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1.
Chem Commun (Camb) ; 55(73): 10920-10923, 2019 Sep 10.
Artigo em Inglês | MEDLINE | ID: mdl-31441463

RESUMO

The development of new NIR-II fluorophores, particularly those with facile syntheses, high fluorescence quantum yields, and stable and tunable photophysical properties, is challenging. Herein, we report a new class of small molecular NIR-II fluorophores based on aza-dipyrromethene boron difluoride (aza-BODIPY) dyes. We demonstrate promising photophysical properties of these dyes, such as large Stokes shift, superior photostability, and good fluorescence brightness as nanoparticles in aqueous solution. Because of these properties and high resolution and deep penetration NIR-II imaging ability, the aza-BODIPY based dyes show great potential as NIR-II imaging agents.


Assuntos
Compostos de Boro/química , Corantes Fluorescentes/química , Imagem Óptica/métodos , Pirróis/química , Animais , Compostos de Boro/síntese química , Compostos de Boro/efeitos da radiação , Compostos de Boro/toxicidade , Linhagem Celular Tumoral , Teoria da Densidade Funcional , Desenho de Drogas , Fluorescência , Corantes Fluorescentes/síntese química , Corantes Fluorescentes/efeitos da radiação , Corantes Fluorescentes/toxicidade , Raios Infravermelhos , Camundongos , Modelos Químicos , Nanopartículas/química , Poloxâmero/química , Pirróis/síntese química , Pirróis/efeitos da radiação , Pirróis/toxicidade
2.
Inorg Chem ; 58(13): 8587-8595, 2019 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-31117633

RESUMO

A new N,O-based BODIPY ligand was synthesized and further utilized to develop highly fluorescent and photostable Ru(II), Rh(III), and Ir(III) metal complexes. The complexes were fully characterized by different analytical techniques including single-crystal XRD studies. The photostabilities and live cell imaging capabilities of the complexes were investigated via confocal microscopy. The complexes localized specifically in the mitochondria of live cells and showed negligible cytotoxicities at a concentration used for imaging purposes. They also exhibited high photostabilities, with fluorescence intensities remaining above 50% after 1800 scans.


Assuntos
Compostos de Boro/metabolismo , Complexos de Coordenação/metabolismo , Corantes Fluorescentes/metabolismo , Mitocôndrias/metabolismo , Transporte Biológico , Compostos de Boro/síntese química , Compostos de Boro/efeitos da radiação , Compostos de Boro/toxicidade , Complexos de Coordenação/síntese química , Complexos de Coordenação/efeitos da radiação , Complexos de Coordenação/toxicidade , Corantes Fluorescentes/síntese química , Corantes Fluorescentes/efeitos da radiação , Corantes Fluorescentes/toxicidade , Células HeLa , Humanos , Irídio/química , Ligantes , Microscopia Confocal , Fotodegradação , Ródio/química , Rutênio/química
3.
Anal Chim Acta ; 1049: 219-225, 2019 Feb 21.
Artigo em Inglês | MEDLINE | ID: mdl-30612654

RESUMO

In this work, taking full advantage of the intramolecular charge transfer (ICT) mechanism, a hydroxynaphthalimide-based ratiometric two-photon fluorescent probe RTP-PN was synthesized to detect ONOO-. Probe RTP-PN could accurately detect ONOO- in the range of 1.4 nM-1.4 µM with the detection limit of 1.4 nM by a ratiometric fluorescence spectroscopy method. Additionally, probe RTP-PN exhibited an ultrafast response for ONOO- than other various species including H2O2 and ClO-. Finally, probe RTP-PN was successfully adopted to detect intracellular ONOO- by the two-photon excitation microscopy.


Assuntos
Compostos de Boro/química , Corantes Fluorescentes/química , Naftalimidas/química , Ácido Peroxinitroso/análise , Animais , Compostos de Boro/síntese química , Compostos de Boro/efeitos da radiação , Compostos de Boro/toxicidade , Corantes Fluorescentes/síntese química , Corantes Fluorescentes/efeitos da radiação , Corantes Fluorescentes/toxicidade , Raios Infravermelhos , Limite de Detecção , Camundongos , Microscopia de Fluorescência/métodos , Naftalimidas/síntese química , Naftalimidas/efeitos da radiação , Naftalimidas/toxicidade , Células RAW 264.7
4.
Inorg Chem ; 57(16): 10137-10145, 2018 Aug 20.
Artigo em Inglês | MEDLINE | ID: mdl-30074794

