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1.
Small ; 11(2): 215-21, 2015 Jan 14.
Artículo en Inglés | MEDLINE | ID: mdl-25201285

RESUMEN

Lung cancer is the most common and most fatal cancer worldwide. Thus, improving early diagnosis and therapy is necessary. Previously, gadolinium-based ultra-small rigid platforms (USRPs) were developed to serve as multimodal imaging probes and as radiosensitizing agents. In addition, it was demonstrated that USRPs can be detected in the lungs using ultrashort echo-time magnetic resonance imaging (UTE-MRI) and fluorescence imaging after intrapulmonary administration in healthy animals. The goal of the present study is to evaluate their theranostic properties in mice with bioluminescent orthotopic lung cancer, after intrapulmonary nebulization or conventional intravenous administration. It is found that lung tumors can be detected non-invasively using fluorescence tomography or UTE-MRI after nebulization of USRPs, and this is confirmed by histological analysis of the lung sections. The deposition of USRPs around the tumor nodules is sufficient to generate a radiosensitizing effect when the mice are subjected to a single dose of 10 Gy conventional radiation one day after inhalation (mean survival time of 112 days versus 77 days for irradiated mice without USRPs treatment). No apparent systemic toxicity or induction of inflammation is observed. These results demonstrate the theranostic properties of USRPs for the multimodal detection of lung tumors and improved radiotherapy after nebulization.


Asunto(s)
Carcinoma de Pulmón de Células no Pequeñas/terapia , Gadolinio , Neoplasias Pulmonares/terapia , Nanopartículas del Metal , Nebulizadores y Vaporizadores , Animales , Carcinoma de Pulmón de Células no Pequeñas/patología , Humanos , Neoplasias Pulmonares/patología , Ratones
2.
Nanomedicine ; 11(3): 657-70, 2015 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-25645959

RESUMEN

Photodynamic therapy (PDT) for brain tumors appears to be complementary to conventional treatments. A number of studies show the major role of the vascular effect in the tumor eradication by PDT. For interstitial PDT (iPDT) of brain tumors guided by real-time imaging, multifunctional nanoparticles consisting of a surface-localized tumor vasculature targeting neuropilin-1 (NRP-1) peptide and encapsulated photosensitizer and magnetic resonance imaging (MRI) contrast agents, have been designed. Nanoplatforms confer photosensitivity to cells and demonstrate a molecular affinity to NRP-1. Intravenous injection into rats bearing intracranial glioma exhibited a dynamic contrast-enhanced MRI for angiogenic endothelial cells lining the neovessels mainly located in the peripheral tumor. By using MRI completed by NRP-1 protein expression of the tumor and brain adjacent to tumor tissues, we checked the selectivity of the nanoparticles. This study represents the first in vivo proof of concept of closed-head iPDT guided by real-time MRI using targeted ultrasmall nanoplatforms. From the clinical editor: The authors constructed tumor vascular peptide targeting multifunctional silica-based nanoparticles, with encapsulated gadolinium oxide as MRI contrast agent and chlorin as a photosensitizer, as a proof of concept novel treatment for glioblastoma in an animal model.


Asunto(s)
Neoplasias Encefálicas , Glioma , Angiografía por Resonancia Magnética , Fotoquimioterapia/métodos , Fármacos Fotosensibilizantes , Animales , Neoplasias Encefálicas/diagnóstico por imagen , Neoplasias Encefálicas/tratamiento farmacológico , Línea Celular Tumoral , Femenino , Glioma/diagnóstico por imagen , Glioma/tratamiento farmacológico , Humanos , Nanopartículas/química , Nanopartículas/uso terapéutico , Neuropilina-1/química , Neuropilina-1/uso terapéutico , Fármacos Fotosensibilizantes/química , Fármacos Fotosensibilizantes/farmacología , Radiografía , Ratas , Ratas Desnudas
3.
Small ; 2014 Feb 04.
Artículo en Inglés | MEDLINE | ID: mdl-24677791

