrated to activate classical photoCORM Mn2(CO)10 using red light (635 nm). By mixing in solution a triplet photosensitizer (PS) with the photoCORM and shining red light, energy transfer occurs from triplet excited-state 3PS* to a photolabile triplet state of Mn2(CO)10, which, like under near-UV irradiation, led to complete release of carbonyls. Crucially, such "triplet-sensitized CO-release" occurred in solid-state materials: when PS and Mn2(CO)10 were embedded in electrospun nonwoven fabrics, CO was liberated upon irradiation with low-intensity red light (≤36 mW 635 nm).


Assuntos
Monóxido de Carbono/química , Cor , Luz , Compostos de Manganês/química , Compostos de Manganês/efeitos da radiação , Polímeros/química , Monóxido de Carbono/efeitos da radiação , Transferência de Energia/efeitos da radiação , Polímeros/efeitos da radiação , Raios Ultravioleta/efeitos adversos
8.
Philos Trans A Math Phys Eng Sci ; 374(2061)2016 Feb 28.
Artigo em Inglês | MEDLINE | ID: mdl-26755752

RESUMO

Artificial photosynthesis to carry out both the oxidation and the reduction of water has emerged to be an exciting area of research. It has been possible to photochemically generate oxygen by using a scheme similar to the Z-scheme, by using suitable catalysts in place of water-oxidation catalyst in the Z-scheme in natural photosynthesis. The best oxidation catalysts are found to be Co and Mn oxides with the e(1) g configuration. The more important aspects investigated pertain to the visible-light-induced generation of hydrogen by using semiconductor heterostructures of the type ZnO/Pt/Cd1-xZnxS and dye-sensitized semiconductors. In the case of heterostructures, good yields of H2 have been obtained. Modifications of the heterostructures, wherein Pt is replaced by NiO, and the oxide is substituted with different anions are discussed. MoS2 and MoSe2 in the 1T form yield high quantities of H2 when sensitized by Eosin Y. Two-step thermochemical splitting of H2O using metal oxide redox pairs provides a strategy to produce H2 and CO. Performance of the Ln0.5A0.5MnO3 (Ln = rare earth ion, A = Ca, Sr) family of perovskites is found to be promising in this context. The best results to date are found with Y0.5Sr0.5MnO3.


Assuntos
Cobalto/química , Hidrogênio/isolamento & purificação , Compostos de Manganês/química , Óxidos/química , Oxigênio/isolamento & purificação , Processos Fotoquímicos/efeitos da radiação , Água/química , Catálise , Cobalto/efeitos da radiação , Temperatura Alta , Hidrogênio/química , Hidrogênio/efeitos da radiação , Luz , Compostos de Manganês/efeitos da radiação , Óxidos/efeitos da radiação , Oxigênio/química , Oxigênio/efeitos da radiação , Fotoquímica/métodos , Semicondutores , Energia Solar
9.
J Hazard Mater ; 285: 356-65, 2015 Mar 21.
Artigo em Inglês | MEDLINE | ID: mdl-25528234

RESUMO

In this paper, the photodegradation of Acid Orange 7 (AO7) in aqueous solutions with peroxymonosulfate (PMS) was studied with manganese oxide octahedral molecular sieves (OMS-2) as the catalyst. The activities of different systems including OMS-2 under visible light irradiation (OMS-2/Vis), OMS-2/PMS and OMS-2/PMS/Vis were evaluated. It was found that the efficiency of OMS-2/PMS was much higher than that of OMS-2/Vis and could be further enhanced by visible light irradiation. The catalyst also exhibited stable performance for multiple runs. Results from ESR and XPS analyses suggested that the highly catalytic activity of the OMS-2/PMS/Vis system possible involved the activation of PMS to sulfate radicals meditated by the redox pair of Mn(IV)/Mn(III) and Mn(III)/Mn(II), while in the OMS-2/PMS system, only the redox reaction between Mn(IV)/Mn(III) occurred. Several operational parameters, such as dye concentration, catalyst load, PMS concentration and solution pH, affected the degradation of AO7.


