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1.
Chemphyschem ; 17(1): 128-35, 2016 Jan 04.
Artigo em Inglês | MEDLINE | ID: mdl-26538240

RESUMO

The photophysical and nonlinear optical properties of water-soluble chromophore-functionalised tris-dipicolinate complexes [LnL3](3-) (Ln=Yb and Nd) are thoroughly studied, revealing that only the Yb(III) luminescence can be sensitized by a two-photon excitation process. The stability of the complex in water is strongly enhanced by embedding in dispersible organosilicate nanoparticles (NPs). Finally, the spectroscopic properties of [NBu4]3 [YbL3] are studied in solution and in the solid state. The high brightness of the NPs allows imaging them as single objects using a modified two-photon microscopy setup in a NIR-to-NIR configuration.


Assuntos
Complexos de Coordenação/efeitos da radiação , Microscopia Confocal/métodos , Nanopartículas/efeitos da radiação , Ácidos Picolínicos/efeitos da radiação , Itérbio/química , Complexos de Coordenação/síntese química , Complexos de Coordenação/química , Luz , Nanopartículas/química , Ácidos Picolínicos/síntese química , Ácidos Picolínicos/química , Espectroscopia de Luz Próxima ao Infravermelho
2.
Chemistry ; 20(28): 8636-46, 2014 Jul 07.
Artigo em Inglês | MEDLINE | ID: mdl-24938657

RESUMO

A series of europium and terbium complexes based on a functionalized triazacyclononane carboxylate or phosphinate macrocyclic ligand is described. The influence of the anionic group, that is, carboxylate, methylphosphinate, or phenylphosphinate, on the photophysical properties was studied and rationalized on the basis of DFT calculated structures. The nature, number, and position of electron-donating or electron-withdrawing aryl substituents were varied systematically within the same phenylethynyl scaffold in order to optimize the brightness of the corresponding europium complexes and investigate their two-photon absorption properties. Finally, the europium complexes were examined in cell-imaging applications, and selected terbium complexes were studied as potential oxygen sensors.


Assuntos
Alquinos/química , Compostos Aza/química , Európio/química , Compostos Organometálicos/química , Piperidinas/química , Térbio/química , Ligantes , Estrutura Molecular
3.
Biomaterials ; 34(33): 8344-51, 2013 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-23915950

RESUMO

We describe the design of original nanocarriers that allows for ultrahigh chromophore loading while maintaining the photo-activity of each individual molecule. They consist in shells of charged biocompatible polymers grafted on gold nanospheres. The self-organization of extended polymer chains results from repulsive charges and steric interactions that are optimized by tuning the surface curvature of nanoparticles. This type of nano-scaffolds can be used as light-activated theranostic agents for fluorescence imaging and photodynamic therapy. We demonstrate that, labeled with a fluorescent photosensitizer, it can localize therapeutic molecules before triggering the cell death of B16-F10 melanoma with an efficiency that is similar to the efficiency of the polymer conjugate alone, and with the advantage of extremely high local loading of photosensitizers (object concentration in the picomolar range).


Assuntos
Fluorescência , Ouro/química , Nanopartículas/química , Imagem Óptica/métodos , Fotoquimioterapia/métodos , Linhagem Celular Tumoral , Humanos , Estrutura Molecular
4.
Langmuir ; 29(34): 10915-21, 2013 Aug 27.
Artigo em Inglês | MEDLINE | ID: mdl-23886357

RESUMO

Light-matter interactions are of great interest for potential biological applications (bioimaging, biosensing, phototherapy). For such applications, sharp nanostructures exhibit interesting features since their extinction bands (surface plasmon resonance) cover a large bandwidth in the whole visible wavelength region due to the existence of "hot spots" located at the end of the tips. In this context, gold nanostars appear to be interesting objects. However, their study remains difficult, mainly due to complicated synthetic methods and further functionalization. This paper reports the synthesis, functionalization, and photophysics of luminescent hybrid gold nanostars prepared using a layer-by-layer (LbL) deposition method for the tuning of chromophore-to-particle distances together with the impact of the spectral overlap between the plasmon and the emission/absorption of the dyes. Several luminescent dyes with different optical signatures were selectively adsorbed at the nanoparticle surface. The optimized systems, exhibiting the highest luminescence recovery, clearly showed that overlap must be as low as possible. Also, the fluorescence intensities were quenched in close vicinity of the metal surface and revealed a distance-dependence with almost full recovery of the dyes emission for 11 LbL layers, which corresponded to 15 nm distances evaluated on dried samples. The photophysics of the luminescent core-shell particles were carried out in suspension and correlated with the response of isolated single objects.