RESUMEN

Owing to the high atomic number (Z) of gold element, the gold nanoparticles appear as very promising radiosensitizing agents. This character can be exploited for improving the selectivity of radiotherapy. However, such an improvement is possible only if irradiation is performed when the gold content is high in the tumor and low in the surrounding healthy tissue. As a result, the beneficial action of irradiation (the eradication of the tumor) should occur while the deleterious side effects of radiotherapy should be limited by sparing the healthy tissue. The location of the radiosensitizers is therefore required to initiate the radiotherapy. Designing gold nanoparticles for monitoring their distribution by magnetic resonance imaging (MRI) is an asset due to the high resolution of MRI which permits the accurate location of particles and therefore the determination of the optimal time for the irradiation. We recently demonstrated that ultrasmall gold nanoparticles coated by gadolinium chelates (Au@DTDTPA-Gd) can be followed up by MRI after intravenous injection. Herein, Au@DTDTPA and Au@DTDTPA-Gd were prepared in order to evaluate their potential for radiosensitization. Comet assays and in vivo experiments suggest that these particles appear well suited for improving the selectivity of the radiotherapy. The dose which is used for inducing similar levels of DNA alteration is divided by two when cells are incubated with the gold nanoparticles prior to the irradiation. Moreover, the increase in the lifespan of tumor bearing rats is more important when the irradiation is performed after the injection of the gold nanoparticles. In the case of treatment of rats with a brain tumor (9L gliosarcoma, a radio-resistant tumor in a radiosensitive organ), the delay between the intravenous injection and the irradiation was determined by MRI.

4.
Small ; 10(6): 1116-24, 2014 Mar 26.
Artículo en Inglés | MEDLINE | ID: mdl-24659273

RESUMEN

Owing to the high atomic number (Z) of gold element, the gold nanoparticles appear as very promising radiosensitizing agents. This character can be exploited for improving the selectivity of radiotherapy. However, such an improvement is possible only if irradiation is performed when the gold content is high in the tumor and low in the surrounding healthy tissue. As a result, the beneficial action of irradiation (the eradication of the tumor) should occur while the deleterious side effects of radiotherapy should be limited by sparing the healthy tissue. The location of the radiosensitizers is therefore required to initiate the radiotherapy. Designing gold nanoparticles for monitoring their distribution by magnetic resonance imaging (MRI) is an asset due to the high resolution of MRI which permits the accurate location of particles and therefore the determination of the optimal time for the irradiation. We recently demonstrated that ultrasmall gold nanoparticles coated by gadolinium chelates (Au@DTDTPA-Gd) can be followed up by MRI after intravenous injection. Herein, Au@DTDTPA and Au@DTDTPA-Gd were prepared in order to evaluate their potential for radiosensitization. Comet assays and in vivo experiments suggest that these particles appear well suited for improving the selectivity of the radiotherapy. The dose which is used for inducing similar levels of DNA alteration is divided by two when cells are incubated with the gold nanoparticles prior to the irradiation. Moreover, the increase in the lifespan of tumor bearing rats is more important when the irradiation is performed after the injection of the gold nanoparticles. In the case of treatment of rats with a brain tumor (9L gliosarcoma, a radio-resistant tumor in a radiosensitive organ), the delay between the intravenous injection and the irradiation was determined by MRI.


Asunto(s)
Medios de Contraste , Oro , Imagen por Resonancia Magnética , Nanopartículas del Metal , Fármacos Sensibilizantes a Radiaciones , Animales , Encéfalo/patología , Línea Celular Tumoral , Supervivencia Celular , Humanos , Osteosarcoma/diagnóstico , Osteosarcoma/patología , Ratas , Ratas Sprague-Dawley , Bazo/citología , Análisis de Supervivencia
5.
Phys Chem Chem Phys ; 16(28): 14826-33, 2014 Jul 28.
Artículo en Inglés | MEDLINE | ID: mdl-24921680

RESUMEN

The synthesis and photophysical properties of small gold nanoparticles (NPs, AuNP-[Ru-PFF]) surface functionalized by 5-substituted-1,10-phenanthroline-ligand based Ru(II) complexes are described. Luminescence of the grafted and confined Ru(II) complexes is totally quenched on the gold surface. Nonlinear optical properties were determined via Z-scan measurements in the range 600-1300 nm for both the free Ru(II) complex and the related NPs. In the short wavelength range (around 600 nm) the behaviour switches from that of two-photon absorption (2PA) for the complex to saturable absorption for the NPs. 2PA applications such as optical power limiting or two-photon dioxygen sensitization can be anticipated for these nanoplatforms.


