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2.
ACS Sens ; 3(9): 1683-1689, 2018 09 28.
Artigo em Inglês | MEDLINE | ID: mdl-30095257

RESUMO

Detection of dopamine, an important neurotransmitter, is vital for understanding its roles in mammals and disease diagnosis. However, commonly available methods for dopamine detection typically rely on a single signal readout, which can be susceptible to interference by internal or external factors. Here, we report a dual-signal detection of dopamine based on label-free luminescent NaGdF4:Tb nanoparticles. In the presence of dopamine, the NaGdF4:Tb nanoparticles exhibit luminescence quenching under the excitation of 272 nm, while they give enhanced luminescence under 297 nm excitation, realizing both turn off and turn on detection of dopamine. The nanoparticle-based dual-signal sensors exhibit high sensitivity, with a detection limit of ∼30 nM, and good selectivity, which offers the possibility to identify potential interferents in the samples. We further demonstrate that the dual-signal response results from different energy-transfer processes within the nanoparticles under the excitation of different light. The new strategy demonstrated here should pave the way for the development of multiresponse nanosensors based on lanthanide-doped luminescent nanomaterials.


Assuntos
Dopamina/análise , Substâncias Luminescentes/química , Medições Luminescentes/métodos , Nanopartículas Metálicas/química , Neurotransmissores/análise , Dopamina/sangue , Dopamina/efeitos da radiação , Dopamina/urina , Transferência de Energia , Gadolínio/química , Gadolínio/efeitos da radiação , Humanos , Limite de Detecção , Luminescência , Substâncias Luminescentes/efeitos da radiação , Nanopartículas Metálicas/efeitos da radiação , Neurotransmissores/sangue , Neurotransmissores/efeitos da radiação , Neurotransmissores/urina , Térbio/química , Térbio/efeitos da radiação , Raios Ultravioleta
3.
J Phys Chem A ; 122(32): 6558-6569, 2018 Aug 16.
Artigo em Inglês | MEDLINE | ID: mdl-30024161

RESUMO

The light-switch mechanism of the complex [Ru(bpy)2(Br-dpqp)](PF6)2 (1, bpy = 2,2'-bipyridine, Br-dpqp = 12-bromo-14-ethoxydipyrido[3,2- a:2',3'- c]quinolino[3,2- h]phenazine), i.e., a light-up probe for the selective labeling of G-quadruplexes, is investigated by time-resolved transient absorption and emission spectroscopy. We show that, in contrast to the prototypical light-switch complex [Ru(bpy)2(dppz)](PF6)2 (2, dppz = dipyrido[3,2- a:2',3'- c]phenazine), a 3ππ* state localized on the π-extended ligand is the state determining the excited-state properties in both protic and aprotic environments. In aprotic environments, emission originates from a bright 3MLCTphen state, which is thermally accessible from the 3ππ* state at ambient temperature. In the presence of water, i.e., in environments resembling in cellulo situations, the thermally accessible 3MLCT state is altered and becomes close in energy to the 3ππ* state, which induces a rapid excited-state deactivation of the 3ππ* state and a comparably weak emission.


Assuntos
Complexos de Coordenação/efeitos da radiação , DNA/química , Quadruplex G , Substâncias Luminescentes/efeitos da radiação , Rutênio/química , Complexos de Coordenação/química , Técnicas Eletroquímicas , Ligantes , Luz , Substâncias Luminescentes/química , Modelos Químicos , Oxirredução , Fenazinas/química , Piridinas/química , Teoria Quântica , Espectrofotometria , Análise Espectral Raman , Água/química
6.
Chem Commun (Camb) ; 54(3): 275-278, 2018 Jan 02.
Artigo em Inglês | MEDLINE | ID: mdl-29231935

RESUMO

Two novel bola-amphiphilic oligo-p-(phenyleneethynylene) (OPE) dicarboxylates have been synthesized having non-polar and mixed-polar side chains. This led to gelation in both with vesicular morphology. Upon in situ loading of a suitable dye and redox-active molecule, pure white light emitting and charge transfer (CT)-gels, respectively, were realized.