Assuntos
Corantes/química , Ouro/química , Nanopartículas Metálicas/química
5.
Chemphyschem ; 14(14): 3361-7, 2013 Oct 07.
Artigo em Inglês | MEDLINE | ID: mdl-23873827

RESUMO

The synthesis of tris(2-thenoyltrifluoroacetonate)lanthanide(III) complexes featuring a diethylaminostyryl-2,2'-bipyridine coligand was achieved for lanthanum; the near-infrared (NIR) emitters neodymium, erbium, and ytterbium; and the transition-metal yttrium. The photophysical properties were thoroughly studied, and it was demonstrated that the conjugated bipyridine ligand acts as a good antenna for the sensitization of the NIR emitters. The two-photon absorption (TPA) properties of all five complexes were investigated by using both two-photon excited fluorescence and the Z-scan method. We demonstrate that the nature of the rare earth ion has almost no influence on the TPA properties centered on the conjugated bipyridyl ligand. Finally, we show that Yb(III) is sensitized by a two-photon antenna effect, and that Nd(III) is mostly sensitized by a one-photon process involving direct excitation of forbidden f-f transitions.

6.
Opt Express ; 20(24): 26542-7, 2012 Nov 19.
Artigo em Inglês | MEDLINE | ID: mdl-23187509

RESUMO

Miniature optical components at the wavelength scale remain today a theoretically opened challenging problem of great technological interest. Appart from refractive micro-optics, plasmonics have been proposed to realize micro lenses with properly designed planar metallic nano-patterns. We show in this paper that efficient light focusing at the diffraction limit with higher transmission can be obtained with micro-structures much easier to fabricate than nano ones, such as a simple micro-slit studied here as an example. Optical properties are attributed to diffraction and a quantitative excellent agreement between experiment and theory is obtained.


Assuntos
Lentes , Luz , Nanoestruturas/química , Dispositivos Ópticos , Espalhamento de Radiação , Ressonância de Plasmônio de Superfície/instrumentação , Desenho Assistido por Computador , Desenho de Equipamento , Humanos
7.
Nanotechnology ; 23(46): 465602, 2012 Nov 23.
Artigo em Inglês | MEDLINE | ID: mdl-23095344

RESUMO

A great number of works have focused their research on the synthesis, design and optical properties of gold nanoparticles for potential biological applications (bioimaging, biosensing). For this kind of application, sharp gold nanostructures appear to exhibit the more interesting features since their surface plasmon bands are very sensitive to the surrounding medium. In this paper, a complete study of PEGylated gold nanostars and PEGylated bipyramidal-like nanostructures is presented. The nanoparticles are prepared in high yield and their surfaces are covered with a biocompatible polymer. The photophysical properties of gold bipyramids and nanostars, in suspension, are correlated with the optical response of single and isolated objects. The resulting spectra of isolated gold nanoparticles are subsequently correlated to their geometrical structure by transmission electron microscopy. Finally, the PEGylated gold nanoparticles were incubated with melanoma B16-F10 cells. Dark-field microscopy showed that the biocompatible gold nanoparticles were easily internalized and most of them localized within the cells.