Assuntos
Compostos Azo/química , Benzenossulfonatos/química , Corantes/química , Compostos de Manganês/química , Óxidos/química , Peróxidos/química , Catálise , Luz , Compostos de Manganês/efeitos da radiação , Óxidos/efeitos da radiação , Peróxidos/efeitos da radiação , Fotólise , Purificação da Água/métodos
10.
Environ Technol ; 34(5-8): 637-44, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-23837313

RESUMO

The removal of polychlorinated biphenyls (PCBs) from soil contaminated with capacitor oil, using microwave (MW)-irradiated manganese dioxide (MnO2), was examined under different conditions. The effects of different types of MnO2 added as oxidant, as well as the initial amount of water, MnO2, and sulphuric acid solution, were also investigated. The removal efficiencies for dichlorobiphenyls, trichlorobiphenyls, tetrachlorobiphenyls, pentachlorobiphenyls, hexachloro-biphenyls, heptachlorobiphenyls, and octachlorobiphenyls were approximately 95.9%, 82.5%, 52.0%, 71.6%, 62.5%, 28.6%, and 16.1%, respectively, by 800 W MW irradiation for 45 min with the assistance of 0.1 g delta-MnO2 and 0.2 mL water in 1.0 g severely PCB-contaminated soil (sigma PCB = 1560.82 mg/kg); meanwhile, the concentrations of Mn2+ ions detected were from 10.6 +/- 1.9 mg/kg at 0 min to 108.2 +/- 7.8 mg/kg after 45 min MW irradiation, indicating that MnO2 acted as not only a MW absorber but also an oxidizer. Removal efficiencies of PCBs from contaminated soil increased with increasing the amounts of water and MnO2 added. The type of MnO2 also affected the removal of PCBs, following an order of delta-MnO2 > alpha-MnO2 > beta-MnO2. The addition of low concentration of sulphuric acid (such as 1.0 mol/L) solution was favourable for the removal of low chloro-substituted PCBs, but the addition of more than 1.0 mol/L sulphuric acid reduced the removal of all PCBs. The pronounced removal of PCBs from contaminated soil in a short treatment time indicates that MW irradiation with the assistance of MnO2 is an efficient and promising technology for the remediation of PCB-contaminated soil.


Assuntos
Eletrônica , Óleos Industriais , Compostos de Manganês/química , Óxidos/química , Bifenilos Policlorados/isolamento & purificação , Poluentes do Solo/química , Poluentes do Solo/isolamento & purificação , Gerenciamento de Resíduos/métodos , Capacitância Elétrica , Compostos de Manganês/efeitos da radiação , Micro-Ondas , Óxidos/efeitos da radiação , Bifenilos Policlorados/química , Bifenilos Policlorados/efeitos da radiação , Poluentes do Solo/efeitos da radiação
11.
Opt Express ; 20(27): 28494-9, 2012 Dec 17.
Artigo em Inglês | MEDLINE | ID: mdl-23263085

RESUMO

A current-pulse-induced enhancement effect of transient photovoltage has been discovered in tilted manganite La(2/3)Ca(1/3)MnO(3) film at room temperature. Here, by applying a pulsed current stimulus before pulse laser irradiation, we observed a significant enhancement of more than 50% in photovoltaic sensitivity. The current-pulse-induced photovoltaic enhancement can be tuned not only by the stimulating current value but also by the stimulating time. Such enhancement is time-sensitive and reproducible. This electrically induced effect, observed at room temperature, has both the benefit of a discovery in materials properties and the promise of applications for thin film manganites in photodetectors.


Assuntos
Condutometria/instrumentação , Compostos de Manganês/química , Membranas Artificiais , Fotometria/instrumentação , Desenho de Equipamento , Análise de Falha de Equipamento , Compostos de Manganês/efeitos da radiação
12.
Environ Sci Technol ; 46(24): 13160-6, 2012 Dec 18.
Artigo em Inglês | MEDLINE | ID: mdl-23153016