Assuntos
Alquinos/química , Derivados de Benzeno/química , Substâncias Luminescentes/química , Tensoativos/química , Alquinos/síntese química , Alquinos/efeitos da radiação , Compostos Azo/química , Derivados de Benzeno/síntese química , Derivados de Benzeno/efeitos da radiação , Géis , Luz , Substâncias Luminescentes/síntese química , Substâncias Luminescentes/efeitos da radiação , Nitrilos/química , Tensoativos/síntese química , Tensoativos/efeitos da radiação
7.
Chem Asian J ; 13(4): 373-385, 2018 Feb 16.
Artigo em Inglês | MEDLINE | ID: mdl-29285898

RESUMO

Photon upconversion that is characterized by high-energy photon emission followed by lower-energy excitation has been conventionally studied in bulk materials for several decades. This unique nonlinear luminescence process has become a subject of great attention since 2000 when upconverted emission was demonstrated in nanostructured crystals. In comparison with their bulk counterparts, nanostructured materials provide more room for optical fine-tuning by allowing flexible compositional integration and structural engineering. Moreover, the high colloidal stability of nanoparticles coupled with high amenability to surface functionalization opens up a number of new applications for upconversion, especially in the fields of biology and life science. In this focus review, we discuss recent developments in upconversion materials through nanostructural design and review emerging biomedical applications that involve these nanostructured upconversion materials. We also attempt to highlight challenging problems of these nanomaterials that constrain further progress in utilizing upconversion processes.


Assuntos
Nanopartículas Metálicas/química , Animais , Portadores de Fármacos/química , Portadores de Fármacos/efeitos da radiação , Humanos , Elementos da Série dos Lantanídeos/química , Luz , Luminescência , Substâncias Luminescentes/química , Substâncias Luminescentes/farmacologia , Substâncias Luminescentes/efeitos da radiação , Nanopartículas Metálicas/efeitos da radiação
8.
Chembiochem ; 18(16): 1650-1658, 2017 08 17.
Artigo em Inglês | MEDLINE | ID: mdl-28503897

RESUMO

The use of DNA aggregates could be a promising strategy for the molecular imaging of biological functions. Herein, phosphorescent oligodeoxynucleotides were designed with the aim of visualizing oxygen fluctuation in tumor cells. DNA-ruthenium conjugates (DRCs) that consisted of oligodeoxynucleotides, a phosphorescent ruthenium complex, a pyrene unit for high oxygen responsiveness, and a nitroimidazole unit as a tumor-targeting unit were prepared. In general, oligonucleotides have low cell permeability because of their own negative charges; however, the DRC formed aggregates in aqueous solution due to the hydrophobic pyrene and nitroimidazole groups, and smoothly penetrated the cellular membrane to accumulate in tumor cells in a hypoxia-selective manner. The oxygen-dependent phosphorescence of DRC in cells was also observed. In vivo experiments revealed that aggregates of DRC accumulated in hypoxic tumor tissue that was transplanted into the left leg of mice, and showed that oxygen fluctuations in tumor tissue could be monitored by tracking of the phosphorescence emission of DRC.


Assuntos
Substâncias Luminescentes/química , Oligodesoxirribonucleotídeos/química , Oxigênio/análise , Células A549 , Animais , Complexos de Coordenação/síntese química , Complexos de Coordenação/química , Complexos de Coordenação/efeitos da radiação , Corantes Fluorescentes/química , Humanos , Concentração de Íons de Hidrogênio , Luz , Substâncias Luminescentes/síntese química , Substâncias Luminescentes/efeitos da radiação , Camundongos Endogâmicos BALB C , Imagem Molecular , Nitroimidazóis/síntese química , Nitroimidazóis/química , Oligodesoxirribonucleotídeos/síntese química , Oligodesoxirribonucleotídeos/efeitos da radiação , Oxazinas/química , Oxigênio/química , Pirenos/síntese química , Pirenos/química , Rutênio , Hipóxia Tumoral
10.
Luminescence ; 30(6): 878-82, 2015 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-25620581

RESUMO

Results on optically stimulated luminescence (OSL) in LiCaAlF6:Eu(2+) are reported. Continuous wave OSL signal as recorded using blue (470 nm) stimulation was found to be ~31% that of standard phosphor lithium magnesium phosphate. The rate of OSL depletion for standard phosphor lithium magnesium phosphate is only three times less as compared with that of LiCaAlF6:Eu(2+). Strong photoluminescence (PL) in the near ultraviolet region is observed for LiCaAlF6:Eu(2+) with the characteristic Eu(2+) emission at 369 nm for 254 nm excitation. The thermoluminescence (TL) glow peak for LiCaAlF6:Eu(2+) was observed at around 180°C. The glow peak was about six times more intense compared with the dosimetric peak of the well known thermoluminescence dosimetric (TLD) phosphor LiF-TLD 100. Thus this phosphor deserves much more attention than it has received until now and may be useful as a dosimetric material in radiation dosimetry.