Assuntos
Ouro/química , Nanopartículas Metálicas/química , Nanoestruturas/química , Animais , Linhagem Celular Tumoral , Cetrimônio , Compostos de Cetrimônio/química , Endocitose , Ouro/farmacocinética , Histocitoquímica , Teste de Materiais , Camundongos , Nanoestruturas/ultraestrutura , Tamanho da Partícula , Polietilenoglicóis/química , Compostos de Amônio Quaternário/química , Espectrofotometria Ultravioleta , Tensoativos/química
8.
Opt Express ; 20(14): 15516-21, 2012 Jul 02.
Artigo em Inglês | MEDLINE | ID: mdl-22772246

RESUMO

We theoretically and experimentally demonstrate that the diffraction of microstructures based on silver nanowires leads to very efficient microfocusing effects. Pairs of parallel nanowires act as ultrasmall cylindrical microlenses with diffraction-limited resolution in the Fresnel region. This is a new diffraction scheme to make micron-sized optical lenses with higher transmittance than plasmonic microlens based on nano-aperture arrays. Calculations based on the scalar Rayleigh-Sommerfeld integral highlights the pure scalar diffractive contribution. Thus, the plasmon contribution is negligible in such micron-sized metallic geometry. We demonstrate that two-dimensional grids of nanowires can be used to fabricate dense arrays of microlenses, i.e. 10000x10000 DPI (dots per inch).

9.
Org Biomol Chem ; 10(31): 6275-8, 2012 Aug 21.
Artigo em Inglês | MEDLINE | ID: mdl-22744649

RESUMO

A molecular engineering strategy based on rational variations of the bromine substitution pattern in two-photon absorbing singlet oxygen sensitizers allows studying the relations that exist between the positioning of an inter-system crossing promoter on the charge-transfer chromophore and its ability to generate singlet oxygen.


Assuntos
Bromo/química , Fármacos Fotossensibilizantes/química , Oxigênio Singlete/química , Fótons
11.
Chem Commun (Camb) ; 48(11): 1689-91, 2012 Feb 04.
Artigo em Inglês | MEDLINE | ID: mdl-22182988

RESUMO

A chromophore featuring a diyne bridge that connects two dibromobenzene moieties shows a much improved two-photon singlet oxygen generation ability in the biological transparency window compared to a related and relevant literature benchmark, as a result of a distorted ground state.


Assuntos
Bromobenzenos/química , Fótons , Fármacos Fotossensibilizantes/química , Oxigênio Singlete/química , Absorção
12.
Opt Express ; 19(21): 20604-9, 2011 Oct 10.
Artigo em Inglês | MEDLINE | ID: mdl-21997068

RESUMO

This study presents a photo-driven micro-lever fabricated to multiply optical forces using the two-photon polymerization 3D-microfabrication technique. The micro-lever is a second class lever comprising an optical trapping sphere, a beam, and a pivot. A micro-spring is placed between the short and long arms to characterize the induced force. This design enables precise manipulation of the micro-lever by optical tweezers at the micron scale. Under optical dragging, the sphere placed on the lever beam moves, resulting in torque that induces related force on the spring. The optical force applied at the sphere is approximately 100 to 300 pN, with a laser power of 100 to 300 mW. In this study, the optical tweezers drives the micro-lever successfully. The relationship between the optical force and the spring constant can be determined by using the principle of leverage. The arm ratio design developed in this study multiplies the applied optical force by 9. The experimental results are in good agreement with the simulation of spring property.


Assuntos
Micromanipulação/instrumentação , Pinças Ópticas , Algoritmos , Elasticidade , Desenho de Equipamento , Teste de Materiais , Micromanipulação/métodos , Modelos Estatísticos , Óptica e Fotônica , Fótons , Estresse Mecânico
13.
Cancer Lett ; 311(2): 131-40, 2011 Dec 08.
Artigo em Inglês | MEDLINE | ID: mdl-21840122