RESUMO

We report herein a new ZIF-90-based PDT agent which was synthesized by in situ assembly of imidazole-2-carboxaldehyde (IcaH), Zn(NO3)2, and heavy atom iodine-attached Bodipy. The obtained 2I-BodipyPhNO2@ZIF-90 (1) host-guest photosensitive system featured low cytotoxicity, good biocompatibility, pH-driven selective cancer cell uptake and release, mitochondria targeting, and highly efficient pH-triggered 1O2 generation. Therefore, it can be used as a high-performing PDT agent to selectively kill tumor cells. In comparison to free 2I-BodipyPhNO2, 1 exhibits a much higher antitumor efficacy and selectivity, which was confirmed by in vitro cell experiments.


Assuntos
Antineoplásicos/farmacologia , Compostos de Boro/farmacologia , Estruturas Metalorgânicas/farmacologia , Nanopartículas/química , Fármacos Fotossensibilizantes/farmacologia , Antineoplásicos/síntese química , Antineoplásicos/efeitos da radiação , Antineoplásicos/toxicidade , Apoptose/efeitos dos fármacos , Compostos de Boro/síntese química , Compostos de Boro/efeitos da radiação , Compostos de Boro/toxicidade , Linhagem Celular Tumoral , Estabilidade de Medicamentos , Humanos , Concentração de Íons de Hidrogênio , Estruturas Metalorgânicas/síntese química , Estruturas Metalorgânicas/efeitos da radiação , Estruturas Metalorgânicas/toxicidade , Mitocôndrias/metabolismo , Nanopartículas/efeitos da radiação , Nanopartículas/toxicidade , Fotoquimioterapia/métodos , Fármacos Fotossensibilizantes/síntese química , Fármacos Fotossensibilizantes/efeitos da radiação , Fármacos Fotossensibilizantes/toxicidade , Oxigênio Singlete/metabolismo
5.
Inorg Chem ; 57(16): 10040-10049, 2018 Aug 20.
Artigo em Inglês | MEDLINE | ID: mdl-30070839

RESUMO

A novel, photochromic N^C-chelate organoboron functionalized dipicolinic acid (H2L) has been designed and synthesized. Lanthanide(III) complexes based on this ligand (L) with the general formula [NBu4]3[LnL3] (Ln = Eu or Tb) were prepared. The new ligand was found to be effective in both sensitizing and photomodulating the emission of a Eu(III) ion. The photoisomerization conversion of the boryl chromophore attached to the ligand of the lanthanide complex was determined to be quantitative by NMR analysis of the La(III) analogue.


Assuntos
Compostos de Boro/química , Complexos de Coordenação/química , Elementos da Série dos Lantanídeos/química , Compostos de Boro/síntese química , Compostos de Boro/efeitos da radiação , Complexos de Coordenação/síntese química , Complexos de Coordenação/efeitos da radiação , Isomerismo , Ligantes , Luminescência , Modelos Químicos , Teoria Quântica , Raios Ultravioleta
6.
Chem Asian J ; 13(8): 989-995, 2018 Apr 16.
Artigo em Inglês | MEDLINE | ID: mdl-29377582

RESUMO

The development of robust photothermal agents for near-infrared (NIR) imaging is a great challenge. Herein, we report the design and synthesis of a new photothermal agent, based on the aza-boron-dipyrromethene framework (azaBDP). This compound possessed excellent photostability and high photothermal-conversion efficiency (50 %) under NIR laser irradiation. When the photothermal properties of this compound were utilized for tumor inhibition, stable long-term fluorescence was observed in living animals. Photothermal treatment efficiently suppressed tumor growth, as evidenced by in vitro and in vivo experiments. Furthermore, NIR emission could be detected by using an imaging system and therapeutic self-monitoring was achieved by using NIR imaging.


