Investigation of the Molecular Surface Coating on the Stability of Insulating Magnetic Oils

Viali, Wesley Renato; Alcantara, Glaucia Braz; Sartoratto, P.P.C.; Soler, Maria A. G.; Mosiniewicz-Szablewska, E.; Andrzejewski, B.; Morais, P.C.

doi:10.1021/jp908732b

Cited by 66 publications

(69 citation statements)

References 65 publications

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“…The observed saturation magnetization (MS) obtained was 39 emu/g. This value is smaller than the values reported for bulk maghemite at 300 K (MS=76 emu/g) [31] but is similar to the MS values previously reported for maghemite nanoparticles in the range size of 5-10 nm [32]. The difference in the saturation magnetization between the bulk and the nanosized material can be attributed to the small particle size effect [33].…”

Section: Characterization Of the Maghemite Nanoparticles And Colloidasupporting

confidence: 59%

High Efficacy in Hyperthermia-associated with Polyphosphate Magnetic Nanoparticles for Oral Cancer Treatment

Taboga¹

2014

J Nanomed Nanotechnol

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Nanotherapy applied to cancer treatment is constantly evolving, and new approaches to current techniques, such as magnetohyperthermia, are being implemented to solve and minimize the limitations of conventional therapeutic strategies. The purpose of this study was to investigate the action of polyphosphate-coated maghemite nanoparticles (MNPs) on oral squamous cell carcinoma. Human oral cancer cells (UM-SCC14A) were incubated with MNPs at various concentrations and subjected to cell proliferation tests (MTT), apoptosis assays and transmission electron image analysis. Viability and apoptotic events were time and dose dependent. These in vitro tests showed that at the intermediate concentration tested there is no significant toxicity, as confirmed by transmission electron microscopy. For this reason this MNPs concentration was chosen for the subsequent in vivo tests. Oral tumor induction was performed by applying the carcinogen DMBA to Syrian hamsters. Animals were then treated by magnetohyperthermia using MNPs. No signs of general clinical symptoms of toxicity or abnormal behavioral reactions were observed. However, animals treated with MNPs and exposed to the alternating magnetic field in the hyperthermia procedure exhibited a significant and time dependent cancer regression, as confirmed by histopathological analyses and immunohistochemistry. Actually, in quantitative terms of the magnetotherapy efficacy involving these polyphosphate-coated MNPs, 100% recovery (12/12) was observed in the oral cancer tumor bearing Syrian hamsters seven days after the treatment with the magnetohyperthermia procedure. Data supports the suggestion that the MNPs-mediated hyperthermia represents a promising strategy for the treatment of oral cancer.in patients with malignancies in the mouth region. Unlike many other oncology subspecialties, however, the rates of recurrence and overall survival have improved only modestly over the past decades, despite the continuous search for new therapeutic techniques [6,7]. Thus, it is expected that the identification and use of specific agents will lead to individualized treatments, which in turn will lead to significantly better results as manifested by more cures and better quality of life by decreasing toxicity [8].Over the last years, maghemite nanoparticles (MNPs) have appeared as a well-established technology and an important field of research in superparamagnetism of colloidal materials, characteristic which allows them to be guided with an external magnetic field [9]. Recently, MNPs have been investigated for therapeutic purposes such as hyperthermic treatment [10,11]. Magnetohyperthermia (MHT) represents a novel and promising therapy for cancer treatment [11,12], being capable of promoting the specific lysis of tumor cells, thereby improving patient outcomes while minimizing the subsequent toxicity effects [13]. The Citation: Candido NM, Calmon MF, Taboga SR, Bonilha JL, dos Santos MC, et al. (2014) High Efficacy in Hyperthermia-associated with Polyphosphate

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Section: Characterization Of the Maghemite Nanoparticles And Colloidasupporting

confidence: 59%

High Efficacy in Hyperthermia-associated with Polyphosphate Magnetic Nanoparticles for Oral Cancer Treatment

Taboga¹

2014

J Nanomed Nanotechnol

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“…Nevertheless, it was noted that magnetic nanoparticles have a tendency to agglomerate into larger particles, particularly at higher concentrations, leading to an abrupt decease in the breakdown performance of nanofluids [31]. Currently, many efforts have been made to raise the dispersion stability of NPs in the host liquid, e.g., by applying certain dispersants or surfactants [32][33][34][35][36]. It has been noted that surface modified iron oxide NPs show better dispersion stability in the mineral oil by using various synthesizing and modifying procedures at room temperature [32].…”

Section: Breakdown Phenomenon In Insulating Fluidsmentioning

confidence: 99%

“…The transformer oil-based ferrofluids possess many performance advantages as compared to transformer oils and are summarized as follows [9][10][11][12][13][21][22][23][24][30][31][32][33][40][41][42][43][44]:…”

Section: Advantages Of Transformer Oil-based Ferrofluidsmentioning

confidence: 99%

“…Currently, many efforts have been made to raise the dispersion stability of NPs in the host liquid, e.g., by applying certain dispersants or surfactants [32][33][34][35][36]. It has been noted that surface modified iron oxide NPs show better dispersion stability in the mineral oil by using various synthesizing and modifying procedures at room temperature [32]. The dispersion of other NPs in base oil may also be enhanced by tailoring the quantity of modifying agents for surface modification of nanoparticles [33].…”

Section: Introductionmentioning

confidence: 99%

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Study of Dielectric Breakdown Performance of Transformer Oil Based Magnetic Nanofluids

