Página 1 dos resultados de 3124 itens digitais encontrados em 0.022 segundos

Micro-flow visualization of magnetic nanoparticles for biomedical applications

Lima, R.; Joseyphus, R. J.; Ishikawa, Takuji; Imai, Yohsuke; Yamaguchi, Takami
Fonte: Bentham Science Publicador: Bentham Science
Tipo: Parte de Livro
ENG
Relevância na Pesquisa
66.32%
An investigation to measure the flow behavior of magnetic nanoparticles through a 100mm microchannel is conducted. The magnetic field is applied externally by a permanent magnet and by using a micro-PTV system it was possible to measure the flow behavior of magnetic nanoparticles at different flow rates and magnetic fields through a 100mm glass capillary. A strong dependence on both magnetic and hydrodynamic force is observed on the nanoparticles fluidic paths. Based on these in vitro studies, important parameters and issues that require further understanding and investigation are point out.

Improving the catalytic activity of formate dehydrogenase from Candida boidinii by using magnetic nanoparticles

Netto, Caterina Gruenwaldt Cunha Marques; Nakamura, Marcelo; Andrade, Leandro H.; Toma, Henrique Eisi
Fonte: ELSEVIER SCIENCE BV; AMSTERDAM Publicador: ELSEVIER SCIENCE BV; AMSTERDAM
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
66.26%
Formate dehydrogenase from Candida boidinii (FDH) was immobilized on three different magnetic supports: one composed by magnetite nanoparticles directly silanized with ARTS (aminopropyltriethoxysilane), i.e. MagNP-APTS: the second one containing a silica gel coated magnetite core which was further silanized with APTS (MagNP@SiO2-APTS), and the third one consisting of magnetite-APTS coated with Glyoxyl-Agarose (MagNP-Glyoxyl-Agarose). The catalytic activity of the three FDH systems was investigated as a function of pH and temperature. The silica gel coated nanoparticles provided the highest conversion rates; however, in terms of recycling, magnetite without the silica shell led to the most stable system. By using the enzyme tryptophan residues as internal fluorescence probes, the structure-activity behavior was investigated in the presence of the formate and NAD(+) substrates, revealing a rather contrasting behavior in the three cases. Because of its peculiar behavior, a direct interaction of the magnetic nanoparticles with the catalytic sites seems to be implicated in the case of MagNP-APTS. (C) 2012 Elsevier B.V. All rights reserved.

A detailed investigation on the interactions between magnetic nanoparticles and cell membrane models

Uehara, Thiers Massami; Marangoni, Valéria Spolon; Pasquale, Nicholas; Miranda, Paulo Barbeitas; Lee, Ki-Bum; Zucolotto, Valtencir
Fonte: American Chemical Society - ACS; Washington, DC Publicador: American Chemical Society - ACS; Washington, DC
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
66.33%
The understanding of the interactions between small molecules and magnetic nanoparticles is of great importance for many areas of bioapplications. Although a large array of studies in this area have been performed, aspects involving the interaction of magnetic nanoparticles with phospholipids monolayers, which can better mimic biological membranes, have not yet been clarified. This study was aimed at investigating the interactions between Langmuir films of dipalmitoyl phosphatidylglycerol and dipalmitoyl phosphatidylcholine, obtained on an aqueous subphase, and magnetic nanoparticles. Sum-Frequency Generation (SFG) Vibrational Spectroscopy was used to verify the orientation, molecular conformation, and to better understand the interactions between phospholipids and the magnetic nanoparticles. Surface pressure - area isotherms and SFG spectroscopy made it possible to investigate the interaction of these nanomaterials with components of phospholipids membranes at the water surface.; FAPESP; CAPES; FINEP

Imobilização da lipase de Burkholderia cepacia em nanopartículas magnéticas e sua applicação em resolução cinética de alcoóis secundários quirais; Immobilization of Burkholderia cepacia lipase on magnetic nanoparticles and its application in enzymatic kinetic resolution of chiral secondary alcohols

