Your browser doesn't support javascript.
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 21
Filtrar
Mais filtros










Tipo de estudo
Intervalo de ano de publicação
1.
Nanoscale ; 2020 Jun 25.
Artigo em Inglês | MEDLINE | ID: mdl-32583829

RESUMO

The development of reproducible protocols to synthesize hard/soft nano-heterostructures (NHSs) with tailored magnetic properties is a crucial step to define their potential application in a variety of technological areas. Thermal decomposition has proved to be an effective tool to prepare such systems, but it has been scarcely used so far for the synthesis of Co-based metal/ferrite NHSs, despite their intriguing physical properties. We found a new approach to prepare this kind of nanomaterial based on a simple one-pot thermal decomposition reaction of metal-oleate precursors in the high boiling solvent docosane. The obtained NHSs are characterized by the coexistence of Co metal and Co doped magnetite and are highly stable in an air atmosphere, thanks to the passivation of the metal with a very thin oxide layer. The investigation of the influence of the metal precursor composition (a mixed iron-cobalt oleate), of the ligands (oleic acid and sodium oleate) and of the reaction time on the chemical and structural characteristics of the final product, allowed us to rationalize the reaction pathway and to determine the role of each parameter. In particular, the use of sodium oleate is crucial to obtain a metal phase in the NHSs. In such a way, the one-pot approach proposed here allows the fine control of the synthesis, leading to the formation of stable, high performant, metal/ferrite NHSs with tailored magnetic properties. For instance, the room temperature maximum energy product was increased up to 19 kJ m-3 by tuning the Co content in the metal precursor.

2.
Sci Rep ; 9(1): 3992, 2019 03 08.
Artigo em Inglês | MEDLINE | ID: mdl-30850704

RESUMO

The Linear Response Theory (LRT) is a widely accepted framework to analyze the power absorption of magnetic nanoparticles for magnetic fluid hyperthermia. Its validity is restricted to low applied fields and/or to highly anisotropic magnetic nanoparticles. Here, we present a systematic experimental analysis and numerical calculations of the specific power absorption for highly anisotropic cobalt ferrite (CoFe2O4) magnetic nanoparticles with different average sizes and in different viscous media. The predominance of Brownian relaxation as the origin of the magnetic losses in these particles is established, and the changes of the Specific Power Absorption (SPA) with the viscosity of the carrier liquid are consistent with the LRT approximation. The impact of viscosity on SPA is relevant for the design of MNPs to heat the intracellular medium during in vitro and in vivo experiments. The combined numerical and experimental analyses presented here shed light on the underlying mechanisms that make highly anisotropic MNPs unsuitable for magnetic hyperthermia.

3.
Macromol Rapid Commun ; 40(2): e1800333, 2019 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-30027594

RESUMO

This article presents the synthesis of poly(methacrylic acid)-b-poly(methyl methacrylate) diblock copolymer via polymerization-induced self-assembly in the presence of iron-oxide nanoparticles. Detailed phase diagrams with and without inorganic nanoparticles were constructed. Scanning transmission electron microscopy and energy dispersive X-ray photometry studies confirme the decoration of the polymeric nanoparticles with the iron-oxide nanoparticles. These hybrid nanoparticles were used to prepare porous thin film membranes by spin coating. Finally, the magneto-responsive properties of the membranes were assessed using water filtration tests in the presence and absence of a magnetic field.


Assuntos
Técnicas de Química Sintética/métodos , Nanopartículas de Magnetita/química , Nanopartículas/química , Polímeros/química , Ácidos Polimetacrílicos/química , Polimetil Metacrilato/química , Materiais Revestidos Biocompatíveis/química , Campos Magnéticos , Nanopartículas de Magnetita/ultraestrutura , Membranas Artificiais , Microscopia Eletrônica de Transmissão e Varredura , Nanopartículas/ultraestrutura , Polimerização , Polímeros/síntese química , Porosidade
4.
Nanoscale ; 11(7): 3164-3172, 2019 Feb 14.
Artigo em Inglês | MEDLINE | ID: mdl-30520920