Assuntos
Európio/química , Substâncias Luminescentes/química , Partículas beta , Lítio/química , Luminescência , Substâncias Luminescentes/efeitos da radiação , Estrôncio/química , Dosimetria Termoluminescente/métodos , Difração de Raios X
11.
Water Res ; 62: 281-92, 2014 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-24968075

RESUMO

Wastewater-derived organic matter (WOM) is an important constituent of discharge to urban rivers and is suspected of altering the naturally occurring dissolved organic matter (DOM) in water systems. This study investigated sunlight-induced changes in chromophores and fluorophores of WOM with different salinities (S = 0, 10, 20 and 30) that were collected from two wastewater treatment plants (WWTP-A and WWTP-B). The results showed that exposure to sunlight for 5.3 × 10(5) J/m(2) caused significant decreases in UV254-absorbing WOM (45-59% loss) compared to gross dissolved organic carbon (<15% loss). An increase in salinity accelerated the overall photo-degradation rates of the UV254-absorbing chromophores from both WOM and natural DOM. In addition, irradiated WOM at a higher salinity had a larger molecular size than that at a lower salinity. However, natural DOM did not display such behavior. Parallel factor analysis of the excitation-emission matrix determined the presence of two humic-like components (C1 and C2) and two protein-like components (C3 and C4). All the components in WOM followed second-order kinetics, except for the C4 component in WWTP-A, which fit zero-order photoreaction kinetics. The photo-degradation of the C1 component in both WWTPs appeared to be independent of salinity; however, the photo-degradation rates of the C2 and C3 components in both WWTPs and C4 in WWTP-B increased significantly with increasing salinity. In comparison, the photo-degradation of the C1 component was significantly facilitated by increased salinity in natural DOM, fitting first-order photoreaction kinetics. As such, the current knowledge concerning the photo-degradation of naturally occurring DOM cannot be extrapolated for the understanding of WOM photo-degradation.


Assuntos
Substâncias Luminescentes/efeitos da radiação , Compostos Orgânicos/química , Salinidade , Luz Solar , Águas Residuárias/química , Poluentes Químicos da Água/efeitos da radiação , Carbono/análise , Meio Ambiente , Cinética , Fotólise/efeitos da radiação , Espectrometria de Fluorescência , Raios Ultravioleta , Purificação da Água
12.
Ultrason Sonochem ; 17(1): 116-22, 2010 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-19481969

RESUMO

Using amino-acid histidine as chelating agent, CdS nanoparticles have been synthesized by sonochemical method. It is found that by varying the ultrasonic irradiation time, we can tune the band gap and particle size of CdS nanoparticles. The imidazole ring of histidine captures the Cd ions from the solution, and prevents the growth of the CdS nanoparticles. The deviation in the linear relation in between cube of radius of nanoparticles and ultrasonic irradiation time confirms the growth of CdS nanoparticles occur via two process; one is the diffusion process of the reactants as well as reaction at the surface of the crystallite. CdS nanoparticles synthesized using histidine as organic chelating agent have band edge emission at approximately 481 nm and have greater photoluminescence intensity with blue-shift to higher energy due to typical quantum confinement effect.