Assuntos
Antineoplásicos/uso terapêutico , Compostos de Boro/uso terapêutico , Corantes Fluorescentes/uso terapêutico , Neoplasias/diagnóstico por imagem , Neoplasias/tratamento farmacológico , Animais , Antineoplásicos/síntese química , Antineoplásicos/farmacologia , Antineoplásicos/efeitos da radiação , Apoptose/efeitos dos fármacos , Compostos de Boro/síntese química , Compostos de Boro/farmacologia , Compostos de Boro/efeitos da radiação , Linhagem Celular Tumoral , Corantes Fluorescentes/síntese química , Corantes Fluorescentes/farmacologia , Corantes Fluorescentes/efeitos da radiação , Calefação , Humanos , Camundongos Endogâmicos BALB C , Necrose/induzido quimicamente , Fotoquimioterapia , Fármacos Fotossensibilizantes/síntese química , Fármacos Fotossensibilizantes/farmacologia , Fármacos Fotossensibilizantes/efeitos da radiação , Fármacos Fotossensibilizantes/uso terapêutico
7.
Sci Rep ; 8(1): 988, 2018 01 17.
Artigo em Inglês | MEDLINE | ID: mdl-29343841

RESUMO

We here propose a new model for estimating the biological effectiveness for boron neutron capture therapy (BNCT) considering intra- and intercellular heterogeneity in 10B distribution. The new model was developed from our previously established stochastic microdosimetric kinetic model that determines the surviving fraction of cells irradiated with any radiations. In the model, the probability density of the absorbed doses in microscopic scales is the fundamental physical index for characterizing the radiation fields. A new computational method was established to determine the probability density for application to BNCT using the Particle and Heavy Ion Transport code System PHITS. The parameters used in the model were determined from the measured surviving fraction of tumor cells administrated with two kinds of 10B compounds. The model quantitatively highlighted the indispensable need to consider the synergetic effect and the dose dependence of the biological effectiveness in the estimate of the therapeutic effect of BNCT. The model can predict the biological effectiveness of newly developed 10B compounds based on their intra- and intercellular distributions, and thus, it can play important roles not only in treatment planning but also in drug discovery research for future BNCT.


Assuntos
Boroidretos/efeitos da radiação , Compostos de Boro/efeitos da radiação , Terapia por Captura de Nêutron de Boro/métodos , Modelos Estatísticos , Nêutrons/uso terapêutico , Fenilalanina/análogos & derivados , Eficiência Biológica Relativa , Compostos de Sulfidrila/efeitos da radiação , Animais , Boroidretos/farmacocinética , Compostos de Boro/farmacocinética , Morte Celular/efeitos da radiação , Linhagem Celular Tumoral , Núcleo Celular/metabolismo , Núcleo Celular/efeitos da radiação , Sobrevivência Celular , Citoplasma/metabolismo , Citoplasma/efeitos da radiação , Dano ao DNA , Espaço Extracelular/metabolismo , Espaço Extracelular/efeitos da radiação , Humanos , Camundongos , Fenilalanina/farmacocinética , Fenilalanina/efeitos da radiação , Radiometria , Compostos de Sulfidrila/farmacocinética , Distribuição Tecidual
8.
Inorg Chem ; 56(20): 12457-12468, 2017 Oct 16.
Artigo em Inglês | MEDLINE | ID: mdl-28972748

RESUMO

Ternary oxidovanadium(IV) complexes of curcumin (Hcur), dipicolylamine (dpa) base, and its derivatives having pendant noniodinated and di-iodinated boron-dipyrromethene (BODIPY) moiety (L1 and L2, respectively), namely, [VO(dpa)(cur)]ClO4 (1), [VO(L1)(cur)]ClO4 (2), and [VO(L2)(cur)]ClO4 (3) and their chloride salts (1a-3a) were prepared, characterized, and studied for anticancer activity. The chloride salts were used for biological studies due to their aqueous solubility. Complex 1 was structurally characterized by single-crystal X-ray crystallography. The complex has a VO2+ moiety bound to dpa ligand showing N,N,N-coordination in a facial mode, and curcumin is bound in its mono-anionic enolic form. The V-O(cur) distances are 1.950(18) and 1.977(16) Å, while the V-N bond lengths are 2.090(2), 2.130(2), and 2.290(2) Å. The bond trans to V═O is long due to trans effect. The complexes are stable in a solution phase over a long period of time of 48 h without showing any apparent degradation of the curcumin ligand. The diiodo-BODIPY ligand (L2) or Hcur alone showed limited solution stability in dark. The emissive BODIPY (L1) containing complex 2a showed preferential mitochondrial localization in MCF-7 cells in cellular imaging experiments. The cytotoxicity of the complexes was studied by MTT assay. The BODIPY complex 3a showed excellent photodynamic therapy effect in visible light (400-700 nm) giving IC50 values of 2-6 µM in HeLa and MCF-7 cancer cells, while being less toxic in dark (∼100 µM). The cell death was apoptotic in nature involving reactive oxygen species (ROS). Mechanistic data from pUC19 DNA photocleavage studies revealed photogenerated ROS as primarily 1O2 from the BODIPY moiety and ·OH radicals from the curcumin ligand.