Asunto(s)
Oro/química , Nanopartículas del Metal/química , Compuestos Organometálicos/química , Fenantrolinas/química , Rutenio/química , Estructura Molecular , Compuestos Organometálicos/síntesis química , Tamaño de la Partícula , Propiedades de Superficie
6.
Nanomaterials (Basel) ; 14(12)2024 Jun 19.
Artículo en Inglés | MEDLINE | ID: mdl-38921929

RESUMEN

Monodisperse and semi-faceted ultra-small templated mesoporous silica nanoparticles (US-MSNs) of 20-25 nm were synthesized using short-time hydrolysis of tetraethoxysilane (TEOS) at room temperature, followed by a dilution for nucleation quenching. According to dynamic light scattering (DLS), a two-step pH adjustment was necessary for growth termination and colloidal stabilization. The pore size was controlled by cetyltrimethylammonium bromide (CTAB), and a tiny amount of neutral surfactant F127 was added to minimize the coalescence between US-MSNs and to favor the transition towards internal ordering. Flocculation eventually occurred, allowing us to harvest a powder by centrifugation (~60% silica yield after one month). Scanning transmission electron microscopy (STEM) and 3D high-resolution transmission electron microscopy (3D HR-TEM) images revealed that the US-MSNs are partially ordered. The 2D FT transform images provide evidence for the coexistence of four-, five-, and sixfold patterns characterizing an "on-the-edge" crystallization step between amorphous raspberry and hexagonal pore array morphologies, typical of a protocrystalline state. Calcination preserved this state and yielded a powder characterized by packing, developing a hierarchical porosity centered at 3.9 ± 0.2 (internal pores) and 68 ± 7 nm (packing voids) of high potential for support for separation and catalysis.

7.
Bioconjug Chem ; 24(9): 1584-97, 2013 Sep 18.
Artículo en Inglés | MEDLINE | ID: mdl-23978076

RESUMEN

Gadolinium based Small Rigid Plaforms (SRPs) have previously demonstrated their efficiency for multimodal imaging and radiosensitization. Since the RGD sequence is well-known to be highly selective for αvß3 integrins, a cyclic pentapeptide containing the RGD motif (cRGDfK) has been grafted onto the SRP surface. An appropriate protocol led to the grafting of two targeting ligands per nano-object. The resulting nanoparticles have demonstrated a strong association with αvß3 integrins in comparison with cRADfK grafted SRPs as negative control. Flow cytometry and fluorescence microscopy have also been used to highlight the ability of the nanoparticles to target efficiently HEK293(ß3) and U87MG cells. Finally the grafted radiosensitizing nanoparticles were intravenously injected into Nude mice bearing subcutaneous U87MG tumors and the signal observed by optical imaging was twice as high for SRP-cRGDfK compared to their negative analogue.


Asunto(s)
Integrina alfaVbeta3/metabolismo , Nanopartículas , Neoplasias/diagnóstico , Péptidos Cíclicos , Animales , Línea Celular Tumoral , Femenino , Células HEK293 , Humanos , Ratones , Ratones Desnudos , Imagen Molecular/métodos , Nanopartículas/química , Nanopartículas/metabolismo , Imagen Óptica/métodos , Péptidos Cíclicos/química , Péptidos Cíclicos/metabolismo
8.
Chemistry ; 19(19): 6122-36, 2013 May 03.
Artículo en Inglés | MEDLINE | ID: mdl-23512788