RESUMO

One of the relevant directions that nanotechnology is taking nowadays is connected with nanomedicine and specifically related to the use of light and nanoparticles in early diagnosis and effective therapeutics of cancer. Noble-metal nanoparticles can act under laser irradiation as effective photothermal transducers for triggering localized hyperthermia of tumors. In this work we report the performance of newly synthesized chitosan-coated silver nanotriangles (Chit-AgNTs) with strong resonances in near-infrared (NIR) to operate as photothermal agents against a line of human non-small lung cancer cells (NCI-H460). The hyperthermia experiments were conducted by excitation of nanoparticles-loaded cells at 800 nm wavelength from a Ti:Sapphire laser. We found that the rate of cell mortality in the presence of Chit-AgNTs is higher than in the presence of thiolated poly(ethylene) glycol capped gold nanorods (PEG-AuNRs) - a common hyperthermia agent used as reference-, while no destructive effects were noticed on the control sample (cells without nanoparticles) under identical irradiation conditions. Additionally, we conducted cytotoxicity assays and found Chit-AgNTs to be efficiently uptaken by the cells while exhibiting good biocompatibility for healthy human embryonic cells (HEK), which is essential for any in vivo applications. Our results reveal a novel class of biocompatible plasmonic nanoparticles with high potential to be implemented as effective phototherapeutic agents in the battle against cancer.


Assuntos
Quitosana/farmacologia , Hipertermia Induzida/métodos , Nanopartículas Metálicas/administração & dosagem , Neoplasias/tratamento farmacológico , Fototerapia/métodos , Prata/química , Linhagem Celular Tumoral , Sobrevivência Celular/efeitos dos fármacos , Sobrevivência Celular/efeitos da radiação , Materiais Revestidos Biocompatíveis/química , Materiais Revestidos Biocompatíveis/uso terapêutico , Humanos , Nanopartículas Metálicas/química , Neoplasias/patologia , Espectroscopia de Luz Próxima ao Infravermelho
14.
Opt Express ; 19(9): 8267-76, 2011 Apr 25.
Artigo em Inglês | MEDLINE | ID: mdl-21643076

RESUMO

Archimedes micro-screws have been fabricated by three-dimensional two-photon polymerization using a Nd:YAG Q-switched microchip laser at 532nm. Due to their small sizes they can be easily manipulated, and made to rotate using low power optical tweezers. Rotation rates up to 40 Hz are obtained with a laser power of 200 mW, i.e. 0.2 Hz/mW. A photo-driven micropump action in a microfluidic channel is demonstrated with a non-optimized flow rate of 6 pL/min. The optofluidic properties of such type of Archimedes micro-screws are quantitatively described by the conservation of momentum that occurs when the laser photons are reflected on the helical micro-screw surface.


Assuntos
Técnicas Analíticas Microfluídicas/instrumentação , Pinças Ópticas , Desenho de Equipamento , Análise de Falha de Equipamento , Integração de Sistemas
15.
Inorg Chem ; 50(11): 4987-99, 2011 Jun 06.
Artigo em Inglês | MEDLINE | ID: mdl-21553848

RESUMO

Two europium complexes with bis(bipyridine) azamacrocyclic ligands featuring pendant arms with or without π-conjugated donor groups are synthesized and fully characterized by theoretical calculations and NMR spectroscopy. Their photophysical properties, including two-photon absorption, are investigated in water and in various organic solvents. The nonfunctionalized ligand gives highly water-stable europium complexes featuring bright luminescence properties but poor two-photon absorption cross sections. On the other hand, the europium complex with an extended conjugated antenna ligand presents a two-photon absorption cross section of 45 GM at 720 nm but is poorly luminescent in water. A detailed solvent-dependent photophysical study indicates that this luminescence quenching is not due to the direct coordination of O-H vibrators to the metal center but to the increase of nonradiative processes in a protic solvent induced by an internal isomerization equilibrium.


Assuntos
Compostos Aza/química , Európio/química , Compostos Macrocíclicos/química , Compostos Organometálicos/química , Cristalografia por Raios X , Espectroscopia de Ressonância Magnética , Modelos Moleculares , Estrutura Molecular , Compostos Organometálicos/síntese química , Processos Fotoquímicos , Estereoisomerismo
16.
Nano Lett ; 11(5): 2043-7, 2011 May 11.
Artigo em Inglês | MEDLINE | ID: mdl-21488657