Assuntos
Antineoplásicos/farmacologia , Compostos de Boro/farmacologia , Complexos de Coordenação/farmacologia , Curcumina/análogos & derivados , Curcumina/farmacologia , Mitocôndrias/metabolismo , Fármacos Fotossensibilizantes/farmacologia , Vanádio/química , Aminas/síntese química , Aminas/química , Aminas/farmacologia , Antineoplásicos/síntese química , Antineoplásicos/química , Antineoplásicos/efeitos da radiação , Apoptose/efeitos dos fármacos , Compostos de Boro/síntese química , Compostos de Boro/química , Compostos de Boro/efeitos da radiação , Linhagem Celular Tumoral , Complexos de Coordenação/síntese química , Complexos de Coordenação/química , Complexos de Coordenação/efeitos da radiação , Curcumina/síntese química , Curcumina/efeitos da radiação , Clivagem do DNA , Estabilidade de Medicamentos , Pontos de Checagem da Fase G1 do Ciclo Celular/efeitos dos fármacos , Humanos , Ligantes , Luz , Mitocôndrias/genética , Fármacos Fotossensibilizantes/síntese química , Fármacos Fotossensibilizantes/química , Fármacos Fotossensibilizantes/efeitos da radiação , Ácidos Picolínicos/síntese química , Ácidos Picolínicos/química , Ácidos Picolínicos/farmacologia , Espécies Reativas de Oxigênio/metabolismo , Oxigênio Singlete/química
9.
Inorg Chem ; 56(7): 3754-3762, 2017 Apr 03.
Artigo em Inglês | MEDLINE | ID: mdl-28080031

RESUMO

Sensitizing the antitumor activity of monofunctional PtII complexes is a reliable approach to developing antitumor agents different from the classic Pt-based drugs. Considering the poor intracellular accumulation of monofunctional PtII complexes, in this study, the photosensitizing monofunctional PtII complex Pt-BA was derived from a weak BODIPY (boron-dipyrromethene)-derived photosensitizer BA, with the purpose to improve its antitumor cytotoxicity via enhancing its intracellular accumulation with a short time photo-irradiation. Photoinduced reactive oxygen species (ROS) determination indicated that the PtII center in Pt-BA is able to improve the photoinduced ROS production ability of BA, which makes Pt-BA a mild photosensitizer. Fluorescence imaging disclosed that dark incubation makes Pt-BA accumulate mainly on the surface of cell membrane, and the later short time photo-irradiation (5 min) promotes distinctly the intracellular accumulation of Pt-BA, which has been confirmed by inductively coupled plasma-mass spectrometry determination. Flow cytometric Annexin V-FITC assay indicated that the short time irradiation of Pt-BA induces in situ the cell membrane damage, which might finally enhance the intracellular accumulation of this monofunctional complex. 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay confirmed that the short time photo-irradiation promotes distinctly the antitumor cytotoxicity of Pt-BA against MCF-7, SGC-7901, A549, and HeLa cell lines. The photopromoted antitumor activity of Pt-BA implies that modifying monofunctional PtII complex as a mild photosensitizer to promote its cell accumulation is a useful approach to sensitizing the antitumor activity of monofunctional PtII complex and renders the possibility of monofunctional PtII prodrugs for precise chemotherapy via only short time photoactivation.


Assuntos
Antineoplásicos/farmacologia , Compostos de Boro/farmacologia , Compostos Organoplatínicos/farmacologia , Fármacos Fotossensibilizantes/farmacologia , Antineoplásicos/síntese química , Antineoplásicos/química , Antineoplásicos/efeitos da radiação , Compostos de Boro/síntese química , Compostos de Boro/química , Compostos de Boro/efeitos da radiação , Linhagem Celular Tumoral , Membrana Celular/efeitos dos fármacos , Fluorescência , Humanos , Luz , Microscopia Confocal , Microscopia de Fluorescência , Compostos Organoplatínicos/síntese química , Compostos Organoplatínicos/química , Compostos Organoplatínicos/efeitos da radiação , Fármacos Fotossensibilizantes/síntese química , Fármacos Fotossensibilizantes/química , Fármacos Fotossensibilizantes/efeitos da radiação , Espécies Reativas de Oxigênio
10.
J Am Chem Soc ; 138(22): 6952-5, 2016 06 08.
Artigo em Inglês | MEDLINE | ID: mdl-27186856