RESUMO

We report a simple and effective way to control the heat generation of a magnetic colloid under alternate magnetic fields by changing the shell composition of bimagnetic core-shell Fe3O4/ZnxCo1-xFe2O4 nanoparticles. The core-shell structure constitutes a magnetically-coupled biphase system, with an effective anisotropy that can be tuned by the substitution of Co2+ by Zn2+ ions in the shell. Magnetic hyperthermia experiments of nanoparticles dispersed in hexane and butter oil showed that the magnetic relaxation is dominated by Brown relaxation mechanism in samples with higher anisotropy (i.e., larger concentration of Co within the shell) yielding high specific power absorption values in low viscosity media as hexane. Increasing the Zn concentration of the shell, diminishes the magnetic anisotropy, which results in a change to a Néel relaxation that dominates the process when the nanoparticles are dispersed in a high-viscosity medium. We demonstrate that tuning the Zn contents at the shell of these exchange-coupled core/shell nanoparticles provides a way to control the magnetic anisotropy without loss of saturation magnetization. This ability is an essential prerequisite for most biomedical applications, where high viscosities and capturing mechanisms are present.

5.
Chem Sci ; 9(40): 7766-7778, 2018 Oct 28.
Artigo em Inglês | MEDLINE | ID: mdl-30429985

RESUMO

Herein we report on a novel inorganic peroxidase-mimicking nanocatalyst activated under blue LED photoirradiation. A novel flash-pyrolysis method has been developed for the generation of strong blue photoluminescence (PL) centers attributed to silicon and carbon-based sites within a mesoporous SBA-15 silica nanorod platform. The type of centers and their PL response can be controlled by varying the flash thermal treatment conditions. By tailoring the operating conditions the system can be driven towards the preferential generation of carbon-based luminescent centers, with or without the simultaneous generation of silicon-based centers. The properties and the nature of these luminescent centers within the mesoporous nanorods have been thoroughly corroborated by a battery of characterization techniques including fluorescence spectroscopy, X-ray photoelectron spectroscopy (XPS) and electron energy loss spectroscopy (EELS) at the local level of the structures combined with scanning transmission electron microscopy (STEM) imaging. In addition, these luminescent mesoporous nanorods have been successfully tested as robust photocatalysts able to display peroxidase-like activity and indirect glucose sensing in a wider range of pH conditions compared to the natural enzyme, especially when carbogenic dots and oxygen-deficient silica centers are simultaneously present in the structure.

6.
Int J Pharm ; 528(1-2): 429-439, 2017 Aug 07.
Artigo em Inglês | MEDLINE | ID: mdl-28627453

RESUMO

The aim of this study is to design and develop delivery platforms made of liposomes and multi-walled carbon nanotubes (MWCNTs). We used different lipids with different main transition temperature (Tm) and differently functionalized MWCNTs with organic addends possessing either positive or negative charge. The phospholipids used for the formulations were 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) (Tm=41°C) and L-α-phosphatidylcholine, hydrogenated Soy (HSPC) (Tm=53°C). By Differential Scanning Calorimetry (DSC), we studied the interaction between the DPPC and HSPC bilayers and MWCNTs. Liposome-MWCNTs delivery platforms prepared according to the protocol used in the literature. We used dynamic and electrophoretic light scattering in order to investigate the physicochemical characteristics of these mixed nanocarriers. The presence of MWCNTs causes alterations of the size of the conventional HSPC and DPPC liposomes. The ζ-potential values of mixed nanocarriers are near zero. This observation indicates the effective incorporation of MWCNTs into the lipid bilayer of liposomes. Fluorescence spectroscopy has been utilized to exact some qualitative information on the internal nanostructure and nanoenvironment of the lipid/carbon nanotube mixed structures. Finally, we conclude that we successfully prepare and completely characterize mixed nanocarriers composed of lipids and MWCNTs, with low toxicity as indicated by in vitro screening.