Rebelo, Lya Pantoja
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 11/05/2009 PT
Relevância na Pesquisa
66.33%
Esta dissertação apresenta um estudo de diferentes metodologias de imobilização (fisissorção, quimissorção com carboxibenzaldeído e quimissorção com glutaraldeído) da lipase de Burkholderia cepacia em nanopartículas magnéticas e sua aplicação na resolução cinética de alcoóis secundários racêmicos. O método de imobilização por fisissorção resultou na imobilização de 0,21 mg de proteína em 20 mg de nanopartículas magnéticas. Para a mesma quantidade de nanopartículas magnéticas, o método de quimissorção com carboxibenzaldeído imobilizou 0,26 mg de proteína contra 0,28 mg de proteína pelo método de quimissorção com glutaraldeído, a melhor relação encontrada neste trabalho. A atividade enzimática foi avaliada na resolução cinética de alcoóis secundários racêmicos [(RS)-2-bromo-1-(fenil)etanol, (RS)-2-bromo-1-(4-nitrofenil)etanol, (RS)-1-(4-nitrofenil)etanol e (RS)-1-(fenil)-1,2-etanodiol] via reação de transesterificação enantiosseletiva. O efeito de diferentes parâmetros reacionais para a resolução cinética foi estudado, como agente acilante, quantidade de substrato, solvente, quantidade de nanopartículas magnéticas (suporte), velocidade de agitação, tempo e temperatura reacionais. Os melhores parâmetros encontrados foram acetato de vinila como agente acilante...

Nanopartículas magnéticas metálicas recobertas com óxido de ferro: intensificação das propriedades magnéticas da nanopartícula e funcionalização para aplicação em biomedicina; Iron oxide-coated metal magnetic nanoparticles: improved magnetic properties and surface functionalization for biomedical applications

Beck Júnior, Watson
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 28/02/2011 PT
Relevância na Pesquisa
66.48%
A utilização de nanopartículas (NP) magnéticas em várias áreas da biomedicina e biotecnologia vem recebendo elevado destaque nos últimos anos, graças à versatilidade de aplicações tais como: reparo de tecidos, diagnósticos, imagens por ressonância magnética, tratamento contra o câncer, separação celular, transporte controlado de drogas, entre outras. Atualmente, as NP com potencialidade de aplicação em biomedicina baseiam-se principalmente em óxidos magnéticos de ferro, os quais apresentam comportamento superparamagnético a temperatura ambiente e baixa magnetização da ordem de 60 emu g-1. A utilização dos óxidos se baseia em duas razões principais: facilidade e versatilidade de modificação da superfície e funcionalização devido aos grupos hidroxila na superfície das NP e pela baixa toxicidade comparada às NP magnéticas metálicas. Biocompatibilidade e funcionalidade específica são obtidas geralmente pela incorporação de materiais paramagnéticas e/ou diamagnéticos na superfície das NP contribuindo para diminuir ainda mais o baixo valor de magnetização de saturação dos óxidos. Nesse contexto, é necessário o desenvolvimento de novos núcleos magnéticos com elevado valor de magnetização...

Obtenção de nanopartículas magnéticas sensíveis a estímulos para aplicações biomédicas; Preparation of stimuli-responsive magnetic nanoparticles for biomedical applications

Medeiros, Simone de Fátima
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 21/12/2010 PT
Relevância na Pesquisa
66.37%
Partículas poliméricas com propriedades magnéticas podem ser utilizadas tanto em aplicações terapêuticas in vivo, como agentes de liberação controlada de princípios ativos, ex vivo, na extração de células cancerígenas do organismo, ou ainda in vitro, em diagnósticos. A necessidade de materiais inteligentes e biocompatíveis, como agentes de encapsulação destas partículas magnéticas, leva ao uso de polímeros sensíveis a estímulos. Em aplicações terapêuticas, esta tecnologia é baseada na localização das partículas através da aplicação de um campo magnético e na concentração da droga na área de interesse. Esta etapa é seguida pela liberação da droga, utilizando-se as propriedades sensíveis dos polímeros. Dessa forma, este trabalho de tese se dedica ao estudo da obtenção de nanopartículas constituídas de uma matriz polimérica sensível a estímulos e de partículas de óxido de ferro (?-Fe2O3 e Fe3O4). Inicialmente, nanogéis à base de poli(NVCL-co-AA) foram obtidos através do método de polimerização por precipitação. A Poli(Nvinilcaprolactama) (PNVCL) é um polímero termo-sensível, que possui temperatura crítica inferior de solubilização (LCST) próxima à temperatura fisiológica (35-38 ºC) e é conhecida...