RESUMEN

New, ultrasmall nanoparticles with sizes below 5 nm have been obtained. These small rigid platforms (SRP) are composed of a polysiloxane matrix with DOTAGA (1,4,7,10-tetraazacyclododecane-1-glutaric anhydride-4,7,10-triacetic acid)-Gd(3+) chelates on their surface. They have been synthesised by an original top-down process: 1) formation of a gadolinium oxide Gd2O3 core, 2) encapsulation in a polysiloxane shell grafted with DOTAGA ligands, 3) dissolution of the gadolinium oxide core due to chelation of Gd(3+) by DOTAGA ligands and 4) polysiloxane fragmentation. These nanoparticles have been fully characterised using photon correlation spectroscopy (PCS), transmission electron microscopy (TEM), a superconducting quantum interference device (SQUID) and electron paramagnetic resonance (EPR) to demonstrate the dissolution of the oxide core and by inductively coupled plasma mass spectrometry (ICP-MS), mass spectrometry, fluorescence spectroscopy, (29)Si solid-state NMR, (1)H NMR and diffusion ordered spectroscopy (DOSY) to determine the nanoparticle composition. Relaxivity measurements gave a longitudinal relaxivity r1 of 11.9 s(-1) mM(-1) per Gd at 60 MHz. Finally, potentiometric titrations showed that Gd(3+) is strongly chelated to DOTAGA (complexation constant logß110 =24.78) and cellular tests confirmed the that nanoconstructs had a very low toxicity. Moreover, SRPs are excreted from the body by renal clearance. Their efficiency as contrast agents for MRI has been proved and they are promising candidates as sensitising agents for image-guided radiotherapy.


Asunto(s)
Gadolinio/química , Compuestos Heterocíclicos con 1 Anillo/química , Dióxido de Silicio/química , Siloxanos/química , Sustancia P/análogos & derivados , Medios de Contraste/química , Imagen por Resonancia Magnética/métodos , Espectroscopía de Resonancia Magnética , Microscopía Electrónica de Transmisión , Nanopartículas/química , Radioterapia Guiada por Imagen , Espectrometría de Fluorescencia , Sustancia P/química
9.
Nanotechnology ; 24(28): 285502, 2013 Jul 19.
Artículo en Inglés | MEDLINE | ID: mdl-23792456

RESUMEN

Plasmonic refractometric nanosensors based on single nanostructures, i.e. spherical, nanorodand bipyramid-shaped gold nanoparticles, are investigated and compared numerically by employing the finite-difference time-domain method. The results show that the plasmonic sensing ability is distributed anisotropically around the nanorod and bipyramid, even for spherical nanoparticles when the illumination light is linearly polarized. To optimize nanosensor performance, some anisotropy in the shape of nanoparticles is required, this latter serving as an intrinsic light polarization filter to suppress the disturbance from localized surface plasmon resonance in other directions. The plasmonic near-field can be engineered by controlling the shape to achieve a concentrated and localized electromagnetic field, in direct relation with the sensing ability. Taking these factors into account, the gold bipyramid nanoconstruct which is easily available in experiment is proposed as an efficient plasmonic sensing platform. The bipyramid presents both highly localized sensitivity and high scattering cross-section, thus avoiding the trade-off during the selection of the widely used nanorod-shaped sensors. The parameters of the bipyramid structure can be optimized by numerical simulation to improve the plasmonic sensing. Our findings permit a deeper understanding of single-nanoparticle-sensor behavior, and the study provides an opportunity to optimize the plasmonic sensor.


Asunto(s)
Oro/química , Nanopartículas del Metal/química , Nanopartículas del Metal/ultraestructura , Resonancia por Plasmón de Superficie/métodos , Simulación por Computador , Sensibilidad y Especificidad , Dióxido de Silicio/química , Agua/química
10.
Bioconjug Chem ; 22(6): 1145-52, 2011 Jun 15.
Artículo en Inglés | MEDLINE | ID: mdl-21545181

RESUMEN

Nanometric hybrid gadolinium oxide particles (Gado-6Si-NP) for diagnostic and therapeutic applications (mean diameter 3-4 nm) were obtained by encapsulating Gd(2)O(3) cores within a polysiloxane shell, which carries organic fluorophore (Cy 5) and is derivatized by a hydrophilic carboxylic layer. As residency time in the living body and methods of waste elimination are crucial to defining a good nanoparticle candidate and moving forward with steps for validation, this study was aimed at evaluating the biodistribution of these multimodal Gado-6Si-NP in rodents. Gado-6Si-NP were imaged following intravenous injection in control Wistar rats and mice using MRI (7 T), optical fluorescent imaging, and SPECT. A clear correlation was observed among MRI, optical imaging, and SPECT regarding the renal elimination. Quantitative biodistribution using gamma-counting of each sampled organ confirmed that these nanoparticles circulated freely in the blood pool and were rapidly cleared by renal excretion without accumulation in liver and RES uptake. These results demonstrate that Gado-6Si-NP display optimal biodistribution properties, enabling them to be developed as multimodal agents for in vivo imaging and theragnostics, especially in oncological applications.