Assuntos
Portadores de Fármacos/química , Lipossomos/química , Nanotubos de Carbono/química , Fosfolipídeos/química
7.
Histochem Cell Biol ; 146(5): 557-567, 2016 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-27373548

RESUMO

Extracellular vesicles (EVs) have emerged as an intercellular communication mediator in cancer. They seem to be involved in tumor processes by means of transformation of surrounding cells previous to metastasis by transferring miRNAs and oncogenic proteins. It is known that EVs, depending on their source, can be exosomes or ectosomes. Although the first type constitutes a specific population formed from the endosomal system, via multivesicular bodies, the ectosome biogenesis is not yet well known. In this study, we report a new type of EVs which has been termed spheresomes. While exosomes come from multivesicular bodies and ectosomes from direct budding of plasma membrane, spheresomes present a new mechanism of shedding from a spherical membrane structure which we have named multivesicular spheres. These EVs are first described in gastrointestinal stromal tumor cells in the present study. But moreover, these new membrane spherical structures appear not only next to tumoral cells but also different distances from them. Since some other authors have evidenced oncogenic KIT-containing EVs, it is also suggested here that surrounding cells uptake of these first described EVs, GIST-derived spheresomes, could induce tumor invasiveness. That is why the prevention of signaling processes developed by these new EVs may represent an alternative approach for GIST treatment.


Assuntos
Exossomos/metabolismo , Exossomos/ultraestrutura , Vesículas Extracelulares/metabolismo , Vesículas Extracelulares/ultraestrutura , Tumores do Estroma Gastrointestinal/patologia , Tumores do Estroma Gastrointestinal/ultraestrutura , Membrana Celular/metabolismo , Membrana Celular/ultraestrutura , Tumores do Estroma Gastrointestinal/metabolismo , Tumores do Estroma Gastrointestinal/cirurgia , Humanos
8.
Langmuir ; 31(12): 3687-95, 2015 Mar 31.
Artigo em Inglês | MEDLINE | ID: mdl-25741589

RESUMO

Biomimetic silica particles can be synthesized as a nanosized material within minutes in a process mimicked from living organisms such as diatoms and sponges. In this work, we have studied the effect of bovine serum albumin (BSA) as a template to direct the synthesis of silica nanoparticles (NPs) with the potential to associate proteins on its surface. Our approach enables the formation of spheres with different physicochemical properties. Particles using BSA as a protein template were smaller (∼250-380 nm) and were more monodisperse than those lacking the proteic core (∼700-1000 nm) as seen by dynamic light scattering (DLS), scanning electron microscopy (SEM), and environmental scanning electron microscopy (ESEM) analysis. The absence of BSA during synthesis produced silica nanoparticles without any porosity that was detectable by nitrogen adsorption, whereas particles containing BSA developed porosity in the range of 4 to 5 nm which collapsed on the removal of BSA, thus producing smaller pores. These results were in accordance with the pore size calculated by high-resolution transmission electron microscopy (HTEM). The reproducibility of the BSA-templated nanoparticle properties was determined by analyzing four batches of independent synthesizing experiments that maintained their properties. The high positive superficial charge of the nanoparticles facilitated adsorption under mild conditions of a range of proteins from an E. coli extract and a commercial preparation of laccase from Trametes versicolor. All of the proteins were quantitatively desorbed. Experiments conducted showed the reusability of the particles as supports for the ionic adsorption of the biomolecules. The protein loading capacity of the BSA-based biomimetic particles was determined using laccase as 98.7 ± 6.6 mg·g(-1) of particles.


Assuntos
Materiais Biomiméticos/química , Nanopartículas/química , Soroalbumina Bovina/química , Dióxido de Silício/química , Animais , Bovinos , Fenômenos Químicos , Tamanho da Partícula , Propriedades de Superfície
9.
ACS Appl Mater Interfaces ; 6(12): 9100-10, 2014 Jun 25.
Artigo em Inglês | MEDLINE | ID: mdl-24853082

RESUMO

For several years now, nanoscaled materials have been implemented in biotechnological applications related to animal (in particular human) cells and related pathologies. However, the use of nanomaterials in plant biology is far less widespread, although their application in this field could lead to the future development of plant biotechnology applications. For any practical use, it is crucial to elucidate the relationship between the nanomaterials and the target cells. In this work we have evaluated the behavior of two types of nanomaterials, quantum dots and superparamagnetic nanoparticles, on Fusarium oxysporum, a fungal species that infects an enormous range of crops causing important economic losses and is also an opportunistic human pathogen. Our results indicated that both nanomaterials rapidly interacted with the fungal hypha labeling the presence of the pathogenic fungus, although they showed differential behavior with respect to internalization. Thus, whereas magnetic nanoparticles appeared to be on the cell surface, quantum dots were significantly taken up by the fungal hyphae showing their potential for the development of novel control approaches of F. oxysporum and related pathogenic fungi following appropriate functionalization. In addition, the fungal germination and growth, accumulation of ROS, indicative of cell stress, and fungal viability have been evaluated at different nanomaterial concentrations showing the low toxicity of both types of nanomaterials to the fungus. This work represents the first study on the behavior of quantum dots and superparamagnetic particles on fungal cells, and constitutes the first and essential step to address the feasibility of new nanotechnology-based systems for early detection and eventual control of pathogenic fungi.