RESUMO

We report a discovery that perfunctionalized icosahedral dodecaborate clusters of the type B12(OCH2Ar)12 (Ar = Ph or C6F5) can undergo photo-excitation with visible light, leading to a new class of metal-free photooxidants. Excitation in these species occurs as a result of the charge transfer between low-lying orbitals located on the benzyl substituents and an unoccupied orbital delocalized throughout the boron cluster core. Here we show how these species, photo-excited with a benchtop blue LED source, can exhibit excited-state reduction potentials as high as 3 V and can participate in electron-transfer processes with a broad range of styrene monomers, initiating their polymerization. Initiation is observed in cases of both electron-rich and electron-deficient styrene monomers at cluster loadings as low as 0.005 mol%. Furthermore, photo-excitation of B12(OCH2C6F5)12 in the presence of a less activated olefin such as isobutylene results in the production of highly branched poly(isobutylene). This work introduces a new class of air-stable, metal-free photo-redox reagents capable of mediating chemical transformations.


Assuntos
Compostos de Boro/química , Luz , Oxidantes/química , Polienos/química , Polímeros/química , Compostos de Boro/efeitos da radiação , Transporte de Elétrons , Modelos Moleculares , Estrutura Molecular , Oxirredução , Processos Fotoquímicos , Polimerização
11.
Chembiochem ; 17(13): 1233-40, 2016 07 01.
Artigo em Inglês | MEDLINE | ID: mdl-27038199

RESUMO

Investigation of the unexpected photo-instability of 2,6-sulfonamide-substituted derivatives of the boron dipyrromethene (BODIPY) fluorophore led to the discovery of a photoreaction accompanied by multiple bond scissions. We characterized the photoproducts and utilized the photoreaction to design a caged γ-aminobutyric acid (GABA) derivative that can release GABA upon irradiation in the visible range (>450 nm). This allowed us to stimulate neural cells in mouse brain slices.


Assuntos
Compostos de Boro/efeitos da radiação , Sulfonamidas/efeitos da radiação , Ácido gama-Aminobutírico/análogos & derivados , Ácido gama-Aminobutírico/farmacologia , Acetaldeído/análise , Animais , Baclofeno/farmacologia , Complexo Nuclear Basolateral da Amígdala/efeitos dos fármacos , Complexo Nuclear Basolateral da Amígdala/fisiologia , Compostos de Boro/síntese química , Compostos de Boro/química , Formaldeído/análise , Antagonistas GABAérgicos/farmacologia , Células HeLa , Humanos , Luz , Metilaminas/análise , Camundongos , Picrotoxina/farmacologia , Sulfonamidas/síntese química , Sulfonamidas/química
12.
Biosens Bioelectron ; 77: 242-8, 2016 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-26409025

RESUMO

Fluorescent boron dipyrromethene (BODIPY) analogs are often used as sensors for detecting various species because of their relatively high extinction coefficients, outstanding fluorescence quantum yields, photostability, and pH-independent fluorescence. However, there is little-to-no information in the literature that describes the use of BODIPY analogs for detecting alkaline phosphatase (ALP) activity and inhibition. This study discovered that the fluorescence of BODIPY-conjugated adenosine triphosphate (BODIPY-ATP) was quenched by Fe(III) ions through photoinduced electron transfer. The ALP-catalyzed hydrolysis of BODIPY-ATP resulted in the formation of BODIPY-adenosine and phosphate ions. The fluorescence of the generated BODIPY-adenosine was insensitive to the change in the concentration of Fe(III) ions. Thus, the Fe(III)-induced fluorescence quenching of BODIPY-ATP can be paired with its ALP-mediated dephosphorylation to design a turn-on fluorescence probe for ALP sensing. A method detection limit at a signal-to-noise ratio of 3 for ALP was estimated to be 0.02 units/L (~6 pM; 1 ng/mL). This probe was used for the screening of ALP inhibitors, including Na3VO4, imidazole, and arginine. Because ALP is widely used in enzyme-linked immunosorbent assays, the probe was coupled to an ALP-linked immunosorbent assay for the sensitive and selective detection of immunoglobulin G (IgG). The lowest detectable concentration for IgG in this system was 5 ng/mL. Compared with the use of 3,6-fluorescein diphosphate as a signal reporter in an ALP-linked immunosorbent assay, the proposed system provided comparable sensitivity, large linear range, and high stability over temperature and pH changes.