Desenvolvimento, síntese e caracterização de nanopartículas magnéticas hidrofílicas e lipofílicas para aplicação em nanotecnologia do petróleo; Development, synthesis and characterization of hydrophilic and lipophilic magnetic nanoparticles applied to oil nanotechnology

Silva, Delmarcio Gomes da
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 22/04/2014 PT
Relevância na Pesquisa
66.41%
A tese de doutorado tem como foco o desenvolvimento de nanopartículas superparamagnéticas (Fe3O4 - magnetita) hidrofílicas e lipofílicas aplicadas à nanotecnologia do petróleo. Inicialmente, os objetivos foram voltados para a elaboração e transferência de tecnologia envolvendo uma rota de síntese de nanopartículas lipofílicas, em escala semi-industrial. Para isso, foram realizados ensaios piloto num reator com capacidade de uma tonelada, visando a produção de nanopartículas magnéticas recobertas com ácido esteárico. Mais tarde, esse trabalho foi otimizado, permitindo sua execução em laboratório, prosseguindo depois, com um escopo mais amplo, incluindo a síntese de nanopartículas recobertas com polímero hidrofílico. Nesse sentido, foram desenvolvidas duas rotas inéditas para produção desses nanomateriais. Em um segundo estágio, as investigações foram voltadas para a utilização das nanopartículas sintetizadas, em estudos de avaliação das condições dos reservatórios de petróleo. Para isso, a técnica de ressonância magnética nuclear (RMN) foi explorada, monitorando o efeito da concentração dessas nanopartículas superparamagnéticas sobre o tempo de relaxação dos prótons, e o consequente efeito de contraste nas imagens em função da magnetização. A aplicação desse tipo de ferramenta (RMN) já vem sendo feita (sem nanopartículas magnéticas) pelas empresas prestadoras de serviço ao setor de petróleo e gás...

Magnetic nanoparticles potential for stem cell functionalization

Gonçalves, A. I.; Rodrigues, Márcia T.; Santo, Vítor E.; Reis, R. L.; Gomes, Manuela E.
Fonte: Wiley Online Library Publicador: Wiley Online Library
Tipo: Conferência ou Objeto de Conferência
Publicado em /09/2013 ENG
Relevância na Pesquisa
66.23%
Publicado em "Journal of Tissue Engineering and Regenerative Medicine", vol. 7, supp. 1 (2013); Stem cells have the capacity to migrate within tissues to damaged areas. The ability to remotely monitor and manipulate cells encouraging their precise positioning to desired sites for tissue regeneration would have a potential impact in tissue engineering and regenerative medicine. Cell monitoring and cell localization can be potentially achieved by the internalization of magnetic nanoparticles (MNPs) in the cells. This might allow for the investigation of migratory patterns through tracking studies, the targeting of particle-labeled cells to desired locations via the application of an external magnetic field and, finally, for activation stem cells to initiate various cellular responses to induce the differentiation [1]. The application of a magnetic field can then enhance biological performance through the stimulation of cell proliferation, migration and differentiation. This study focus on determining the effect of magnetic stimulation in human adipose stem cells (hASCs) behavior in order to establish the interactions between MNPs uptake by the cell, the MNPs concentrations, and magnitude/frequency of the external magnetic field during the internalization process.