Assuntos
Fusarium/isolamento & purificação , Nanopartículas/química , Plantas/microbiologia , Pontos Quânticos , Animais , Fusarium/patogenicidade , Humanos , Nanotecnologia
10.
Langmuir ; 30(18): 5238-47, 2014 May 13.
Artigo em Inglês | MEDLINE | ID: mdl-24694292

RESUMO

Superparamagnetic iron oxide nanoparticles coated with titanium dioxide have been synthesized, growing the titanium dioxide directly either on the magnetic nuclei or on magnetic nanoparticles previously coated with a semihydrophobic silica layer. Both coatings have been obtained by sol-gel. Since it is well-known that the existence of the intermediate silica layer influences the physicochemical properties of the material, a detailed characterization of both types of coatings has been carried out. The morphology, structure, and composition of the synthesized nanomatrices have been locally analyzed with subangstrom spatial resolution, by means of aberration corrected transmission electron microscopy (HRTEM and STEM-HAADF). Besides magnetization measurements, proton relaxivity experiments have been also performed on water suspensions of the as-synthesized nanoparticles to investigate the role of the silica interlayer in the relaxometric properties. The silica interlayer leads to nanoparticles with much higher water stability and to higher relaxivity of the suspensions.


Assuntos
Nanopartículas de Magnetita/química , Dióxido de Silício/química , Titânio/química
11.
Nanomedicine ; 10(7): 1549-58, 2014 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-24407149

RESUMO

There is a growing body of evidence indicating the importance of physical stimuli for neuronal growth and development. Specifically, results from published experimental studies indicate that forces, when carefully controlled, can modulate neuronal regeneration. Here, we validate a non-invasive approach for physical guidance of nerve regeneration based on the synergic use of magnetic nanoparticles (MNPs) and magnetic fields (Ms). The concept is that the application of a tensile force to a neuronal cell can stimulate neurite initiation or axon elongation in the desired direction, the MNPs being used to generate this tensile force under the effect of a static external magnetic field providing the required directional orientation. In a neuron-like cell line, we have confirmed that MNPs direct the neurite outgrowth preferentially along the direction imposed by an external magnetic field, by inducing a net angle displacement (about 30°) of neurite direction. From the clinical editor: This study validates that non-invasive approaches for physical guidance of nerve regeneration based on the synergic use of magnetic nanoparticles and magnetic fields are possible. The hypothesis was confirmed by observing preferential neurite outgrowth in a cell culture system along the direction imposed by an external magnetic field.


Assuntos
Magnetismo , Nanopartículas , Neurônios/citologia , Animais , Microscopia Eletrônica de Varredura , Microscopia Eletrônica de Transmissão , Células PC12 , Ratos
12.
ACS Nano ; 7(4): 3297-305, 2013 Apr 23.
Artigo em Inglês | MEDLINE | ID: mdl-23530668

RESUMO

Magnetotactic bacteria biosynthesize magnetite nanoparticles of high structural and chemical purity that allow them to orientate in the geomagnetic field. In this work we have followed the process of biomineralization of these magnetite nanoparticles. We have performed a time-resolved study on magnetotactic bacteria Magnetospirillum gryphiswaldense strain MSR-1. From the combination of magnetic and structural studies by means of Fe K-edge X-ray absorption near edge structure (XANES) and high-resolution transmission electron microscopy we have identified and quantified two phases of Fe (ferrihydrite and magnetite) involved in the biomineralization process, confirming the role of ferrihydrite as the source of Fe ions for magnetite biomineralization in M. gryphiswaldense. We have distinguished two steps in the biomineralization process: the first, in which Fe is accumulated in the form of ferrihydrite, and the second, in which the magnetite is rapidly biomineralized from ferrihydrite. Finally, the XANES analysis suggests that the origin of the ferrihydrite could be at bacterial ferritin cores, characterized by a poorly crystalline structure and high phosphorus content.