Assuntos
Compostos de Cádmio/síntese química , Compostos de Cádmio/efeitos da radiação , Histidina/química , Substâncias Luminescentes/síntese química , Substâncias Luminescentes/efeitos da radiação , Nanopartículas/química , Compostos de Selênio/síntese química , Compostos de Selênio/efeitos da radiação , Sonicação/métodos , Quelantes/química , Quelantes/efeitos da radiação , Cristalização/métodos , Histidina/efeitos da radiação , Teste de Materiais , Nanopartículas/efeitos da radiação , Nanopartículas/ultraestrutura , Nanotecnologia/métodos , Tamanho da Partícula , Doses de Radiação
14.
Nat Nanotechnol ; 4(2): 114-20, 2009 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-19197314

RESUMO

Nanoscale sensing elements offer promise for single-molecule analyte detection in physically or biologically constrained environments. Single-walled carbon nanotubes have several advantages when used as optical sensors, such as photostable near-infrared emission for prolonged detection through biological media and single-molecule sensitivity. Molecular adsorption can be transduced into an optical signal by perturbing the electronic structure of the nanotubes. Here, we show that a pair of single-walled nanotubes provides at least four modes that can be modulated to uniquely fingerprint agents by the degree to which they alter either the emission band intensity or wavelength. We validate this identification method in vitro by demonstrating the detection of six genotoxic analytes, including chemotherapeutic drugs and reactive oxygen species, which are spectroscopically differentiated into four distinct classes, and also demonstrate single-molecule sensitivity in detecting hydrogen peroxide. Finally, we detect and identify these analytes in real time within live 3T3 cells, demonstrating multiplexed optical detection from a nanoscale biosensor and the first label-free tool to optically discriminate between genotoxins.


Assuntos
Técnicas Biossensoriais/métodos , Células/efeitos dos fármacos , Medições Luminescentes/métodos , Nanotubos de Carbono/química , Células 3T3 , Alquilantes/farmacologia , Animais , Técnicas Biossensoriais/instrumentação , Citotoxinas/farmacologia , Dano ao DNA/efeitos dos fármacos , DNA de Cadeia Simples/efeitos dos fármacos , Raios Infravermelhos , Luminescência , Substâncias Luminescentes/análise , Substâncias Luminescentes/efeitos da radiação , Medições Luminescentes/instrumentação , Camundongos , Nanotecnologia/métodos , Espécies Reativas de Oxigênio/farmacologia , Sensibilidade e Especificidade , Espectrofotometria Infravermelho/instrumentação , Espectrofotometria Infravermelho/métodos , Eletricidade Estática
15.
Chemistry ; 15(14): 3355-8, 2009.
Artigo em Inglês | MEDLINE | ID: mdl-19235190

RESUMO

Triangular luminescent box: Self-assembly of a new multidentate receptor with europium cations results in the formation of trinuclear discrete complexes. X-ray crystallography shows that nine-coordinate cations are linked by ligands to provide a triangular complex in the solid state and in solution. Despite the coordinated solvent molecules, this topologically unusual complex exhibits remarkable luminescent properties.


Assuntos
Európio/química , Substâncias Luminescentes/química , Compostos Organometálicos/química , Cátions/química , Cristalografia por Raios X , Substâncias Luminescentes/efeitos da radiação
18.
Org Biomol Chem ; 6(6): 1020-33, 2008 Mar 21.
Artigo em Inglês | MEDLINE | ID: mdl-18327327

RESUMO

A set of three pH-responsive ratiometric Eu(III)complexes has been synthesised incorporating a coordinated azathioxanthone sensitiser and a pH dependent alkylsulfonamide moiety. Emission properties, anion binding affinities, pH response curves and protein binding constants were studied in detail in aqueous media, and solutions containing various concentrations of interfering anions and protein were also examined. The complex, [EuL3] exhibited some interference from protein and endogenous anions, e.g. lactate and hydrogen carbonate, but possessed a protonation constant of 7.2 in human serum solution. A suitable calibration curve was obtained and was used to determine the local pH using a 680/589 nm intensity ratio vs. pH plot. Confocal fluorescence microscopy images revealed fast uptake of the complex and a well distributed localisation within the cell; fast egress also occurred. Ribosomal localisation, with a high concentration within the protein-dense nucleoli was observed, in a similar manner to structurally related complexes bearing the same coordinated sensitising moiety. An IC(50) value of 67 (+/-20) microM was estimated using an MTT assay. Selected emission band ratio versus pH plots allow pH measurement in the range 6 to 8, enabling intracellular pH to be measured by microscopy. A value of 7.4 was estimated for NIH 3T3 cells in the protein rich regions of the nucleolus and ribosomes.