Magnetic nanoparticles for biocatalysis and bioseparation

Santana, Sara Daniela Filipe
Fonte: Faculdade de Ciências e Tecnologia Publicador: Faculdade de Ciências e Tecnologia
Tipo: Dissertação de Mestrado
Publicado em //2011 ENG
Relevância na Pesquisa
66.22%
Dissertação para obtenção do Grau de Mestre em Biotecnologia; This work aimed to prepare iron oxide magnetic nanoparticles (MNPs) coated with biopolymers and further modified with enzymes and synthetic affinity ligands in order to study their applications in biocatalysis and bioseparation areas. The adsorption of different biopolymers - Gum Arabic (Ga), Dextran (Dex) and Extracellular Polysaccharide (EPS) - was performed during the synthesis of the particles, and the amount of polymer bound was determined and compared to the adsorption profiles of each polymer. Additionally, the storage and chemical modification stability of these supports was also evaluated. All supports showed high stability. The eventual application of these magnetic supports in biocatalysis was evaluated through the immobilization of an enzyme, Enterokinase (EK), through two distinct chemistries. The enzyme was then tested with a synthetic substrate and two fusion proteins. After the enzyme’s immobilization, its activity was observed to decrease, which was compensated by its re-utilization up to ten times. The most promising magnetic support was the MNP_Dex since it presented an activity retention of 35% and a conversion percentage of 0.4% in the first reaction cycle. The utilization of magnetic supports for the purification of IgG was tested through the immobilization of the synthetic affinity ligand 22/8 using three different methods. The MNP_Dex support modified with the ligand synthesized directly on the solid support adsorbed around 130 mg of IgG/g of MNP and presented less nonspecific adsorption. Moreover...

Application of β-cyclodextrin/MnFe2O4 magnetic nanoparticles as a catalyst for fast chemiluminescence determination of glutathione in human blood using luminol-diperiodatoargentate(III) System

Rezaei,Behzad; Ensafi,Ali A.; Haghighatnia,Fariba; Aalaye,Saeed E.
Fonte: Sociedade Brasileira de Química Publicador: Sociedade Brasileira de Química
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/12/2012 EN
Relevância na Pesquisa
66.14%
This work is based on the enhanced chemiluminescence (CL) of the reaction between luminol and diperiodatoargentate(III) (DPA) {K[Ag(H3IO6)2]} in alkaline solution for determination of glutathione (GSH). In the presence of inclusion complex β-cyclodextrin (β-CD)/MnFe2O4 magnetic nanoparticles (MNPs), the experimental results showed that the CL emission was very fast (response time of about 1 s, which is a very important parameter in the clinical analysis) and sharp (CL signal increased 9 times). The catalytic effects of β-CD/MnFe2O4 MNPs on the CL response of luminol-DPA system were investigated. The linearly of method depended on GSH concentration in the ranges of 5.0 × 10-8 to 4.0 × 10-6 mol L-1 and limit of detection calculated was 1.5 × 10-8 mol L-1 and relative standard deviation of 2.8% for 9 replicated measurements of 8.0 × 10-7 mol L-1 GSH. The proposed method was successfully applied for rapid and sensitive determination of GSH in human blood samples.

Surface Functionalization of Monodisperse Magnetic Nanoparticles

Lattuada, Marco; Hatton, T. Alan
Fonte: MIT - Massachusetts Institute of Technology Publicador: MIT - Massachusetts Institute of Technology
Tipo: Artigo de Revista Científica Formato: 11308 bytes; application/pdf
EN
Relevância na Pesquisa
66.31%
We present a systematic methodology to functionalize magnetic nanoparticles through surface-initiated atom-transfer radical polymerization (ATRP). The magnetite nanoparticles are prepared according to the method proposed by Sun et al. (2004), which leads to a monodisperse population of ~ 6 nm particles stabilized by oleic acid. The functionalization of the nanoparticles has been performed by transforming particles into macro-initiators for the ATRP, and to achieve this two different routes have been explored. The first one is the ligand-exchange method, which consists of replacing some oleic acid molecules adsorbed on the particle surface with molecules that act as an initiator for ATRP. The second method consists in using the addition reaction of bromine to the oleic acid double bond, which turns the oleic acid itself into an initiator for the ATRP. We have then grown polymer brushes of a variety of acrylic polymers on the particles, including polyisopropylacrylamide and polyacrylic acid. The nanoparticles so functionalized are water soluble and show responsive behavior: either temperature responsive behavior when polyisopropylacrylamide is grown from the surface or PH responsive in the case of polyacrylic acid. This methodology has potential applications in the control of clustering of magnetic nanoparticles.; Singapore-MIT Alliance (SMA)