Assuntos
Óxido Ferroso-Férrico/metabolismo , Nanopartículas de Magnetita/química , Magnetossomos/metabolismo , Magnetospirillum/metabolismo , Minerais/química , Minerais/metabolismo , Óxido Ferroso-Férrico/isolamento & purificação , Campos Magnéticos , Nanopartículas de Magnetita/análise , Teste de Materiais , Minerais/isolamento & purificação
13.
Arch Pharm Res ; 35(1): 93-100, 2012 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-22297747

RESUMO

The in vivo biodistribution of Fe@C nanoparticles (NP) was tested in mice bearing an inflammatory focus induced by injecting carrageenan into an air pouch previously formed on their back. The animals were intravenously injected NP with a high (60 mg/kg) or a low iron dose (6 mg/kg) and sacrificed 2 h later. Blood and organ samples (liver, spleen, lung, and kidney) were obtained; washed exudates were also collected. Iron concentration in plasma, blood cells, organs, and exudates was determined by flameless atomic-absorption-spectroscopy after digestion of organic material. Pouch exudate volume increased in all groups of mice with experimental inflammation. After i.v. administration of the high and low dose of NP, iron in exudate increased by 83.3% and 92.2%, respectively. A similar increase in hepatic iron appeared after the high dose (78%), but no increase appeared after the low dose. When the magnet was present, a 157% and 119% increase of iron in exudate appeared after both doses of NPs, but only the high dose of NP increased iron liver (60%). The presence of a magnetic field in the pouch favored selective biodistribution of NP in the inflammatory focus. These results indicate that mice with an inflammatory compartment are suitable for primary screening of different NP types. They also show that selective biodistribution is greater when a low dose of NP was used and that distribution in the target organ was increased by the magnetic field.


Assuntos
Ferro/metabolismo , Campos Magnéticos , Imãs , Nanopartículas Metálicas , Animais , Feminino , Ferro/química , Nanopartículas Metálicas/química , Camundongos , Distribuição Aleatória , Distribuição Tecidual
14.
Nanoscale Res Lett ; 6(1): 592, 2011 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-22085532

RESUMO

Nanolithography techniques in a scanning electron microscope/focused ion beam are very attractive tools for a number of synthetic processes, including the fabrication of ferromagnetic nano-objects, with potential applications in magnetic storage or magnetic sensing. One of the most versatile techniques is the focused electron beam induced deposition, an efficient method for the production of magnetic structures highly resolved at the nanometric scale. In this work, this method has been applied to the controlled growth of magnetic nanostructures using Co2(CO)8. The chemical and structural properties of these deposits have been studied by electron energy loss spectroscopy and high-resolution transmission electron microscopy at the nanometric scale. The obtained results allow us to correlate the chemical and structural properties with the functionality of these magnetic nanostructures.

15.
Methods Mol Biol ; 544: 559-69, 2009.
Artigo em Inglês | MEDLINE | ID: mdl-19488723

RESUMO

This chapter is a brief description of the state of the art of the field of targeted drug delivery using magnetic implants. It describes the advantages and drawbacks of the use of internal magnets to concentrate magnetic nanoparticles near tumor locations, and the different approaches to this task performed in vitro and in vivo reviewed in literature are presented.


Assuntos
Sistemas de Liberação de Medicamentos , Nanopartículas Metálicas , Animais , Implantes de Medicamento , Humanos , Rim/anatomia & histologia , Rim/metabolismo , Magnetismo , Nanotecnologia , Neoplasias/tratamento farmacológico , Coelhos
16.
BMC Plant Biol ; 9: 45, 2009 Apr 23.
Artigo em Inglês | MEDLINE | ID: mdl-19389253