Asunto(s)
Gadolinio/farmacocinética , Gadolinio/uso terapéutico , Imagen por Resonancia Magnética , Imagen Molecular , Nanopartículas/química , Silicio/química , Animales , Fluorescencia , Radioisótopos de Indio , Riñón/metabolismo , Tamaño de la Partícula , Ratas , Ratas Wistar , Solubilidad , Propiedades de Superficie , Distribución Tisular , Tomografía Computarizada de Emisión de Fotón Único
11.
Langmuir ; 26(16): 13493-501, 2010 Aug 17.
Artículo en Inglés | MEDLINE | ID: mdl-20695596

RESUMEN

The accessibility of metal(II) complexes in 2D hexagonal mesostructured porous silicas obtained by direct synthesis is controlled using an appropriate organosilane ligand. This is exemplified here using copper(II) as a transition metal probe and a neutral or negatively charged ligand: N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, L(A), and, N-salicylaldimine-propylamine-trimethoxysilane, L(B)(-), respectively. L(A) leads to inaccessible complexes located into the pore wall and called "embedded" sites here where silanolate groups from the siliceous network block the access to Cu(II) ions. By contrast, L(B)(-) generates accessible complexes, named "showing-on" sites here. The copper-containing silicas were synthesized with various metal molar ratios (M/SiO(2) = 0.5-3%) in basic media, with cetyltrimethylammonium p-toluenesulfonate (CTATos) as template and with sodium silicate solution as silicon source. A soft template extraction procedure has been developed to preserve the complex integrity of the showing-on copper sites during the treatment. The embedded copper(II) and nickel(II) sites were compared. Materials containing embedded, showing-on, and grafted sites were also compared with regard to pore size, surface polarity, and metal leaching. The material containing showing-on sites was found to be catalytically active for the hydroxylation of phenol into catechol and hydroquinone. Both textural and structural properties of the material and the copper sites were investigated using XRD, TEM, N(2) sorption isotherms, TGA, FT-IR, UV-visible, and EPR spectroscopies.

12.
Small ; 5(22): 2565-75, 2009 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-19768700

RESUMEN

Fluorescent nanoparticles containing a gadolinium oxide core are very attractive because they are able to combine both imaging (fluorescence imaging, magnetic resonance imaging) and therapy (X-ray therapy and neutron-capture therapy) techniques. The exploitation of these multifunctional particles for in vivo applications requires accurate control of their biodistribution. The postfunctionalization of these particles by four different poly(ethylene glycol) derivatives, which differ by chain length and end group, exerts a great influence on the zeta potential of the nanoparticles and on their biodistribution after intravenous injection to HEK-beta3-tumor-bearing mice. This study reveals that the behavior of PEGylated nanoparticles, which was monitored by in vivo fluorescence imaging, depends on both the chain length and the end group of the PEG chain.


Asunto(s)
Gadolinio/farmacocinética , Neoplasias Renales/metabolismo , Nanopartículas/química , Polietilenglicoles/farmacocinética , Animales , Línea Celular Tumoral , Materiales Biocompatibles Revestidos/farmacocinética , Neoplasias Renales/diagnóstico , Espectroscopía de Resonancia Magnética/métodos , Tasa de Depuración Metabólica , Ratones , Ratones Desnudos , Nanopartículas/ultraestructura , Especificidad de Órganos , Distribución Tisular
13.
J Am Chem Soc ; 130(18): 5908-15, 2008 May 07.
Artículo en Inglés | MEDLINE | ID: mdl-18407638

RESUMEN

Functionalized gold nanoparticles were applied as contrast agents for both in vivo X-ray and magnetic resonance imaging. These particles were obtained by encapsulating gold cores within a multilayered organic shell which is composed of gadolinium chelates bound to each other through disulfide bonds. The contrast enhancement in MRI stems from the presence of gadolinium ions which are entrapped in the organic shell, whereas the gold core provides a strong X-ray absorption. This study revealed that these particles suited for dual modality imaging freely circulate in the blood vessels without undesirable accumulation in the lungs, spleen, and liver.