Synthesis and Characterization of Magnetic Nanoparticles with High Magnetization and Good Oxidation Resistibility

Yu, Shi; Chow, Gan-Moog
Fonte: MIT - Massachusetts Institute of Technology Publicador: MIT - Massachusetts Institute of Technology
Tipo: Artigo de Revista Científica Formato: 13595 bytes; application/pdf
EN
Relevância na Pesquisa
66.39%
Magnetic nanoparticles attract increasing attention because of their current and potential biomedical applications, such as, magnetically targeted and controlled drug delivery, magnetic hyperthermia and magnetic extraction. Increased magnetization can lead to improved performance in targeting and retention in drug delivery and a higher efficiency in biomaterials extraction. We reported an approach to synthesize iron contained magnetic nanoparticles with high magnetization and good oxidation resistibility by pyrolysis of iron pentacarbonyl (Fe(CO)[subscript 5]) in methane (CH[subscript 4]). Using the high reactivity of Fe nanoparticles, decomposition of CH[subscript 4] on the Fe nanoparticles leads to the formation of nanocrystalline iron carbides at a temperature below 260°C. Structural investigation indicated that the as-synthesized nanoparticles contained crystalline bcc Fe, iron carbides and spinel iron oxide. The Mössbauer and DSC results testified that the as-synthesized nanoparticle contained three crystalline iron carbide phases, which converted to Fe[subscript 3]C after a heat treatment. Surface analysis suggested that the as-synthesized and subsequently heated iron-iron carbide particles were coated by iron oxide, which originated from oxidization of surface Fe atoms. The heat-treated nanoparticles exhibited a magnetization of 160 emu/g...

Vetorização termoinduzida de nanopartículas magnéticas biocompatíveis: uma aplicação no recobrimento de Stents nus por via líquida; Thermally induced vectorization of Biocompatible Magnetic Nanoparticles: an application to cover Bare Metal Stents by Dip Coating

RODRIGUES, Harley Fernandes
Fonte: Universidade Federal de Goiás; BR; UFG; Mestrado em Física; Ciências Exatas e da Terra Publicador: Universidade Federal de Goiás; BR; UFG; Mestrado em Física; Ciências Exatas e da Terra
Tipo: Dissertação Formato: application/pdf
POR
Relevância na Pesquisa
66.43%
In this work we developed a Dip Coating method that could control the temperature gradient between a substrate and the material that one wants to adsorb at its surface. In particular, the adsorption of biocompatible magnetic nanoparticles at the surface of bare metal Stents, under different experimental conditions, was investigated. The magnetic nanoparticles consisted of magnetite coated with tripoliphosphate (mean diameter 7.68 nm and standard deviation 1.88 nm) dispersed in water at physiological conditions, while the Stent was a CoCr based-one (Cronus stent from Scitech with 16 mm length). Nine series of experiments were performed where it was controlled parameters as: time of adsorption, stent temperature and magnetic fluid temperature. The stents coated with nanoparticles were magnetically characterized using a vibrating sample magnetometer (VSM), which allowed us to determine the number of nanoparticles at the stent surface. The increase of the magnetic moment of the stent with the increase of the adsorption time was theoretically modeled, with an excellent experimental agreement, as a transient diffusion process of nanoparticles at the interface stent-magnetic fluid, which clearly indicates an important diffusive contribution. Strong evidences of thermal diffusion (Soret effect)...