RESUMO

BACKGROUND: In recent years, the application of nanotechnology in several fields of bioscience and biomedicine has been studied. The use of nanoparticles for the targeted delivery of substances has been given special attention and is of particular interest in the treatment of plant diseases. In this work both the penetration and the movement of iron-carbon nanoparticles in plant cells have been analyzed in living plants of Cucurbita pepo. RESULTS: The nanoparticles were applied in planta using two different application methods, injection and spraying, and magnets were used to retain the particles in movement in specific areas of the plant. The main experimental approach, using correlative light and electron microscopy provided evidence of intracellular localization of nanoparticles and their displacement from the application point. Long range movement of the particles through the plant body was also detected, particles having been found near the magnets used to immobilize and concentrate them. Furthermore, cell response to the nanoparticle presence was detected. CONCLUSION: Nanoparticles were capable of penetrating living plant tissues and migrating to different regions of the plant, although movements over short distances seemed to be favoured. These findings show that the use of carbon coated magnetic particles for directed delivery of substances into plant cells is a feasible application.


Assuntos
Transporte Biológico , Cucurbita/metabolismo , Compostos Férricos/metabolismo , Nanopartículas Metálicas , Magnetismo , Microscopia Eletrônica de Transmissão , Microscopia de Contraste de Fase , Caules de Planta/metabolismo , Caules de Planta/ultraestrutura
17.
Small ; 4(11): 2025-34, 2008 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-18855973

RESUMO

Inorganic nanoparticles (NPs) show great potential for medicinal therapy. However, biocompatibility studies are essential to determine if they are safe. Here, five different NPs are compared for their cytotoxicity, internalization, aggregation in medium, and reactive oxygen species (ROS) production, using tumoral and normal human blood cells. Differences depending on the cell type are analyzed, and no direct correlation between ROS production and cell toxicity is found. Results are discussed with the aim of standardizing the procedures for the evaluation of the toxicity.


Assuntos
Células Sanguíneas/citologia , Nanopartículas/química , Animais , Células Sanguíneas/efeitos dos fármacos , Linhagem Celular , Humanos , Camundongos , Nanopartículas/toxicidade , Estresse Oxidativo/fisiologia , Tamanho da Partícula , Espécies Reativas de Oxigênio/metabolismo
18.
Arch Esp Urol ; 60(1): 5-14, 2007.
Artigo em Espanhol | MEDLINE | ID: mdl-17408166

RESUMO

OBJECTIVES: The use of nanoparticules for drug transport is one of the topics with priority interest within the field of biomedical research. Our objective is to show the initial results of an innovative method to focalize drug carrier ferro-carbon nanoparticules to solid organs. We obtained and characterized various types of ferrous magnetic nanoparticules and studied their behaviour in vitro and in vivo in laboratory animals with intrarenal magnetic targets laparoscopically implanted. METHODS: Using a plasma arch we obtained ferro-carbon nanoparticules with the ability to absorb and deliver doxorubicin, showing an excellent behaviour in in vitro rheological studies. Under general anesthesia and control we inserted a gold covered magnetic microharpoon in the left kidney of New Zealand rabbits. At the same time we injected intravenously different doses of various types of nanoparticules. The animals were sacrified ofter pre-established times and pathologic studies of their kidneys, spleens, livers, lungs and bone marrow were carried out. RESULTS: After selection of the most adequafe nanoparticules for our purposes, we ascertained significant differences in the distribution of nanoparticules in postmortem studies, with accumulation in the magnetic target and surrounding renal parenchyma. Nevertheless, the reticuloendothelial system retains a great amount of the injected dose. CONCLUSIONS: Although our magnetic focalization system is effective, nanoparticule temporary protection systems should be tested to allow us avoid the action of the immune system.


Assuntos
Antibióticos Antineoplásicos/administração & dosagem , Doxorrubicina/administração & dosagem , Portadores de Fármacos , Neoplasias Renais/tratamento farmacológico , Nanopartículas/administração & dosagem , Animais , Humanos , Injeções Intravenosas , Coelhos
19.
Arch. esp. urol. (Ed. impr.) ; 60(1): 5-14, ene.-feb. 2007. ilus
Artigo em Espanhol | IBECS | ID: ibc-054447