RESUMO

Manganese is one of the common elements in the Earth's crust and an essential micronutrient for all living things. The reductive dissolution of particulate manganese oxide is a dominant process to enhance mobility and bioavailability of manganese for the use of living organisms. In this work, we investigated the reductive dissolution of manganese oxides trapped in ice (at -20 °C) under dark and light irradiation (visible: λ > 400 nm and UV: λ > 300 nm) in comparison with their counterparts in aqueous solution (at 25 °C). The reductive dissolution of synthetic MnO2, which took place slowly in aqueous solution, was significantly accelerated in ice phase both in the presence and absence of light: about 5 times more dissolution in ice phase than in liquid water after 6 h UV irradiation in the presence of formic acid. The enhanced dissolution in ice was observed under both UV and visible irradiation although the rate was much slower in the latter condition. The reductive dissolution rate of Mn(II)(aq) (under both irradiation and dark conditions) gradually increased with decreasing pH below 6 in both aqueous and ice phases, and the dissolution rates were consistently faster in ice under all tested conditions. The enhanced generation of Mn(II)(aq) in ice can be mainly explained in terms of freeze concentration of electron donors, protons, and MnO2 in liquid-like ice grain boundaries. The outdoor solar experiment conducted in Arctic region (Ny-Ålesund, Svalbard, 78°55'N) also showed that the photoreductive dissolution of manganese oxide is enhanced in ice. The present results imply that the dissolution of natural minerals like manganese oxides can be enhanced in icy environments such as polar region, upper atmosphere, and frozen soil.


Assuntos
Gelo/análise , Luz , Compostos de Manganês/química , Compostos de Manganês/efeitos da radiação , Óxidos/química , Óxidos/efeitos da radiação , Água/química , Coloides/química , Escuridão , Meio Ambiente , Concentração de Íons de Hidrogênio , Solubilidade , Espectrofotometria Ultravioleta , Fatores de Tempo
13.
Nanoscale ; 4(20): 6393-400, 2012 Oct 21.
Artigo em Inglês | MEDLINE | ID: mdl-22951578

RESUMO

A visible-light-active ZnO photocatalyst system in the presence of manganese ions (Mn/ZnO) was prepared via a simple and rapid approach. XRD, XPS, Raman scattering and UV-Vis DRS confirmed the manganese exists in multivalent forms (Mn(3+)/Mn(2+)) in the ZnO lattice, furthermore, ZnO light absorption is extended to the visible region. The photocatalytic activities of the catalysts were evaluated by measuring the photodegrading efficiency of 2,4-dichlorophenol (DCP) under visible light irradiation. With an optimal molar ratio of 5% in Mn/ZnO the highest rate photodegradation was achieved under the experimental conditions. We have characterized the separation and transfer behavior of the photogenerated charges in the visible region by means of surface photovoltage (SPV), surface photocurrent (SPC) and transient photovoltage (TPV) techniques. Based on the comprehensive investigation of the photovoltaic properties of Mn/ZnO photocatalyst, we illustrate the behavior of photogenerated charges have distinct effects on the photocatalytic activity. It is demonstrated that the incorporation of multivalent Mn in ZnO promoted the separation of photogenerated charges, inhibited the recombination of photogenerated carriers, and thus prolonged the charges lifetime to participate in the photocatalytic reaction, resulting in highly efficient photocatalytic activity, which is attributed to the formation of a strong electronic interaction between the multivalent Mn and ZnO.


Assuntos
Compostos de Manganês/química , Compostos de Manganês/efeitos da radiação , Nanotubos/química , Nanotubos/efeitos da radiação , Óxidos/química , Óxidos/efeitos da radiação , Óxido de Zinco/química , Óxido de Zinco/efeitos da radiação , Clorofenóis/química , Luz , Microscopia Eletrônica , Nanotecnologia/métodos , Fotólise , Análise Espectral
14.
Radiat Prot Dosimetry ; 152(4): 400-5, 2012 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-22628526

RESUMO

In this study, an approximate symmetric cylindrical manganese bath system with equal diameter and height was appraised using a Monte Carlo simulation. For nine sizes of the tank filled with MnSO(4).H(2)O solution of three different concentrations, the necessary correction factors involved in the absolute measurement of neutron emission rate were determined by a detailed modelling of the MCNP4C code with the ENDF/B-VII.0 neutron cross section data library. The results obtained were also used to determine the optimum dimensions of the bath for each concentration of solution in the calibration of (241)Am-Be and (252)Cf sources. Also, the amount of gamma radiation produced as a result of (n,γ) the reaction with the nuclei of the manganese sulphate solution that escaped from the boundary of each tank was evaluated. This gamma can be important for the background in NaI(Tl) detectors and issues concerned with radiation protection.