Assuntos
Európio/química , Corantes Fluorescentes/química , Líquido Intracelular/química , Substâncias Luminescentes/química , Compostos Organometálicos/química , Ligação Competitiva , Calibragem , Corantes Fluorescentes/síntese química , Corantes Fluorescentes/efeitos da radiação , Concentração de Íons de Hidrogênio , Líquido Intracelular/metabolismo , Substâncias Luminescentes/síntese química , Substâncias Luminescentes/efeitos da radiação , Microscopia de Fluorescência , Estrutura Molecular , Compostos Organometálicos/síntese química , Compostos Organometálicos/efeitos da radiação , Raios Ultravioleta
20.
J Nanosci Nanotechnol ; 7(2): 463-73, 2007 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-17450780

RESUMO

A novel synthesis method is presented for the preparation of eco-friendly, doped semiconductor nanocrystals encapsulated within oxide-shells, both formed sequentially from a single-source solid-precursor. Highly luminescent ZnS nanoparticles, in situ doped with Cu(+)-Al3+ pairs and encapsulated with ZnO shells are prepared by the thermal decomposition of a solid-precursor compound, zinc sulfato-thiourea-oxyhydroxide, showing layered crystal structure. The precursor compound is prepared by an aqueous wet-chemical reaction involving necessary chemical reagents required for the precipitation, doping and inorganic surface capping of the nanoparticles. The elemental analysis (C, H, N, S, O, Zn), quantitative estimation of different chemical groups (SO4(2-) and NH4(-)) and infrared studies suggested that the precursor compound is formed by the intercalation of thiourea, and/or its derivatives thiocarbamate (CSNH2(-)), dithiocarbamate (CS2NH2(-)), etc., and ammonia into the gallery space of zinc-sulfato-oxyhydroxide corbel where the Zn(II) ions are both in the octahedral as well as tetrahedral coordination in the ratio 3 : 2 and the dopant ions are incorporated within octahedral voids. The powder X-ray diffraction of precursor compound shows high intensity basal reflection corresponding to the large lattice-plane spacing of d = 11.23 angstroms and the Rietveld analysis suggested orthorhombic structure with a = 9.71 angstroms, b = 12.48 angstroms, c = 26.43 angstroms, and beta = 90 degrees. Transmission electron microscopy studies show the presence of micrometer sized acicular monocrystallites with prismatic platy morphology. Controlled thermolysis of the solid-precursor at 70-110 degrees C leads to the collapse of layered structure due to the hydrolysis of interlayer thiourea molecules or its derivatives and the S2- ions liberated thereby reacts with the tetrahedral Zn(II) atoms leading to the precipitation of ZnS nanoparticles at the gallery space. During this process, the dopant ions situated at octahedral voids gets incorporated into the nano-ZnS lattice and results in bright photoluminescence. On further heat treatment above 1100 degrees C, the corbel zinc-oxyhydroxide sheets undergo dehydroxylation to form ZnO which eventually encapsulates the ZnS nanoparticles at the gallery leading to significant enhancement in the luminescence quantum efficiency, up to approximately 22%. The emission color of thus formed nano-ZnS/micro-ZnO composites could be tuned over wide spectral ranges from 480 to 618 nm and the spectral changes are attributed to a number of factors including lattice defects, Cu(+)-Al3+ dopant-pairs and iso-electronic oxygen in nano-ZnS and oxygen-vacancy or -interstitial centers in non-stoichiometric ZnO.


Assuntos
Luminescência , Substâncias Luminescentes/química , Nanopartículas/química , Nanotecnologia/métodos , Alumínio/química , Amônia/química , Cor , Cobre/química , Cristalização , Temperatura Alta , Luz , Substâncias Luminescentes/análise , Substâncias Luminescentes/efeitos da radiação , Teste de Materiais , Microscopia Eletrônica de Transmissão , Modelos Químicos , Nanopartículas/análise , Nanopartículas/efeitos da radiação , Nanopartículas/ultraestrutura , Tamanho da Partícula , Semicondutores , Espectroscopia de Infravermelho com Transformada de Fourier , Sulfetos/análise , Sulfetos/química , Sulfetos/efeitos da radiação , Tiocarbamatos/química , Tioureia/química , Água/química , Difração de Raios X , Compostos de Zinco/análise , Compostos de Zinco/química , Compostos de Zinco/efeitos da radiação , Óxido de Zinco/química
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