Estudo do efeito de nanopartículas magnéticas biocompatíveis no sistema cardiovascular de ratos e investigação do processo de captura e exocitose das nanoestruturas por cardiomiócitos; Study of the effect of magnetic nanoparticles biocampatible in the rat cardiovascular system and investigation of capture process and exocytosis for cardiomyocytes of nanostructures

RAMALHO, Laylla Silva
Fonte: Universidade Federal de Goiás; BR; UFG; Mestrado em Física; Ciências Exatas e da Terra Publicador: Universidade Federal de Goiás; BR; UFG; Mestrado em Física; Ciências Exatas e da Terra
Tipo: Dissertação Formato: application/pdf
POR
Relevância na Pesquisa
66.42%
Magnetic fluids consist of surface-coated magnetic nanoparticles dispersed in a liquid carrier. These nanostructures have attracted a lot of attention of the biomedical community because of its possible applications as drug carriers, disease detection, and also on the treatment of several diseases, including cardiovascular ones. This work had the following objectives: (i) evaluate the effect ex-vivo of biocompatible magnetic nanoparticles in the rat heart function and, in-vivo, in the arterial blood pressure and heart rate of the rats, as well as, (ii) investigate the endocytosis and exocytosis of the nanoparticles through a magnetophoresis technique. The samples were characterized by X-ray diffraction (XRD), Dynamic light sacttering (DLS) and Vibrating sample magnetometer (VSM). The cardiac function was evaluated by the Langendorf technique under constant flow. On the other hand, in order to evaluate the effect of nanoparticles in the cardiovascular parameters, femoral artery and vein were cannulated and arterial pressure and heart rate were measure after 24 hs. The magnetic fluid infusion in the isolated heart showed a tiny increase of the intraventricular diastólic pressure and a decrease of the intraventricular systolic pressure. No changes were observed in perfusion pressure. The infusion of the magnetic nanoparticles in the rats had not promoted any significant variations of the artery pressure or the heart rate. These results suggest that magnetic nanoparticles can be used on clinical trials. In addition...

Caracterização do estado indiferenciado de células tronco embrionárias murinas expandidas na presença de nanopartículas magnéticas e isolamento de células tronco embrionárias a partir de blastócitos bovinos; Characterization of undifferentiated state of murine embryonic stem cells expanded in the presence of magnetic nanoparticles and isolation of embryonic stem cells from bovine blastocysts

FREITAS, Erika Regina Leal de
Fonte: Universidade Federal de Goiás; BR; UFG; Doutorado em Biologia; Ciencias Biologicas Publicador: Universidade Federal de Goiás; BR; UFG; Doutorado em Biologia; Ciencias Biologicas
Tipo: Tese de Doutorado Formato: application/pdf
POR
Relevância na Pesquisa
66.26%
Magnetic nanoparticles (MNPs) have been used in a great variety of biomedical applications, especially in cancer treatment, drug delivery, and diagnosis by magnetic resonance imaging. Embryonic stem cells (ESCs), due to its capacity of auto-renewal and differentiation in some types of cells, offer a great potential for its use in tissue regeneration and in alternative treatments for many degenerative diseases. The study had as aims: i) to evaluate in vitro citotoxicity of maghemite nanoparticles functionalized with lauric acid, DMSA, and citrate in human melanoma cells (SK-MEL-37) by the MTT assay, electronic microscopy, and DNA electroforesis by agarose gel; ii) to develop a culture system using the previously selected MNPs and a magnet to expand in vitro murine embryonic stem cells (mESCs) in the absence of a co-culture of murine embryonic fibroblasts (MEF) (the indifferentiated state of the mES was analyzed by alkaline phosphatase cytochemistry, electronic microscopy, and analysis of Oct-4 and Nanog gene expression by RT-PCR); iii) to isolate and expand ESCs from bovine blastocysts, and to characterize its pluripotency by analysis of Oct-4 and STAT-3 gene expression by RT-PCR. The MNPs coated with lauric acid, citrate, and DMSA showed no citotoxicity...