Assuntos
Trifosfato de Adenosina/química , Fosfatase Alcalina/análise , Fosfatase Alcalina/química , Compostos de Boro/química , Ensaio de Imunoadsorção Enzimática/instrumentação , Ferro/química , Trifosfato de Adenosina/efeitos da radiação , Compostos de Boro/efeitos da radiação , Transporte de Elétrons/efeitos da radiação , Desenho de Equipamento , Análise de Falha de Equipamento , Ferro/efeitos da radiação , Luz , Nanoconjugados/química , Nanoconjugados/efeitos da radiação
13.
Dalton Trans ; 44(28): 12726-34, 2015 Jul 28.
Artigo em Inglês | MEDLINE | ID: mdl-26087131

RESUMO

BODIPY (boron dipyrromethene) derivatives and Ru(ii) complexes are two types of functional compounds that have found wide applications in the fields of biology and medicine. We herein synthesized two new Ru(ii) arene complexes based on an iodized BODIPY-containing pyridine (py-I-BODIPY) ligand, [(p-cym)Ru(bpy)(py-I-BODIPY)](2+) (2) and [(p-cym)Ru(2-pydaT)(py-I-BODIPY)](2+) (3), where p-cym = para-cymene, bpy = 2,2'-bipyridine, and 2-pydaT = 2,4-diamino-6-(2-pyridyl)-1,3,5-triazine. The photophysical, photochemical and photobiological properties of 2 and 3 were compared with that of [(p-cym)Ru(bpy)(py-BODIPY)](2+) (1). While 1 undergoes efficient monodentate ligand dissociation upon visible light irradiation and therefore may photobind DNA as a potential photoactivated chemotherapy (PACT) agent, 2 and 3 can generate (1)O2 effectively and thus may serve as photosensitizers in photodynamic therapy (PDT). In electrophoresis experiments, 2 and 3 are even able to retard the mobility of plasmid DNA in the dark at high concentrations. More importantly, the cytotoxicities of 2 and 3 against human ovarian adenocarcinoma SKOV3 cells are enhanced about ten times under irradiation, leading to cytotoxicities more than one order of magnitude higher than that of cisplatin, demonstrating an efficient hybridization of the iodized BODIPY chromophore and the Ru(ii) arene complex.


Assuntos
Compostos de Boro , Complexos de Coordenação , Fármacos Fotossensibilizantes , Rutênio , Compostos de Boro/química , Compostos de Boro/farmacologia , Compostos de Boro/efeitos da radiação , Linhagem Celular Tumoral , Sobrevivência Celular/efeitos dos fármacos , Sobrevivência Celular/efeitos da radiação , Complexos de Coordenação/química , Complexos de Coordenação/farmacologia , Complexos de Coordenação/efeitos da radiação , DNA/efeitos dos fármacos , DNA/metabolismo , DNA/efeitos da radiação , Clivagem do DNA , Humanos , Ligantes , Luz , Fotoquimioterapia , Fármacos Fotossensibilizantes/química , Fármacos Fotossensibilizantes/farmacologia , Fármacos Fotossensibilizantes/efeitos da radiação , Plasmídeos , Rutênio/química , Rutênio/farmacologia , Rutênio/efeitos da radiação
14.
J Synchrotron Radiat ; 20(Pt 3): 449-54, 2013 May.
Artigo em Inglês | MEDLINE | ID: mdl-23592624

RESUMO

B4C-based multilayers have important applications for soft to hard X-rays. In this paper, X-ray grazing-incidence reflectivity and diffuse scattering, combining various analysis methods, were used to characterize the structure of B4C-based multilayers including layer thickness, density, interfacial roughness, interdiffusion, correlation length, etc. Quantitative results for W/B4C, Mo/B4C and La/B4C multilayers were compared. W/B4C multilayers show the sharpest interfaces and most stable structures. The roughness replications of La/B4C and Mo/B4C multilayers are not strong, and oxidations and structure expansions are found in the aging process. This work provides guidance for future fabrication and characterization of B4C-based multilayers.