Rafiq

et al. 2017

Energies

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Abstract:Research on the transformer oil-based nanofluids (NFs) has been raised expeditiously over the past decade. Although, there is discrepancy in the stated results and inadequate understanding of the mechanisms of improvement of dielectric nanofluids, these nanofluids have emerged as a potential substitute of mineral oils as insulating and heat removal fluids for high voltage equipment. The transformer oil (TO) based magnetic fluids (ferrofluids) may be regarded as the posterity insulation fluids as they propose inspiring unique prospectus to improve dielectric breakdown strength, as well as heat transfer efficiency, as compared to pure transformer oils. In this work, transformer oil-based magnetic nanofluids (MNFs) are prepared by dispersal of Fe 3 O 4 nanoparticles (MNPs) into mineral oil as base oil, with various NPs loading from 5 to 80% w/v. The lightning impulse breakdown voltages (BDV) measurement was conducted in accordance with IEC 60897 by using needle to sphere electrodes geometry. The test results showed that dispersion of magnetic NPs may improve the insulation strength of MO. With the increment of NPs concentrations, the positive lightning impulse (LI) breakdown strength of TO is first raised, up to the highest value at 40% loading, and then tends to decrease at higher concentrations. The outcomes of negative LI breakdown showed that BDV of MNFs, with numerous loadings, were inferior to the breakdown strength of pure MO. The 40% concentration of nanoparticles (optimum concentration) was selected, and positive and negative LI breakdown strength was also further studied at different sizes (10 nm, 20 nm, 30 nm and 40 nm) of NPs and different electrode gap distances. Augmentation in the BDV of the ferrofluids (FFs) is primarily because of dielectric and magnetic features of Fe 3 O 4 nanoaprticles, which act as electron scavengers and decrease the rate of free electrons produced in the ionization process. Research challenges and technical difficulties associated with ferrofluids for practical applications are mentioned. The advantages and disadvantages linked with magnetic fluids are also presented.

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“…Additionally, the use of SPIO particles may also have a profound impact on new industrial technologies as for instance while developing insulating magnetic oil for transformers, 16 structures for spin electronics, 17 bioelectrochemistry, 18 catalysis, 19 and chemical sensing. 20 Specific applications include surface modification of SPIO particles to allow covalent attachment with biomolecules which are then used as molecular recognition sites for sensing.…”

Section: Introductionmentioning

confidence: 99%

Adsorption of cobalt ferrite nanoparticles within layer-by-layer films: a kinetic study carried out using quartz crystal microbalance

Alcantara

Paterno

Afonso

et al. 2011

Phys. Chem. Chem. Phys.

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The paper reports on the successful use of the quartz crystal microbalance technique to assess accurate kinetics and equilibrium parameters regarding the investigation of in situ adsorption of nanosized cobalt ferrite particles (CoFe 2 O 4 -10.5 nm-diameter) onto two different surfaces. Firstly, a single layer of nanoparticles was deposited onto the surface provided by the gold-coated quartz resonator functionalized with sodium 3-mercapto propanesulfonate (3-MPS). Secondly, the layer-by-layer (LbL) technique was used to build multilayers in which the CoFe 2 O 4 nanoparticle-based layer alternates with the sodium sulfonated polystyrene (PSS) layer. The adsorption experiments were conducted by modulating the number of adsorbed CoFe 2 O 4 /PSS bilayers (n) and/or by changing the CoFe 2 O 4 nanoparticle concentration while suspended as a stable colloidal dispersion. Adsorption of CoFe 2 O 4 nanoparticles onto the 3-MPS-functionalized surface follows perfectly a first order kinetic process in a wide range (two orders of magnitude) of nanoparticle concentrations. These data were used to assess the equilibrium constant and the adsorption free energy. Alternatively, the Langmuir adsorption constant was obtained while analyzing the isotherm data at the equilibrium. Adsorption of CoFe 2 O 4 nanoparticles while growing multilayers of CoFe 2 O 4 /PSS was conducted using colloidal suspensions with CoFe 2 O 4 concentration in the range of 10 À8 to 10 À6 (moles of cobalt ferrite per litre) and for different numbers of cycles n = 1, 3, 5, and 10. We found the adsorption of CoFe 2 O 4 nanoparticles within the CoFe 2 O 4 /PSS bilayers perfectly following a first order kinetic process, with the characteristic rate constant growing with the increase of CoFe 2 O 4 nanoparticle concentration and decreasing with the rise of the number of LbL cycles (n). Additionally, atomic force microscopy was employed for assessing the LbL film roughness and thickness. We found the film thickness increasing from about 20 to 120 nm while shifting from 3 to 10 CoFe 2 O 4 /PSS bilayers, using the 8.9 Â 10 À6 (moles of cobalt ferrite per litre) suspension.

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Investigation of the Molecular Surface Coating on the Stability of Insulating Magnetic Oils

Cited by 66 publications

References 65 publications

High Efficacy in Hyperthermia-associated with Polyphosphate Magnetic Nanoparticles for Oral Cancer Treatment

High Efficacy in Hyperthermia-associated with Polyphosphate Magnetic Nanoparticles for Oral Cancer Treatment

Study of Dielectric Breakdown Performance of Transformer Oil Based Magnetic Nanofluids

Adsorption of cobalt ferrite nanoparticles within layer-by-layer films: a kinetic study carried out using quartz crystal microbalance

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