Efeito anti-proliferativo de curcumina associada á nanopartículas magnéticas funcionalizadas com bicamada de ácido láurico sobre células de melanoma humano skmel 37; Antiproliferative effect of curcumin combined with magnetic nanoparticles functionalized with bicamada of lauric acid on human melanoma cells SKMEL 37

Souza, Fernanda França de
Fonte: Universidade Federal de Goiás; Brasil; UFG; Programa de Pós-graduação em Biologia (ICB); Instituto de Ciências Biológicas - ICB (RG) Publicador: Universidade Federal de Goiás; Brasil; UFG; Programa de Pós-graduação em Biologia (ICB); Instituto de Ciências Biológicas - ICB (RG)
Tipo: Dissertação Formato: application/pdf
POR
Relevância na Pesquisa
66.33%
Curcumin has emerged as a great promise for cancer treatment and chemoprophylaxis with curcumin, but its low solubility in water is minimal systemic bioavailability. Attempts were made to improve its solubility in aqueous solutions by incorporating curcumin in liposomes or micelles, but these systems have low stability. In addition, magnetic nanoparticles have been used as promising drug delivery systems because they can be functionalized to become water soluble and biocompatible. Studies with curcumin incorporated into the magnetic nanoparticles are still scarce. This study aims to evaluate the antiproliferative effect of curcumin combined with magnetic nanoparticles functionalized bilayer of lauric acid in human melanoma cell line SKMEL 37. Human melanoma cells were treated at different concentrations and cytotoxicity was evaluated by MTT assay. The cell morphology was evaluated by light microscopy and fluorescence. Our studies have shown that curcumin has incorporated into nanoparticles cytotoxic effect at concentrations above 40,8 μg/ml or 111 μM. Since free curcumin caused significant death at concentrations above 11.5 μM. We also observed morphological changes typical of apoptosis such as chromatin condensation, nuclear fragmentation and bleb formation. These findings show us that both their cytotoxic activity...

NANOPARTÍCULAS MAGNÉTICAS FUNCIONALIZADAS COM BICAMADAS DE LAURATO/LAURATO E LAURATO/PLURONIC: ESTUDO DA ASSOCIAÇÃO COM ANFOTERICINA; MAGNETIC NANOPARTICLES FUNCTIONALIZED WITH AMPHOTERICIN B OF BILAYERS LAURATE/LAURATE AND LAURATE/PLURONIC: STUDY OF THE ASSOCIATION WITH AMPHOTERICIN B

SILVA, Joel Rocha da
Fonte: Universidade Federal de Goiás; BR; UFG; Mestrado em Química; Educação em Química Publicador: Universidade Federal de Goiás; BR; UFG; Mestrado em Química; Educação em Química
Tipo: Dissertação Formato: application/pdf
POR
Relevância na Pesquisa
66.43%
Magnetite nanoparticles were prepared by the coprecipitation of ions Fe2+ and Fe3+ using ammonia solution as precipitating agent. Maghemite nanoparticles were prepared by forced oxidation of magnetite nanoparticles in acidic medium using nitrate ions as oxidizing agent. The magnetic nanoparticles were used to the preparation of aqueous magnetic fluids samples by the functionalization of the nanoparticles with bilayers of laurate/laurate and laurate/Pluronic. Aliquots of the magnetic fluids were dried and the resultant powders were characterized by chemical analysis (the contents of ions Fe2+ and Fe3+), X-ray powder diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR). The contents of ions Fe2+ and Fe3+ in all the samples showed that the nanoparticles are not pure magnetite or maghemite phases. X-ray powder diffraction (XRD) indicated the existence of inverse cubic spinel phase, but didn't permit the distinction between magnetite and maghemite phases. Based on the results of chemical and XRD analyses, the nanoparticles could be better characterized as reduced maghemite, which mean maghemite phase containing ions Fe2+. The average sizes of the oxide nanoparticles estimated by XRD were around of 10 nm. FTIR analyses showed that the nanoparticles were functionalized with bilayers of laurate/laurate and laurate/Pluronic. FTIR analyses also were indicative of the maghemite phase. The hydrodynamic size of the functionalized nanoparticles measured by PCS were in the range of 70-90 nm for the samples based on laurate and in the range of 100-200 nm for the samples containing Pluronic. The measurements of zeta potential showed that the magnetic fluids based on laurate bilayers presented better colloidal stability than that one based on bilayers of laurate/Pluronic. On the other hand...