Assuntos
Algoritmos , Compostos de Manganês/química , Compostos de Manganês/efeitos da radiação , Modelos Estatísticos , Método de Monte Carlo , Radiometria/métodos , Sulfatos/química , Sulfatos/efeitos da radiação , Simulação por Computador , Nêutrons , Doses de Radiação , Espalhamento de Radiação
15.
Ultrason Sonochem ; 19(3): 560-9, 2012 May.
Artigo em Inglês | MEDLINE | ID: mdl-22088978

RESUMO

In this study, the synthesis of Mn(3)O(4) (husmannite) nanoparticles was carried out in two different alkali media under sonication by ultrasonic bath and conventional method. Manganese acetate was used as precursor, sodium hydroxide and hexamethylenetetramine (HMT) as basic reagents in this synthesis. An ultrasonic bath with low intensity was used for the preparation of nanomaterials. The as prepared samples were characterized with X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, transmission electron microscopy (HRTEM, TEM), energy-dispersive spectrum (EDS), and superconducting quantum interference device (SQUID) analysis. The XRD patterns exhibit the nanocrystals are in pure tetragonal phase. The chemical composition was obtained by EDS analysis and confirmed the presence of Mn and O in the sample. According to the TEM and HRTEM results, both nanorods and nanoparticles of Mn(3)O(4) were obtained in the presence of ultrasonic irradiation. The average size of nanoparticles was 10nm, and the size of nanorods was 12 nm in diameter and 100-900 nm in length for the samples prepared in basic medium with sodium hydroxide. In the conventional method with the same basic medium, the nanorod was not observed and the nearly cubic nanoparticles was appeared with an average size of 2.5 nm. The selected area electron diffraction (SAED) patterns revealed that the nanocrystals are polycrystalline in nature. When HMT was used as a basic reagent in the presence of ultrasonic irradiation, it was led to a higher size of nanoparticles and nanorods than when sodium hydroxide was used as a basic reagent. The average size of nanoparticles was about 15 nm and its shape was nearly cubic. The diameter for nanorods was 50 nm and the length was about a few micrometers. The magnetic measurements were carried out on the sample prepared in sodium hydroxide under ultrasonic irradiation. These measurements as a function of temperature and field strength showed a reduction in ferrimagnetic temperature (T(c) = 40K) as compared to those reported for the bulk (T(c) = 43K). The superparamagnetic behavior was observed at room temperature with no saturation magnetization and hysteresis in the region of measured field strength.


Assuntos
Dextranos/síntese química , Dextranos/efeitos da radiação , Nanopartículas de Magnetita/efeitos da radiação , Compostos de Manganês/química , Compostos de Manganês/efeitos da radiação , Nanoestruturas/química , Nanoestruturas/efeitos da radiação , Óxidos/química , Óxidos/efeitos da radiação , Sonicação/métodos , Ondas de Choque de Alta Energia , Magnetismo , Nanoestruturas/ultraestrutura , Tamanho da Partícula , Doses de Radiação
16.
Ultrason Sonochem ; 19(3): 652-8, 2012 May.
Artigo em Inglês | MEDLINE | ID: mdl-22113061

RESUMO

In the present investigation, synthesis of manganese zinc ferrite (Mn(0.5)Zn(0.5)Fe(2)O(4)) nanoparticles with narrow size distribution have been prepared using ultrasound assisted emulsion (consisting of rapeseed oil as an oil phase and aqueous solution of Mn(2+), Zn(2+) and Fe(2+) acetates) and evaporation processes. The as-prepared ferrite was nanocrystalline. In order to remove the small amount of oil present on the surface of the ferrite, it was subjected to heat treatment at 300 °C for 3h. Both the as-prepared and heat treated ferrites have been characterized by X-ray diffraction (XRD), infrared spectroscopy (IR), TGA/DTA, transmission electron microscopy (TEM) and energy dispersion X-ray spectroscopy (EDS) techniques. As-prepared ferrite is of 20 nm, whereas the heat treated ferrite shows the size of 33 nm. In addition, magnetic properties of the as-prepared as well as the heat treated ferrites have also been carried out and the results of which show that the spontaneous magnetization (σ(s)) of the heat treated sample (24.1 emu/g) is significantly higher than that of the as-synthesized sample (1.81 emu/g). The key features of this method are avoiding (a) the cumbersome conditions that exist in the conventional methods; (b) usage of necessary additive components (stabilizers or surfactants, precipitants) and (c) calcination requirements. In addition, rapeseed oil as an oil phase has been used for the first time, replacing the toxic and troublesome organic nonpolar solvents. As a whole, this simple straightforward sonochemical approach results in more phase pure system with improved magnetization.