Assuntos
Compostos de Boro/química , Carbono/química , Lentes , Refratometria/instrumentação , Raios X , Compostos de Boro/efeitos da radiação , Carbono/efeitos da radiação , Desenho de Equipamento , Análise de Falha de Equipamento , Teste de Materiais , Espalhamento de Radiação
15.
ACS Nano ; 7(4): 3491-7, 2013 Apr 23.
Artigo em Inglês | MEDLINE | ID: mdl-23458341

RESUMO

In many previous reports, the engineering of nanostructures using electron beam irradiation (EBI) in a high vacuum has primarily been based on the knock-on atom displacement. Herein, we report a new phenomenon under EBI that can also be effectively used to engineer a nanostructure: local Coulomb explosion (LCE) of cantilevered multiwalled boron nitride nanotubes (BNNTs) resulted from their profound positive charging. The nanotubes are gradually shortened, while the tubular shells at free ends are torn into graphene-like pieces and then removed during LCE. The phenomenon is dependent not only on the characteristics of an incident electron beam, as in the case of a common knock-on process, but also on the cantilevered tube length. Only after the electron beam density and tube length exceed the threshold values can LCE take place, and the threshold value for one of the parameters decreases with increasing the value of the other one. A model based on the diffusion of electron-irradiation-induced holes along a BNNT is proposed to describe the positive charge accumulation and can well explain the observed LCE. LCE opens up an efficient and versatile way to engineer BNNTs and other dielectric nanostructures with a shorter time and a lower beam density than those required for the knock-on effect-based engineering.


Assuntos
Compostos de Boro/química , Compostos de Boro/efeitos da radiação , Nanotubos/química , Nanotubos/efeitos da radiação , Elétrons , Teste de Materiais , Nanotubos/ultraestrutura , Tamanho da Partícula , Doses de Radiação , Eletricidade Estática
16.
Appl Radiat Isot ; 77: 38-43, 2013 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-23518037

RESUMO

We have reported the first-ever experimental Compton profile (CP) of TaB2 using 20 Ci(137)Cs Compton spectrometer. To compare the experimental data, we have also computed the theoretical CPs using density functional theory (DFT) and hybridization of DFT and Hartree-Fock (HF) within linear combination of the atomic orbitals (LCAO) method. In addition, we have reported energy bands and density of states of TaB2 using LCAO and full potential-linearized augmented plane wave (FP-LAPW) methods. A real space analysis of CP of TaB2 confirms its metallic character which is in tune with the cross-overs of Fermi level by energy bands and Fermi surface topology. A comparison of equal-valence-electron-density (EVED) experimental profiles of isoelectronic TaB2 and NbB2 show more covalent (or less ionic) character of TaB2 than that of NbB2 which is in agreement with available ionicity data.


Assuntos
Compostos de Boro/química , Teste de Materiais/métodos , Modelos Químicos , Radiometria/métodos , Tantálio/química , Compostos de Boro/análise , Compostos de Boro/efeitos da radiação , Simulação por Computador , Transporte de Elétrons , Radiação , Espalhamento de Radiação , Tantálio/análise , Tantálio/efeitos da radiação
17.
Radiat Prot Dosimetry ; 154(3): 375-80, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-23019599

RESUMO

Recently, due to space and weight limitations, scientists have tried to design and produce concrete shields with increased attenuation of radiation but not increased mass density. Over the past years, the authors' had focused on the production of heavy concrete for radiation shielding, but this is the first experience of producing intermediate-weight concrete. In this study, ulexite (hydrated sodium calcium borate hydroxide) and galena (lead ore) have been used for the production of a special intermediate-weight concrete. Shielding properties of this intermediate-weight concrete against photons have been investigated by exposing the samples to narrow and broad beams of gamma rays emitted from a 6°Co radiotherapy unit. Densities of the intermediate-weight concrete samples ranged 3.64-3.90 g cm⁻³, based on the proportion of the ulexite in the mix design. The narrow-beam half-value layer (HVL) of the ulexite-galena concrete samples for 1.25 MeV 6°Co gamma rays was 2.84 cm, much less than that of ordinary concrete (6.0 cm). The Monte Carlo (MC) code MCNP4C was also used to model the attenuation of 6°Co gamma-ray photons and Am-Be neutrons of the ulexite-galena concrete with different thicknesses. The 6°Co HVL calculated by MCNP simulation was 2.87 cm, indicating a good agreement between experimental measurements and MC simulation. Furthermore, MC-calculated results showed that thick ulexite-galena concrete shields (60-cm thickness) had a 7.22 times (722 %) greater neutron attenuation compared with ordinary concrete. The intermediate-weight ulexite-galena concrete manufactured in this study may have many important applications in the construction of radiation shields with weight limitations such as the swing or sliding doors that are currently used for radiotherapy treatment rooms.