RESUMO

Numerous research efforts are investigating the possibility of using light interactions with metallic nanoparticles to improve the fluorescence properties of nearby molecules. Few investigations have considered the encapsulation of molecules in metallic nanocavities. In this paper, we present the optical properties of new hybrid nanoparticles consisting of gold nanoshells and fluorescent organic dyes in their liquid cores. Microspectroscopy on single nanoparticle demonstrates that the extinction spectra are in good agreement with Mie's theory. Finite difference time domain (FDTD) calculations reveal that excitation and emission radiations are efficiently transmitted through the thin gold nanoshells. Thus, they can be considered as transparent plasmonic nanocontainers for photoactive cores. In agreement with FDTD calculations, measurements show that fluorophores encapsulated in gold nanoshells keep their brightness, but they show fluorescence lifetimes 1 order of magnitude shorter. As a salient consequence, the photoresistance of encapsulated organic dyes is also improved by an order of magnitude. This unusual ultraviolet photoresistance results from the reduced probability of triplet-singlet conversion that eventually exposes dyes to singlet oxygen photodegradation.


Assuntos
Nanotecnologia/métodos , Compostos Orgânicos/química , Animais , Bovinos , Fluorescência , Corantes Fluorescentes/química , Ouro/química , Luz , Nanopartículas Metálicas/química , Nanoestruturas/química , Fotodegradação , Rodaminas/química , Soroalbumina Bovina/química , Ressonância de Plasmônio de Superfície , Fatores de Tempo , Raios Ultravioleta
17.
J Nanosci Nanotechnol ; 10(10): 6958-61, 2010 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-21137833

RESUMO

Two- and three-photon absorption properties of the fluorene-based chromophores have been investigated. The two- and three-photon absorption cross-section are found to be increased with the strength of the electron donor groups in the order of N-ethylcarbazoyl (1), triphenylamino (2), and N,N-dibutylanilino (3) groups. This nonlinear absorption enhancement can be interpreted by the increase of intramolecular charge transfer facilitated by strong electron donors and the decreased detuning energy (deltaE). Furthermore, direct laser microfabrication by two-photon photopolymerization with compound 2 as a two-photon sensitizer was carried out. Laser exposure time-dependent lateral voxel size has also been studied.

18.
Inorg Chem ; 48(19): 9112-9, 2009 Oct 05.
Artigo em Inglês | MEDLINE | ID: mdl-19728694

RESUMO

New boron containing two-photon absorbing fluorophores have been prepared. Centered on a pyrazabole central core, various conjugated systems and end groups were investigated to modulate their physicochemical properties (alkoxy, diphenylamino, and boron dipyromethene groups). One and two-photon photophysical characterizations were performed, showing efficient fluorescence in organic solvents. High two-photon absorption cross sections were determined in the 500-800 nm range. Two-photon excited microscopy images were also obtained with these new boron containing fluorescent bioprobes with laser intensities in the milliwatt range.


Assuntos
Técnicas Biossensoriais/métodos , Boro/química , Corantes Fluorescentes/química , Fótons , Espectrometria de Fluorescência/métodos , Absorção , Cor , Fluorescência , Fotoquímica/métodos
19.
Nanotechnology ; 20(35): 355603, 2009 Sep 02.
Artigo em Inglês | MEDLINE | ID: mdl-19671982

RESUMO

The tremendous development of materials with fine tuning of their composition, shape, size and chemical functionalities at the nanometer scale has opened a wide range of applications, particularly in medicine. Metallic nanoparticles are extremely interesting for such developments. The fundamental study of surface plasmon resonance (SPR) versus the shape/size of a particle is an important challenge. In this field, we propose a synthetic strategy using an original biphasic emulsion process linked to chemo-reduction of gold salt HAuCl(4). This method allows the preparation of new functional nanocapsules. These nanomaterials are fully characterized.

20.
Chem Commun (Camb) ; (30): 4590-2, 2009 Aug 14.
Artigo em Inglês | MEDLINE | ID: mdl-19617993

RESUMO

A novel water-soluble Ru(ii) complex has been prepared, which represents a promising new class of selective two-photon sensitizers for use in photodynamic therapy within a confined space.


Assuntos
Etilenoglicol/química , Compostos Organometálicos/química , Fármacos Fotossensibilizantes/química , Rutênio/química , Humanos , Estrutura Molecular , Fotoquimioterapia , Fótons , Solubilidade , Água
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