Assuntos
Compostos Férricos/síntese química , Compostos de Manganês/síntese química , Nanoestruturas/química , Óleos de Plantas/química , Óleos de Plantas/efeitos da radiação , Sonicação/métodos , Água/química , Zinco/química , Cristalização/métodos , Emulsões/química , Emulsões/efeitos da radiação , Compostos Férricos/efeitos da radiação , Ondas de Choque de Alta Energia , Magnetismo , Compostos de Manganês/efeitos da radiação , Nanoestruturas/efeitos da radiação , Nanoestruturas/ultraestrutura , Doses de Radiação
17.
J Comb Chem ; 12(3): 363-9, 2010 May 10.
Artigo em Inglês | MEDLINE | ID: mdl-20225882

RESUMO

On the basis of the idea of equilateral ingredient triangle, a material library of the TiO(2)/WO(3)/MnO(2) composite material system was designed, which consisted of 66 ingredient points. Each point in the library corresponded with a device. To fabricate the device, the technology of screen printing was used. The pastes which were suitable for this technology were prepared by ball milling. After we printed the pastes onto the alumina substrate which had been preprinted with Au interdigital electrodes, these printed samples were sintered at 550 degrees C for 2 h in air. The photocurrent of each device under different light sources was measured respectively using a high-throughput screening system. The largest photocurrent was observed when the mole ratio of TiO(2)/WO(3) was 2/8 in the composite system. X-ray diffraction (XRD) was used to investigate the phase structure of the powder which had excellent photoelectric response.


Assuntos
Eletroquímica , Compostos de Manganês , Óxidos , Processos Fotoquímicos , Titânio , Tungstênio , Ensaios de Triagem em Larga Escala , Compostos de Manganês/química , Compostos de Manganês/efeitos da radiação , Óxidos/química , Óxidos/efeitos da radiação , Titânio/química , Titânio/efeitos da radiação , Tungstênio/química , Tungstênio/efeitos da radiação
18.
Ultrason Sonochem ; 17(1): 123-31, 2010 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-19502092

RESUMO

This paper addresses the matter of mechanistic features of ultrasound-assisted permanganate oxidation of organic compounds in aqueous phase. This reaction system is essentially a liquid-liquid heterogeneous one, which is limited by the mass transfer characteristics. Previous research has established that ultrasound irradiation of reaction mixture enhances the kinetics and yield of permanganate oxidation. The principal physical effect of ultrasonic cavitation is formation of fine emulsion between immiscible phases that eliminates the mass transfer resistance, while principal chemical effect is production of radicals through transient collapse of cavitation bubbles, which accelerate the reaction. In this paper, we have tried to discriminate between these physical and chemical effects by coupling experiments with different conditions (which alter the nature of cavitation phenomena in the medium) to simulations of cavitation bubble dynamics. It is revealed that in absence of radical conserving agent, the enhancement effect is merely physical. Diffusion of radicals towards interface between phases, where the oxidation reaction occurs is the limiting factor in contribution of chemical effect of ultrasonic cavitation towards enhancement of oxidation. Enhancement of total radical production in the aqueous phase (by degassing of the medium) increases the overall oxidation yield, but only marginally. On the other hand, addition of a radical conserver such as FeSO(4).7H(2)O results in marked enhancement in oxidation yield, as the conserver assists deeper penetration of radicals in the aqueous medium and diffusion towards interface.


Assuntos
Compostos de Manganês/química , Compostos de Manganês/efeitos da radiação , Modelos Químicos , Óxidos/química , Óxidos/efeitos da radiação , Sonicação/métodos , Simulação por Computador , Oxirredução/efeitos da radiação , Doses de Radiação
19.
Nanotechnology ; 20(10): 105706, 2009 Mar 11.
Artigo em Inglês | MEDLINE | ID: mdl-19417534

RESUMO

Hydrohausmannite nanoparticles (approximately 10 nm) were prepared by the hydrothermal method at 100 degrees C for 72 h. Subsequent annealing was done in air at 400 degrees C and 800 degrees C for 10 h, Mn(3)O(4) nanoparticles (approximately 25 nm) and 3D Mn(2)O(3) porous networks were obtained, respectively. The products were characterized by XRD, TEM, SAED and FESEM. Time-dependent experiments were carried out to exhibit the formation process of the Mn(2)O(3) networks. Their microwave absorption properties were investigated by mixing the product and paraffin wax with 50 vol%. The Mn(3)O(4) nanoparticles possess excellent microwave absorbing properties with the minimum reflection loss of -27.1 dB at 3.1 GHz. In contrast, the Mn(2)O(3) networks show the weakest absorption of all samples. The absorption becomes weaker with the annealing time increasing at 800 degrees C. The attenuation of microwave can be attributed to dielectric loss and their absorption mechanism was discussed in detail.