Asunto(s)
Medios de Contraste/química , Gadolinio/química , Oro/química , Imagen por Resonancia Magnética/métodos , Nanopartículas del Metal/química , Ácido Pentético/análogos & derivados , Tomografía Computarizada por Rayos X/métodos , Animales , Gadolinio/farmacocinética , Oro/farmacocinética , Ratones , Ácido Pentético/farmacocinética , Ratas , Distribución Tisular
14.
Photochem Photobiol ; 84(5): 1244-8, 2008.
Artículo en Inglés | MEDLINE | ID: mdl-18422876

RESUMEN

Au and Ag biochips were fabricated to investigate the influence of pH upon the chemiluminescence (CL) of luminol at vicinity of surface-adsorbed peroxidase. A nanoscaled-corrugation of the metal induces an enhancement of the luminol CL which is maximal in the pH range favoring peroxidase catalysis and greater for gold than for silver. This is the proof that, in the CL process, the reactions involving peroxidase are surface-enhanced near corrugated surfaces.


Asunto(s)
Oro/química , Luminol/química , Luminol/metabolismo , Membranas Artificiales , Nanopartículas del Metal/química , Peroxidasa/metabolismo , Plata/química , Adsorción , Biocatálisis , Peróxido de Hidrógeno/química , Concentración de Iones de Hidrógeno , Luminiscencia , Nanotecnología , Tamaño de la Partícula , Propiedades de Superficie
16.
Sci Rep ; 6: 29678, 2016 07 14.
Artículo en Inglés | MEDLINE | ID: mdl-27411781

RESUMEN

We recently developed the synthesis of ultrasmall gadolinium-based nanoparticles (GBN), (hydrodynamic diameter <5 nm) characterized by a safe behavior after intravenous injection (renal clearance, preferential accumulation in tumors). Owing to the presence of gadolinium ions, GBN can be used as contrast agents for magnetic resonance imaging (MRI) and as radiosensitizers. The attempt to determine the most opportune delay between the intravenous injection of GBN and the irradiation showed that a very low content of radiosensitizing nanoparticles in the tumor area is sufficient (0.1 µg/g of particles, i.e. 15 ppb of gadolinium) for an important increase of the therapeutic effect of irradiation. Such a promising and unexpected result is assigned to a suited distribution of GBN within the tumor, as revealed by the X-ray fluorescence (XRF) maps.


Asunto(s)
Gadolinio/administración & dosificación , Gliosarcoma/radioterapia , Nanopartículas/administración & dosificación , Fármacos Sensibilizantes a Radiaciones/administración & dosificación , Animales , Línea Celular , Medios de Contraste/administración & dosificación , Imagen por Resonancia Magnética/métodos , Masculino , Ratas , Ratas Endogámicas F344 , Rayos X
17.
J Colloid Interface Sci ; 467: 271-279, 2016 Apr 01.
Artículo en Inglés | MEDLINE | ID: mdl-26803605

RESUMEN

Since it was demonstrated that nanostructured surfaces are more efficient for the detection based on the specific capture of analytes, there is a real need to develop strategies for grafting nanoparticles onto flat surfaces. Among the different routes for the functionalization of a surface, the reduction of diazonium salts appears very attractive for the covalent immobilization of nanoparticles because this method does not require a pre-treatment of the surface. For achieving this goal, gold nanoparticles coated by precursor of diazonium salts were synthesized by reduction of gold salt in presence of mercaptoaniline. These mercaptoaniline-coated gold nanoparticles (Au@MA) were successfully immobilized onto various conducting substrates (indium tin oxide (ITO), glassy carbon (GC) and gold electrodes with flat terraces) after addition of sodium nitrite at fixed potential. When applied onto the gold electrodes, such a grafting strategy led to an obvious enhancement of the luminescence of luminol used for the biodetection.


Asunto(s)
Compuestos de Diazonio/química , Técnicas Electroquímicas , Oro/química , Mediciones Luminiscentes/métodos , Nanopartículas del Metal/química , Compuestos Orgánicos de Oro/análisis , Compuestos de Diazonio/síntesis química , Electrodos , Concentración de Iones de Hidrógeno , Luminiscencia , Tamaño de la Partícula , Propiedades de Superficie
18.
Chem Commun (Camb) ; (3): 369-71, 2005 Jan 21.
Artículo en Inglés | MEDLINE | ID: mdl-15645040

RESUMEN

Dihydrolipoic acid (DHLA) capped gold nanoparticles (Au@DHLA) are characterized in solid and liquid states by sulfur K-edge XANES spectroscopy; it clearly shows that DHLA is anchored to gold thanks to both sulfur ends.