Assuntos
Compostos de Boro/química , Materiais de Construção/análise , Chumbo/química , Proteção Radiológica/instrumentação , Proteção Radiológica/métodos , Sulfetos/química , Compostos de Boro/efeitos da radiação , Materiais de Construção/efeitos da radiação , Desenho de Equipamento , Análise de Falha de Equipamento , Raios gama , Chumbo/efeitos da radiação , Teste de Materiais , Gravidade Específica , Sulfetos/efeitos da radiação
18.
Anticancer Res ; 31(7): 2477-81, 2011 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-21873162

RESUMO

BACKGROUND: We previously designed the boron tracedrugs UTX-42, UTX-43, and UTX-44, which possess antioxidant potency. In order to explore their destructive dynamic effects when bombarded by weak thermal neutrons, we performed thermal neutron irradiation of bovine serum albumin (BSA) treated with the boron tracedrugs. MATERIALS AND METHODS: Boron tracedrugs, including the boron dipyrromethene (BODIPY)-containing compounds UTX-42, UTX-44, and UTX-47 and the curcuminoid compounds UTX-50 and UTX-51, were designed for neutron dynamic therapy based on their molecular orbital calculation. Newly designed UTX-47, UTX-50, and UTX-51 were synthesized. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) was performed to detect decomposition by thermal neutron irradiation of BSA treated with these boron tracedrugs. RESULTS: The combination of 1.0 µM BSA with 100 µM of each of the boron tracedrugs showed a decrease in band intensity after irradiation. CONCLUSION: All boron tracedrugs tested caused destructive dynamic damage of BSA during thermal neutron irradiation, suggesting that boron tracedrugs could be used as dynamic drugs for neutron dynamic therapy.


Assuntos
Compostos de Boro/efeitos da radiação , Terapia por Captura de Nêutron de Boro/métodos , Curcumina/efeitos da radiação , Radiossensibilizantes/efeitos da radiação , Animais , Compostos de Boro/química , Bovinos , Curcumina/análogos & derivados , Curcumina/química , Desenho de Drogas , Eletroforese em Gel de Poliacrilamida , Raios gama , Estrutura Molecular , Radiossensibilizantes/síntese química , Radiossensibilizantes/química , Soroalbumina Bovina/efeitos dos fármacos , Soroalbumina Bovina/efeitos da radiação , Relação Estrutura-Atividade
19.
ACS Nano ; 5(5): 3977-86, 2011 May 24.
Artigo em Inglês | MEDLINE | ID: mdl-21510623

RESUMO

We show that hexagonal boron nitride membranes synthesized by chemical exfoliation are more resistant to electron beam irradiation at 80 kV than is graphene, consistent with quantum chemical calculations describing the radiation damage processes. Monolayer hexagonal boron nitride does not form vacancy defects or amorphize during extended electron beam irradiation. Zigzag edge structures are predominant in thin membranes for both a freestanding boron nitride monolayer and for a supported multilayer step edge. We have also determined that the elemental termination species in the zigzag edges is predominantly N.


Assuntos
Compostos de Boro/química , Compostos de Boro/efeitos da radiação , Membranas Artificiais , Modelos Químicos , Simulação por Computador , Elétrons , Teste de Materiais , Doses de Radiação
20.
Opt Express ; 17(1): 208-17, 2009 Jan 05.
Artigo em Inglês | MEDLINE | ID: mdl-19129890

RESUMO

We report the first observation of single-shot soft x-ray laser induced desorption occurring below the ablation threshold in a thin layer of poly (methyl methacrylate)--PMMA. Irradiated by the focused beam from the Free-electron LASer in Hamburg (FLASH) at 21.7 nm, the samples have been investigated by atomic-force microscope (AFM) enabling the visualization of mild surface modifications caused by the desorption. A model describing non-thermal desorption and ablation has been developed and used to analyze single-shot imprints in PMMA. An intermediate regime of materials removal has been found, confirming model predictions. We also report below-threshold multiple-shot desorption of PMMA induced by high-order harmonics (HOH) at 32 nm. Short-time exposure imprints provide sufficient information about transverse beam profile in HOH's tight focus whereas long-time exposed PMMA exhibits radiation-initiated surface ardening making the beam profile measurement infeasible.


Assuntos
Lasers , Raios X , Compostos de Boro/efeitos da radiação , Carbono/efeitos da radiação , Elétrons , Terapia a Laser/métodos , Microscopia de Força Atômica , Polimetil Metacrilato , Espectrofotometria , Propriedades de Superfície , Raios Ultravioleta
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