Self-assembly of magnetic nanoparticles into complex superstructures: Spokes and spirals

Neto, Chiara; Bonini, Massimo; Baglioni, Piero
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
66.33%
Dipole-dipole interactions in the most commonly used ferrofluids are relatively weak and there are only a few reports of chain formation in zero magnetic field. Here we report on the pronounced aggregation of a ferrofluid formed by maghemite nanoparticles (10 nm in diameter), investigated by atomic force microscopy (AFM), small angle neutron scattering (SANS) and small angle X-ray scattering (SAXS). The ferrofluid forms chain-like filaments independently of particle concentration. Furthermore, the ferrofluid forms self-assembled patterns, namely ordered superstructures, such as spirals, concentric rings and spokes (radially directed lines), when deposited on a substrate under a magnetic field. Our results reveal an unprecedented level of complexity in the self-assembly of magnetic nanoparticles. Further optimization of the working conditions could eventually enable the reproducible creation of three-dimensional magnetic structures with chosen architecture on submicron length scales.

Monodisperse magnetic nanoparticles: Effects of surfactants on the reaction between iron acetylacetonate and platinum acetylacetonate

Chokprasombat,K.; Sirisathitkul,C.; Harding,P.; Chandarak,S.; Yimnirun,R.
Fonte: Sociedad Mexicana de Física Publicador: Sociedad Mexicana de Física
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/06/2013 EN
Relevância na Pesquisa
66.32%
Magnetic properties of monodisperse nanoparticles for ultrahigh density recording and biomedical applications are sensitive to their shape and size distributions. These attributes are, in turns, dictated by several parameters during the synthesis and heat treatments. In this work, monodisperse FePt-based magnetic nanoparticles around 5 nm in diameter were synthesized by the reaction between iron acetylacetonate (Fe(acac)3) and platinum acetylacetonate (Pt(acac)2) in benzyl ether. X-ray absorption near-edge structure (XANES) spectra agreed with transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy (EDS) that as-synthesized nanoparticles were composed of Pt-rich nuclei and iron oxides. Whereas their composition and size was not sensitive to the variation in the amount of surfactants (oleic acid and oleylamine), the nanoparticles exhibited a larger variation in shape with the increase in each surfactant from 1.5 to 4.5 mmol. After annealing in argon atmosphere at 650°C for 1 hour, the nanoparticles tended to agglomerate. Higher amounts of surfactants surrounded the nanoparticles apparently allowed more sintering because the decomposed carbon from the excess surfactants facilitated the reduction ofiron oxides. More Fe in the large annealed particles then resulted in ferromagnetic properties. By contrast...

The feasibility of using magnetic nanoparticles modified as gene vector

Chen,D; Tang,Q; Xue,W; Wang,X
Fonte: West Indian Medical Journal Publicador: West Indian Medical Journal
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/06/2010 EN
Relevância na Pesquisa
66.29%
OBJECTIVE: To evaluate the feasibility of using magnetic nanoparticles (MNPs) as gene vector and the effect of magnetic field on efficiency of transfection. METHODS: Magnetic nanoparticles were prepared by controlling some chemical reaction parameters through a partially reduction precipitation method with ferric chloride aqueous solution as precursor material. The surface of particles was modified by polyethyleneimine (PEI) agents. The appearance, the size distribution, structure and phase constitute of MNPs were characterized by Transmission electron microscope (TEM), X-ray diffraction (XRD); the potential of absorbing DNA of MNPs was analysed by electrophoresis. Transfection was determined by delivering reporter gene, PGL2-control encoding luciferase, to different cell lines using MNPs-PLL as vector. The effect of magnetic field on the efficiency of transfection was determined using Nd-Fe-B permanent magnet. RESULTS: Foreign gene could be delivered to various cell lines by MNPs-PLL and expressed with high efficiency but the transfection efficiency and time course varied in the different cell lines studied. Magnetic field could enhance the efficiency of transfection by 5-10 fold. CONCLUSION: MNPs- PLL can be used as a novel non-viral gene vector in vitro...