19.
Phys Med Biol ; 60(11): 4449-64, 2015 Jun 07.
Artículo en Inglés | MEDLINE | ID: mdl-25988839

RESUMEN

The goal of the present study was to evaluate and compare the radiosensitizing properties of gadolinium nanoparticles (NPs) with the gadolinium contrast agent (GdCA) Magnevist(®) in order to better understand the mechanisms by which they act as radiation sensitizers. This was determined following either low energy synchrotron irradiation or high energy gamma irradiation of F98 rat glioma cells exposed to ultrasmall gadolinium NPs (GdNPs, hydrodynamic diameter of 3 nm) or GdCA. Clonogenic assays were used to quantify cell survival after irradiation in the presence of Gd using monochromatic x-rays with energies in the 25 keV-80 keV range from a synchrotron and 1.25 MeV gamma photons from a cobalt-60 source. Radiosensitization was demonstrated with both agents in combination with X-irradiation. At the same concentration (2.1 mg mL(-1)), GdNPS had a greater effect than GdCA. The maximum sensitization-enhancement ratio at 4 Gy (SER4Gy) was observed at an energy of 65 keV for both the nanoparticles and the contrast agent (2.44 ± 0.33 and 1.50 ± 0.20, for GdNPs and GdCA, respectively). At a higher energy (1.25 MeV), radiosensitization only was observed with GdNPs (1.66 ± 0.17 and 1.01 ± 0.11, for GdNPs and GdCA, respectively). The radiation dose enhancements were highly 'energy dependent' for both agents. Secondary-electron-emission generated after photoelectric events appeared to be the primary mechanism by which Gd contrast agents functioned as radiosensitizers. On the other hand, other biological mechanisms, such as alterations in the cell cycle may explain the enhanced radiosensitizing properties of GdNPs.


Asunto(s)
Medios de Contraste/efectos de la radiación , Gadolinio/efectos de la radiación , Nanopartículas del Metal/efectos de la radiación , Fotones , Fármacos Sensibilizantes a Radiaciones/efectos de la radiación , Animales , Línea Celular Tumoral , Supervivencia Celular/efectos de los fármacos , Medios de Contraste/efectos adversos , Nanopartículas del Metal/efectos adversos , Nanopartículas del Metal/química , Fármacos Sensibilizantes a Radiaciones/efectos adversos , Ratas , Rayos X
20.
Contrast Media Mol Imaging ; 10(4): 309-19, 2015.
Artículo en Inglés | MEDLINE | ID: mdl-25483609

RESUMEN

Nanoparticles made of a polysiloxane matrix and surrounded by 1,4,7,10-tetraazacyclododecane-1-glutaric anhydride-4,7,10-triacetic acid (DOTAGA)[Gd(3+) ] and 2,2'-(7-(1-carboxy-4-((2,5-dioxopyrrolidin-1-yl)oxy)-4-oxobutyl)-1,4,7-triazonane-1,4-diyl)diacetic acid) NODAGA[(68) Ga(3+) ] have been synthesized for positron emission tomography/magnetic resonance (PET/MRI) dual imaging. Characterizations were carried out in order to determine the nature of the ligands available for radiolabelling and to quantify them. High radiolabelling purity (>95%) after (68) Ga labelling was obtained. The MR and PET images demonstrate the possibility of using the nanoparticles for a combined PET/MR imaging scanner. The images show fast renal elimination of the nanoparticles after intravenous injection.


Asunto(s)
Medios de Contraste , Gadolinio , Galio , Imagen por Resonancia Magnética/métodos , Nanopartículas/química , Tomografía de Emisión de Positrones/métodos , Acetatos/química , Acetatos/farmacología , Anhídridos/química , Anhídridos/farmacología , Animales , Línea Celular Tumoral , Medios de Contraste/química , Medios de Contraste/farmacología , Gadolinio/química , Gadolinio/farmacología , Galio/química , Galio/farmacología , Compuestos Heterocíclicos con 1 Anillo/química , Compuestos Heterocíclicos con 1 Anillo/farmacología , Humanos , Ratones
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