Assuntos
Cristalização/métodos , Compostos de Manganês/química , Nanoestruturas/química , Nanoestruturas/ultraestrutura , Nanotecnologia/métodos , Óxidos/química , Absorção , Substâncias Macromoleculares/química , Compostos de Manganês/efeitos da radiação , Teste de Materiais , Micro-Ondas , Conformação Molecular , Nanoestruturas/efeitos da radiação , Óxidos/efeitos da radiação , Tamanho da Partícula , Porosidade , Espalhamento de Radiação , Propriedades de Superfície
20.
Biomaterials ; 29(17): 2673-9, 2008 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-18396332

RESUMO

One of the main advantages of gene therapy over traditional therapy is the potential to target the expression of therapeutic genes in desired cells or tissues. To achieve targeted gene expression, we developed a novel heat-inducible gene expression system in which thermal energy generated by Mn-Zn ferrite magnetic nanoparticles (MZF-NPs) under an alternating magnetic field (AMF) was used to activate gene expression. MZF-NPs, obtained by co-precipitation method, were firstly surface modified with cation poly(ethylenimine) (PEI). Then thermodynamic test of various doses of MZF-NPs was preformed in vivo and in vitro. PEI-MZF-NPs showed good DNA binding ability and high transfection efficiency. In AMF, they could rise to a steady temperature. To analyze the heat-induced gene expression under an AMF, we combined P1730OR vector transfection with hyperthermia produced by irradiation of MZF-NPs. By using LacZ gene as a reporter gene and Hsp70 as a promoter, it was demonstrated that expression of a heterogeneous gene could be elevated to 10 to 500-fold over background by moderate hyperthermia (added 12.24 or 25.81 mg MZF-NPs to growth medium) in tissue cultured cells. When injected with 2.6 or 4.6 mg MZF-NPs, the temperature of tumor-bearing nude mice could rise to 39.5 or 42.8 degrees C, respectively, and the beta-gal concentration could increase up to 3.8 or 8.1 mU/mg proteins accordingly 1 day after hyperthermia treatment. Our results therefore supported hyperthermia produced by irradiation of MZF-NPs under an AMF as a feasible approach for targeted heat-induced gene expression. This novel system made use of the relative low Curie point of MZF-NPs to control the in vivo hyperthermia temperature and therefore acquired safe and effective heat-inducible transgene expression.


Assuntos
Materiais Revestidos Biocompatíveis/efeitos da radiação , Compostos Férricos/efeitos da radiação , Regulação Neoplásica da Expressão Gênica , Hipertermia Induzida , Compostos de Manganês/efeitos da radiação , Nanopartículas/efeitos da radiação , Compostos de Zinco/efeitos da radiação , Animais , Carcinoma Hepatocelular/patologia , Carcinoma Hepatocelular/radioterapia , Linhagem Celular , Células Cultivadas , Materiais Revestidos Biocompatíveis/metabolismo , Materiais Revestidos Biocompatíveis/farmacologia , DNA/metabolismo , Relação Dose-Resposta a Droga , Estudos de Viabilidade , Compostos Férricos/metabolismo , Compostos Férricos/farmacologia , Genes Reporter , Vetores Genéticos , Proteínas de Choque Térmico HSP70/genética , Humanos , Rim/citologia , Óperon Lac , Neoplasias Hepáticas/patologia , Neoplasias Hepáticas/radioterapia , Luciferases/metabolismo , Magnetismo/uso terapêutico , Masculino , Compostos de Manganês/metabolismo , Compostos de Manganês/farmacologia , Camundongos , Camundongos Nus , Tamanho da Partícula , Polietilenoimina/química , Regiões Promotoras Genéticas , Distribuição Aleatória , Termodinâmica , Transfecção , Ensaios Antitumorais Modelo de Xenoenxerto/métodos , Compostos de Zinco/metabolismo , Compostos de Zinco/farmacologia , beta-Galactosidase/análise , beta-Galactosidase/metabolismo
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