X-DLVO Interactions between nanocolloidal magnetic particles: the quantitative interpretation of the pH-dependent phase diagram of EDL-MF

Campos, Alex Fabiano Cortez; Marinho, Epitácio Pinto; Ferreira, Márcia de Aguiar; Tourinho, F.A.; Paula, Fábio Luís de Oliveira; Depeyrot, J.

doi:10.1590/s0103-97332009000200018

Cited by 5 publications

(6 citation statements)

References 22 publications

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“…Therefore, samples with different levels of NP clustering may be achieved by decreasing the ion/counterion ratio in the medium (pH effect). This disturbance of the ionic balance of the solvent medium can induce different states of NP cluster formation and can drive the sample to several colloidal phases (sol, gel, flocculated, and coagulated) . Additionally, it is expected that the reduction in the interparticle distance increases the intensity of magnetic dipolar interactions, which consequently may improve cluster formation.…”

Section: Introductionmentioning

confidence: 99%

Colloidal Stability and Concentration Effects on Nanoparticle Heat Delivery for Magnetic Fluid Hyperthermia

et al. 2021

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The heat produced by magnetic nanoparticles, when they are submitted to a time-varying magnetic field, has been used in many auspicious biotechnological applications. In the search for better performance in terms of the specific power absorption (SPA) index, researchers have studied the influence of the chemical composition, size and dispersion, shape, and exchange stiffness in morphochemical structures. Monodisperse assemblies of magnetic nanoparticles have been produced using elaborate synthetic procedures, where the product is generally dispersed in organic solvents. However, the colloidal stability of these rough dispersions has not received much attention in these studies, hampering experimental determination of the SPA. To investigate the influence of colloidal stability on the heating response of ferrofluids, we produced bimagnetic core@shell NPs chemically composed of a ZnMn mixed ferrite core covered by a maghemite shell. Aqueous ferrofluids were prepared with these samples using the electric double layer (EDL) as a strategy to maintain colloidal stability. By starting from a proper sample, ultrastable concentrated ferrofluids were achieved by both tuning the ion/counterion ratio and controlling the water content. As the colloidal stability mainly depends on the ion configuration on the surface of the magnetic nanoparticles, different levels of nanoparticle clustering are achieved by changing the ionic force and pH of the medium. Thus, the samples were submitted to two procedures of EDL destabilization, which involved dilution with an alkaline solution and a neutral pH viscous medium. The SPA results of all prepared ferrofluid samples show a reduction of up to half the efficiency of the standard sample when the ferrofluids are in a neutral pH or concentrated regime. Such results are explained in terms of magnetic dipolar interactions. Our results point to the importance of ferrofluid colloidal stability in a more reliable experimental determination of the NP heat generation performance.

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Section: Introductionmentioning

confidence: 99%

Colloidal Stability and Concentration Effects on Nanoparticle Heat Delivery for Magnetic Fluid Hyperthermia

et al. 2021

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“…For pH values lower than 4⋅0 and higher than 11⋅0 the particle surface tends to be charge-saturated, which ensure the colloidal stability of the magnetic sol for convenient ionic strength conditions. Around the neutral region the particle charge tends to zero and rapid coagulation can be evidenced (Campos et al 2009). The concentration of particle surface sites was plotted in figure 4(b) as a function of pH.…”

Section: Resultsmentioning

confidence: 99%

Using speciation diagrams to improve synthesis of magnetic nanosorbents for environmental applications

et al. 2011

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This work addresses environmental applications of magnetic nanoparticles. We highlight the chemical design of filtration aids based on magnetic nanoferrites coated with specific ligands potentially used in magnetic separation of pollutants from water. From electrochemical measurements, we determined the concentration of the surface sites in function of pH for the precursor magnetic nanoparticles. Then, coupling the speciation diagrams of the precursor nanoferrite particle surface with that of the specific ligand, it was possible to provide a theoretical prediction of the optimal pH for particle surface-ligand complexation, leading to advances in nanosorbents developing.

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“…Meanwhile, each method leads the¯nal products to special size, morphology, colloidal stability and other features. [23][24][25] Simultaneously, these synthesis roots have extensive e®ect on applied features of¯nal products, such as magnetic properties. In the other overview, many of these methods have their own problems for large-scale synthesis of Fe 3 O 4 -NP.…”

Section: Introductionmentioning

confidence: 99%

Biocompatibility and Hyperthermia Efficiency of Sonochemically Synthesized Magnetic Nanoparticles

Talebi

Balasi

Ahadian

et al. 2019

SPIN

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Hereby, a sonochemical method for synthesis of pure magnetic Fe3O4 nanoparticles (Fe3O4-NPs) in large scale is being introduced. Synthesis proceeds via simple approach, at room temperature, under sonication, using cheap reagents, green antioxidant-reductant reagent and without using inert gas purge as protective atmosphere condition. During this procedure, hydrogen gas releases continuously as valuable byproduct at the anaerobic step of reaction. Characterizations’ results indicate that the final product is pure spherical Fe3O4-NPs, with narrow size distribution and about less than 32[Formula: see text]nm in mean diameter while more than 99% of particles size were less than 40[Formula: see text]nm. According to Vibrational Sampling Magnetometer (VSM) result, NPs pose high saturation magnetization of about 77 (emu/g) and magnetization curve shows superparamagnetic behavior with no hysteresis loop. Also by various weight ratios, these NPs performed stable dispersion in aqueous media for long times. Iron oxide NPs show nontoxicity for lower dosage of 10[Formula: see text][Formula: see text][Formula: see text]g/mL in 24[Formula: see text]h on fibroblast cell. Hyperthermia results show maximum heating efficiency in 100[Formula: see text]KHz for 1[Formula: see text]mg/mL of NPs.

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X-DLVO Interactions between nanocolloidal magnetic particles: the quantitative interpretation of the pH-dependent phase diagram of EDL-MF

Cited by 5 publications

References 22 publications

Colloidal Stability and Concentration Effects on Nanoparticle Heat Delivery for Magnetic Fluid Hyperthermia

Colloidal Stability and Concentration Effects on Nanoparticle Heat Delivery for Magnetic Fluid Hyperthermia

Using speciation diagrams to improve synthesis of magnetic nanosorbents for environmental applications

Biocompatibility and Hyperthermia Efficiency of Sonochemically Synthesized Magnetic Nanoparticles

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