RESUMO

OBJETIVOS: El empleo de nanopartículas en el transporte de fármacos es actualmente uno de los temas de interés prioritario dentro del campo de la investigación biomédica. Nuestro objetivo es mostrar los resultados iniciales de un método inédito para focalizar en órganos sólidos nanopartículas ferro carbonosas quimioportadoras. Hemos obtenido y caracterizado diversos tipos de nanopartículas ferromagnéticas, y hemos estudiado su comportamiento in vitro e in vivo en animales de experimentación con dianas magnéticas intrarrenales implantadas laparoscópicamente. METODOS: Obtenemos mediante arco de plasma nanopartículas ferro carbonosas capaces de absorber y desorber doxorrubicina y mostrar excelente comportamiento en estudios reológicos in vitro. Bajo anestesia general insertamos mediante control laparoscópico en el riñón izquierdo de conejos de raza neozelandesa un microarpón magnético encapsulado en oro. En el mismo acto inyectamos por vía intravenosa diferentes dosis de distintos tipos de nanopartículas. Los diversos lotes de animales se sacrifican tras diferentes tiempos y se analizan histológicamente ambos riñones, bazo, hígado, pulmones y médula ósea. RESULTADOS: Tras haber seleccionado las nanopartículas más adecuadas para nuestros fines, hemos constatado en los estudios post-mortem diferencias significativas en la distribución de las nanopartículas, con cúmulos de las mismas en la diana magnética y en el parénquima renal circundante. No obstante, el sistema retículoendotelial retiene gran parte de la carga inyectada. CONCLUSIONES: Aunque nuestro sistema de focalización magnética resulta efectivo, deben ensayarse sistemas de blindaje temporal de las nanopartículas que les permita eludir la acción del sistema inmune (AU)


OBJECTIVES: The use of nanoparticules for drug transport is one of the topics with priority interest within the field of biomedical research. Our objective is to show the initial results of an innovative method to focalize drug carrier ferro-carbon nanoparticules to solid organs. We obtained and characterized various types of ferrous magnetic nanoparticules and studied their behaviour in vitro and in vivo in laboratory animals with intrarenal magnetic targets laparoscopically implanted. METHODS: Using a plasma arch we obtained ferro-carbon nanoparticules with the ability to absorb and deliver doxorubicin, showing an excellent behaviour in in vitro rheological studies. Under general anesthesia and control we inserted a gold covered magnetic microharpoon in the left kidney of New Zealand rabbits. At the same time we injected intravenously different doses of various types of nanoparticules. The animals were sacrified ofter pre-established times and pathologic studies of their kidneys, spleens, livers, lungs and bone marrow were carried out. RESULTS: After selection of the most adequafe nanoparticules for our purposes, we ascertained significant differences in the distribution of nanoparticules in postmortem studies, with accumulation in the magnetic target and surrounding renal parenchyma. Nevertheless, the reticuloendothelial system retains a great amount of the injected dose. CONCLUSIONS: Although our magnetic focalization system is effective, nanoparticule temporary protection systems should be tested to allow us avoid the action of the immune system (AU)


Assuntos
Animais , Coelhos , Humanos , Antibióticos Antineoplásicos/administração & dosagem , Portadores de Fármacos , Doxorrubicina/administração & dosagem , Neoplasias Renais/tratamento farmacológico , Injeções Intravenosas
20.
Nanotechnology ; 17(16): 4057-64, 2006 Aug 28.
Artigo em Inglês | MEDLINE | ID: mdl-21727538

RESUMO

Nanocomposites consisting of magnetite and FAU zeolite with a high surface area and adsorption capacity have been prepared by mechanical activation using high-energy milling at room temperature. FTIR results, as well as HRTEM, EFTEM, and XPS measurements, show that the resulting magnetic nanoparticles are covered by a thin aluminosilicate coating. A saturation magnetization as high as 16 emu g(-1) and 94.2 Oe of coercivity were observed for the obtained composites. The main advantages of this synthesis procedure are (i) simplicity of the preparation procedure, (ii) prevention of agglomeration of the magnetite nanoparticles to a large extent, and (iii) absence of free magnetite outside the zeolitic matrix. In addition, in vitro experiments revealed that the nanoparticles prepared were able to store and release substantial amounts of doxorubicin. In view of these advantages, these magnetic nanoparticles can be considered as potential candidates for drug-delivery applications.

SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA